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Background: The neuropeptide oxytocin, produced in the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus, is now understood to function as a neurotransmitter critical for various aspects of social cognition and pro-social behaviour. While patients with Frontotemporal dementia (FTD) display prominent and progressive deficits in such social behaviours, the integrity of these nuclei in FTD is not known., Methods: We conducted a quantitative neuropathologic examination of the SON and PVN from patients with FTLD with TDP-43 proteinopathy, Alzheimer's disease, Lewy body disease and controls to determine whether significant pathologic changes or neuronal loss may contribute to the striking behavioural symptoms of FTD., Results: Contrary to predictions, we found both nuclei to be free of significant pathologic change (TDP-43) in FTLD. In contrast, tau related pathology was found in the PVN in Alzheimer's disease, and alpha-synuclein pathology in the SON in patients with Lewy body dementia., Conclusions: These results indicate that the SON and PVN are resistant to FTLD TDP-43 pathology. They also support prior suggestions that the SON is resistant to Alzheimer's disease (AD) related pathology, and extend this to demonstrate SON susceptibility to alpha-synuclein pathology in patients with Lewy body dementia.

The present study demonstrates a key role for the oxysterol receptor liver X receptor β (LXRβ) in the etiology of diabetes insipidus (DI). Given free access to water, LXRβ(-/-) but not LXRα(-/-) mice exhibited polyuria (abnormal daily excretion of highly diluted urine) and polydipsia (increased water intake), both features of diabetes insipidus. LXRβ(-/-) mice responded to 24-h dehydration with a decreased urine volume and increased urine osmolality. To determine whether the DI was of central or nephrogenic origin, we examined the responsiveness of the kidney to arginine vasopressin (AVP). An i.p. injection of AVP to LXRβ(-/-) mice revealed a partial kidney response: There was no effect on urine volume, but there was a significant increase of urine osmolality, suggesting that DI may be caused by a defect in central production of AVP. In the brain of WT mice LXRβ was expressed in the nuclei of magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus. In LXRβ(-/-) mice the expression of AVP was markedly decreased in the magnocellular neurons as well as in urine collected over a 24-h period. The persistent high urine volume after AVP administration was traced to a reduction in aquaporin-1 expression in the kidney of LXRβ(-/-) mice. The LXR agonist (GW3965) in WT mice elicited an increase in urine osmolality, suggesting that LXRβ is a key receptor in controlling water balance with targets in both the brain and kidney, and it could be a therapeutic target in disorders of water balance.

The immunoglobulin heavy chain binding protein (BiP) is an endoplasmic reticulum (ER) chaperone that facilitates the proper folding of newly synthesized secretory and transmembrane proteins. Here we report that BiP mRNA was expressed in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus in wild-type mice under basal conditions. Dual in situ hybridization in the SON and PVN demonstrated that BiP mRNA was expressed in almost all the neurons of arginine vasopressin (AVP), an antidiuretic hormone. BiP mRNA expression levels were increased in proportion to AVP mRNA expression in the SON and PVN under dehydration. These data suggest that BiP is involved in the homeostasis of ER function in the AVP neurons in the SON and PVN., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background & Aims: Gastric electrical stimulation (GES) is an effective therapy to treat patients with chronic dyspepsia refractory to medical management. However, its mechanisms of action remain poorly understood., Methods: Gastric pain was induced by performing gastric distension (GD) in anesthetized rats. Pain response was monitored by measuring the pseudo-affective reflex (e.g., blood pressure variation), while neuronal activation was determined using c-fos immunochemistry in the central nervous system. Involvement of primary afferents was assessed by measuring phosphorylation of ERK1/2 in dorsal root ganglia., Results: GES decreased blood pressure variation induced by GD, and prevented GD-induced neuronal activation in the dorsal horn of the spinal cord (T9-T10), the nucleus of the solitary tract and in CRF neurons of the hypothalamic paraventricular nucleus. This effect remained unaltered within the spinal cord when sectioning the medulla at the T5 level. Furthermore, GES prevented GD-induced phosphorylation of ERK1/2 in dorsal root ganglia., Conclusions: GES decreases GD-induced pain and/or discomfort likely through a direct modulation of gastric spinal afferents reducing central processing of visceral nociception.

Aims: This study sought to investigate the effects of physical detraining on blood pressure (BP) and cardiac morphology and function in hypertension, and on pro- and anti-inflammatory cytokines (PICs and AIC) and oxidative stress within the brain of hypertensive rats., Methods and Results: Hypertension was induced in male Sprague-Dawley rats by delivering AngiotensinII for 42 days using implanted osmotic minipumps. Rats were randomized into sedentary, trained, and detrained groups. Trained rats underwent moderate-intensity exercise (ExT) for 42 days, whereas, detrained groups underwent 28 days of exercise followed by 14 days of detraining. BP and cardiac function were evaluated by radio-telemetry and echocardiography, respectively. At the end, the paraventricular nucleus (PVN) was analyzed by Real-time RT-PCR and Western blot. ExT in AngII-infused rats caused delayed progression of hypertension, reduced cardiac hypertrophy, and improved diastolic function. These results were associated with significantly reduced PICs, increased AIC (interleukin (IL)-10), and attenuated oxidative stress in the PVN. Detraining did not abolish the exercise-induced attenuation in MAP in hypertensive rats; however, detraining failed to completely preserve exercise-mediated improvement in cardiac hypertrophy and function. Additionally, detraining did not reverse exercise-induced improvement in PICs in the PVN of hypertensive rats; however, the improvements in IL-10 were abolished., Conclusion: These results indicate that although 2 weeks of detraining is not long enough to completely abolish the beneficial effects of regular exercise, continuing cessation of exercise may lead to detrimental effects.

Background: Excessive sympathetic activity contributes to the pathogenesis and progression of hypertension. Enhanced cardiac sympathetic afferent reflex (CSAR) is involved in sympathetic activation. This study was designed to determine the roles of angiotensin (Ang)-(1-7) in paraventricular nucleus (PVN) in modulating sympathetic activity and CSAR and its signal pathway in renovascular hypertension., Methodology/principal Findings: Renovascular hypertension was induced with two-kidney, one-clip method. Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in sinoaortic-denervated and cervical-vagotomized rats with anesthesia. CSAR was evaluated with the RSNA and MAP responses to epicardial application of capsaicin. PVN microinjection of Ang-(1-7) and cAMP analogue db-cAMP caused greater increases in RSNA and MAP, and enhancement in CSAR in hypertensive rats than in sham-operated rats, while Mas receptor antagonist A-779 produced opposite effects. There was no significant difference in the angiotensin-converting enzyme 2 (ACE2) activity and Ang-(1-7) level in the PVN between sham-operated rats and hypertensive rats, but the Mas receptor protein expression in the PVN was increased in hypertensive rats. The effects of Ang-(1-7) were abolished by A-779, adenylyl cyclase inhibitor SQ22536 or protein kinase A (PKA) inhibitor Rp-cAMP. SQ22536 or Rp-cAMP reduced RSNA and MAP in hypertensive rats, and attenuated the CSAR in both sham-operated and hypertensive rats., Conclusions: Ang-(1-7) in the PVN increases RSNA and MAP and enhances the CSAR, which is mediated by Mas receptors. Endogenous Ang-(1-7) and Mas receptors contribute to the enhanced sympathetic outflow and CSAR in renovascular hypertension. A cAMP-PKA pathway is involved in the effects of Ang-(1-7) in the PVN.

