Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HYPOTHALAMUS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources
PubMed2003

Dietary exposure to genistein increases vasopressin but does not alter beta-endorphin in the rat hypothalamus.

Genistein is a plant-derived estrogenic isoflavone commonly found in soy-based products such as soymilk and soy-based dietary supplements for treating menopausal symptoms, for example. Vasopressin is a neurosecretory nonapeptide synthesized primarily in neurons of the hypothalamus and secreted into the bloodstream from the posterior lobe of the pituitary. The endogenous opiate peptide beta-endorphin is synthesized both in neurons of the hypothalamus and in pituitary cells, primarily of the neurointermediate lobe. It has been reported that exposure to 17beta-estradiol or diethylstilbesterol increased the vasopressin content of the hypothalamus, and that estradiol valerate selectively damages hypothalamic beta-endorphin-containing neurons. Since little was known of the potential effects of estrogenic endocrine-disruptor compounds on hypothalamic neuropeptides, we fed Sprague-Dawley fetuses from day 7 in utero until sacrifice at postnatal day 77, with either a control diet (<1 ppm) or an experimental diet containing 25, 250, or 1250 ppm of genistein. We then conducted ELISA assays for hypothalamic content of both beta-endorphin and vasopressin immunoreactivity. Whereas there were no statistically reliable effects of dietary genistein on hypothalamic beta-endorphin content, vasopressin levels were significantly elevated in the 1250-ppm genistein group (p < 0.05). Elevated vasopressin levels may be associated with fluid balance, altered blood pressure, and cardiovascular effects. These data are consistent with the known actions of estradiol and may serve to explain our finding in a previous study that estrogenic endocrine-disruptors such as genistein increased sodium preference in rats exposed through their diet.

Animals↗
PubMed2002

Neuronal inputs from the hypothalamus and brain stem to the medial preoptic area of the ram: neurochemical correlates and comparison to the ewe.

The retrograde tracer, FluoroGold, was used to trace the neuronal inputs from the septum, hypothalamus, and brain stem to the region of the GnRH neurons in the rostral preoptic area of the ram and to compare these imputs with those in the ewe. Sex differences were found in the number of retrogradely labeled cells in the dorsomedial and ventromedial nuclei. Retrogradely labeled cells were also observed in the lateral septum, preoptic area, organum vasculosum of the lamina terminalis, bed nucleus of the stria terminalis, stria terminalis, subfornical organ, periventricular nucleus, anterior hypothalamic area, lateral hypothalamus, arcuate nucleus, and posterior hypothalamus. These sex differences may partially explain sex differences in how GnRH secretion is regulated. Fluorescence immunohistochemistry was used to determine the neurochemical identity of some of these cells in the ram. Very few tyrosine hydroxylase-containing neurons in the A14 group (<1%), ACTH-containing neurons (<1%), and neuropeptide Y-containing neurons (1-5%) in the arcuate nucleus contained FluoroGold. The ventrolateral medulla and parabrachial nucleus contained the main populations of FluoroGold-containing neurons in the brain stem. Retrogradely labeled neurons were also observed in the nucleus of the solitary tract, dorsal raphe nucleus, and periaqueductal gray matter. Virtually all FluoroGold-containing cells in the ventrolateral medulla and about half of these cells in the nucleus of the solitary tract also stained for dopamine beta-hydroxylase. No other retrogradely labeled cells in the brain stem were noradrenergic. Although dopamine, beta-endorphin, and neuropeptide Y have been implicated in the regulation of GnRH secretion in males, it is unlikely that these neurotransmitters regulate GnRH secretion via direct inputs to GnRH neurons.

Adrenocorticotropic Hormone↗
PubMed2003

Effects of applying gamma-aminobutyric acid(B) drugs into the medial basal hypothalamus on basal luteinizing hormone concentrations and on luteinizing hormone surges in the female sheep.

