尾仲 達史

Food intake activates neurones expressing prolactin-releasing peptide (PrRP) in the medulla oblongata and oxytocin neurones in the hypothalamus. Both PrRP and oxytocin have been shown to have an anorexic action. In the present study, we investigated whether the activation of oxytocin neurones following food intake is mediated by PrRP. We first examined the expression of PrRP receptors (also known as GPR10) in rats. Immunoreactivity of PrRP receptors was observed in oxytocin neurones and in vasopressin neurones in the paraventricular and supraoptic nuclei of the hypothalamus and in the bed nucleus of the stria terminalis. Application of PrRP to isolated supraoptic nuclei facilitated the release of oxytocin and vasopressin. In mice, re-feeding increased the expression of Fos protein in oxytocin neurones of the hypothalamus and bed nucleus of the stria terminalis. The increased expression of Fos protein in oxytocin neurones following re-feeding or i.p. administration of cholecystokinin octapeptide (CCK), a peripheral satiety factor, was impaired in PrRP-deficient mice. CCK-induced oxytocin increase in plasma was also impaired in PrRP-deficient mice. Furthermore, oxytocin receptor-deficient mice showed an increased meal size, as reported in PrRP-deficient mice and in CCKA receptor-deficient mice. These findings suggest that PrRP mediates, at least in part, the activation of oxytocin neurones in response to food intake, and that the CCKPrRPoxytocin pathway plays an important role in the control of the termination of each meal.

In magnocellular neurones of the supraoptic nucleus (SON), the neuropeptides vasopressin and oxytocin are synthesised and packaged into large dense-cored vesicles (LDCVs). These vesicles undergo regulated exocytosis from nerve terminals in the posterior pituitary gland and from somata/dendrites in the SON. Regulated exocytosis of LDCVs is considered to involve the soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor (SNARE) complex [comprising vesicle associated membrane protein 2 (VAMP-2), syntaxin-1 and soluble N-ethylmaleimide attachment protein-25 (SNAP-25)] and regulatory proteins [such as synaptotagmin-1, munc-18 and Ca2+-dependent activator protein for secretion (CAPS-1)]. Using fluorescent immunocytochemistry and confocal microscopy, in both oxytocin and vasopressin neurones, we observed VAMP-2, SNAP-25 and syntaxin-1-immunoreactivity in axon terminals. The somata and dendrites contained syntaxin-1 and other regulatory exocytosis proteins, including munc-18 and CAPS-1. However, the distribution of VAMP-2 and synaptotagmin-1 in the SON was limited to putative pre-synaptic contacts because they co-localised with synaptophysin (synaptic vesicle marker) and had no co-localisation with either oxytocin or vasopressin. SNAP-25 immunoreactivity in the SON was limited to glial cell processes and was not detected in oxytocin or vasopressin somata/dendrites. The present results indicate differences in the expression and localisation of exocytosis proteins between the axon terminals and somata/dendritic compartment. The absence of VAMP-2 and SNAP-25 immunoreactivity from the somata/dendrites suggests that there might be different SNARE protein isoforms expressed in these compartments. Alternatively, exocytosis of LDCVs from somata/dendrites may use a different mechanism from that described by the SNARE complex theory.

Oxytocin neurones are activated by stressful stimuli, food intake and social attachment. Activation of oxytocin neurones in response to stressful stimuli or food intake is mediated, at least in part, by noradrenaline/prolactin-releasing peptide (PrRP) neurones in the nucleus tractus solitarius, whereas oxytocin neurones are activated after social stimuli via medial amygdala neurones. Activation of oxytocin neurones induces the release of oxytocin not only from their axon terminals, but also from their dendrites. Oxytocin acts locally where released or diffuses and acts on remote oxytocin receptors widely distributed within the brain, resulting in anxiolytic, anorexic and pro-social actions. The action sites of oxytocin appear to be multiple. Oxytocin shows anxiolytic actions, at least in part, via serotoninergic neurones in the median raphe nucleus, has anorexic actions via pro-opiomelanocortin neurones in the nucleus tractus solitarius and facilitates social recognition via the medial amygdala. Stress, obesity and social isolation are major risk factors for mortality in humans. Thus, the oxytocinoxytocin receptor system is a therapeutic target for the promotion of human health.

A recently discovered satiety molecule, nesfatin-1, is localized in neurons of the hypothalamus and brain stem and colocalized with stress-related substances, corticotropin-releasing hormone (CRH), oxytocin, proopiomelanocortin, noradrenaline (NA) and 5-hydroxytryptamine (5-HT). Intracerebroventricular (icv) administration of nesfatin-1 produces fear-related behaviors and potentiates stressor-induced increases in plasma adrenocorticotropic hormone (ACTH) and corticosterone levels in rats. These findings suggest a link between nesfatin-1 and stress. In the present study, we aimed to further clarify the neuronal network by which nesfatin-1 could induce stress responses in rats. Restraint stress induced c-Fos expressions in nesfatin-1-immunoreactive neurons in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus, and in the nucleus of solitary tract (NTS), locus coeruleus (LC) and dorsal raphe nucleus (DR) in the brain stem, without altering plasma nesfatin-1 levels. Icv nesfatin-1 induced c-Fos expressions in the PVN, SON, NTS, LC, DR and median raphe nucleus, including PVN-CRH, NTS-NA, LC-NA and DR-5-HT neurons. Nesfatin-1 increased cytosolic Ca(2+) concentration in the CRH-immunoreactive neurons isolated from PVN. Icv nesfatin-1 increased plasma ACTH and corticosterone levels. These results indicate that the central nesfatin-1 system is stimulated by stress and activates CRH, NA and 5-HT neurons and hypothalamic-pituitary-adrenal axis, evoking both central and peripheral stress responses.

Brain-derived neurotrophic factor (BDNF) has been implicated in learning, depression and energy metabolism. However, the neuronal mechanisms underlying the effects of BDNF on energy metabolism remain unclear. The present study aimed to elucidate the neuronal pathways by which BDNF controls feeding behaviour and energy balance. Using an osmotic mini-pump, BDNF or control artificial cerebrospinal fluid was infused i.c.v. at the lateral ventricle or into the paraventricular nucleus of the hypothalamus (PVN) for 12 days. Intracerebroventricular BDNF up-regulated mRNA expression of corticotrophin-releasing hormone (CRH) and urocortin in the PVN. TrkB, the receptor for BDNF, was expressed in the PVN neurones, including those containing CRH. Both i.c.v. and intra-PVN-administered BDNF decreased food intake and body weight. These effects of BDNF on food intake and body weight were counteracted by the co-administration of alpha-helical-CRH, an antagonist for the CRH and urocortin receptors CRH-R1/R2, and partly attenuated by a selective antagonist for CRH-R2 but not CRH-R1. Intracerebroventricular BDNF also decreased the subcutaneous and visceral fat mass, adipocyte size and serum triglyceride levels, which were all attenuated by alpha-helical-CRH. Furthermore, BDNF decreased the respiratory quotient and raised rectal temperature, which were counteracted by alpha-helical-CRH. These results indicate that the CRH-urocortin-CRH-R2 pathway in the PVN and connected areas mediates the long-term effects of BDNF to depress feeding and promote lipolysis.

