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PubMed1992

Immunohistochemical detection of proluteinizing hormone-releasing hormone peptides in neurons in the human hypothalamus.

To determine the presence of LHRH prohormone products in the human hypothalamus, antisera raised against LHRH and GnRH-associated peptide (GAP) were used to search for the presence of the corresponding antigens in the human adult and fetal hypothalamus by an immunohistochemical approach. The comparison of immunostaining on adjacent sections shows that all of the cells labeled with LHRH antiserum are also labeled with GAP antiserum and vice versa. Labeled cells are detectable during the 9th week of fetal life, this being the earliest time evaluated. At this time, the LHRH/GAP-positive cells frequently have a neuroblastic appearance. The first detectable fibers appear during the 11th week, and these were observed in the lamina terminalis cinerea and median eminence. In the adult brain, fibers and endings labeled with LHRH or GAP antiserum in the median eminence demonstrate the same topography and morphological characteristics, which are distinct from fibers labeled with other neuropeptide antisera. These results show that the LHRH precursor molecule is produced throughout life in the human hypothalamus, including the earliest stages of development of the peptidergic neurons. Moreover, the detection of LHRH- and GAP-positive fibers in the median eminence by the 11th week of fetal life suggests the possibility of an early role of LHRH and, possibly, other LHRH prohormone-derived peptides in the development of anterior pituitary function during the fetal period.

Adult↗
PubMed2001

A developmental increase in the expression of messenger ribonucleic acid encoding a second form of gonadotropin-releasing hormone in the rhesus macaque hypothalamus.

GnRH-I is thought to represent the primary neuroendocrine link between the brain and the reproductive axis. Recently, however, a second molecular form of this decapeptide (GnRH-II) was found to be highly expressed in the brains of humans and nonhuman primates. In this study, in situ hybridization was used to examine the regional expression of GnRH-II messenger ribonucleic acid in the hypothalamus of immature (0.6 yr) and adult (10-15 yr) male and female rhesus macaques (Macaca mulatta). Overall, no sex-related differences were observed. In all of the animals (n = 3 animals/group), intense hybridization of a monkey GnRH-II riboprobe was evident in the paraventricular nucleus and supraoptic nucleus and to a lesser extent in the suprachiasmatic nucleus, but no age- or sex-related differences were apparent. Intense hybridization of the riboprobe also occurred in the mediobasal hypothalamus, and this was markedly greater in the adults than in the immature animals. These data show that the expression of GnRH-II messenger ribonucleic acid increases developmentally in a key neuroendocrine center of the brain. Moreover, because GnRH-II can stimulate LH release in vivo, it is plausible that changes in its gene expression represent an important component of the mechanism by which the hypothalamus controls reproductive function.

Animals↗
PubMed1980

Effects of CS-386 and diazepam upon the gastric contraction and excitation of lumbar gamma-motoneurons following stimulation of the hypothalamus in the cat.

Effects of a new minor tranquilizer, CS-386 and diazepam were studied upon the gastric contraction and excitation of lumbar gamma-motoneurons following stimulation of some of the brain structures as well as upon the spontaneous gastric motility in the cat. CS-386 inhibited the hypothalamus-induced gastric contraction with little changes in spontaneous motility at doses of 5 and 10 mg/kg (i.d.). Diazepam inhibited both the hypothalamus-induced contraction and spontaneous motility at these doses. The vagal nerve-induced gastric contraction was suppressed by diazepam (5 mg/kg, i.d.) but not by the same dose of CS-386. Bemegride (5 mg/kg, i.v.) antagonized almost completely the depression caused by 5 mg/kg of CS-386, but not that by a dose of 10 mg/kg or 5 as well as 10 mg/kg of diazepam. Excitation of the lumbar gamma-motoneuron following stimulation of the posterior hypothalamus or the mesencephalic reticular formation was depressed by CS-386 or diazepam (10 mg/kg, p.o.), but not by lower doses. Based on the these evidences, it was suggested that CS-386 could be effective in stress-induced gastric lesions with lower side effects in digestive organs than diazepam.

Animals↗
PubMed1982

A novel effect of salmon calcitonin on in vitro Ca-uptake by rat brain hypothalamus: the regional and hormonal specificities.