Prior investigations have shown that localized infusion by microdialysis of gamma-aminobutyric acid(B) (GABA(B)) agonists into the medial basal hypothalamus of male sheep rapidly increases GnRH and LH pulse amplitude. The objectives of these studies were to determine if infusion of GABA(B) agonists SKF 97541 or baclofen into the medial basal hypothalamus of female sheep would affect basal LH secretion and if infusion of a potent antagonist would alter expression of LH surges induced by injection of estrogen. Infusion of either SKF 97541 (10 or 40 microM) or baclofen (1 mM) into estrogen-treated ovariectomized ewes did not alter basal LH secretory patterns, whereas both drugs significantly elevated mean LH and LH pulse amplitude in ovariectomized ewes during the nonbreeding season. Infusion of the antagonist CGP 52432 (250 or 500 microM) did not affect expression of estrogen-induced LH surges in ovariectomized ewes. These observations support the concept that GABA(B) receptors in the medial basal hypothalamus regulate basal LH secretion but do not regulate the surge mode of LH secretion in the female sheep.

Animals↗
PubMed2003

Immunity and beta-endorphin concentrations in hypothalamus and plasma in rats with steroid-induced polycystic ovaries: effect of low-frequency electroacupuncture.

The human endocrinological disorder polycystic ovary syndrome (PCOS) is a common cause of reproductive failure. Even though the cause of PCOS is unknown, hormone and immune disturbances as well as hyperactivity in the sympathetic nervous system are likely to be involved in the pathogenesis of the disease. The present study was undertaken to elucidate if rats with estradiol valerate (EV)-induced polycystic ovaries (PCO) have altered beta-endorphin concentrations in the hypothalamus and in plasma and if they have alterations in circulating immune cell populations and the activity. Repeated low-frequency (2 Hz) electroacupuncture (EA) treatments are known to modulate the release of beta-endorphin, immune responses, and the activity in the autonomic nervous system. We therefore also investigated the effect of EA treatments on the beta-endorphin and the immune systems. Low-frequency EA was given 12 times, 25 min each, over 30 days starting 2-3 days after i.m. injection of EV. The beta-endorphin concentrations in the hypothalamus and in plasma as well as the frequencies of CD4+ T cells and CD8+ T cells were significantly lower in EV-injected control rats as compared to oil-injected control rats. Repeated EA treatments in EV-injected rats significantly increased beta-endorphin concentrations in the hypothalamus. In conclusion, these findings show that both the beta-endorphinergic and the immune system are significantly impaired in rats with steroid-induced PCO and that repeated EA treatments can restore some of these disturbances.

Animals↗
PubMed1987

Duration of the melatonin pulse in the hypothalamus controls testicular function in pinealectomized mice (Peromyscus leucopus).

Forty-four pinealectomized white-footed mice (Peromyscus leucopus) were stereotaxically implanted with a guide tube-cannula assembly in the area of the preoptic/anterior hypothalamus. Easy insertion and removal of the melatonin-loaded cannula in the basal medial hypothalamus made it possible to examine whether duration of the melatonin pulse at the putative target site controls reproduction in mice. Mice receiving melatonin every day for 10 h during either the day or night underwent gonadal regression within 7 wk, as indexed by substantial decreases in combined testicular weight and seminal vesicle weight. Sperm production in these mice was also reduced or absent. Melatonin pulses given for 5 h, or as two 5-h pulses (separated by 3 h) did not alter reproduction in that these mice resembled sham-implanted controls. These results indicate that duration of the melatonin pulse, acting in the hypothalamus, may regulate seasonal reproduction in P. leucopus.

Animals↗
PubMed2000

Gestational profile of leptin messenger ribonucleic acid (mRNA) content in the placenta and adipose tissue in the rat, and regulation of the mRNA levels of the leptin receptor subtypes in the hypothalamus during pregnancy and lactation.