The expression of the relaxin-3 gene, detected as a new member of the insulin superfamily using human genomic databases, is abundantly present in the brain and testis. Intracerebroventricularly (icv) administered relaxin-3 stimulates food intake. Icv administered relaxin (identical to relaxin-2 in humans) affects the secretion of vasopressin and drinking behavior. Relaxin-3 partly binds relaxin family peptide receptor 1, which is a specific receptor to relaxin. Thus, we hypothesized that relaxin-3 would have physiological effects in the body fluid balance. However, the effects of relaxin-3 in the body fluid balance remain unknown. In the present study, we revealed that icv administered relaxin-3 induced dense Fos-like immunoreactivity (Fos-LI) in the rat hypothalamus and circumventricular organs including the organum vasculosum of the lamina terminalis, the median preoptic nucleus, supraoptic nucleus (SON), the subfornical organ (SFO) and the paraventricular nucleus (PVN), that are related to the central regulation of body fluid balance. Icv administered relaxin-3 (54, 180 and 540 pmol/rat) also induced a significant increase in c-fos gene expression in a dose-dependent manner in the SON, SFO and PVN. Further, icv administered relaxin-3 (180 pmol/rat) significantly increased water intake, and the effect was as strong as that of relaxin-2 (180 pmol/rat). These results suggest that icv administered relaxin-3 activates osmosensitive areas in the brain and plays an important role in the regulation of body fluid balance. (C) 2010 Elsevier Inc. All rights reserved.

Cell adhesion molecule 1 (CADM1), a member of the immunoglobulin superfamily, mediates synaptic cell adhesion. Missense mutations in the CADM1 gene have been identified in autism spectrum disorder (ASD) patients. In the present study, we examined emotional behaviors, social behaviors and motor performances in Cadm1-knockout (KO) mice. Cadm1-KO mice showed increased anxiety-related behavior in open-field and light-dark transition tests. Social behaviors of Cadm1-KO mice were impaired in social interaction, resident-intruder and social memory/recognition tests. Furthermore, motor coordination and gait of Cadm1-MO mice were impaired in rotarod and footprint tests. Our study demonstrates that CADM1 plays roles in regulating emotional behaviors, social behaviors and motor performances, and that CADM1 has important implications for psychiatric disorders with disruptions in social behavior, such as autism. (C) 2010 Elsevier Inc. All rights reserved.

In the modern world, improvements in human health can be offset by unhealthy lifestyle factors, including the deleterious consequences of stress and obesity. For energy homeostasis, humoral factors and neural afferents from the gastrointestinal tract, in combination with long-term nutritional signals, communicate information to the brain to regulate energy intake and expenditure. Energy homeostasis and stress interact with each other, and stress affects both food intake and energy expenditure. Prolactin-releasing peptide, synthesized in discrete neuronal populations in the hypothalamus and brain-stem, plays an important role in integrating these responses. This review describes how prolactin-releasing peptide neurons receive information concerning both internal metabolic states and environmental conditions, and play a key role in energy homeostasis and stress responses.

The hypothalamo-neurohypophyseal system is known to be involved in the regulation of body fluid balance, reproduction and stress response. Galanin-like peptide (GALP) is a 60-amino acid peptide, which has been isolated and cloned from porcine hypothalamus. GALP is abundantly expressed in the arcuate nucleus (Arc) neurons of the hypothalamus and the pituicytes of the posterior pituitary gland (PP). Intracerebroventricular administration of GALP causes significant increases of neurohypophyseal hormones (arginine vasopressin and oxytocin) and ACTH in rat plasma. GALP-containing neurons in the Arc are activated by foot shock stress. The expression of the GALP gene in the Arc is up-regulated by acute inflammatory stress but not chronic stress. On the other hand, the expression of the GALP gene in the pituicytes of the PP is up-regulated by both acute and chronic stress such as nociception, inflammation and osmotic challenge. These results suggest that GALP in the hypothalamus and PP has different pathophysiological roles in the regulation of stress responses involving the hypothalamo-neurohypophyseal system. © 2009 Elsevier Ireland Ltd. All rights reserved.

We have generated rats bearing an oxytocin (OXT)-enhanced cyan fluorescent protein (eCFP) fusion transgene designed from a murine construct previously shown to be faithfully expressed in transgenic mice. In situ hybridisation histochemistry revealed that the Oxt-eCfp fusion gene was expressed in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) in these rats. The fluorescence emanating from eCFP was observed only in the SON, the PVN, the internal layer of the median eminence and the posterior pituitary (PP). In in vitro preparations, freshly dissociated cells from the SON and axon terminals showed clear eCFP fluorescence. Immunohistochemistry for OXT and arginine vasopressin (AVP) revealed that the eCFP fluorescence co-localises with OXT immunofluorescence, but not with AVP immunofluorescence in the SON and the PVN. Although the expression levels of the Oxt-eCfp fusion gene in the SON and the PVN showed a wide range of variations in transgenic rats, eCFP fluorescence was markedly increased in the SON and the PVN, but decreased in the PP after chronic salt loading. The expression of the Oxt gene was significantly increased in the SON and the PVN after chronic salt loading in both non-transgenic and transgenic rats. Compared with wild-type animals, euhydrated and salt-loaded male and female transgenic rats showed no significant differences in plasma osmolality, sodium concentration and OXT and AVP levels, suggesting that the fusion gene expression did not disturb any physiological processes. These results suggest that our new transgenic rats are a valuable new tool to identify OXT-producing neurones and their terminals. Journal of Endocrinology (2010) 204, 275-285

Many peptides, when released as chemical messengers within the brain, have powerful influences on complex behaviours. Most strikingly, vasopressin and oxytocin, once thought of as circulating hormones whose actions were confined to peripheral organs, are now known to be released in the brain, where they have fundamentally important roles in social behaviours(1). In humans, disruptions of these peptide systems have been linked to several neurobehavioural disorders, including Prader-Willi syndrome, affective disorders and obsessive-compulsive disorder, and polymorphisms of V1a vasopressin receptor have been linked to autism(2,3). Here we report that the rat olfactory bulb contains a large population of interneurons which express vasopressin, that blocking the actions of vasopressin in the olfactory bulb impairs the social recognition abilities of rats and that vasopressin agonists and antagonists can modulate the processing of information by olfactory bulb neurons. The findings indicate that social information is processed in part by a vasopressin system intrinsic to the olfactory system.