Both the hypothalamus-pituitary-adrenal (HPA) axis and the extrahypothalamic brain stress system are key elements of the neural circuitry that regulates the negative states during abstinence from chronic drug exposure. Orexins have recently been hypothesized to modulate the extended amygdala and to contribute to the negative emotional state associated with dependence. This study examined the impact of chronic morphine and withdrawal on the lateral hypothalamic (LH) orexin A (OXA) gene expression and activity as well as OXA involvement in the brain stress response to morphine abstinence. Male Wistar rats received chronic morphine followed by naloxone to precipitate withdrawal. The selective OX1R antagonist SB334867 was used to examine whether orexins' activity is related to somatic symptoms of opiate withdrawal and alterations in HPA axis and extended amygdala in rats dependent on morphine. OXA mRNA was induced in the hypothalamus during morphine withdrawal, which was accompanied by activation of OXA neurons in the LH. Importantly, SB334867 attenuated the somatic symptoms of withdrawal, and reduced morphine withdrawal-induced c-Fos expression in the nucleus accumbens (NAc) shell, bed nucleus of stria terminalis, central amygdala and hypothalamic paraventricular nucleus, but did not modify the HPA axis activity. These results highlight a critical role of OXA signalling, via OX1R, in activation of brain stress system to morphine withdrawal and suggest that all orexinergic subpopulations in the lateral hypothalamic area contribute in this response.

In this study, hypothalamic activation was performed by dehydration-induced anorexia (DIA) and overnight food suppression (OFS) in female rats. The assessment of the hypothalamic response to these challenges by manganese-enhanced MRI showed increased neuronal activity in the paraventricular nuclei (PVN) and lateral hypothalamus (LH), both known to be areas involved in the regulation of food intake. The effects of DIA and OFS were compared by generating T-score maps. Increased neuronal activation was detected in the PVN and LH of DIA rats relative to OFS rats. In addition, the neurochemical profile of the PVN and LH were measured by (1) H MRS at 14.1T. Significant increases in metabolite levels were measured in DIA and OFS relative to control rats. Statistically significant increases in γ-aminobutyric acid were found in DIA (p=0.0007) and OFS (p<0.001) relative to control rats. Lactate increased significantly in DIA (p=0.03), but not in OFS, rats. This work shows that manganese-enhanced MRI coupled to (1) H MRS at high field is a promising noninvasive method for the investigation of the neural pathways and mechanisms involved in the control of food intake, in the autonomic and endocrine control of energy metabolism and in the regulation of body weight., (Copyright © 2011 John Wiley & Sons, Ltd.)

Suppression of TSH release from the hypothyroid thyrotrophs is one of the most rapid effects of 3,3',5'-triiodothyronine (T(3)) or thyroxine (T(4)). It is initiated within an hour, precedes the decrease in TSHβ mRNA inhibition and is blocked by inhibitors of mRNA or protein synthesis. TSH elevation in primary hypothyroidism requires both the loss of feedback inhibition by thyroid hormone in the thyrotrophs and the positive effects of TRH. Another event in this feedback regulation may be the thyroid hormone-mediated induction of the TRH-inactivating pyroglutamyl peptidase II (PPII) in the hypothalamic tanycytes. This study compared the chronology of the acute effects of T(3) or T(4) on TSH suppression, TRH mRNA in the hypothalamic paraventricular nucleus (PVN), and the induction of tanycyte PPII. In wild-type mice, T(3) or T(4) caused a 50% decrease in serum TSH in hypothyroid mice by 5  h. There was no change in TRH mRNA in PVN over this interval, but there was a significant increase in PPII mRNA in the tanycytes. In mice with genetic inactivation of the type 2 iodothyronine deiodinase, T(3) decreased serum TSH and increased PPII mRNA levels, while T(4)-treatment was ineffective. We conclude that the rapid suppression of TSH in the hypothyroid mouse by T(3) occurs prior to a decrease in TRH mRNA though TRH inactivation may be occurring in the median eminence through the rapid induction of tanycyte PPII. The effect of T(4), but not T(3), requires the type 2 iodothyronine deiodinase.

Motilin, an important endocrine regulator of gastrointestinal motility, was once considered to be produced in the gastrointestinal tract and brain. In recent years, however, motilin has been found in the human thyroid, as well as in that of the guinea pig. The physiological function and central modulation of thyroidal motilin remain poorly understood. To determine the functional role of thyroidal motilin, we observed the concentration of motilin in the plasma and also gastric motility before and after thyroidectomy. Our studies show that both the concentration of plasma motilin and gastric motility were decreased after thyroidectomy. To explore modulation-related nuclei, a c-Fos immune response experiment was carried out. The PVN of the hypothalamus was the main area of reactivity after thyroidectomy. Subsequently, we studied the effects of electrical excitation and PVN lesions on gastric motility and the expression of motilin in the thyroid and plasma. Excitation of the PVN was shown to prompt gastric motility that was partly prevented by the motilin receptor antagonist, GM-109. The effects of PVN excitation on gastric contraction were significantly reduced in thyroidectomised rats. In addition, the expression of motilin in the thyroid was significantly increased after PVN excitation and decreased after PVN lesions. The changes in the concentration of motilin in plasma induced by PVN stimulation were positively correlated with changes of gastric motility. In our in vitro study, the motilin secreted from TT cells (a parafollicular cell line originating from human thyroid medullary carcinoma) gradually increased on day 6 of culture, and motilin and calcitonin (CT) were co-expressed in TT cells. These results demonstrate that motilin from the thyroid could be secreted into the peripheral plasma and affect gastric motility and that PVN was a central nucleus for modulating gastric motility and motilin expression in the thyroid., (© 2011 The Authors. Journal of Neuroendocrinology © 2011 Blackwell Publishing Ltd.)

Arginine vasopressin (AVP) from the paraventricular nucleus (PVN) of hypothalamus has important roles in regulation of the hypothalamic-pituitary-adrenal (HPA) axis and stress-related behaviors during chronic stress. It is unknown, however, whether AVP in the PVN is involved in the modulation of HPA activity after chronic cocaine exposure. Here, we examined the gene expression alterations of AVP in the hypothalamus, and V1b receptor and pro-opiomelanocortin (POMC) in the anterior pituitary, as well as HPA hormonal changes, in Fischer rats after chronic cocaine and withdrawal, using two different chronic (14-day) 'binge' pattern administration regimens: steady-dose cocaine (SDC, 45 mg/kg/day) and escalating-dose cocaine (EDC, 45 up to 90 mg/kg/day). There was a significant (7-fold) plasma adrenocorticotropic hormone (ACTH) elevation after chronic EDC (but not SDC), coupled with increased V1b and POMC mRNA levels in the anterior pituitary. From acute (1-day) to protracted (14-day) withdrawal from chronic EDC (but not from SDC), we found persistent elevations of both plasma ACTH and corticosterone levels and AVP mRNA levels in the PVN. Selective V1b antagonist SSR149415 (5 mg/kg) attenuated acute withdrawal-induced HPA activation after EDC. To study potential roles of endogenous opioids in modulating the AVP gene, we administered naloxone (1 mg/kg); we found that opioid receptor antagonism increased AVP mRNA levels in cocaine-naive rats, but not in cocaine-withdrawn rats, suggesting less tonic opioid inhibition of PVN AVP neurons after chronic EDC. To assess the effects of cocaine withdrawal on sub-populations of PVN AVP neurons, we utilized AVP-enhanced green fluorescent protein (EGFP) promoter transgenic mice and found that acute withdrawal following chronic EDC increased the number of AVP-EGFP neurons in the parvocellular PVN (pPVN). These results suggest that during protracted withdrawal, enhanced pPVN AVP gene expression is associated with persistent elevations of basal HPA activity; a hyposensitivity of PVN AVP gene expression to naloxone is indicative of reduced opioidergic tone. Our studies indicate that the AVP and its V1b receptor system may be a potential therapeutic target for treating anxiety and depressive symptoms associated with cocaine addiction.

Experimental study of the effects of endogenous toxic compounds on endocrine organs showed that the pathomorphological changes were caused by the cytopathic effects of endogenous toxic compounds involving the development of stereotypical reactions to injury. The severity of these reactions depended on the initial functional status of the gland and its involvement in systemic mechanisms of adaptation to the toxic process.