Serum leptin levels were significantly increased during rat gestation. Our data showed that leptin mRNA levels in both the adipose tissue and placenta were higher as pregnancy progressed, suggesting a role for both tissues in the hyperproduction of leptin. This paradoxical increase in leptin concentration during gestation suggests that a physiological state of leptin resistance may exist at the hypothalamic level that may explain the hyperphagia observed in pregnant rats. In order to study this issue further, levels of the mRNA encoding the different leptin receptor isoforms were determined in the hypothalamus of pregnant and nonpregnant rats. We found a specific reduction of the mRNA levels encoding the leptin receptor isoform Ob-Rb in the hypothalamus of pregnant rats compared to nonpregnant animals, suggesting that during pregnancy the hypothalamus shows a physiological resistance to the high levels of leptin due, at least in part, to a decrease in the expression of the long, biologically active form of the leptin receptor (Ob-Rb). During lactation, serum leptin levels returned to values observed in nonpregnant rats. In the hypothalami of these animals, Ob-Rb mRNA content was similar to that observed in nonpregnant rats, but we found an increased expression of some of the short forms of the leptin receptor (Ob-Re and Ob-Rf). This could contribute to induction of the hyperphagia present during lactation. These data provide new insights into the adaptive mechanisms that take place during pregnancy and lactation in order to meet increased metabolic requirements.

Adipose Tissue↗
PubMed1995

Dopamine-glutamic acid interaction in the anterior hypothalamus: modulatory effect of melatonin.

The aim of the present study was to investigate the role of melatonin as neuromodulator. For that, the effects of melatonin on the extracellular concentrations of excitatory amino acids, glutamic and aspartic acids, were investigated in the anterior hypothalamus and parieto-temporal cortex of the conscious rat using an intracerebral perfusion system. Melatonin at doses of 250 nM and 1 microM produced no effects on extracellular glutamate and aspartate concentrations in these two areas of the brain. Since amphetamine releases dopamine we perfused melatonin into the anterior hypothalamus and parieto-temporal cortex after a previous injection of amphetamine. Interestingly, we found a release of glutamic acid (p < 0.01) and aspartic acid (p < 0.01) produced by melatonin only when the increase (157%) of the extracellular dopamine concentration evoked by amphetamine was inhibited by melatonin in the anterior hypothalamus. The possibility is discussed of melatonin exerting its effects when the dopaminergic system is activated.

Animals↗
PubMed1995

Monosodium glutamate increases NGF and NPY concentrations in rat hypothalamus and pituitary.

The effects of MSG treatment on NGF and NPY levels were analysed in the hypothalamus, pituitary, adrenal, thyroid and testis of adult rats. Daily i.v. injections of MSG (1 g kg-1 for 1 week) induced an increase of NGF in the hypothalamus (control (C) = 378 +/- 54; saline (S) = 369 +/- 36; MSG = 479 +/- 35 pg g-1 tissue; p < 0.001) and pituitary (C = 310 +/- 34; S = 376 +/- 114; MSG = 576 +/- 98 pg g-1 tissue; p < 0.01). Hypothalamic and pituitary NPY concentrations were also altered in the MSG-treated rats. Compared with saline-treated rats, the NPY concentration increased by 43% in the hypothalamus and 37.5% in the pituitary of MSG-treated rats. No significant changes in NGF and NPY content were found in the adrenal or thyroid of treated animals. These results suggest that hypothalamic and pituitary NGF and NPY levels may be involved in the control of neuroendocrine functions that are affected by MSG treatment.

Animals↗
PubMed1996

Glutamatergic projections from the rostral hypothalamus to the periaqueductal grey.

Retrograde transport of fluorescent latex microspheres was combined with immunocytochemistry for glutamate to determine the organization of the projections from glutamate-containing neurones in the rostral hypothalamus to the different subdivisions of the periaqueductal grey (PAG). Double-labelled neurones, i.e. neurones immunoreactive for glutamate and projecting to the PAG, were found throughout the rostral hypothalamus. There were no apparent differences, however, in the origins of presumed glutamatergic projections from the rostral hypothalamus to the different subdivisions of the PAG.

Animals↗
PubMed1998

Expression of mRNAs encoding BDNF and its receptor in adult rat hypothalamus.

