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At least 649 records · Page 36Linked to original sources
PubMed1985

Electroconvulsive shock increases preproenkephalin messenger RNA abundance in rat hypothalamus.

Daily administration of electroconvulsive shock (ECS) to rats for 10 days increased the content of [Met5]enkephalin in the hypothalamus and the striatum by 64% and 45%, respectively. The effect of ECS on the relative abundance of mRNA coding for the enkephalin precursor preproenkephalin was investigated. Analysis by cell-free translation of polyadenylylated RNA and immunoprecipitation of preproenkephalin revealed ECS-elicited increases of 79% and 14% in preproenkephalin mRNA activity in the hypothalamus and striatum, respectively. ECS treatment did not affect the general translational activity of total polyadenylylated RNA from these brain regions. A 32P-labeled probe prepared from a rat preproenkephalin cDNA clone hybridized with an apparently single species of polyadenylylated RNA of approximately equal to 1450 nucleotides from both hypothalamus and striatum. Dot-blot hybridization of polyadenylylated RNA with the rat probe indicated that ECS elicits a 76% increase in the preproenkephalin mRNA abundance in the hypothalamus and no significant change in the striatum. These results suggest that ECS treatment leads to enhanced biosynthesis of the enkephalin precursor in hypothalamic neurons.

Animals↗
PubMed2006

Diet-induced obesity alters AMP kinase activity in hypothalamus and skeletal muscle.

AMP-activated protein kinase (AMPK) is a key regulator of cellular energy balance and of the effects of leptin on food intake and fatty acid oxidation. Obesity is usually associated with resistance to the effects of leptin on food intake and body weight. To determine whether diet-induced obesity (DIO) impairs the AMPK response to leptin in muscle and/or hypothalamus, we fed FVB mice a high fat (55%) diet for 10-12 weeks. Leptin acutely decreased food intake by approximately 30% in chow-fed mice. DIO mice tended to eat less, and leptin had no effect on food intake. Leptin decreased respiratory exchange ratio in chow-fed mice indicating increased fatty acid oxidation. Respiratory exchange ratio was low basally in high fat-fed mice, and leptin had no further effect. Leptin (3 mg/kg intraperitoneally) increased alpha2-AMPK activity 2-fold in muscle in chow-fed mice but not in DIO mice. Leptin decreased acetyl-CoA carboxylase activity 40% in muscle from chow-fed mice. In muscle from DIO mice, acetyl-CoA carboxylase activity was basally low, and leptin had no further effect. In paraventricular, arcuate, and medial hypothalamus of chow-fed mice, leptin inhibited alpha2-AMPK activity but not in DIO mice. In addition, leptin increased STAT3 phosphorylation 2-fold in arcuate of chow-fed mice, but this effect was attenuated because of elevated basal STAT3 phosphorylation in DIO mice. Thus, DIO in FVB mice alters alpha2-AMPK in muscle and hypothalamus and STAT3 in hypothalamus and impairs further effects of leptin on these signaling pathways. Defective responses of AMPK to leptin may contribute to resistance to leptin action on food intake and energy expenditure in obese states.

AMP-Activated Protein Kinases↗
PubMed2002

Preference for a solution of branched-chain amino acids plus glutamine and arginine correlates with free running activity in rats: involvement of serotonergic-dependent processes of lateral hypothalamus.

Rats were given free access to a running wheel, food, water, and a solution composed of branched-chain amino acids plus glutamine and arginine (the "BCAA-based" solution). A positive relationship between dark-period running distance and preference for the BCAA-based solution was observed. Serotonin release in the lateral hypothalamus, the central nucleus of amygdala and the medial nucleus raphe in overnight fluid-deprived rats during their first subsequent free drinking was also measured. A lowered serotonin release in the lateral hypothalamus characterized the rats that consumed the BCAA-based solution. No drink-related changes were observed in the amygdala. A separate group of rats was trained on a treadmill. Following the training period, plasma amino acids and brain serotonin release were measured during running. The BCAA-based solution infused before running elevated the branched chain amino acids/tryptophan plasma ratio at the end of, and after, running. Additionally, a decreased lateral hypothalamus serotonin release was seen 80 min after running, when compared with water-infused rats. No fluid-related changes in the amygdala were observed. The exercise-related shift in the fluid preference towards a BCAA-based solution suggests an ergogenic benefit. The forced-running study shows the lateral hypothalamus as a critical region in the effects of a BCAA-based solution.