The melanocortin system in the hypothalamus controls food intake and energy expenditure. Its disruption causes severe obesity in mice and humans. cAMP-response element-binding protein 1 (CREB1) has been postulated to play an important role downstream of the melanocortin-4 receptor (MC4R), but this hypothesis has never been confirmed in vivo. To test this, we generated mice that lack CREB1 in SIM1-expressing neurons, of the paraventricular nucleus (PVN), which are known to be MC4R-positive. Interestingly, CREB1(ΔSIM1) mice developed obesity as a result of decreased energy expenditure and impairment in maintaining their core body temperature and not because of hyperphagia, defining a new role for CREB1 in the PVN. In addition, the lack of CREB1 in the PVN caused a reduction in vasopressin expression but did not affect adrenal or thyroid function. Surprisingly, MC4R function tested pharmacologically was normal in CREB1(ΔSIM1) mice, suggesting that CREB1 is not required for intact MC4R signaling. Thus CREB1 may affect other pathways that are implicated in the regulation of body weight.

Background: Although the higher prevalence of depression in women than in men is well known, the neuronal basis of this sex difference is largely elusive., Methods: Male and female rats were exposed to chronic variable mild stress (CVMS) after which immediate early gene products, corticotropin-releasing factor (CRF) mRNA and peptide, various epigenetic-associated enzymes and DNA methylation of the Crf gene were determined in the hypothalamic paraventricular nucleus (PVN), oval (BSTov) and fusiform (BSTfu) parts of the bed nucleus of the stria terminalis, and central amygdala (CeA)., Results: CVMS induced site-specific changes in Crf gene methylation in all brain centers studied in female rats and in the male BST and CeA, whereas the histone acetyltransferase, CREB-binding protein was increased in the female BST and the histone-deacetylase-5 decreased in the male CeA. These changes were accompanied by an increased amount of c-Fos in the PVN, BSTfu and CeA in males, and of FosB in the PVN of both sexes and in the male BSTov and BSTfu. In the PVN, CVMS increased CRF mRNA in males and CRF peptide decreased in females., Conclusions: The data confirm our hypothesis that chronic stress affects gene expression and CRF transcriptional, translational and secretory activities in the PVN, BSTov, BSTfu and CeA, in a brain center-specific and sex-specific manner. Brain region-specific and sex-specific changes in epigenetic activity and neuronal activation may play, too, an important role in the sex specificity of the stress response and the susceptibility to depression.

Perinatal exposure to polychlorinated biphenyls (PCBs) leads to significant alterations of neural and hormonal systems. These alterations have been shown to impair motor and sensory development. Less is known about the influence of PCB exposure on developing emotional and motivational systems involved in social interactions and social learning. The present study examined the impact of perinatal PCB exposure (mixture of congeners 47 and 77) on social recognition in juvenile animals, conspecific-directed investigation in adults and on neural and hormonal systems involved in social functions. We used a standard habituation-dishabituation paradigm to evaluate juvenile recognition and a social port paradigm to monitor adult social investigation. Areal measures of the periventricular nucleus (PVN) of the hypothalamus were obtained to provide correlations with related hormone and brain systems. PCB exposed rats were significantly impaired in social recognition as indicated by persistent conspecific-directed exploration by juvenile animals regardless of social experience. As adults, PCB exposure led to a dampening of the isolation-induced enhancement of social investigation. There was not a concomitant alteration of social investigation in pair-housed PCB exposed animals at this stage of development. Interestingly, PVN area was significantly decreased in juvenile animals exposed to PCB during the perinatal period. Shifts in hypothalamic regulation of hormones involved in social behavior and stress could be involved in the behavioral changes observed. Overall, the results suggest that PCB exposure impairs context or experience-dependent modulation of social approach and investigation. These types of social-context deficits are similar to behavioral deficits observed in social disorders such as autism and other pervasive developmental disorders., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Our aim was to investigate the effect of central NOS inhibition on hypothalamic arginine vasopressin (AVP) gene expression, hormone release and on the cardiovascular response during experimental sepsis. Male Wistar rats were intracerebroventricularly injected with the non-selective NO synthase (NOS) inhibitor (L-NAME) or aminoguanidine, a selective inhibitor of the inducible isoform (iNOS). After 30 min, sepsis was induced by cecal ligation and puncture (CLP) causing an increase in heart rate (HR), as well as a reduction in median arterial pressure (MAP) and AVP expression ratio (AVP(R)), mainly in the supraoptic nucleus. AVP plasma levels (AVPp) increased in the early but not in the late phase of sepsis. L-NAME pretreatment increased MAP but did not change HR. It also resulted in an increase in AVPp at all time points, except 24h, when it returned to basal levels. AVP(R), however remained reduced in both nuclei. Aminoguanidine pretreatment resulted in increased MAP in the early phase and higher AVP(R) in the supraoptic, but not in the paraventricular nucleus, while AVPp remained elevated at all time points. We suggest that increased central NO production, mainly inducible NOS-derived, reduces AVP gene expression differentially in supraoptic and paraventricular nuclei, and that this may contribute to low AVP plasma levels and hypotension in the late phase of sepsis., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Oxytocin (OT) is a nonapeptide essential for maternal care. The development of the OT neuroendocrine system is a multi-step process dependent on the action of many transcription factors, but upstream signaling molecules regulating this process are still poorly understood. In this study, we examined if fibroblast growth factor 8 (FGF8), a signaling molecule critical for forebrain development, is essential for the proper formation of the OT system. Using immunohistochemistry, we showed a significant reduction in the number of neurons immunoreactive for the mature OT peptide in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) in the hypothalamus of homozygous (HOMO) FGF8 hypomorphic mice compared to wild-type mice. The number of neurons positive for oxyphysin prohormone in the SON but not the PVN was also significantly reduced in FGF8 HOMO hypomorphs. However, steady-state mRNA levels of the oxyphysin prohormone were not significantly different between FGF8 hypomorphs and WT mice. These data suggest that a global reduction in FGF8 signaling leads to an overall reduction of mature OT and oxyphysin prohormone levels that may have resulted from defects in multiple stages of the hormone-synthesis pathway. Since proper hormone synthesis is a hallmark of mature OT neurons, this study suggests that FGF8 signaling may contribute to the phenotypic maturation of a neuroendocrine system that originates within the diencephalon.

The existence of an immunological homunculus has been proposed, but evidence for location-specific response of the central nervous system to immunological stimulation is lacking. In this study, we show that inflammation induced by injection of casein into one of the causes c-fos expression in the paraventricular nucleus of the hypothalamus (PVN) in an asymmetrical manner: much stronger activation is always induced in the contralateral PVN. Unilateral sciatic nerve transection abolished the casein-induced PVN activation if casein was injected into the hindlimb with the nerve transection, but had no effect if casein was injected into the hindlimb with intact nerve innervation. Injection of casein into one the forelimbs also caused contralateral PNV activation. Further, stronger PVN activation was found in the anterior PVN after the forelimb injection, but in the posterior PVN after the hindlimb injection. Casein-induced PVN activation is absent in IL-1R1 KO, IL-6 KO, TNFα KO, and in C3H/HeJ (TLR4 mutant) animals. In comparison, injection of LPS, a systemic inflammagen, into one hindlimb induced bilateral PVN activation but injection of live Escherichia coli into one hindlimb induced contralateral PVN activation. These results support the notion that local inflammation may activate the PVN by neural routes in a location-specific manner., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Chronic intermittent hypoxia (CIH) is a concomitant of sleep apnea that produces a slowly developing chemosensory-dependent blood pressure elevation ascribed in part to NMDA receptor-dependent plasticity and reduced nitric oxide (NO) signaling in the carotid body. The hypothalamic paraventricular nucleus (PVN) is responsive to hypoxic stress and also contains neurons that express NMDA receptors and neuronal nitric oxide synthase (nNOS). We tested the hypothesis that extended (35 d) CIH results in a decrease in the surface/synaptic availability of the essential NMDA NR1 subunit in nNOS-containing neurons and NMDA-induced NO production in the PVN of mice. As compared with controls, the 35 d CIH-exposed mice showed a significant increase in blood pressure and an increased density of NR1 immunogold particles located in the cytoplasm of nNOS-containing dendrites. Neither of these between-group differences was seen after 14 d, even though there was already a reduction in the NR1 plasmalemmal density at this time point. Patch-clamp recording of PVN neurons in slices showed a significant reduction in NMDA currents after either 14 or 35 d exposure to CIH compared with sham controls. In contrast, NO production, as measured by the NO-sensitive fluorescent dye 4-amino-5-methylamino-2',7'-difluorofluorescein, was suppressed only in the 35 d CIH group. We conclude that CIH produces a reduction in the surface/synaptic targeting of NR1 in nNOS neurons and decreases NMDA receptor-mediated currents in the PVN before the emergence of hypertension, the development of which may be enabled by suppression of NO signaling in this brain region.