The prolactin-releasing peptide (PrRP) has been proposed to be a co-transmitter or modulator of noradrenaline (NA) because it colocalises with NA in the A1 (in the ventrolateral reticular formation) and A2 (in the nucleus of the solitary tract; NTS) cell groups in the caudal medulla. The baroreceptor signals, originating from the great vessels, are transmitted primarily to the NTS, and then part of the signals is conveyed to the hypothalamic neuroendocrine neurones via the ascending NA neurones. The hypotensive haemorrhagic paradigm was employed to examine whether the PrRP-containing neurones in the caudal medulla participate in conveying signals to the hypothalamic neuroendocrine neurones. Among the caudal medullary A1 or A2 neurones, the majority of the PrRP-immunoreactive (-ir) neurones became c-Fos-ir at 2 h after hypotensive haemorrhage. Hypothalamic corticotrophin-releasing hormone-ir neurones and vasopressin-ir neurones became c-Fos positive in parallel with the activation of medullary PrRP-ir neurones. After delivery of retrograde tracer fluorogold (FG) to the paraventricular nucleus of the hypothalamus (PVN), part of the PrRP/FG double-labelled neurones in the A1 and A2 became c-Fos-ir after haemorrhage, demonstrating that PrRP-ir neurones participate in conveying the haemorrhagic stress-induced signals from the medulla to the PVN. PrRP and/or NA were microinjected directly to the PVN of conscious rats, and they presented a synergistic action on arginine vasopressin release, whereas an additive action was observed for adrenocorticotrophin release. These results suggest that the PrRP-containing NA neurones in the caudal medulla may relay the haemorrhagic stress-induced medullary inputs to the hypothalamic neuroendocrine neurones.

Peripherally secreted arginine vasopressin (AVP) plays a role in controlling body fluid homeostasis, and central endogenous AVP acts as a neurotransmitter or neuromodulator. The limbic system, which appears to exert an inhibitory effect on the endocrine hypothalamus, is also innervated by fibres that contain AVP. We examined whether central endogenous AVP is also involved in the control of body fluid homeostasis. To explore this possibility, we examined neuronal activity in the paraventricular nucleus of the hypothalamus (PVN), periventricular parts of the PVN and limbic brain areas, as well as AVP mRNA expression in the PVN and the peripheral secretion of AVP after central salt-loading in rats that had been pretreated i.c.v. with the AVP V(1) receptor antagonist OPC-21268. Neuronal activity in the PVN evaluated in terms of Fos-like immunoreactivity (FLI), especially in the parvocellular subdivisions, was suppressed. On the other hand, FLI was enhanced in the lateral septum, the bed nucleus of the stria terminalis and the anterior hypothalamic area. Similarly, AVP mRNA expression was enhanced in the magnocellular subnucleus of the PVN, despite the lack of a significant difference in the peripheral AVP level between OPC-21268- and vehicle-pretreated groups. We recorded renal sympathetic nerve activity (RSNA) as sympathetic nerve outflow during central salt-loading. The suppression of RSNA was significantly attenuated by i.c.v. pretreatment with OPC-21268. These results suggest that the suppression of RSNA during central salt-loading might be the result of a decrease in neuronal activity in the parvocellular subdivisions of the PVN via the inhibitory action of central endogenous AVP. The parvocellular and magnocellular neurones in the PVN might show different responses to central salt-loading to maintain body fluid homeostasis as a result of the modulatory role of central endogenous AVP.

The hypothalamic paraventricular nucleus (PVN) functions as a center to integrate various neuronal activities for regulating feeding behavior. Nesfatin-1, a recently discovered anorectic molecule, is localized in the PVN. However, the anorectic neural pathway of nesfatin-1 remains unknown. Here we show that central injection of nesfatin-1 activates the PVN and brain stem nucleus tractus solitarius (NTS). In the PVN, nesfatin-1 targets both magnocellular and parvocellular oxytocin neurons and nesfatin-1 neurons themselves and stimulates oxytocin release. Immunoelectron micrographs reveal nesfatin-1 specifically in the secretory vesicles of PVN neurons, and immunoneutralization against endogenous nesfatin-1 suppresses oxytocin release in the PVN, suggesting paracrine/autocrine actions of nesfatin-1. Nesfatin-1-induced anorexia is abolished by an oxytocin receptor antagonist. Moreover, oxytocin terminals are closely associated with and oxytocin activates pro-opiomelanocortin neurons in the NTS. Oxytocin induces melanocortin-dependent anorexia in leptin-resistant Zucker-fatty rats. The present results reveal the nesfatin-1-operative oxytocinergic signaling in the PVN that triggers leptin-independent melanocortin-mediated anorexia.

Oxytocin (OT) has been shown to play an important role in social bonding in animals. However, it is unclear whether OT is related to inter-species social bonding. In this study, to examine the possibility that urinary OT concentrations of owners were increased by their "dog's gaze", perhaps representing social attachment to their owners, we measured urinary OT concentrations of owners before and after interaction with their dogs. Dog owners interacted with their dogs as usual for 30 min (interaction experiment) or were instructed not to look at their dogs directly (control experiment). We observed the behaviors of owners and their dogs during the experiments, and measured OT concentrations by radioimmunoassay in urine samples from the owners collected just before and 20 min after interaction with their dogs. Using a cluster analysis, owners could be divided into two groups: one received a longer duration of gaze from their dogs and reported a higher degree of relationship with their dogs (LG); the other received a shorter duration of gaze and reported a lower degree of relationship (SG). Urinary OT was higher in LG than SG after usual interaction with their dogs, but not in the control experiment. In the interaction experiment, a high correlation was found in LIS between the frequency of behavioral exchanges initiated by the dog's gaze and the increase in urinary OT. We conclude that interactions with dogs, especially those initiated by the dog's gaze, can increase the urinary OT concentrations of their owners as a manifestation of attachment behavior. (C) 2008 Elsevier Inc. All rights reserved.