It was found that salmon calcitonin-I (sCT) inhibited in vitro 45Ca2+-uptake by rat brain hypothalamus blocks in a dose-dependent manner. The minimum effective concentration was estimated to be 10 nM or less. The effect appeared to be specific to the hypothalamus and was not observed with the pons plus medulla oblongata or the cerebral cortex. Two C-terminal fragments of the fish hormone, sCT (10-32) and sCT (22-32), and porcine calcitonin failed to inhibit the ion-uptake though tested in concentrations abolishing 125I-sCT binding to these brain tissues, indicating that the whole structure of sCT is essential for the inhibitory effect but not for the binding. Another finding to be noted was a possible dependency of this effect on the integrity of the cell membrane structure. A crude synaptosomal fraction subsequently prepared from sCT-exposed hypothalamus blocks exhibited a decreased uptake of 45Ca2+, while a corresponding fraction from unexposed tissue did not respond to the hormone. These characteristics of this novel in vitro effect of sCT suggest its possible relevancy to the anorectic effect which also appears to be specific to the fish hormone.

Animals↗
PubMed1989

Dual effects on gastric acid secretion of electrical stimulation of anterior parts of the rat hypothalamus.

The effect of electrical stimulation of anterior parts of the hypothalamus on gastric acid secretion was examined in rats anesthetized with urethane. Electrical stimulation (0.5 mA, 2 msec, 10 Hz, for 10 min) of the lateral hypothalamic area (LHA) induced a marked increase in basal gastric acid output. Electrical stimulation of the preoptic area (PO), the paraventricular nucleus (PVN) and the anterior hypothalamus (AH) also induced increases in basal acid secretion. Electrical stimulation of the PO, PVN and AH inhibited the increase in acid secretion induced by electrical stimulation of the vagus nerve (1 mA, 0.5 msec, 3 Hz). These inhibitory effects were abolished by bilateral cutting of the splanchnic nerves. On the other hand, the stimulation of the LHA had no effects on vagally stimulated gastric acid secretion. Electrical stimulation of the anterior parts of the hypothalamus induces dual effects, vagally mediated increases in basal gastric acid output and splanchnic mediated inhibition of the vagally stimulated gastric acid output.

Animals↗
PubMed2003

Pyrogens enhance beta-endorphin release in hypothalamus and trigger fever that can be attenuated by buprenorphine.

At first, we investigated whether both beta-endorphin release level in the hypothalamus and body temperature can be altered after intracerebroventricular (i.c.v.) injection of either lipopolysaccharide (LPS), interleukin-1beta (IL-1beta), or prostaglandin E(2) (PGE(2)) in rats. It was found that in the rat, i.c.v. administration of either LPS (0.5 microg in 10 microl), IL-1beta (10 ng in 10 microl), or PGE(2) (200 ng in 10 microl), in addition to producing fever, upregulated the immunoreactivity of beta-endorphin in the preoptic anterior hypothalamus of rat brain. Secondarily, we assessed whether the fever induced by either LPS, IL-1beta, or PGE(2) can be altered by pretreatment with buprenorphine (an opioid receptor antagonist). The results revealed that i.c.v. administration of buprenorphine (1 - 10 microg in 10 microl) alone had an insignificant effect on the body temperature. However, the fever induced by i.c.v. injection of either LPS, IL-1beta, or PGE(2) was significantly attenuated by pretreatment with i.c.v. injection of buprenorphine 1 h before the pyrogen injection in rats. The results suggest that pyrogens enhance beta-endorphin release in the hypothalamus and trigger fever which can be attenuated by buprenorphine, an opioid receptor antagonist.

Animals↗
PubMed2003

Expression analyses of sex steroid-regulated genes in neonatal rat hypothalamus.

Estrogen plays an important role in sexual differentiation of the brain in rats during the perinatal period. To elucidate molecular mechanisms underlying sexual differentiation of the brain, in this study we investigated genes differentially expressed between sexes or induced to express by estrogen in neonatal rat hypothalamus using DNA microarray analysis in combination with real-time RT-PCR. It was found that the levels of expression of the genes encoding glutamic acid decarboxylase 65 and coronin 1b were higher in male than female hypothalamus on postnatal day (PN) 5 and those of collagen type 3 alpha1 and thioredoxin reductase 2 genes in female hypothalamus on PN5 were decreased and increased, respectively, by treatment with estradiol on PN2. Then the developmental changes in the expression of these 4 genes were examined from 1 day before the parturition to PN9, and they all showed sexual dimorphic patterns. In addition, dependence of the expression of these genes on either estradiol, testosterone or dihydrotestosterone during the neonatal period was confirmed. These results suggest that these four genes are involved in sexual differentiation of the rat brain, and that androgen per se as well as estrogen may take part in the processes.