Reproductive aging in males is characterized by a diminution in sexual behavior beginning in middle age. We investigated the relationships among testosterone, androgen receptor (AR) and estrogen receptor alpha (ERalpha) cell numbers in the hypothalamus, and their relationship to sexual performance in male rats. Young (3months) and middle-aged (12months) rats were given sexual behavior tests, then castrated and implanted with vehicle or testosterone capsules. Rats were tested again for sexual behavior. Numbers of AR and ERalpha immunoreactive cells were counted in the anteroventral periventricular nucleus and the medial preoptic nucleus, and serum hormones were measured. Middle-aged intact rats had significant impairments of all sexual behavior measures compared to young males. After castration and testosterone implantation, sexual behaviors in middle-aged males were largely comparable to those in the young males. In the hypothalamus, AR cell density was significantly (5-fold) higher, and ERalpha cell density significantly (6-fold) lower, in testosterone- than vehicle-treated males, with no age differences. Thus, restoration of serum testosterone to comparable levels in young and middle-aged rats resulted in similar preoptic AR and ERalpha cell density concomitant with a reinstatement of most behaviors. These data suggest that age-related differences in sexual behavior cannot be due to absolute levels of testosterone, and further, the middle-aged brain retains the capacity to respond to exogenous testosterone with changes in hypothalamic AR and ERalpha expression. Our finding that testosterone replacement in aging males has profound effects on hypothalamic receptors and behavior has potential medical implications for the treatment of age-related hypogonadism in men., (Copyright 2010 Elsevier Inc. All rights reserved.)

Following a myocardial infarction (MI), inflammatory cytokines are elevated in the brain, as well as in plasma, indicating that inflammation is occurring in the brain in addition to the periphery. Microglia are the immune cells in the central nervous system and can produce cytokines when they are activated by an insult or injury. In the present study, we investigated whether MI in rats induces activation of microglia in the brain. We used immunohistochemistry to detect CD11b (clone OX-42) and morphological changes to identify activated microglia. Compared to control rats that had undergone sham surgical procedures, there was a significant increase in activated microglia in the hypothalamic paraventricular nucleus (PVN) following myocardial infarction. Activated microglia were not observed in the ventral hypothalamus, adjacent to the PVN, nor in the cortex, indicating the response was not the result of a generalized inflammatory reaction in the brain. Echocardiography and haemodynamic parameters after myocardial infarction indicated that reduced left ventricular function but congestive heart failure had not developed. In conclusion, microglia are activated in the PVN but not in the adjacent hypothalamus following myocardial infarction. The activated microglia may contribute to the increased local production of pro-inflammatory cytokines observed in the PVN after myocardial infarction and resulting in reduced left ventricular function., (Copyright 2010 Elsevier B.V. All rights reserved.)

Single-minded 1 (SIM1) mutations are one of the few known causes of nonsyndromic monogenic obesity in both humans and mice. Although the role of Sim1 in the formation of the hypothalamus has been described, its postdevelopmental, physiological functions have not been well established. Here we demonstrate that postnatal CNS deficiency of Sim1 is sufficient to cause hyperphagic obesity. We conditionally deleted Sim1 after birth using CaMKII-Cre (alpha-calcium/calmodulin-dependent protein kinase II-Cre) lines to recombine a floxed Sim1 allele. Conditional Sim1 heterozygotes phenocopied germ line Sim1 heterozygotes, displaying hyperphagic obesity and increased length. We also generated viable conditional Sim1 homozygotes, demonstrating that adult Sim1 expression is not essential for mouse or neuron survival and revealing a dosage-dependent effect of Sim1 on obesity. Using stereological cell counting, we showed that the phenotype of both germ line heterozygotes and conditional Sim1 homozygotes was not attributable to global hypocellularity of the paraventricular nucleus (PVN) of the hypothalamus. We also used retrograde tract tracing to demonstrate that the PVN of germ line heterozygous mice projects normally to the dorsal vagal complex and the median eminence. Finally, we showed that conditional Sim1 homozygotes and germ line Sim1 heterozygotes exhibit a remarkable decrease in hypothalamic oxytocin (Oxt) and PVN melanocortin 4 receptor (Mc4r) mRNA. These results demonstrate that the role of Sim1 in feeding regulation is not limited to formation of the PVN or its projections and that the hyperphagic obesity in Sim1-deficient mice may be attributable to changes in the leptin-melanocortin-oxytocin pathway.

Neonatal monosodium glutamate (MSG) administration increases adiposity, decreases energy expenditure and is associated with arcuate nucleus (Arc) destruction. Disrupted brown adipose tissue (BAT) thermogenesis underlies some of these effects, although, interscapular BAT temperature (T(IBAT)) has not been measured. Therefore, we tested the effects of neonatal MSG or vehicle administration in Siberian hamsters and, when they were adults, measured T(IBAT) during acute cold exposure. The Arc and its projection to the hypothalamic paraventricular nucleus (PVH) are both components of the CNS outflow circuits to IBAT, with the latter implicated in BAT thermogenesis that could be compromised by MSG treatment. Using a viral transneuronal tract tracer, pseudorabies virus (PRV), we also tested whether the components of these circuits were intact. As adults, MSG-treated hamsters had significantly increased body mass and some white fat pad masses, markedly reduced Arc Nissl and neuropeptide staining, and PVH neuropeptide fiber staining. Cold-exposed (18 h at 5 degrees C) MSG- and vehicle-treated hamsters initially maintained T(IBAT), but the ability of the former waned after 2 h being significantly decreased by 18 h. PRV immunoreactive fibers/cells were not altered by neonatal MSG treatment despite substantial Arc and PVH destruction. MSG- and vehicle-treated hamsters given an exogenous norepinephrine challenge showed identical increases in the duration and peak of T(IBAT). Thus, the inability of MSG-treated animals to sustain T(IBAT) in the cold is not due to any obvious MSG-induced deletions of central sympathetic outflow circuits to IBAT, but appears to be extrinsic to the tissue nevertheless.

Menopause is one of the triggers that induce obesity. Estradiol (E2), corticotropin-releasing hormone (CRH), and hypothalamic neuronal histamine are anorexigenic substances within the hypothalamus. This study examined the interactions among E2, CRH, and histamine during the regulation of feeding behavior and obesity in rodents. Food intake was measured in rats after the treatment of E2, alpha-fluoromethyl histidine, a specific suicide inhibitor of histidine decarboxylase that depletes hypothalamic neuronal histamine, or CRH antagonist. We measured food intake and body weight in wild-type mice or mice with targeted disruption of the histamine receptors (H1-R) knockout (H1KO mice). Furthermore, we investigated CRH content and histamine turnover in the hypothalamus after the E2 treatment or ovariectomy (OVX). We used immunohistochemical staining for estrogen receptors (ERs) in the histamine neurons. The E2-induced suppression of feeding was partially attenuated in rats pre-treated with alpha-fluoromethyl histidine or CRH antagonist and in H1KO mice. E2 treatment increased CRH content and histamine turnover in the hypothalamus. OVX increased food intake and body weight, and decreased CRH content and histamine turnover in the hypothalamus. In addition, E2 replacement reversed the OVX-induced changes in food intake and body weight in wild-type mice but not in H1KO mice. Immunohistochemical analysis revealed ERs were expressed on histamine neurons and western blotting analysis and pre-absorption study confirmed the specificity of ER antiserum we used. These results indicate that CRH and hypothalamic neuronal histamine mediate the suppressive effects of E2 on feeding behavior and body weight.