Amino Acids, Branched-Chain↗
PubMed2003

Low dietary protein is associated with an increase in food intake and a decrease in the in vitro release of radiolabeled glutamate and GABA from the lateral hypothalamus.

Moderately low-protein diets lead to a rapid increase in food intake and body fat. The increase in feeding is associated with a decrease in the concentration of serum urea nitrogen, suggesting that the low-protein-induced increase in food intake may be related to the decreased metabolism of nitrogen from amino acids. We hypothesized that low dietary protein would be associated with a decrease in the synaptic release of two nitrogen-containing neurotransmitters, GABA and glutamate, whose nitrogen can be derived from amino acids. In this study, we examined the effects of a low-protein diet (10% casein) in Sprague-Dawley rats on the in vitro release of 3H-GABA and 14C-glutamate from the lateral and medial hypothalamus. The low-protein diet increased food intake by about 25% after one day. After four days, the in vitro release of radiolabeled GABA and glutamate was assessed. The calcium-dependent, potassium-stimulated release of radiolabeled GABA and glutamate from the lateral hypothalamus was decreased in rats fed the low-protein diet. The magnitude of neurotransmitter release from the lateral hypothalamus inversely correlated with food intake. No dietary differences in the release of neurotransmitters from the medial hypothalamus were observed. These results support the contention that alterations in nitrogen metabolism are associated with low-protein-induced feeding.

Ammonia↗
PubMed2003

Expression of vasoactive intestinal peptide receptor messenger RNA in the hypothalamus and pituitary throughout the turkey reproductive cycle.

Vasoactive intestinal peptide (VIP) has been implicated in the regulation of avian reproductive activity and appears to act at the level of the hypothalamus and pituitary. This in situ hybridization histochemistry study describes the distribution of VIP receptor mRNA expression in the hypothalamus and the pituitary of reproductively active (laying) and quiescent (nonphotostimulated, incubating, and photorefractory) female turkeys and characterizes the differences observed in VIP receptor gene expression. VIP receptor mRNA, while expressed throughout the hypothalamus, was specifically expressed in areas known to contain GnRH-I neurons in the chicken, i.e., the lateral septum, medial preoptic area, anterior hypothalamus, and paraventricular nucleus. Significant differences in VIP receptor mRNA expression between different reproductive states was observed only within the infundibular nuclear complex. VIP receptor mRNA was markedly less in nonphotostimulated and photorefractory hens as compared with laying and incubating hens. The most dense VIP receptor mRNA was found in the anterior pituitary, where it was 2.4- and 3.0-fold greater in laying and incubating hens, respectively, as compared with that in nonphotostimulated ones. Hens that stopped incubating and became photorefractory displayed pituitary VIP receptor mRNA levels similar to those of nonphotostimulated birds. The changes in pituitary VIP receptor mRNA expression were positively correlated with known changes in pituitary prolactin (PRL) mRNA expression and PRL content and release. These findings indicate that the variations in PRL secretion observed across the turkey reproductive cycle are, in part, regulated by changes in VIP receptors at the pituitary level.

Animals↗
PubMed1998

Fos expression in luteinizing hormone-releasing hormone neurons of guinea pigs, with knife cuts separating the preoptic area and the hypothalamus, demonstrating luteinizing hormone surges.

LHRH neurons in guinea pigs, as in primates and other non-rodent species, are broadly distributed in the basal forebrain. In this study, knife cuts were made in the anterior hypothalamus, effectively separating more caudally positioned hypothalamic LHRH neurons from those in rostral preoptic areas. Guinea pigs with knife cuts displayed an LH surge in response to steroid administration. There was no significant difference in the number of LHRH neurons that expressed Fos in conjunction with an LH surge, although fewer total LHRH neurons were detected in the forebrain of knife-cut versus sham-cut animals. Knife-cut animals displayed a larger percentage of LHRH/Fos neurons in one region of the caudal hypothalamus than sham-cut animals. The area and perimeter of the LHRH reaction product within the cytoplasm of LHRH/Fos neurons were smaller than those of single-labeled LHRH neurons in sham-cut animals and in the caudal hypothalamus, but not the rostral preoptic area, of knife-cut animals. We conclude that caudal hypothalamic LHRH neurons separated from rostral preoptic regions are capable of sustaining an LH surge in guinea pigs. This finding is important, as LHRH neurons are present in the caudal hypothalamus, as well as in preoptic areas, of a large number of mammalian species, including humans.