We used a digoxigenin-UTP-labeled cRNA probe with in situ hybridization and Northern blot analysis to investigate the localization of brain derived neurotrophic factor (BDNF) mRNA and expression of its different transcripts in adult rat hypothalamus. As the BDNF gene is under the control of alternative multiple promoters, which provide tissue-specific gene expression, we studied whether these transcripts were expressed in adult hypothalamus. Our data revealed two novel sources of hypothalamic BDNF mRNA: the supraoptic and periventricular nuclei. In addition, we observed the expression of transcripts from exons, I, II and III as well as the presence of 1.6 and 4.2 kb BDNF mRNAs. Finally, our findings confirmed expression of mRNA encoding neurotrophins receptors in the hypothalamus.

Animals↗
PubMed2001

Initial demonstration of rhythmic Per gene expression in the hypothalamus of a non-mammalian vertebrate, the house sparrow.

In mammals, the major pacemaker controlling circadian rhythmicity is located in the hypothalamic suprachiasmatic nuclei which are characterized by specific molecular features including the expression of three homologues of the Drosophila clock gene period (per). Until now, no comparable structure has been unambiguously described in the brain of any non-mammalian vertebrate. We cloned the PAS-domain of the Per2 gene in the house sparrow (Passer domesticus), a model organism in circadian research. Hypothalamic expression of passerPer2 (pPer2) showed a marked diurnal rhythm in the suprachiasmatic nucleus, a cell group located in the anterior hypothalamus directly above the optic chiasm and adjacent to the third ventricle. Additionally, pPer2 was diurnally expressed in the lateral hypothalamus. This first demonstration of rhythmic clock gene expression in the hypothalamus of a non-mammalian vertebrate provides basic information for future research on the evolution of circadian pacemaking systems.

Animals↗
PubMed1984

Simultaneous presence of estrogen receptors and gonadotropin-releasing hormone in the hypothalamus and of estrogen receptors and follicle-stimulating hormone in the pituitary of the fetal guinea pig.

Early studies in our laboratory have shown the presence of estrogen receptors (ER) in the fetal brain of guinea pig. Ontogenetic evaluation indicated maximal values of these specific binding sites between 50 and 62 days of gestation. We have now characterized ER in both the hypothalamus and the pituitary at the end of gestation. Autoradiographic studies after subcutaneous injection of [3H]estradiol to the fetus showed the nuclear localization of radioactivity in the hypothalamus to be in the neurons of the preoptic area and the nucleus arcuatus where gonadotropin-releasing hormone was also present. Nuclear localization of radioactivity also occurred in the anterior pituitary where the number of labeled cells increased from the border of the intermediate part to the periphery of the anterior lobe. These labeled cells were predominantly gonadotropes containing follicle-stimulating hormone. Since the fetal uterus responds very actively to estrogens, it is suggested that reciprocal influences of the hypothalamus-hypophyseal axis and gonadal steroid hormones are present in the fetal guinea pig.

Animals↗
PubMed1988

Synthesis of catecholamines in the hypothalamus and brainstem in one-kidney, one clip and two-kidney, one clip hypertension in rabbits.

In order to examine the role of central catecholaminergic neurons in hypertension, the activity of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamines, was studied in the hypothalamus, midbrain, pons-upper medulla, mid-medulla and lower medulla of one-kidney, one clip (1-K,1C) and two-kidney, one clip (2-K,1C) hypertensive rabbits and their respective operated controls (1-K,1 Cc and 2-K,1 Cc). Comparing the 1-K,1 C group to the 1-K, 1 Cc group, the activity of TH was increased by 79% in the hypothalamus (P less than 0.02), 37% in the mid-medulla region (P less than 0.02) and was unchanged in the midbrain, pons-upper medulla and the lower medulla. Comparing the 2-K,1 C group to the 2-K,1 Cc group, the activity of TH was increased by 89% in the mid-medulla (P less than 0.01), decreased by 36% in the pons-upper medulla (P less than 0.01) and unchanged in the hypothalamus, midbrain and lower medulla. These results indicate that similarities and differences exist in the contribution of central catecholaminergic neurons to the pathophysiology of 1-K,1 C and 2-K,1 C hypertension in rabbits.