Arginine vasopressin (AVP) and corticotrophin-releasing hormone (CRH) in the parvocellular neurosecretory cells of the paraventricular nucleus (PVN) play a major role in activating the hypothalamic-pituitary-adrenal axis, which is the main neuroendocrine response against the many kinds of stress. We examined the effects of chronic inflammatory/nociceptive stress on the expression of the AVP-enhanced green fluorescent protein (eGFP) fusion gene in the hypothalamus, using the adjuvant arthritis (AA) model. To induce AA, the AVP-eGFP rats were intracutaneously injected heat-killed Mycobacterium butyricum (1 mg/rat) in paraffin liquid at the base of their tails. We measured AVP, oxytocin and corticosterone levels in plasma and changes in eGFP and CRH mRNA in the hypothalamus during the time course of AA development. Then, we examined eGFP fluorescence in the PVN, the supraoptic nucleus (SON), median eminence (ME) and posterior pituitary gland (PP) when AA was established. The plasma concentrations of AVP, oxytocin and corticosterone were significantly increased on days 15 and 22 in AA rats, without affecting the plasma osmolality and sodium. Although CRH mRNA levels in the PVN were significantly decreased, eGFP mRNA levels in the PVN and the SON were significantly increased on days 15 and 22 in AA rats. The eGFP fluorescence in the SON, the PVN, internal and external layers of the ME and PP was apparently increased in AA compared to control rats. These results suggest that the increases in the concentrations of ACTH and corticosterone in AA rats are induced by hypothalamic AVP, based on data from AVP-eGFP transgenic rats.

The oxytocin receptor has been implicated in the regulation of reproductive physiology as well as social and emotional behaviors. The neurochemical mechanisms by which oxytocin receptor modulates social and emotional behavior remains elusive, in part because of a lack of sensitive and selective antibodies for cellular localization. To more precisely characterize oxytocin receptor-expressing neurons within the brain, we generated an oxytocin receptor-reporter mouse in which part of the oxytocin receptor gene was replaced with Venus cDNA (a variant of yellow fluorescent protein). Examination of the Venus expression revealed that, in the raphe nuclei, about one-half of tryptophan hydroxylase-immunoreactive neurons were positive for Venus, suggesting a potential role for oxytocin in the modulation of serotonin release. Oxytocin infusion facilitated serotonin release within the median raphe nucleus and reduced anxiety-related behavior. Infusion of a 5-HT(2A/2C) receptor antagonist blocked the anxiolytic effect of oxytocin, suggesting that oxytocin receptor activation in serotonergic neurons mediates the anxiolytic effects of oxytocin. This is the first demonstration that oxytocin may regulate serotonin release and exert anxiolytic effects via direct activation of oxytocin receptor expressed in serotonergic neurons of the raphe nuclei. These results also have important implications for psychiatric disorders such as autism and depression in which both the oxytocin and serotonin systems have been implicated.

Food intake is regulated by a network of signals that emanate from the gut and the brainstem. The peripheral satiety signal cholecystokinin is released from the gut following food intake and acts on fibers of the vagus nerve, which project to the brainstem and activate neurons that modulate both gastrointestinal function and appetite. In this study, we found that neurons in the nucleus tractus solitarii of the brainstern that express prolactin-releasing peptide (PrRP) are activated rapidly by food ingestion. To further examine the role of this peptide in the control of food intake and energy metabolism, we generated PrRP-deficient mice and found that they displayed late-onset obesity and adiposity, phenotypes that reflected an increase in meal size, hyperphagia, and attenuated responses to the anorexigenic signals cholecystokinin and leptin. Hypothalamic expression of 6 other appetite-regulating peptides remained unchanged in the PrRP-deficient mice. Blockade of endogenous PrRP signaling in WT rats by central injection of PrRP-specific mAb resulted in an increase in food intake, as reflected by an increase in meal size. These data suggest that PrRP relays satiety signals within the brain and that selective disturbance of this system can result in obesity and associated metabolic disorders.

Vasopressin (AVP) plays an important role in anxiety-related and social behaviors. Single-prolonged stress (SPS) has been established as an animal acute severe stress model and has been shown to induce a lower adrenocorticotropic hormone (ACTH) response upon cortisol challenge. Here, we show results from immunoassays for AVP, ACTH, and corticosterone (CORT), and in situ hybridizations for AVP mRNA performed 7 days after SPS exposure. Immunofluorescence for AVP was also performed during the 7-day period following SPS exposure and after an additional forced swimming stress paradigm. We observed that the plasma concentrations of AVP, ACTH, and CORT were not altered by SPS; ACTH content in the pituitary and AVP mRNA expression in the supraoptic nucleus (SON) were significantly reduced by SPS. During the 7-day period following SPS, the intensity of immunoreactivity, the size of the soma, and the immunoreactive optical density of the dendrites of AVP neurons in the SON all increased. An apparent reduction in the intensity of AVP immunoreactivity was observed in the SON at 4 h after additional stress. Additional forced swimming led to a rapid increase in the dendritic AVP content only in the controls and not in the SPS-treated rats. These findings suggest that AVP is a potential biomarker for past exposure to severe stress and that alterations in AVP may affect the development of pathogenesis in stress-related disorders. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.

The oxytocin receptor has been suggested to be involved in energy metabolism, such as food intake and energy consumption. Here, we demonstrate that oxytocin receptor-deficient (Oxtr(-/-)) male mice exhibited late-onset obesity with increases in abdominal fat pads and fasting plasma triglycerides. Daily food intake and spontaneous motor activity of Oxtr(-/-) mice were not significantly different as compared with wild-type mice. In contrast, brown adipose tissue in Oxtr(-/-) mice contained large lipid droplets and cold-induced thermogenesis was impaired. This study demonstrates that oxytocin receptor plays essential roles in the regulation of energy homeostasis.

Nesfatin-1, a newly discovered satiety molecule, is located in the hypothalamic nuclei, including the paraventricular nucleus (PVN) and supraoptic nucleus (SON). In this study, fine localization and regulation of nesfatin-1 neurons in the PVN and SON were investigated by immunnhistochemistry of neuropeptides and c-Fos. In the PVN, 24% of nesfatin-1 neurons overlapped with oxytocin, 18% with vasopressin, 13% with CRH, and 12% with TRH neurons. In the SON, 35% of nesfatin-1 neurons overlapped with oxytocin and 28% with vasopressin. After a 48-h fast, refeeding for 2 h dramatically increased the number of nesfatin-1 neurons expressing c-Fos immunoreactivity by approximately 10 times in the PVN and 30 times in the SON, compared with the fasting controls. In the SON, refeeding also significantly increased the number of nesfatin-1-immunoreactive neurons and NUCB2 mRNA expression, compared with fasting. These results indicate that nesfatin-1 neurons in the PVN and SON highly overlap with oxytocin and vasopressin neurons and that they are activated markedly by refeeding. Feeding-activated nesfatin-1 neurons in the PVN and SON could play a role in the postprandial regulation of feeding behavior and energy homeostasis.