Animals↗
PubMed1998

Modulation of neuropeptide Y overflow by leptin in the rat hypothalamus, cerebral cortex and medulla.

This study examined whether leptin can exert inhibitory actions on brain NPY overflow in Sprague-Dawley and in lean and obese Zucker rats, and tested the site-specificity of the effect. Slices of rat hypothalamus, cerebral cortex and medulla oblongata were perfused with modified Krebs buffer containing either leptin or KCl. Depolarization of tissues with 40 mM KCl elicited a significant doubling of NPY overflow in all brain regions tested. At 1 microM, leptin significantly reduced NPY overflow only in the rat hypothalamus, while at 3 microM, leptin reduced NPY overflow from all regions. However, no effect of 1 microM leptin was observed in the hypothalamus of obese Zucker rats: this insensitivity to leptin is in keeping with their genetic defect. In conclusion, the inhibitory effect of leptin on hypothalamic NPY overflow provides further evidence for important modulatory actions between these two feeding mediators. Moreover, the effect of leptin observed in the cerebral cortex and medulla oblongata supports a role of leptin in brain regions other than the hypothalamus.

Adipose Tissue↗
PubMed1998

Existence of capsaicin-sensitive glutamatergic terminals in rat hypothalamus.

Capsaicin has been suggested to act not only on thin primary afferents but also on the hypothalamus, but the neurotransmitter(s) of central capsaicin-sensitive neurons are unknown. The present study was conducted to determine whether any central, especially hypothalamic, glutamatergic terminals were sensitive to capsaicin. Capsaicin evoked glutamate release from slices of hypothalamus and lumbar dorsal horn, but not cerebellum. Such capsaicin action was Ca2+ dependent and inhibited by the capsaicin antagonist capsazepine. Vanilloid receptor subtype 1 mRNA was widely distributed in the brain, with a marked level in the hypothalamus and cerebellum, but not in the spinal cord. The results suggest that there are glutamatergic terminals sensitive to capsaicin in the hypothalamus.

Animals↗
PubMed1992

Increased level of atrial natriuretic peptide messenger RNA in the hypothalamus and brainstem of spontaneously hypertensive rats.

OBJECTIVE: The aim of this study was to investigate atrial natriuretic peptide (ANP) gene expression in the central nervous system (CNS) during hypertension. METHODS: We measured and compared immunoreactive atrial natriuretic peptide (irANP) and ANP messenger RNA (mRNA) in the hypothalamus and brainstem of 17-week-old spontaneously hypertensive rats (SHR) with those of age-matched Wistar-Kyoto (WKY) rats using ribonuclease (RNase) protection assay for ANP mRNA and a specific radioimmunoassay for irANP. RESULTS: RNase protection assay revealed that the concentrations of ANP mRNA in the hypothalamus and brainstem of SHR were higher than those of WKY rats. IrANP concentrations in the hypothalamus and brainstem of SHR were determined by a specific radioimmunoassay and found to be higher than those of WKY rats. Elevated mRNA levels in the hypothalamus and brainstem of SHR indicated that increased level of irANP in the CNS resulted from increased synthesis of ANP. CONCLUSION: We propose that increased synthesis of brain ANP in SHR may reflect a compensatory mechanism induced by hypertension.

Animals↗
PubMed2004

Ethanol-induced Fos immunoreactivity in the extended amygdala and hypothalamus of the rat brain: focus on cholinergic interneurons of the nucleus accumbens.