Animals↗
PubMed1998

Histochemical studies on endothelin and the endothelin-A receptor in the hypothalamus.

By use of a rabbit polyclonal antibody specific to the endothelin-A (ETA) receptor, we analyzed the distribution of neurons containing ETA receptors in rat brain. Almost all A1-A7 noradrenergic neurons, A8-A16 and retinal amacrine (A17) dopaminergic neurons (except the A15 group), and C3 adrenergic neurons contained ETA receptors. In addition, hypothalamic magnocellular (noncatecholaminergic) neurons also showed immunoreactivity to ETA receptors, whereas the staining intensity was low. These observations were confirmed by analyzing the expression of c-fos in the hypothalamus after central injection of ET isopeptides. We also examined immunohistochemically the distribution of big ETs and mature ETs in the hypothalamus. The paraventricular and supraoptic magnocellular neurons in the hypothalamus were immunopositive for big ET-1 and mature ET-1. However, their nerve fibers were immunostained only with antibody to big ET-1. The observations on big ET-1 were altered by colchicine treatment. Considering all the evidence, mature ET-1 may regulate neurotransmission in the hypothalamic region, whereas big ET-1 is secreted from nerve terminals into the vessels as a neurohormone. It is also concluded that ET, one of the "brain-vascular peptides," has a close relationship with the catecholamine neuron system in the brain.

Animals↗
PubMed1995

The C-type natriuretic peptide receptor is the predominant natriuretic peptide receptor mRNA expressed in rat hypothalamus.

The natriuretic peptide receptors (NPR) are membrane-bound guanylate cyclases with extracellular binding domains specific for particular members of the natriuretic peptide family. NPR-A binds atrial natriuretic peptide (ANP) with high affinity, whereas the NPR-B appears to be specific for C-type natriuretic peptide (CNP). Previous data indicating extensive overlap between localization of ANP and CNP in hypothalamic neuroendocrine circuits suggest the importance of determining whether specificity of natriuretic peptide action may be conferred via receptor type present on target cells. To address this issue, we used in situ hybridization histochemistry to localize NPR-A and NPR-B mRNA in the hypothalamus. NPR-A mRNA was not found in substantial abundance in any hypothalamic nucleus; however, detectable NPR-A signal was observed in other brain regions, including the subfornical organ and medial habenula. In contrast, NPR-B mRNA was expressed throughout the hypothalamus, including neurons of the magnocellular and parvocellular paraventricular, the arcuate, and the supraoptic nuclei. Expression was also seen in other nuclei essential to neuroendocrine control, including the median preoptic, anteroventral periventricular, tuberomammilary, ventromedial and suprachiasmatic nuclei. NPR-B mRNA was also observed in the neural lobe of the pituitary gland, suggesting expression by pituicytes. The results suggest that NPR-B is the primary natriuretic peptide receptor in hypothalamus, and by inference indicate that CNP is the primary active natriuretic peptide in neuroendocrine regulation.

Animals↗
PubMed2004

Interaction between norepinephrine, oxytocin, and nitric oxide in the stimulation of gonadotropin-releasing hormone release from proestrous rat basal hypothalamus explants.

In the proestrous female rat, norepinephrine, oxytocin and nitric oxide (NO) all participate in the regulation of the preovulatory gonadotropin-releasing hormone (GnRH) surge. Recent studies from our laboratory have demonstrated that oxytocin induces dose-dependent release of GnRH from proestrous basal hypothalamus explants. The present studies were undertaken to determine whether norepinephrine could also stimulate GnRH release from similar explants, to identify the receptors responsible for this effect and to investigate interactions between norepinephrine, oxytocin and NO. Norepinephrine significantly stimulated GnRH release from proestrous basal hypothalamus explants, and coadministration of the alpha(1)-adrenergic antagonist prazosin blocked this effect. Combined administration of oxytocin and norepinephrine stimulated significantly more GnRH release than either drug alone, and this stimulation was blocked by inhibition of NO synthase, or by an oxytocin receptor antagonist. NO production was measured from the same samples using a modified Griess reaction. Oxytocin, but not norepinephrine, significantly increased NO production, as did norepinephrine and oxytocin in combination. Oxytocin receptor antagonist administration attenuated the stimulation of NO production by norepinephrine/oxytocin. These results demonstrate for the first time that oxytocin and norepinephrine dramatically stimulate GnRH release from basal hypothalamus explants harvested on the afternoon of proestrus, and indicate that this involves oxytocin receptor and NO-dependent mechanisms.