4-Butyrolactone↗
PubMed2002

Octylphenol (OP) alters the expression of members of the amyloid protein family in the hypothalamus of the snapping turtle, Chelydra serpentina serpentina.

The gonadal estrogen estradiol-17beta (E(2)) is important for developing and regulating hypothalamic function and many aspects of reproduction in vertebrates. Pollutants such as octylphenol (OP) that mimic the actions of estrogens are therefore candidate endocrine-disrupting chemicals. We used a differential display strategy (RNA-arbitrarily primed polymerase chain reaction) to isolate partial cDNA sequences of neurotransmitter, developmental, and disease-related genes that may be regulated by OP or E(2) in the snapping turtle Chelydra serpentina serpentina hypothalamus. Hatchling and year-old male snapping turtles were exposed to a 10 ng/mL nominal concentration of waterborne OP or E(2) for 17 days. One transcript [421 base pairs (bp)] regulated by OP and E(2) was 93% identical to human APLP-2. APLP-2 and the amyloid precursor protein (APP) regulate neuronal differentiation and are also implicated in the genesis of Alzheimer disease in humans. Northern blot analysis determined that the turtle hypothalamus contains a single APLP-2 transcript of 3.75 kb in length. Exposure to OP upregulated hypothalamic APLP-2 mRNA levels 2-fold (p < 0.05) in month-old and yearling turtles. E(2) did not affect APLP-2 mRNA levels in hatchlings but stimulated a 2-fold increase (p < 0.05) in APLP-2 mRNA levels in yearling males. The protein beta-amyloid, a selectively processed peptide derived from APP, is also involved in neuronal differentiation, and accumulation of this neurotoxic peptide causes neuronal degeneration in the brains of patients with Alzheimer disease. Therefore, we also sought to determine the effects of estrogens on the expression of beta-amyloid. Using homology cloning based on known sequences, we isolated a cDNA fragment (474 bp) from turtle brain with 88% identity to human APP. Northern blot analysis determined that a single 3.5-kb transcript was expressed in the turtle hypothalamus. Waterborne OP also increased the expression of hypothalamic APP after 35 days of exposure. Our results indicate that low levels of OP are bioactive and can alter the expression of APLP-2 and APP. Because members of the APP gene family are involved in neuronal development, we hypothesize that OP exposure may disrupt hypothalamic development in young turtles.

Alzheimer Disease↗
PubMed1997

Immunohistochemical localization of corticotropin-releasing factor, [arginine8]-vasopressin and oxytocin neurons in the goat hypothalamus.

Distribution patterns of corticotropin-releasing factor (CRF), [arginine8]-vasopressin (AVP) and oxytocin (OXY) neurons were examined immunohistochemically in the female goat hypothalamus. The majority of the CRF immunoreactive (-IR) cells were located in the parvocellular part of the paraventricular nucleus (PVN) with smaller population found in the magnocellular part of the PVN. CRF-IR cells were also found in the suprachiasmatic nucleus, the preoptic area and around the fornix in the caudal part of the hypothalamus. AVP- and OXY-IR cells were similarly distributed in the hypothalamus. The majority of AVP- and OXY-IR cells were observed in the magnocellular part of PVN and the supraoptic nucleus. Smaller numbers of AVP- and OXY-IR cells were found in the parvocellular part of the PVN and lateral hypothalamic area. AVP-IR but not OXY-IR cells were located in the suprachiasmatic nucleus. CRF-IR fibers were concentrated in the external palisade zone of the median eminence (ME) with a few fibers found in the internal palisade zone of the ME, whereas AVP- and OXY-IR fibers were concentrated in the internal palisade zone of the ME with a few fibers found in the external zone. These results support the view that not only CRF but also AVP and OXY are released into the hypophysial portal blood and involved in the control of pituitary endocrine function in ruminant species.