BACKGROUND: The primary goal of this study was to investigate the effects of varying doses of ethanol on cellular activation, as measured by Fos immunoreactivity, in brain areas that have been implicated in the reinforcing and anxiolytic effects of substance abuse and dependence, namely, the extended amygdala and hypothalamus. Specific regions examined included the central nucleus of the amygdala, bed nucleus of the stria terminalis, substantia innominata, and nucleus accumbens of the extended amygdala, as well as the paraventricular nucleus of the hypothalamus. The cholinergic interneurons of the nucleus accumbens were of particular interest, because these cells have recently been reported to play a pivotal role in substance abuse. METHODS: Adult Sprague-Dawley rats underwent 10 days of handling and 5 days of habituation. Animals then received an injection of saline or 0.5, 1, or 2 g/kg of ethanol. Rats were perfused 2 hr after the injections, and brain sections were processed for single Fos or dual Fos/choline acetyltransferase immunolabeling procedures. The number of Fos-positive neurons was calculated from a 0.45-mm sample area from each of the brain regions examined. RESULTS: A dose of 2 g/kg of ethanol significantly increased the number of Fos-immunoreactive neurons in the central nucleus of the amygdala by 149%, in the shell nucleus accumbens by 80%, and in the paraventricular nucleus of the hypothalamus by 321%. Additionally, 1 g/kg of ethanol significantly increased the percentage of Fos-immunoreactive cholinergic neurons in the nucleus accumbens by 59%. CONCLUSIONS: The findings reported in this study reveal region-specific and dose-dependent changes in Fos immunoreactivity in the extended amygdala and hypothalamus and, more specifically, an increase in neuronal activation of cholinergic cells in the shell nucleus accumbens. These findings contribute to our current knowledge of the brain areas and cellular microcircuits involved in the underlying basis of substance abuse and dependence.

Amygdala↗
PubMed1995

The POU domain transcription factor Brn-2 is required for the determination of specific neuronal lineages in the hypothalamus of the mouse.

We generated mice carrying a loss-of-function mutation in Brn-2, a gene encoding a nervous system specific POU transcription factor, by gene targeting in embryonic stem cells. In homozygous mutant embryos, migratory precursor cells for neurons of the paraventricular nuclei (PVN) and the supraoptic nuclei (SO) of the hypothalamus die at approximately E12.5. All homozygous mutants suffered mortality within 10 days after birth, possibly because of a complete deficiency of these neurons in the hypothalamus. Although neither developmental nor histological abnormalities were observed in heterozygous mice, the levels of expression of vasopressin and oxytocin in the hypothalamus of these animals were half these of wild-type mice. These results strongly suggest that Brn-2 plays an essential role in the determination and development of the PVN and SO neuronal lineages in the hypothalamus.

Animals↗
PubMed1995

Estrogen-sensitive oxytocin binding sites are differently regulated by progesterone in the telencephalon and the hypothalamus of the rat.

The localization at the cellular level and the regulation by progesterone of the estrogen-sensitive oxytocin binding sites was studied in the rat telencephalon and the hypothalamus by using quantitative film-autoradiography and histoautoradiography. Male rats (castrated or not) and ovariectomized females (estradiol supplemented or not) were used to characterize these sites and to precise their localization. They were detected in the striatal cell bridges, the olfactory tubercle, the principal nucleus of the bed nucleus of the stria terminalis and the medial nucleus of the amygdala of the telencephalon and in the medial preoptic, the ventromedial and the ventral premammillary nuclei of the hypothalamus. Estrogen administration in addition induced expression of oxytocin binding sites in the major island of Calleja, the anterior hypothalamic area and the terete nucleus. The density of the estrogen-sensitive oxytocin binding sites varied during the estrous cycle, but differently in the telencephalon and the hypothalamus. In the telencephalon it peaked at proestrus 9 h and was already decreased at proestrus 21 h, whereas in the hypothalamus it was similarly high at proestrus 9 h and proestrus 21 h, suggesting the intervention of progesterone in the regulation of the hypothalamic estrogen-sensitive oxytocin binding sites.

Amino Acid Sequence↗
PubMed2004

Appetite regulatory neuropeptides are expressed in the sheep hypothalamus before birth.