Adrenergic alpha-Agonists↗
PubMed2004

Sex differences in the distribution and abundance of androgen receptor mRNA-containing cells in the preoptic area and hypothalamus of the ram and ewe.

Rams and ewes show a negative-feedback response to peripheral treatment with testosterone, with both sexes having a similar degree of suppression in luteinizing hormone (LH) secretion during the breeding season. At least part of the action of testosterone to suppress gonadotropin-releasing hormone/LH secretion is exerted via interaction with an androgen receptor. The distribution of androgen receptor-containing cells in the hypothalamus has been described for the ram, but similar studies have not been performed in the ewe. In the present study, we tested the hypothesis that levels of androgen receptor mRNA expression in the preoptic area and hypothalamus would be similar in rams and ewes. Perfusion-fixed brain tissue was obtained from adult Romney Marsh ewes (luteal phase) and rams during the breeding season (n = 4/sex). Androgen receptor mRNA expression was quantified in hypothalamic sections by in situ hybridization using an (35)S-labelled riboprobe and image analysis. Hybridizing cells were found in the medial preoptic area, bed nucleus of the stria terminalis, anterior hypothalamic area, ventromedial nucleus, arcuate nucleus and premamillary nucleus. The level of androgen receptor mRNA expression was higher in rams than ewes in the rostral preoptic area, caudal preoptic area and rostral portion of the bed nucleus of the stria terminalis, with no sex difference in other regions. The preoptic area and bed nucleus of the stria terminalis are important for reproductive behaviour and the sex differences in androgen receptor mRNA expression at these levels may relate to this. The high level of androgen receptor mRNA expression in the basal hypothalamus, with no sex difference, is consistent with the role of this region in the regulation of gonadotropin secretion.

Animals↗
PubMed2005

Biochemical characterisation and immunohistochemical localisation of the secretogranin II-derived peptide EM66 in the hypothalamus of the jerboa (Jaculus orientalis): modulation by food deprivation.

The neuroendocrine protein secretogranin II is the precursor of several neuropeptides, including secretoneurin and a novel 66-amino acid peptide, EM66, the sequence of which has been highly conserved across the vertebrae phylum. The presence of EM66 has been detected in the adult and fetal human adrenal gland, as well as the rat pituitary and adrenal glands. The present study aimed to explore a possible neuroendocrine role of EM66 by analysing its occurrence and distribution within the jerboa hypothalamus, and its potential implication in the control of feeding behaviour. High-performance liquid chromatography analysis of jerboa hypothalamic extracts combined with a radioimmunoassay of EM66 revealed a single peak of immunoreactive material exhibiting the same retention time as recombinant EM66. Immunocytochemical labelling showed that EM66-producing neurones are widely distributed in several hypothalamic regions, including the preoptic area, the suprachiasmatic, supraoptic, parvocellular paraventricular and arcuate nuclei, and the lateral hypothalamus. Food deprivation for 5 days induced a significant increase in the number of EM66-containing neurones within the arcuate nucleus (105% increase) and the parvocellular aspect of the paraventricular nucleus (115% increase), suggesting that EM66 could be involved in the control of feeding behaviour and/or the response to stress associated with fasting. Altogether, these data reveal the physiological plasticity of the EM66 system in the hypothalamus and implicate this novel peptide in the regulation of neuroendocrine functions.

Amino Acid Sequence↗