Animals↗
PubMed2002

Dehydroepiandrosterone regulates insulin-like growth factor-1 system in adult rat hypothalamus.

Dehydroepiandrosterone (DHEA) and its sulfate ester (DHEA-S) exert multiple effects in rodent and human brain. Several findings suggest that insulin-like growth factor-1 (IGF-1) is involved in the actions of DHEA. In this study, we assessed whether systemic administration of DHEA regulates the IGF-1 system in the hypothalamus, hippocampus, cerebral cortex, and cerebellum of adult rats. DHEA resulted in a significant reduction in IGF-1 receptor protein levels. This effect was dose dependent and restricted to the hypothalamus. In contrast to IGF-1 receptor, IGF-1-binding protein 2 levels were unaffected by DHEA treatment. IGF-1 levels were significantly increased in the hypothalamus of the rats treated with DHEA, whereas IGF-1 serum levels were not affected by DHEA. The effects of DHEA on the hypothalamic IGF-1 system may be highly relevant to the control and maintenance of hypothalamic neuroendocrine function.

Animals↗
PubMed1998

Expression of activin and follistatin in the rat hypothalamus: anatomical association with gonadotropin-releasing hormone neurons and possible role of central activin in the regulation of luteinizing hormone release.

The central role of activin in the regulation of the reproductive axis remains largely unexplored. Evidence suggests that activin may play a role in control-linggonadotropin-releasing hormone (GnRH) release. We assessed potential neuroanatomical associations between activin- and GnRH-neuronal systems via examination of the distribution of activin betaA-subunit and activin binding protein (follistatin) protein and mRNA signals relative to GnRH neurons in the adult rat brain. Activin betaA-subunit-immunostained fibers were distributed throughout the hypothalamus and GnRH-positive perikarya, and fibers were in close association with betaA-subunit-immunoreactive fibers. Follistatin mRNA-expressing cells were also identified throughout the hypothalamus with GnRH fibers often observed juxtaposed to follistatin cell bodies. Colocalization of either the betaA-subunit or follistatin within GnRH neurons was not detected. The functional significance of central activin in the regulation of the reproductive axis was also demonstrated. The intracerebroventricular infusion of rh-activin A significantly increased luteinizing hormone, but not follicule-stimulating hormone, serum levels in adult male rats. Taken together, the present results support an interaction between activin and GnRH neuronal systems in the rat hypothalamus, and suggest activin may act within the brain to regulate the reproductive axis.

Activins↗
PubMed1994

[Expression of nitric oxide synthase in enkephalin and dynorphin systems of the rat hypothalamus].

Nitric oxide (NO), a simple gas with free radical chemical properties, is synthesized by nitric oxide synthase (NOS) from arginine in neurons and acts as a neurotransmitter in the central and peripheral nervous systems. The immunohistochemical demonstration of NOS-immunoreactivity and its histochemical marker, NADPH-diaphorase activity in many neurons of the hypothalamus, suggest that NO plays a role in controlling the production and/or release of hypothalamic neuroendocrine peptides. In the present study, the expression of NOS in the enkephalin and dynorphin systems of the rat hypothalamus was examined by the combined method of the NADPH-diaphorase histochemistry and the immunocytochemistry of methionine enkephalin (M-Enk) or dynorphin B (Dyn-B). About 6 to 9% of M-Enk immunoreactive neurons in the paraventricular, arcuate and ventromedial nuclei expressed NADPH-diaphorase activity. Dyn-B immunoreactive neurons, however, showed NADPH-diaphorase activity in high ratio (37%-84%) in the supraoptic nucleus and the parvocellular and magnocellular paraventricular nucleus. These results revealed that a part of the enkephalin and dynorphin neurons in the rat hypothalamus have the ability to produce NO. The high ratio of expression of NO in magnocellular neurosecretory dynorphin containing neurons suggested that NO participates in controlling posterior pituitary hormone secretion together with dynorphin.

Amino Acid Oxidoreductases↗
PubMed1977

Further evidence of the presence of progesterone-binding proteins in female rat hypothalamus.