Restraint water-immersion stress (RWIS) can induce anxiety, hypothermia, and severe vagally-mediated gastric dysfunction. The present work explored the effects of different durations of RWIS on neuronal activities of the forebrain by c-Fos expression in conscious rats exposed to RWIS for 0, 30, 60, 120, or 180 min. The peak of c-Fos induction was distinct for different forebrain regions. The most intense c-Fos induction was always observed in the supraoptic nucleus (SON), and then in the hypothalamic paraventricular nucleus (PVN), posterior cortical amygdaloid nucleus (PCoA), central amygdaloid nucleus (CeA), and medial prefrontal cortex (mPFC). Moreover, body temperature was reduced to the lowest degree after 60 min of RWIS, and the gastric lesions tended to gradually worsen with the prolonging of RWIS duration. These data strongly suggest that these nuclei participate in the organismal response to RWIS to different degrees, and may be involved in the hypothermia and gastric lesions induced by RWIS.

In this study we try to simultaneously investigate the response of neurons and astrocytes of rats following hyperosmotic stimulation and test the possibility that the reciprocal pathways between medullary visceral zone (MVZ) and hypothalamic paraventricular nucleus (PVN) or supraoptic nucleus (SON). Hyperosmotic pressure animal model was established by administering 3% sodium chloride as drinking water to rats. The distribution and expression of the HRP retrogradely labeled neurons, Fos, tyrosine hydroxylase (TH) or vasopressin (VP) positive neuron and glial fibrillary acidic protein (GFAP) positive astrocytes in the MVZ, SON and PVN were observed by quadruplicate-labeling methods of WGA-HRP retrograde tracing combined with anti-Fos, TH (or VP) and GFAP immunohistochemical technique. Fos positive neurons within the MVZ, PVN and SON increased markedly. There were also a large number of GFAP positive structures in the brain and their distribution pattern was fundamentally similar or analogous to Fos positive neurons in the above-mentioned areas. The augmented GFAP reactivities took on hypertrophic cell bodies, thicker and longer processes. Quadruplicate immunohistochemical staining showed that a neuron could be closely surrounded by many astrocytes and they formed neuron-astrocytic complex (N-ASC). Fos+/TH+/HRP+/GFAP+ and Fos+/VP+/HRP+/GFAP+ quadruplicate labeled N-ASC could be found in the MVZ, PVN and SON, respectively. The present results indicated that the neurons and astrocytes might be very active following hyperosmotic pressure and N-ASC as a functional unit might serve to modulate osmotic pressure. There were reciprocal osmoregulation pathways between the MVZ and SON or PVN in the brain.

In mammals, stress elicits a stereotyped endocrine response that requires an increase in the activity of hypothalamic parvocellular neuroendocrine neurons. The output of these cells is normally constrained by powerful GABA-mediated synaptic inhibition. We found that acute restraint stress in rats released the system from inhibitory synaptic drive in vivo by down-regulating the transmembrane anion transporter KCC2. This manifested as a depolarizing shift in the reversal potential of GABA(A)-mediated synaptic currents that rendered GABA inputs largely ineffective. Notably, repetitive activation of GABA synapses after stress resulted in a more rapid collapse of the anion gradient and was sufficient to increase the activity of neuroendocrine cells. Our data indicate that hypothalamic neurons integrate psychological cues to mount the endocrine response to stress by regulating anion gradients.

Neuroendocrine mechanisms of development of anxiety-like state in rats in experimental model of human post-traumatic stress disorder (PTSD), referred to as stress-restress paradigm, have been studied. Immunocytochemistry has revealed significant increase of CRH expression in both parvo- and magnocellular subdivisions of paraventricular nuclei up to 10th post-stress day. Significant reduction of vasopressin expression in rats' hypothalamic paravntricular nuclei has been detected on the 1st post-stress day. Vasopressin immunoreactivity in hypothalamus of stressed animals was indistinguishable from that in control group on the 10th post-stress day only in parvocellular subdivision of the paraventricular nucleus, while it was increased in magnocellular subdivision of the nucleus in experimental group compared to controls. The results imply a plausible role of hypothalamic vasopressin along with CRH on the development of PTSD.

Our previous studies have shown that morphine withdrawal increases the hypothalamic-pituitary-adrenocortical axis activity, which is dependent on a hyperactivity of noradrenergic pathways (nucleus tractus solitarius-A(2)) innervating the hypothalamic paraventricular nucleus. The extracellular signal-regulated kinase has been implicated in drug addiction, but its role in activation of paraventricular nucleus and nucleus tractus solitarius during morphine dependence remain poorly understood. We have determined the activation of extracellular signal-regulated kinase during morphine dependence and withdrawal as well as its involvement in morphine withdrawal-induced gene expression. We show that naloxone-induced morphine withdrawal activates extracellular signal-regulated kinases(1/2) and increases c-Fos expression in rat paraventricular nucleus and nucleus tractus solitarius-A(2) neurons. Activated extracellular signal-regulated kinases(1/2) was colocalized with c-Fos in both nuclei, and this response was blocked by SL327, a drug that prevents extracellular signal-regulated kinase activation. In the paraventricular nucleus from morphine-withdrawn rats, the number of neurons expressing CRF was increased. Immunohistochemical study showed a dramatic increase in c-Fos immunoreactivity within CRF-positive cells. These results suggest that extracellular signal-regulated kinases1/2 signaling pathway is necessary for morphine withdrawal-induced activation of brain areas associated with the stress system.

Although it has been reported by several laboratories that vestibular stress activates the hypothalamo-pituitary-adrenocortical axis (HPA), the existence of neuronal connections between vestibular and hypothalamic paraventricular neurons has not yet been demonstrated. By the use of a virus-based retrograde trans-synaptic tracing technique in the rat, here we demonstrate vestibular projections to the paraventricular nucleus (PVN). Pseudorabies virus (Bartha strain, type BDR62) was injected into the PVN, and the progression of the infection along synaptically connected neurons was followed in the pons and the medulla, 3 and 4 days post-inoculation. Virus-infected neurons were revealed mainly in the medial vestibular nucleus. Labeled cells were scattered in the spinal, and very rarely in the superior nuclei, but none of them in the lateral vestibular nucleus. Injections of cholera toxin B subunit, a monosynaptic retrograde tracer into the PVN failed to label any cells in the vestibular nuclei. These results provide anatomical evidence for the existence of a vestibulo-paraventricular polysynaptic pathway and support the view that the HPA axis is modulated by vestibular stress.

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 immunohistochemistry 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.