Salusin-alpha and -beta were recently discovered as bioactive endogenous peptides. In the present study, we investigated the effects of chronic osmotic stimuli on salusin-beta-like immunoreactivity (LI) in the rat hypothalamo-neurohypophyseal system. We examined the effects of salusin-beta on synaptic inputs to the rat magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) and neurohypophyseal hormone release from both freshly dissociated SONs and neurohypophyses in rats. Immunohistochemical studies revealed that salusin-beta-LI neurones and fibres were markedly increased in the SON and the magnocellular division of the paraventricular nucleus after chronic osmotic stimuli resulting from salt loading for 5 days and dehydration for 3 days. Salusin-beta-LI fibres and varicosities in the internal zone of the median eminence and the neurohypophysis were also increased after osmotic stimuli. Whole-cell patch-clamp recordings from rat SON slice preparations showed that salusin-beta did not cause significant changes in the excitatory and inhibitory postsynaptic currents of the MNCs. In vitro hormone release studies showed that salusin-beta evoked both arginine vasopressin (AVP) and oxytocin release from the neurohypophysis, but not the SON. In our hands, in the neurohypophysis, a significant release of AVP and oxytocin was observed only at concentrations from 100 nM and above of salusin-beta. Low concentrations below 100 nM were ineffective both on AVP and oxytocin release. We also measured intracellular calcium ([Ca2+](i)) increase induced by salusin-beta on freshly-isolated single nerve terminals from the neurohypophysis devoid of pars intermedia. Furthermore, this salusin-beta-induced [Ca2+](i) increase was blocked in the presence of high voltage activated Ca(2+)channel blockers. Our results suggest that salusin-beta may be involved in the regulation of body fluid balance by stimulating neurohypophyseal hormone release from nerve endings by an autocrine/paracrine mechanism.

Metabolic conditions affect hypothalamo-pituitary-adrenal responses to stressful stimuli. Here we examined effects of food deprivation, leptin and ghrelin upon noradrenaline release in the hypothalamic paraventricular nucleus (PVN) and plasma adrenocorticotropic hormone (ACTH) concentrations after stressful stimuli. Food deprivation augmented both noradrenaline release in the PVN and the increase in plasma ACTH concentration following electrical footshocks (FSs). An intracerebroventricular injection of leptin attenuated the increases in hypothalamic noradrenaline release and plasma ACTH concentrations after FSs, while ghrelin augmented these responses. These data suggest that leptin inhibits and ghrelin facilitates neuroendocrine stress responses via noradrenaline release and indicate that a decrease in leptin and an increase in ghrelin release after food deprivation might contribute to augmentation of stress-induced ACTH release in a fasting state.

Oxytocin has potent central effects on feeding behaviour, as well as on social and sexual behaviours, and one likely substrate for its anorectic effect is the ventromedial nucleus of the hypothalamus. This nucleus expresses a high density of oxytocin receptors, but contains very few oxytocin-containing fibres, hence it is a likely target of 'neurohormonal' actions of oxytocin, including possibly oxytocin released from the dendrites of magnocellular oxytocin neurones. As oxytocin release from dendrites is regulated independent of electrical activity and of secretion from the neurohypophysis, exactly how this release is regulated by metabolic and reproduction-related signals remains to be established fully. Intriguingly though, it looks as though this central release of oxytocin from magnocellular neurons might be instrumental in a fundamental shift in motivational behaviour - switching behaviour from being driven by the need to find and consume food, to the need to reproduce.

Food intake is controlled by signals from the brainstem that mediate signals from the gut. Prolactin-releasing peptide (PrRP) neurons are localized in the brainstem. In the present study, we investigated whether food intake activates PrRP neurons. We examined expression of phospho-CREB in PrRP neurons after food intake. The percentage of phospho-CREB-positive PrRP neurons in the nucleus of tractus solitarii was increased by food intake, suggesting that food intake activates PrRP neurons in the nucleus tractus solitarii. To further study the role of endogenous PrRP in food intake, we generated PrRP-deficient mice. PrRP-deficient mice developed late onset obestity associated with metabolic disorders due to hyperphagia but not to energy expenditure, and showed an attenuated response to the peripheral satiety signal, cholecystokinin. Blockade of endogenous PrRP signaling by a central injection of monoclonal anti-PrRP neutralizing antibodies increased food intake, reflecting an increase in meal size. Furthermore, we demonstrated that leptin-induced reduction in food intake and body weight was impaired in PrRP-deficient mice. All these data suggest that PrRP relays satiety signals within the brain and that disturbance of this system can result in obesity and associated metabolic disorders. [J Physiol Sci. 2008;58 Suppl:S106]

The calcineurin inhibitor, cyclosporine, is widely used for preventing allograft rejection in organ transplantation. Systemically administered cyclosporine is prevented from entering into the brain by the action of P-glycoprotein, encoded by the multidrug resistant 1. (mdr1) gene. However, in many transplant recipients, cyclosporine administration causes postoperative neuropsychological side effects, such as confusion, depression, and anxiety. Recently, calcineurin-inhibitor-induced pain syndrome, characterized by severe pain in the lower limbs, has also been, recognized in both organ and stem-cell transplantations. METHODS: In the present study, we developed behavioral models in wild-type and mdr1a knockout mice to reveal whether peripheral or central cyclosporine alters pain reactions and hypnotic sensitivities. Cyclosporine's central actions can be better evaluated in mdr1a knockout mice that lack P-glycoprotein. After intraperitoneal administration of cyclosporine, we examined tail-flick latency in the tail immersion test, or duration of loss of righting reflex in response to pentobarbital and ketamine. RESULTS: In wild-type mice, the highest dose of cyclosporine significantly prolonged the duration of loss of righting reflex in response to ketamine, but not to pentobarbital. On the other hand, the lower doses of cyclosporine significantly increased both pentobarbital- and ketamine-induced sleep durations in mdr1a knockout mice. Tailflick latencies in the tail immersion test were significantly shortened in both wild-type and knockout mice by the administration of cyclosporine. CONCLUSIONS: Our results suggest that centrally accumulated cyclosporine enhances the hypnotic response to pentobarbital and ketamine, but peripheral cyclosporine induces hyperalgesia. (Anesth Analg 2007;105:1489-93)

We investigated the prolactin-releasing peptide (PrRP) mRNA levels in the hypothalamus and brainstem of streptozotocin (STZ)-induced diabetic rats and fa/fa Zucker diabetic rats, using in situ hybridization histochemistry. PrRP mRNA levels in the hypothalamus and brainstem of STZ-induced diabetic rats were significantly reduced in comparison with those of control rats. PrRP mRNA levels in the diabetic rats were reversed by both insulin and leptin. PrRP mRNA levels in the fa/fa diabetic rats were significantly reduced in comparison with those of Fa/? rats. PrRP mRNA levels in the fa/fa diabetic rats were significantly increased by insulin-treatment, but did not reach control levels in the Fa/? rats. We also investigated the effect of restraint stress on PrRP mRNA levels in STZ-induced diabetic rats. The PrRP mRNA levels in the control and the STZ-induced diabetic rats increased significantly after restraint stress. The diabetic condition and insulin-treatment may affect the regulation of PrRP gene expression via leptin and other factors, such as plasma glucose level. The diabetic condition may not impair the role of PrRP as a stress mediator. (c) 2007 Elsevier Inc. All rights reserved.