Utilizing techniques of Sephadex G-200 column chromatography, sucrose density gradient ultracentrifugation and dextran-coated charcoal adsorption, the characterization of progesterone-binding proteins was attempted in cytosols obtained from the medial basal hypothalamus including the median eminence, the remaining hypothalamus and the cerebral cortex of ovariectomized estrogen-primed rats. Ater incubation of the medial basal hypothalamic cytosol with 3H-progesterone in the absence or in the presence of various unlabeled steroids, a specific progesterone-binding protein was found in the 7 S region with its binding capacity of approximately 2 X 10(14) moles per mg protein and dissociation constant of approximately 6 X 10(-9) M. No specific binding was, however, found in the remaining hypothalamus and the cerebral cortex.

Animals↗
PubMed1984

Effects of fasting on the distribution of cytoplasmic and nuclear oestrogen receptors in rat liver, uterus, pituitary and hypothalamus before and after exogenous oestrogen administration.

The accumulation of oestrogen receptors in the liver cell nuclei of intact female rats 45 min after administration of 100 micrograms 17 alpha-ethynyloestradiol-17 beta i.p., decreased progressively during a 72-h fast from 2550 +/- 860 to 257 +/- 67 fmol/mg DNA, a level not significantly different from that in uninjected animals. Cytoplasmic oestrogen receptor concentrations also decreased, but only to about 60% of the original level (from 84.1 +/- 27.5 to 50.3 +/- 2.09 fmol/mg protein during the fast). Similar differences were found when these parameters were examined in normally fed and 72-h-fasted ovariectomized rats. On the other hand these parameters were unaffected in uterus, pituitary and hypothalamus. Uterine cytoplasmic receptor concentrations remained at about 500 fmol/mg protein during the fasting period, those in the pituitary and hypothalamus at about 230 and 30 fmol/mg protein, respectively. Nor was in vivo translocation in these organs affected by fasting. Regardless of nutritional status, the nuclear oestrogen receptor concentrations in uterus rose from about 500 to 2000 fmol/mg DNA after ethynyloestradiol administration, those in the pituitary and hypothalamus from approximately 250 to 2000 and from 250 to 500 fmol/mg DNA respectively.

Animals↗
PubMed2006

Corticosterone-sensitive monoamine transport in the rat dorsomedial hypothalamus: potential role for organic cation transporter 3 in stress-induced modulation of monoaminergic neurotransmission.

Glucocorticoid hormones act within the brain to alter physiological and behavioral responses to stress-related stimuli. Previous studies indicated that acute stressors can increase serotonin [5-hydroxytryptamine (5-HT)] concentrations in the dorsomedial hypothalamus (DMH), a midline hypothalamic structure involved in the integration of physiological and behavioral responses to stress. The current study tests the hypothesis that rapid, stress-induced accumulation of 5-HT is attributable to the inhibition of 5-HT transport via organic cation transporters (OCTs). OCTs are a family of high-capacity, bidirectional, multispecific transporters of organic cations (including 5-HT, dopamine, and norepinephrine) only recently described in brain. In peripheral tissues, organic cation transport via some OCTs is inhibited by corticosterone. We examined the expression and function of OCTs in the periventricular medial hypothalamus of male Sprague Dawley rats using reverse-transcriptase (RT)-PCR, immunohistochemistry, and in vitro transport assays. RT-PCR revealed expression of OCT3 mRNA, but not OCT1 or OCT2 mRNA, in the medial hypothalamus. OCT3-like immunoreactivity was observed in ependymal and glial-like cells in the DMH. Acutely prepared minces of rat medial hypothalamic tissue accumulated the OCT substrates [3H]-histamine and [3H]-N-methyl-4-phenylpyridinium ([3H]-MPP+). Consistent with the pharmacological profile of OCT3, corticosterone, 5-HT, estradiol, and the OCT inhibitor decynium22 dose-dependently inhibited histamine accumulation. Corticosterone and decynium22 also inhibited efflux of [3H]-MPP+ from hypothalamic minces. These data support the hypothesis that corticosterone-induced inhibition of OCT3 mediates stress-induced accumulation of 5-HT in the DMH and suggest that corticosterone may acutely modulate physiological and behavioral responses to stressors by altering serotonergic neurotransmission in this brain region.

1-Methyl-4-phenylpyridinium↗
PubMed1980

Ontogeny of somatostatin in the human gastro-intestinal tract, endocrine pancreas and hypothalamus.