This study evaluated the responses of vasopressin (AVP) and oxytocin (OT) neurons to alterations in hypothalamo-pituitary axis activity by adrenalectomy (ADX) or after restraint stress compared with basal conditions. Wistar male rats were perfuse-fixed by cardiac perfusion under anesthesia 3 h, 1, 3 and 14 days after ADX or Sham surgery. Coronal hypothalamic sections were used for evaluation of Fos, AVP and OT expression by immunohistochemistry. Under basal conditions and after stress, Fos-AVP double labeling showed no difference in the magnocellular subdivisions of the paraventricular nuclei (PVN) or in the supraoptic nuclei (SON), suggesting that the magnocellular AVP system is unlikely to contribute to ACTH secretion after restraint in both Sham and ADX rats. Fos-AVP double labeling in the parvocellular medial paraventricular nucleus (PaMP) in ADX groups was increased after 3 h in basal conditions, and in all periods after restraint stress. There were no differences between Sham and ADX groups in Fos-OT double labeling in any subdivision of the PVN; however, in the SON, the number of Fos-OT double labeled cells was increased at all time-points after stress in the ADX group. Fos expression was increased in the PaMP after 3 h and after restraint stress in the Sham and ADX groups, especially in the ADX group. In conclusion, Fos expression in different cell populations of the PVN can be differentially regulated by short- and long-term absence of glucocorticoid negative feedback and also by stress-related excitatory and/or inhibitory neural inputs. The Fos-AVP double labeling findings in the PaMP also indicate a minor participation of these vasopressinergic neurons in the regulation of the HPA axis after ADX.

Bilateral lesions of the hypothalamic paraventricular nuclei (PVN) induce hyperphagia and obesity, and ghrelin stimulates appetite in rodents and humans. Conversely, corticotrophin-releasing hormone (CRH) and melanotan-II (MT-II, a synthetic structural homologue of alpha-melanocyte-stimulating hormone, alphaMSH) inhibit feeding behavior. The purpose of the present study was to determine whether these peptides are involved in the hyperphagia and obesity induced by PVN lesions. After bilateral electrolytic lesions of the PVN, rats were given ghrelin intraperitoneally (i. p.), or intracerebroventricular (i. c. v.) infusion of CRH or MT-II. We measured the cumulative food intake (FI) for 4 h after ghrelin injection in rats fed AD LIB, and the changes in FI at 15 min, 30 min, 1 h, and 2 h after infusion of CRH and MT-II in rats fasted for 24 h. Ghrelin significantly increased cumulative FI, with maximal response 3 h and 4 h after injection, and at these times, the FI of PVN-lesioned rats was greater than that of sham-operated rats. CRH significantly decreased FI in all experimental animals, but at 1 h, there was a more powerful inhibitory effect on FI in the PVN-lesioned group than in the sham-operated group. MT-II decreased FI in sham-operated, but not in PVN-lesioned rats. Thus, ghrelin and CRH showed more potent orexigenic and anorectic effects in PVN-lesioned rats, respectively, but MT-II lost its inhibitory action on feeding behavior. These results suggest that the hyperphagia and obesity induced by PVN lesions may be related to an increased orexigenic action of ghrelin due to the destruction of endogenous CRH and alphaMSH receptors.

The hypothalamic dorsomedial nucleus (DMN) represents an important coordinate center for regulation of autonomic and neuroendocrine systems, especially during stress response. The present study was focused on the gene expression of catecholamine-synthesizing enzymes and the protein levels of tyrosine hydroxylase in DMN, both in control and stressed rats. Moreover, pathways modulating the gene expression of tyrosine hydroxylase in DMN during immobilization (IMO) stress were also investigated. Gene expressions of all catecholamine-synthesizing enzymes were detected in DMN samples. While the levels of tyrosine hydroxylase and phenylethanolamine N-methyltransferase mRNA were increased in IMO rats, aromatic L-amino acid decarboxylase and dopamine-beta-hydroxylase mRNA remained unchanged. Tyrosine hydroxylase protein levels were significantly elevated in the DMN only after repeated IMO stress. Postero-lateral deafferentations of the DMN, or transections of the ascending catecholaminergic pathways originating in the lower brainstem abolished the IMO-induced increase of tyrosine hydroxylase gene expression in the DMN. Nevertheless, postero-lateral deafferentations of the hypothalamic paraventricular nucleus (PVN), which separate the DMN from the PVN, had no effect on IMO-induced elevation of tyrosine hydroxylase mRNA in the DMN. The present data indicate that certain DMN neurons synthesize mRNA of catecholamine enzymes. The stress-induced increase of tyrosine hydroxylase and phenylethanolamine N-methyltransferase mRNA in DMN neurons indicates the involvement of these catecholaminergic neurons in stress response. The gene expression of tyrosine hydroxylase in DMN is modulated by lower brainstem and/or spinal cord, but not by PVN afferents.

Background/aims: Depression occurs in 20-50% of the Alzheimer disease (AD) patients. It is not known whether depression in AD shares its pathophysiology with depressive disorder. Previously we found a fourfold increase of corticotropin-releasing hormone (CRH)-immunoreactive (IR) neurons in the hypothalamic paraventricular nucleus in depression. The objective of the present study was to find out whether in depression in AD the same phenomenon of an increased number of CRH-IR neurons could be observed., Methods: Post-mortem brain tissue was obtained from a cohort of 23 AD patients prospectively studied using the Cornell Scale for Depression in Dementia to measure depressive symptoms. The number of CRH-IR neurons was determined using immunocytochemistry and the Image Pro Plus analysis program., Results: A significant positive correlation was found between the Cornell scores and the number of CRH-IR neurons (p = 0.039) in AD patients., Conclusion: These results suggest that depressive disorder and depression in AD share, at least partly, their pathophysiology., (Copyright 2007 S. Karger AG, Basel.)

Previous studies have shown that the total number of corticotropin-releasing hormone (CRH)-stained neurons in the human hypothalamic paraventricular nucleus (PVN) increases with age. To determine whether this age-related change depends on gender and whether circulating sex hormones play a role, we analyzed the total number of CRH-immunoreactive neurons by means of immunocytochemistry and image analysis in the postmortem hypothalamic PVN of 22 control subjects (11 males and 11 females) between the ages of 22 and 89 years, and of 10 subjects with abnormal sex hormone status. Our data show that men have a significantly larger number of CRH neurons than women (p = 0.004) and that the total number of CRH neurons increases significantly with age, but only in male controls (p = 0.032), not in female controls (p = 0.733). Female controls do not show a significant change in the total number of CRH neurons either before or after the age (50 years) of menopause (p = 0.792). Male subjects with low testosterone levels due to castration showed significantly fewer CRH neurons than well-matched intact males (p = 0.008), while castrated male-to-female (M-F) transsexuals with estrogen replacement showed normal numbers of CRH neurons. One male case, who had high estrogen levels due to an estrogen-producing tumor, showed a large number of CRH neurons. Thus, although circulating androgens and estrogens both seem to play a stimulatory role with respect to CRH neurons, the age-dependent increase in the number of CRH neurons in the PVN of men, which has been interpreted to reflect activation of the CRH neurons with age, seems to result from factors other than age-related changes of circulating sex hormone levels., (Copyright 2007 S. Karger AG, Basel.)

Large- and small-cell hypothalamic nuclei from 30 males who died of craniocerebral trauma were studied. Number of neurons at different stages of neurosecretory process was calculated in the large cell nuclei (supraoptic and paraventricular nuclei). Mean volume of neuron karyon (MVNK) was estimated in all the nuclei as a neuron function index. It was found that the proportion of neurons at different stages of the neurosecretory cycle is changed in large cell nuclei. This points to impaired synthesis of neurosecretion. Significantly increased MVNK of the neurons of paraventricular, arcuate and posterior nuclei was detected. The above evidence demonstrates activation of humoral hypothalamic regulation of the endocrine and immune systems.