Neuropeptide Y (NPY) neurons in the hypothalamic arcuate nucleus ( ARC) play a central role in stimulation of feeding. They sense and integrate peripheral and central signals, including ghrelin and leptin. However, the mechanisms of interaction of these hormones in NPY neurons are largely unknown. This study explored the interaction and underlying signaling cross talk between ghrelin and leptin in NPY neurons. Cytosolic Ca2+ concentration ([Ca2+](i)) in single neurons isolated from ARC of adult rats was measured by fura-2 microfluorometry. Ghrelin increased [Ca2+](i) in 31% of ARC neurons. The [Ca2+](i) increases were inhibited by blockers of phospholipase C, adenylate cyclase, and protein kinase A. Ghrelin-induced [Ca2+](i) increases were suppressed by subsequent administration of leptin. Fifteen of 18 ghrelin-activated, leptin-suppressed neurons (83%) contained NPY. Leptin suppression of ghrelin responses was prevented by pretreatment with inhibitors of phosphatidylinositol 3-kinase and phosphodiesterase 3 (PDE3) but not MAPK. ATP-sensitive potassium channel inhibitors and activators did not prevent and mimic leptin suppression, respectively. Although leptin phosphorylated signal-transducer and activator of transcription 3 (STAT3) in NPY neurons, neither STAT3 inhibitor nor genetic STAT3 deletion altered leptin suppression of ghrelin responses. Furthermore, orexigenic effect of intracerebroventricular ghrelin in rats was counteracted by leptin in a PDE3-dependent manner. These findings indicate that ghrelin increases [Ca2+](i) via mechanisms depending on hospholipase C and adenylate cyclase-PKA pathways in ARC NPY neurons and that leptin counteracts ghrelin responses via a phosphatidylinositol 3-kinase-PDE3 pathway. This interaction may play an important role in regulating ARC NPY neuron activity and, thereby, feeding.

Background. Cyclosporine induces psychological side effects but its mechanisms of action remain to be elucidated. Methods. Mice were injected with cyclosporine (0, 10, 60 mg/kg intraperitoneal) and indexes of both anxiety-related and social behaviors were examined. Release of serotonin and dopamine in the prefrontal cortex was also investigated by microdialysis. Results. Intraperitoneal administration of cyclosporine increased cyclosporine concentrations in the blood and brains in mice. Cyclosporine administration at a higher-dose reduced motor activity, increased indexes of anxiety-related behavior, and decreased an index of social interaction. The administration reduced release of serotonin and dopamine in the prefrontal cortex. Clozapine administration abolished the reduced release of dopamine and partially restored the index of social behavior in cyclosporine-injected mice. Conclusions. This in vivo model suggests that cyclosporine at a high dose induced hypo-function of the prefrontal. cortex as a result of reduced release of serotonin and dopamine, increased anxiety-related behavior, and disturbed social behavior. Clozapine partially restored an index of social behavior. The present findings are pathologically relevant in patients who take cyclosporine.

Exercise around the lactate threshold induces a stress response, defined as "running stress." We have previously demonstrated that running stress is associated with activation of certain regions of the brain, e. g., the paraventricular hypothalamic nucleus (PVN) and supraoptic nucleus, that are hypothesized to play an integral role in regulating stress-related responses, including ACTH release during running. Thus we investigated the role of prolactin-releasing peptide (PrRP), found in the ventrolateral medulla and the nucleus of the solitary tract, which is known to project to the PVN during running-induced ACTH release. Accumulation of c-Fos in PrRP neurons correlated with running speeds, reaching maximal levels under running stress. Intracerebroventricular injection of neutralizing anti-PrRP antibodies led to increased plasma ACTH level and blood lactate accumulation during running stress, but not during restraint stress. Exogenous intracerebroventricular administration of low doses of PrRP had the opposite effects. Therefore, our results suggest that, during running stress, PrRP-containing neurons are activated in an exercise intensity-dependent manner, and likewise the produced endogenous PrRP attenuates ACTH release and blood lactate accumulation during running stress. Here we provide a novel perspective on understanding of PrRP in the endocrine-metabolic response associated with running stress.

The effects of intraperitoneal (i.p.) administration of 2-buten-4-olide (2-B4O), an endogenous sugar acid, on the hypothalamo-adenohypophysial system were examined in Lewis rats that were normal and in adjuvant-induced arthritic (AA) rats. In comparison with vehicle-treated rats, the plasma corticosterone and c-fos mRNA levels in the paraventricular nucleus (PVN) of normal rats increased significantly after i.p. administration of 2-B4O. Dual immunostaining revealed that almost all corticotrophin-releasing factor (CRF)-immunopositive neurones in the parvocellular division of the PVN exhibited Fos-like immunoreactivity (L1) 120 min after i.p. administration of 2-B4O (100 mg/kg). In the AA rats, repeated i.p. administration of 2-B4O (100 mg/kg) after immunisation significantly suppressed the expression of clinical symptoms and significantly increased plasma concentrations of corticosterone. Further, repeated i.p. administration of 2-B4O significantly increased CRF mRNA levels in the PVN and pro-opiomelanocortin mRNA levels in the anterior pituitary; however, they did not change arginine vasopressin mRNA levels in the parvocellular division of the PVN. These results suggest that i.p. administration of 2-B4O activates the hypothalamo-pituitary-adrenal (HPA) axis via the activation of CRF neurones in the PVN, and the activation of the HPA axis by i.p. administration of 2-B4O may be associated with the inhibition of AA in rats.