The appearance, time and distribution of somatostatin in the pancreas, gastro-intestinal tract and hypothalamus were studied comparatively in human foetuses aged 6--32 weeks, by immuno-cytochemistry and radioimmunoassay. Somatostatin was detected by both methods in all segments including the colon. The first cells were observed, and somatostatin was present in measurable amounts at 8 weeks in pancreas, duodenum and intestine, while the peptide was detected at 12 weeks in antrum and colon, at 14 weeks in fundus, and at 16 weeks in hypothalamus. Subsequently, the largest cell population was located in the pancreas, where peptide concentration and age were positively correlated (P less than 0.01, r = 64). From 15 to 21 weeks of age, the mean somatostatin concentration in pancreas (12.4 +/- 1.84 ng/mg) was clearly higher than in hypothalamus (0.05 +/- 0.02 ng/mg) or in any segment of the gut, where values ranged from 0.36 +/- 0.06 (fundus) to 4.74 +/- 0.83 ng/mg (duodenum). The early appearance time of somatostatin, and its specific distribution with preferential location in the pancreas, suggest that the peptide may play a major role for the development of the foetal digestive tract, and that it may be involved in the regulation of other endocrine secretions, especially in the pancreas.

Digestive System↗
PubMed2004

Orexin A and B levels in the hypothalamus of female rats: the effects of the estrous cycle and age.

OBJECTIVE: Orexins have been implicated in the regulation of several physiological functions including reproduction, energy balance and vigilance state. For successful reproduction, the precisely timed hormonal secretions of the estrous cycle must be combined with appropriate nutritional and vigilance states. The steroid- and nutritional state-dependent modulation of LH release by orexins, as well as an increase of vigilance, suggest that orexins may co-ordinate these functions in the course of the estrous cycle. DESIGN: We studied the brain tissue levels of orexins in the course of the estrous cycle in young and middle-aged rats. Young cycling rats (3 months old) and irregularly/non-cycling (7-9 months old) female rats were inspected for vaginal smears and serum hormone levels. METHODS: Tissue concentrations of orexin A and B were measured in the hypothalamus and lateral hypothalamus on different days of the estrous cycle. RESULTS: Orexin A concentration in the hypothalamus of young cycling rats was higher on the day of proestrus 5-6 h after the lights were switched on than on the other days of the estrous cycle at the same circadian time. Orexin B concentration was higher on both the day of proestrus and the day of estrus as compared with the days of diestrus. The hypothalamic concentrations of both orexin A and B in the non-cycling middle-aged rats were lower than those in cycling rats on the days of proestrus and estrus. CONCLUSIONS: We have concluded that the high hypothalamic concentration of orexins on the day of proestrus may contribute to the LH and prolactin surges. High orexin A levels may also contribute to the decreased amount of sleep on the day of proestrus.

Aging↗
PubMed1994

Immunoreactive substance P and neurokinin A in the hypothalamus and anterior pituitary gland of Siberian and Syrian hamsters and of rats.

In this investigation the concentrations of immunoreactive substance P and neurokinin A in the hypothalamus and anterior pituitary of the Siberian hamster were compared with those in the rat and Syrian hamster. The concentrations of immunoreactive neurokinin A in the hypothalamus of Siberian hamsters were significantly higher than those of rats and Syrian hamsters, while male Siberian hamsters had similar amounts of substance P in the hypothalamus to those of male Syrian hamsters, but had higher amounts than those in male rats. However, female Siberian hamsters and significantly higher hypothalamic concentrations of both substance P and neurokinin A than did female Syrian hamsters and rats. In the anterior pituitary glands of Siberian hamsters, concentrations of substance P and neurokinin A were markedly higher than they were in rats and even more so more in Syrian hamsters. Ovariectomy further increased tachykinin concentrations in the anterior pituitary gland of female Siberian hamsters, and this was completely prevented by oestradiol replacement. Female Siberian hamsters kept under conditions of reduced photoperiod had significantly higher tachykinin concentrations in the anterior pituitary than did animals kept under daily photoperiods of 16 h light:8 h dark. The incubation of anterior pituitaries from female Siberian hamsters with a neurokinin A receptor antagonist resulted in a partial blockade of the LH and FSH release in response to LHRH. Thus, the high concentration of tachykinins present in the anterior pituitary of the Siberian hamster may have a local role in modulating the secretion or release of gonadotrophins.

Animals↗