Systemic inflammation is a leading cause of hospital death. Mild systemic inflammation is accompanied by warmth-seeking behavior (and fever), whereas severe inflammation is associated with cold-seeking behavior (and hypothermia). Both behaviors are adaptive. Which brain structures mediate which behavior is unknown. The involvement of hypothalamic structures, namely, the preoptic area (POA), paraventricular nucleus (PVH), or dorsomedial nucleus (DMH), in thermoregulatory behaviors associated with endotoxin (lipopolysaccharide [LPS])-induced systemic inflammation was studied in rats. The rats were allowed to select their thermal environment by freely moving in a thermogradient apparatus. A low intravenous dose of Escherichia coli LPS (10 microg/kg) caused warmth-seeking behavior, whereas a high, shock-inducing dose (5,000 microg/kg) caused cold-seeking behavior. Bilateral electrocoagulation of the PVH or DMH, but not of the POA, prevented this cold-seeking response. Lesioning the DMH with ibotenic acid, an excitotoxin that destroys neuronal bodies but spares fibers of passage, also prevented LPS-induced cold-seeking behavior; lesioning the PVH with ibotenate did not affect it. Lesion of no structure affected cold-seeking behavior induced by heat exposure or by pharmacological stimulation of the transient receptor potential (TRP) vanilloid-1 channel ("warmth receptor"). Nor did any lesion affect warmth-seeking behavior induced by a low dose of LPS, cold exposure, or pharmacological stimulation of the TRP melastatin-8 ("cold receptor"). We conclude that LPS-induced cold-seeking response is mediated by neuronal bodies located in the DMH and neural fibers passing through the PVH. These are the first two landmarks on the map of the circuitry of cold-seeking behavior associated with endotoxin shock.

Structures of the pancreas and magnocellular (supraoptic and paraventricular) nuclei of the hypothalamus of adult male rats were studied in conditions of acute pancreatitis at the light and electron microscopic levels. Histo-and organotypic changes in the parenchymatous and stromal elements of the pancreas were analyzed simultaneously with cytological assessment of the state of the nonapeptidergic neurosecretory centers of the hypothalamus. Blockade of the release of hypothalamic nonapeptides was found to occur at the level of axovasal complexes, and this aggravated the outcome of destructive and necrobiotic changes in the pathologically altered organ.

Rats submitted to fetal growth retardation by in utero malnutrition develop hypertension when adult, showing increased hypothalamic mRNA expression for corticotropin-releasing hormone (CRH) and increased central noradrenergic activity. As hypothalamic CRH serves as an excitatory neurotransmitter within the locus coeruleus (LC) and coerulear norepinephrine plays a similar role within the paraventricular nucleus (PVN) of the hypothalamus, we studied, in both normal and prenatally undernourished 40-day-old anesthetized rats, the effects of intra-LC microinjection of CRH and intra-PVN microinjection of the alpha(1)-adrenoceptor antagonist prazosin on multiunit neuronal activity recorded simultaneously from the two nuclei, as well as the effects on systolic pressure. Undernutrition was induced during fetal life by restricting the diet of pregnant mothers to 10 g daily, whereas mothers of control rats received the same diet ad libitum. At day 40 of postnatal life: (i) undernourished rats showed increased neuronal activity in the PVN and LC, as well as increased systolic pressure; (ii) intra-LC CRH stimulated LC and PVN neurons and increased systolic pressure only in normal rats; (iii) intra-PVN prazosin decreased LC and PVN neuronal activity and systolic pressure only in undernourished rats; and (iv) in normal rats, prazosin prevented the stimulatory effect of CRH only in PVN activity; in undernourished rats, prazosin allowed CRH to regain its stimulatory effects. The results point to the existence of an excitatory PVN-LC closed loop, which seems to be hyperactive in prenatally undernourished rats as a consequence of fetal programming; this loop could be responsible, in part, for the hypertension developed by these animals.

We previously have shown that leptin regulates proTRH in the paraventricular nucleus (PVN) of the hypothalamus through two pathways. The first one acts directly on proTRH neurons, and the second one (indirect) acts through the melanocortin system (arcuate nucleus). However, it is unknown whether the direct or the indirect pathways of leptin action on proTRH neurons occurs on separated or on the same subsets of neurons within the PVN region. We used immunostaining for the phosphorylated signal transducer and activator of transcription 3 to localize direct leptin signaling, and the phosphorylated cAMP response element binding protein to localize indirect signaling on proTRH neurons in animals intracerebroventricularly injected with leptin. With this approach we were able to identify two subsets of neuronal populations responsive to leptin, which are distributed in different regions within the PVN. ProTRH neurons directly responsive to leptin were located mainly in the medial and posterior part of the PVN, and they were not primarily related to the hypothalamic pituitary thyroid axis. Whereas, proTRH neurons indirectly responsive (through alpha-MSH) to leptin were located mainly in the anterior, medial, and periventricular part of the PVN, and related to the hypothalamic pituitary thyroid axis. In addition, alpha-MSH showed to affect the processing of proTRH and up-regulated the prohormone convertase 1/3. In this study, we show evidence supporting the hypothesis that in the PVN there are subpopulations of proTRH neurons responding to leptin, which is dependent upon the way leptin reaches its primary target(s) in the hypothalamus. These findings are critical to a better understanding of leptin-mediated actions in energy expenditure.

The hypothalamic supraoptic and paraventricular nuclei form the neurosecretory system and synthesize the neurohormones oxytocin and arginine-vasopressin. The senescence-accelerated mouse is a model of rapid aging that displays senile amyloidosis and memory problems. This paper presents the characterization of the neurosecretory system and describes the presence of a bilateral constant cluster of neurosecretory neurons in these mice. The stereologic analysis revealed that these groups contain 197 +/- 18 cells (87% synthesize arginine-vasopressin and 13% oxytocin). The presence of these clusters of neurosecretory neurons suggests that these mice could present greater neurohormone synthesis, increasing the deleterious effects of accelerated aging in this strain.

The aim of the present work was to identify the role of cycloferon in the apoptosis of cells in the neurosecretory centers of the hypothalamus in young and old mice in conditions of immobilization stress. Apoptotic cells were identified by staining with ethidium bromide. The optical density of the detection product of the antiapoptotic protein Bcl-2 was also studied in cells of the supraoptic and paraventricular (PVN) nuclei. Cycloferon was found to decrease the level of apoptosis in the neurosecretory centers of the hypothalamus via a Bcl-2-independent pathway. Administration of cycloferon before stress had no effect on the number of apoptotic cells, except in the PVN of old mice, where apoptosis was inhibited.

Although numerous data showing severe morphological impairment of magnocellular and parvocellular hypothalamic neurons due to chronic alcoholic consumption have been gathered from animal experiments, only one study (Harding et al., 1996) was performed on POST MORTEM human brain. This study showed a reduction in the number of vasopressin (VP)-immunoreactive neurons in the supraoptic (SON) and paraventricular (PVN) nuclei, but did not provide any data regarding the effect of chronic alcohol intake on human parvocellular neurons. In order to assess whether the changes observed in the animal model also occur in humans and provide a structural basis for the results of clinical tests, we performed immunohistochemical and morphometric analysis of magnocellular (VP and oxytocin, OT) and parvocellular (corticotropin-releasing hormone, CRH) neurons in post-mortem brains of patients afflicted with chronic alcoholic disease. We analyzed 26-male alcoholics and 22 age-matched controls divided into two age groups--"young" (< 40 yr) and "old" (> 40 yr). Hypothalamic sections were stained for OT, VP, and CRH. The analysis revealed: 1) decrease in VP-immunoreactivity in the SON and PVN as well as OT-immunoreactivity in the SON in alcoholic patients; 2) increase in OT-immunoreactivity in the PVN; 3) increase in CRH-immunoreactivity in parvocellular neurons in the PVN. Furthermore, the proportion of cells containing CRH and VP was increased in alcoholics. These findings indicate that chronic alcohol consumption does indeed impair the morphology of magnocellular neurons. The enhancement of CRH-immunoreactivity and increased co-production of CRH and VP in parvocellular neurons may be due to a decline in glucocorticoid production, implied by the hypoplasic impairment of adrenal cortex we observed in alcoholics during the course of this study.