Salusin-α, and -β were newly discovered as bioactive endogenous peptides (Shichiri et al., 2003). Salusin-β stimulates the secretion of arginine vasopressin (AVP) from perifused rat hypophysis, and coexists with AVP in the rat hypothalamic magnocellular supraoptic (SON) and paraventricular nuclei. In the present study, we investigated the effects of osmotic stimuli on salusin-β-like immunoreactivity (LI) in the rat hypothalamo-neurohypophyseal system, and also examined the effects of salusin-β on the synaptic inputs to the rat magnocellular neurosecretory cells (MNCs) of the SON and the AVP / oxytocin (OXT) release from the rat freshly dissociated SON and neurohypophysis. We demonstrated that salusin-β-LI exhibited markedly increase in the hypothalamo-neurohypophyseal system after osmotic stimuli, and evoked AVP / OXT releases from the neurohypophysis, but not cause significant changes in the excitatory and inhibitory postsynaptic currents of the MNCs. These results suggest that salusin-β is increased by osmotic stimuli, secreted from nerve endings, acting as autocrine / paracrine modulator to stimulate the AVP / OXT release from the neurohypophysis and involved in the regulation of water balance. [J Physiol Sci. 2007;57 Suppl:S172]

We examined the effects of chronic salt loading on the hypothalamic expressions of the enhanced green fluorescent protein (eGFP), arginine vasopressin (AVP) and oxytocin (OXT) genes in AVP-eGFP transgenic rats that expressed eGFP in the hypothalamic AVP-containing neurones. In these rats, salt loading for 5 days caused a marked increase of the eGFP fluorescence in the magnocellular divisions of the paraventricular nucleus (PVN), the supraoptic nucleus (SON) and the internal layer of the median eminence. Expression of the eGFP gene was increased seven- to eight-fold in the PVN and SON of salt-loaded rats in comparison with euhydrated rats. By contrast, none of these changes were observed in the suprachiasmatic nucleus. The expression of the AVP and OXT genes was increased 1.5- to two-fold in the PVN and SON of salt-loaded nontransgenic (control) and transgenic rats. There were no differences in the expression levels of the AVP and OXT genes in the PVN and SON between nontransgenic (control) and transgenic animals under normal conditions and after salt loading. In the posterior pituitary gland, the intensity of the eGFP fluorescence did not change after salt loading for 5 days, but increased after 10 days of salt loading. Upon salt loading, significant increases in the plasma AVP concentrations, plasma osmolality and plasma Na+ were observed. Furthermore, there were no significant differences in changes of water intake, food intake, urine volume, urine osmolality, urine Na+ concentrations, and the body weights in both models under normal or salt-loaded conditions. Our results show that the response of the AVP-eGFP fusion gene to chronic salt loading is exaggerated, and humoral responses such as AVP and OXT and the body fluid homeostasis are maintained in AVP-eGFP transgenic rats. The AVP-eGFP transgenic rat gives us a new opportunity to study the dynamics of the AVP system in vivo.

We examined the effects of i.c.v. administration of neuropeptide W-30 (NPW30) on plasma arginine vasopressin (AVP) and plasma oxytocin (OXT) using RIA. The induction of c-fos mRNA, AVP heteronuclear (hn)RNA, and c-Fos protein (Fos) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of rats were also investigated using hi situ hybridization histochemistry for c-fos mRNA and AVP hnRNA, and immunohistochemistry for Fos. Both plasma AVP and OXT were significantly increased at 5 and 15 min after i.c.v. administration of NPW30 (2(.)8 nmol/rat). In situ hybridization histochemistry revealed that the induction of c-fos mRNA and AVP hnRNA in the SON and PVN were significantly increased 15, 30, and 60 him after i.c.v. administration. of NPW30 (1(.)4 nmol/rat). Dual immunostaining for Fos/AVP and Fos/OXT revealed that both AVP-like innuunoreactive (LI) cells and OXT-LI cells exhibited nuclear Fos-LI in the SON and PVN, 90 min after i.c.v. administration of NPW30 (2(.)8 nmol/rat). These results suggest that central NPW30 may be involved in the regulation of secretion of AVP and OXT in the magnocellular neurosecretory cells in the SON and PVN.

The effects of intraperitoneal (i.p.) administration of 2-buten-4-olide (2-B4O), an endogenous sugar acid, on the hypothalamo-neurohypophyseal system were examined in rats. Plasma oxytocin (OXT) levels were significantly increased 15-60 min after i.p. administration of 2-B4O (100 mg/kg), whereas plasma arginine vasopressin (AVP) did not change. Dual immunostaining revealed that Fos-like immunoreactivity (LI) was predominantly observed in OXT-secreting neurons in the paraventricular (PVN) and the supraoptic nuclei (SON) 120 min after i.p. administration of 2-B4O. In addition, many Fos-LI neurons were observed in the nucleus of the tractus solitarius (NTS) after i.p. administration of 2-B4O. These results suggest that a peripherally administered high dose of 2-B4O activates OXT-secreting neurons in the hypothalamus through activation of NTS neurons, possibly as a result of a stress response. (c) 2006 Elsevier B.V. All rights reserved.

Galanin-like peptide (GALP), a 29-amino-acid neuropeptide, is located in the hypothalamic arcuate nucleus ( ARC), binds to galanin receptor subtype 2, and induces food intake upon intracerebroventricular (icv) injection in rats. However, neural mechanisms underlying its orexigenic action remain unclear. We aimed to identify the nuclei and neuron species that mediate the food intake in response to icv GALP injection. Intracerebroventricular injection of GALP, as powerfully as that of neuropeptide Y ( NYP), increased food intake for the initial 2 h. GALP injected focally into the dorsomedial nucleus (DMN), but not the ARC, lateral hypothalamus, or paraventricular nucleus (PVN), stimulated food intake for 2 h after injection. In contrast, galanin injected into the DMN had no effect. DMN-lesion rats that received icv GALP injection showed attenuated feeding compared with control rats. Intracerebroventricular GALP injection increased c-Fos expression in NPY-containing neurons in the DMN, but not the ARC. GALP increased the cytosolic calcium concentration ([Ca2+](i)) in NPY- immunoreactive neurons isolated from the DMN, but not the ARC. Furthermore, both anti-NPY IgG and NPY antagonists, when preinjected, counteracted the feeding induced by GALP injection. These data show that icv GALP injection induces a potent short-term stimulation of food intake mainly via activation of NPY-containing neurons in the DMN.

The effects of i.c.v. administration of prolactin-releasing peptide on neurons in the paraventricular nucleus of rats and plasma corticosterone levels were examined by measuring changes in Fos-like immunoreactivity, c-fos mRNA using in situ hybridization histochemistry, and plasma corticosterone using a specific radioimmunoassay. Approximately 80% of corticotropin-releasing hormone immunoreactive cells exhibited Fos-like immunoreactivity in the parvocellular division of the paraventricular nucleus 90 min after i.c.v. administration of prolactin-releasing peptide. The greatest induction of the c-fos mRNA expression in the paraventricular nucleus was observed 30 min after administration of prolactin-releasing peptide, and occurred in a dose-related manner. Plasma corticosterone levels were also significantly increased 30 min after administration of prolactin-releasing peptide. Next, the effects of restraint stress, nociceptive stimulus and acute inflammatory stress on the expression of the prolactin-releasing peptide mRNA in the dorsomedial hypothalamic nucleus, nucleus of the solitary tract and ventrolateral medulla were examined using in situ hybridization histochemistry for prolactin-releasing peptide mRNA. Restraint stress and acute inflammatory stress upregulated the prolactin-releasing peptide mRNA expression in the nucleus of the solitary tract and ventrolateral medulla. Nociceptive stimulus upregulated the prolactin-releasing peptide mRNA expression in the ventrolateral medulla. Finally, we observed that pretreatment (i.c.v. administration) with an anti-prolactin-releasing peptide antibody significantly attenuated nociceptive stimulus-induced c-fos mRNA expression in the paraventricular nucleus. These results suggest that prolactin-releasing peptide is a potent and important mediator of the stress response in the brain through the hypothalamic paraventricular nucleus. (c) 2006 IBRO. Published by Elsevier Ltd. All rights reserved.

To confirm a role of prolactin-releasing peptide (PrRP) on stress response, we examined the effects of restraint stress (RTS), nociceptive stimulus and acute inflammatory stress in rats on the expression of the PrRP gene in the hypothalamus and medulla oblongata using in situ hybridization histochemistry. Moreover, we examined the effects of pretreatment with indomethacin on acute inflammation-induced PrRP gene expression and pretreatment with an anti-PrRP antibody on nociceptive stimulus-induced c-fos gene expression in the hypothalamic paraventricular nucleus (PVN). RTS, nociceptive stimulus and acute inflammatory stress upregulated the PrRP gene expression in the medulla oblongata. Acute inflammation-induced increase in the PrRP gene expression was significantly attenuated almost completely by prereatment with indomethacin. Pretreatment with anti-PrRP antibody attenuated significantly nociceptive stimulus-induced c-fos gene expression in the PVN. RTS, nociceptive stimulus and acute inflammatory stress activate PrRP neurons. Especially, activation of PrRP neurons by acute inflammation was mediated mainly by prostaglandins. Pretreatment with anti-PrRP antibody attenuated stress response via neurons in the PVN. These results suggested that PrRP is a potent and important mediator of stress response in the hypothalamic PVN in rats. [J Physiol Sci. 2006;56 Suppl:S218]

Salt loading reduces neuroendocrine responses to stressful stimuli. Noxious stimuli facilitate noradrenaline release in the hypothalamus and, as a result, activate oxytocin neurones. Here, we examined effects of salt loading upon plasma oxytocin concentrations and noradrenaline release in the hypothalamus after footshocks. Male rats were allowed to drink 2% NaCl for 7 days. Salt loading reduced the footshock- induced increase in plasma oxytocin concentrations and noradrenaline release in the supraoptic nucleus (SON). Acute administration of hypertonic saline also attenuated the footshock-induced noradrenaline increase in the supraoptic nucleus. In contrast, salt loading did not significantly change activation of Al catecholaminergic neurones in the medulla oblongata, as measured by expression of Fos protein. These data suggest that salt loading presynaptically Suppresses noradrenaline release in the hypothalamus and oxytocin release into the blood after footshocks. (C) 2005 Elsevier Ireland Ltd. All rights reserved.

The oxytocin receptor (OXTR) and its ligand, oxytocin (OXT), regulate reproductive physiology (i.e., parturition and lactation) and sociosexual behaviors. To define the essential functions of OXTR, we generated mice with a null mutation in the Oxtr gene (Oxtr(-/-)) and compared them with OXT-deficient (Oxt(-/-)) mice. Oxtr(-/-) mice were viable and had no obvious deficits in fertility or reproductive behavior. Oxtr(-/-) dams exhibited normal parturition but demonstrated defects in lactation and maternal nurturing. Infant Oxtr(-/-) males emitted fewer ultrasonic vocalizations than wild-type littermates in response to social isolation. Adult Oxtr(-/-) males also showed deficits in social discrimination and elevated aggressive behavior. Ligand Oxt(-/-) males from Oxt(-/-) dams, but not from Oxt(+/-) dams, showed similar high levels of aggression. These data suggest a developmental role for the OXT/OXTR system in shaping adult aggressive behavior. Our studies demonstrate that OXTR plays a critical role in regulating several aspects of social behavior and may have important implications for developmental psychiatric disorders characterized by deficits in social behavior.

Objective: The Na,K-ATPase alpha 2 subunit gene (Atp1a2) is expressed in the brain, skeletal muscles, heart, and adipocytes. Specific function of the a2 subunit, such as involvement in differentiation and function of adipocytes, has not been addressed. The aim of this study was to examine whether Atp1a2-defective heterozygous mice show obesity and reveal the mechanisms underlying the obesity. Research Methods and Procedures: We measured the differentiation and glucose uptake function of in vitro-differentiated adipocytes derived from embryonic fibroblasts of Atp1a2-defective mice. Food intake, body temperature, metabolic rate, and spontaneous activity and mRNA levels of neuropeptide genes were compared between the heterozygous and wild-type adult mice. Results: Atp1a2 heterozygous female mice developed obesity after middle age. The time course of in vitro adipocyte differentiation of embryonic fibroblasts isolated from wild type, heterozygous, and homozygous mice was not different, glucose and Rb uptake activities of the in vitro-differentiated adipocytes were not altered, and the effects of insulin on glucose uptake and those of monensin and ouabain on Rb uptake were similar among the genotypes. However, food intake in the light phase was significantly greater in the heterozygous mice than the wild type in the 24-hour dark-light cycle, whereas it was similar under constant-light condition. Body temperature, metabolic rate at rest, and spontaneous motor activity of the heterozygous mice were similar to those of the wild type. Orexin mRNA level was lower in heterozygous than wild-type mice. Discussion: The Na,K-ATPase alpha 2 subunit is not involved in the differentiation or in glucose and Rb uptake function of in vitro-differentiated adipocytes. Hyperphagia is the likely primary cause of obesity in Atp1a2 heterozygous mice.

In the present study, we investigated the effects of the cannabinoid receptor agonist CP55,940 on excitatory and inhibitory synaptic transmission in the rat supraoptic nucleus. Whole-cell patch clamp recordings were performed on supraoptic neurones in in vitro brain slice preparations. CP55,940 significantly reduced the frequency of spontaneous excitatory and inhibitory postsynaptic currents in a concentration-dependent manner. These changes were potently reversed by the CB1 receptor antagonist AM251. The results indicate that cannabinoids modulate the activity of magnocellular neurosecretory neurones by presynaptic inhibition of both excitatory and inhibitory synaptic transmission.