Doxapram causes panic anxiety in humans. To determine whether doxapram alters corticotropin-releasing factor (CRF) expression in the central nucleus of the amygdala (CeA), paraventricular nucleus of hypothalamus (PVN), or bed nucleus of the stria terminalis (BNST), we used immunohistochemistry to measure CRF peptide in these brain areas after doxapram injection. Doxapram injection significantly increased CRF-like immunoreactivity (CRF-IR) within the CeA, but not in the BNST or PVN, and this increase was significant 2h after injection. In addition, doxapram significantly increased CRF mRNA expression within the CeA, and this was most prominent 30min after injection. These results suggest that doxapram selectively increases CRF expression within the CeA, and that this is mediated by increased CRF gene transcription. This increase in CRF-IR within the CeA might explain the doxapram-induced anxiety reaction.

Using mu-opioid receptor knockout (MKO) mice, we examined ethanol-induced FOS immunoreactivity (FOSir) in the brain as an indicator of neuronal activation to assess the role of the mu-opioid receptor in modulating ethanol's actions in the central nervous system (CNS). Saline stimulated FOSir in the paraventricular thalamic nucleus (PVA) and the dorsal hypothalamic area (DA) in MKO mice, but not in wild-type (WT), suggesting that MKO homozygotes may differ responsively from WT. Treatment with ethanol (4 g/kg, i.p.) induced FOSir in the PVA, DA, supraoptic (SO), paraventricular hypothalamic (PVN), lateral parabrachial (LPB), locus coeruleus (LC) and Edinger-Westphal (EW) nuclei in both MKO and WT mice. However, ethanol stimulated modest FOSir in the lateral septal division (LSV), suprachiasmatic nucleus (SCh) and the dorsal and ventral lateral geniculate nuclei (DLG and VLG) in WT mice, but not in MKO mice. In contrast, higher levels of ethanol-induced FOSir were observed in the ventral pallidum (VP) and globus pallidus (GP) of MKO mice as compared to WT. These data suggest that ethanol continues to activate several brain regions, even without the mu-opioid receptor pathway. However, the mu-opioid receptor may be significant in mediating ethanol's effects in some restricted areas of the brain.

Spontaneously hypertensive rats (SHR) pathologically elevate blood pressure with age. This elevation is accompanied by specific neuronal degeneration in the hypothalamus and enlargement of the lateral ventricles. The aim of this study was to assess the neuroprotective effect of the monoamine oxidase B (MAO-B) inhibitor, rasagiline on paraventricular (PVN) hypothalamic degeneration in SHR. The S-enantiomer of rasagiline, S-PAI, a much weaker MAO inhibitor, and two antihypertensive drugs, captopril and hydralazine were also tested. Normotensive Wistar Kyoto (WKY) rats served as controls. One month-old SHR or WKY rats were treated daily for 3-4 months. Systolic blood pressure was recorded, parvocellular vasopressin (VP) immunopositive cells were counted and the area of the third ventricle measured. In saline-treated SHR, blood pressure rose significantly and the number of VP parvocellular cells was reduced by about 60% relative to WKY. Rasagiline, 1 mg/kg/day, reduced PVN neuronal cell death in SHR up to 112% relative to saline-treated SHR; 0.3 mg/kg/day exerted a smaller but significant effect. These actions were accompanied by parallel reductions in systolic blood pressure. Captoril, hydralazine and S-PAI did not prevent death of VP neurons. In SHR, the volume of the third ventricle was about double that of WKY. Rasagiline significantly prevented this ventricular dilation. These results indicate than rasagiline protects from cell death in an in vivo animal model in a dose-dependant manner and could be of use as a neuroprotector in the central nervous system.

Oestrogens may modulate the activity of the hypothalamic-pituitary-adrenal (HPA) axis. The present study was to investigate whether the activity of the HPA axis in mood disorders might be directly modulated by oestrogens via oestrogen receptors (ORs) in the corticotropin-releasing hormone (CRH) neurons of the human hypothalamic paraventricular nucleus (PVN). Brains of 13 subjects ranging in age between 45 and 79 years suffering from major depression/major depressive disorder (eight cases) or bipolar disorder (five cases) and of 13 controls, matched for sex, age, brain weight, post-mortem delay, fixation time and season and clock time at death, were studied with double-label immunocytochemistry. The total number of CRH-immunoreactive (IR) neurons, CRH neurons that colocalized ORalpha in the neuronal nucleus and the number of only nuclear ORalpha-containing neurons in the PVN were measured using an image analysis system. In addition, the volume of the PVN delineated on the basis of CRH neurons was determined. It was found that the total number of CRH-IR neurons in patients with mood disorders was nearly 1.7 times higher than in controls (P = 0.034). A novel finding was that the total number of CRH-IR neurons and the number of CRH-nuclear ORalpha double-staining neurons in the PVN were strongly correlated both in controls and in patients with mood disorders (P < 0.001 and P = 0.022, respectively). The ratio of the CRH-nuclear-ORalpha double-staining neurons to the total CRH-IR neurons in patients with mood disorders was similar to that in the controls (P = 0.448). The volume of the sub-region of the PVN that was delineated on the basis of CRH neurons was significantly larger in patients with mood disorders than in controls (P = 0.022). Another novel finding was the large population of extra-hypothalamic CRH neurons that was found in the thalamus. In summary, oestrogens may directly influence CRH neurons in the human PVN. The increased numbers of neurons expressing CRH in mood disorders is accompanied by increased ORalpha colocalization in the nucleus of these neurons. These changes seem to be trait- rather than state-related.

The hypothalamic-pituitary-adrenocortical axis plays an essential role in the maturation of fetal organs and, in sheep, birth. Lesioning the paraventricular nucleus (PVN) in fetal sheep prevents adrenocortical maturation and parturition without altering plasma immunoreactive ACTH concentrations. The purpose of this study was to determine the effect of PVN lesion on anterior pituitary processing of proopiomelanocortin (POMC) to ACTH, plasma concentrations of ACTH and ACTH precursors (POMC; 22-kDa proACTH), and expression of subtilisin-like prohormone convertase 3 (SPC3) in corticotropes in fetal sheep. PVN lesion did not affect anterior pituitary POMC and 22-kDa proACTH levels, whereas ACTH was significantly affected. The ACTH precursor (POMC plus 22-kDa proACTH) to ACTH ratio in the anterior pituitary was significantly increased after PVN lesion. Post-PVN lesion, fetal plasma ACTH(1-39), was below the limit of detection, whereas ACTH precursors (POMC plus 22-kDa proACTH) were not affected. In the inferior region of the anterior pituitary, 40-50% of corticotropes had detectable SPC3 hybridization signal, and PVN lesion did not change the extent of colocalization of POMC and SPC3, or SPC3 mRNA levels within corticotropes. Neither the percent of corticotropes in the superior region containing SPC3 hybridization (7-12%) or hybridization signal strength was altered in response to PVN lesion. In conclusion, the fetal PVN is necessary for sustaining adequate anterior pituitary processing of POMC to ACTH and ACTH release needed for maturing the adrenal cortex in the sheep fetus.

The structural basis for depressive disorders remains unknown. Studies using neuroimaging and postmortem brain tissue indicate that anatomic substrates may contribute to major depression disorder (MDD) and bipolar disorder (BD). The present study used design-based stereology to assess neuron loss in 2 well-defined hypothalamic structures, the paraventricular nucleus (PVN) and supraoptic nucleus (SON), in clinically well-studied cases with severe depression. The left or right diencephalon was blocked from 26 brains removed at autopsy from age-matched controls (5 male/3 female) and patients with MDD (6 male/5 female) and BD (5 male/2 female). Serial sections were cut at an instrument setting of 60 microm through the entire PVN and SON from left hypothalamus and 8 to 10 sections per brain were systematic-random sampled and stained with cresyl violet. A trained operator blind to clinical diagnosis used computerized stereology to estimate total neuron numbers in PVN and SON. The results revealed a selective, robust reduction of approximately 50% in total neuron number in the PVN for major depression and bipolar cases compared with age-matched controls, with no differences in neuron numbers in the SON. This selective neuronal loss in the PVN appears to identify an important neurobiologic substrate for the behavioral manifestations of depression.