In the adult, a hypothalamic neural network acts to maintain energy balance in response to nutritional feedback from the periphery. Although there is an immediate requirement for this system to be functional at birth, it is unknown whether the components of this central neural network are expressed in the developing brain before birth. We therefore examined in the fetal sheep hypothalamus during late gestation gene expression for leptin receptor (OB-Rb) and neuropeptides that regulate energy balance in the adult. Brains were collected from fetal sheep at 110 days (n = 12) and 140 days of gestation (n = 5) (term = 150 days) and gene expression was detected in all hypothalami using in situ hybridization with radiolabelled riboprobes for OB-Rb, neuropeptide Y (NPY), agouti-related peptide, pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript (CART). All mRNAs were expressed in the arcuate nucleus of fetuses at both time points. Additional sites of mRNA expression were the dorsomedial hypothalamus (DMH) for NPY, the paraventricular nucleus (PVN), ventromedial hypothalamus (VMH) and lateral hypothalamic area for CART, and the DMH, PVN and VMH for OB-Rb. We have therefore demonstrated that adult-like localization of gene expression for OB-Rb and key appetite regulatory neuropeptides is established in the ovine hypothalamus before birth. Thus, the fetus possesses a central appetite regulatory neural network with the potential to respond to changes in nutrient supply, which could impact on energy balance regulation both before and after birth.

Age Factors↗
PubMed2005

Expression of three gene families encoding cell-cell communication molecules in the prepubertal nonhuman primate hypothalamus.

Transsynaptic and glial-neuronal communication are important components of the mechanism underlying the pubertal activation of luteinizing hormone-releasing hormone (LHRH) secretion. The molecules required for the architectural organization of these cell-cell interactions have not been identified. We now show that the hypothalamus of the prepubertal female rhesus monkey expresses a multiplicity of genes encoding three families of adhesion/signalling proteins involved in the structural definition of both neurone-to-neurone and bi-directional neurone-glia communication. These include the neurexin/neuroligin (NRX/NRL) and protocadherin-alpha (PCDHalpha) families of synaptic specifiers/adhesion molecules, and key components of the contactin-dependent neuronal-glial adhesiveness complex, including contactin/F3 itself, the contactin-associated protein-1 (CASPR1), and the glial receptor protein tyrosine phosphatase beta. Prominently expressed among members of the NRX family is the neurexin isoform involved in the specification of glutamatergic synapses. Although NRXs, PCDHalphas and CASPR1 transcripts are mostly detected in neurones, the topography of expression appears different. NRX1 mRNA-containing neurones are scattered throughout the hypothalamus, PCDHalpha mRNA transcripts appear more abundant in neurones of the arcuate nucleus and periventricular region, and neurones positive for CASPR1 mRNA exhibit a particularly striking distribution pattern that delineates the hypothalamus. Examination of LHRH neurones, using the LHRH-secreting cell line GT1-7, showed that these cells contain transcripts encoding NRXs and one of their ligands (NRL1), at least one PCDHalpha (CNR-8/PCDHalpha10), and the CASPR1/contactin complex. The results indicate that the prepubertal female monkey hypothalamus contains a plethora of adhesion/signalling molecules with different but complementary functions, and that an LHRH neuronal cell line expresses key components of this structural complex. The presence of such cell-cell communication machinery in the neuroendocrine brain suggests an integrated participation of their individual components in the central control of female sexual development.

Animals↗
PubMed1991

Possible regulation of hypothalamus and lung histidine decarboxylase activity by cAMP-dependent protein kinase.

Activity of crude histidine decarboxylases (HisDC) from the hypothalamus and the lungs, was markedly reduced by incubating with ATP.Mg, cAMP and cAMP-dependent protein kinase A, whereas activity of the crude glandular stomach enzyme changed only slightly under equal condition. The omission of one of these components failed to reduce HisDC activity by as much as the complete system. Addition of bovine heart (type II) or rat cerebellum protein kinase A (types I and II) inhibitor to the assay prevented enzyme inactivation; moreover, protein kinase A inhibitors permitted moderate activation under phosphorylating and control conditions. Cytosolic hypothalamus HisDC activity was elevated 2-2.2-fold by incubating the cytosol for 15 min in the presence of MnCl2, a known stimulator of phosphoprotein phosphatase; this was prevented when 20 mM NaF, a common inhibitor of phosphoprotein phosphatase, was added to the cytosol. The apparent Km of ATP.Mg-treated hypothalamus HisDC for histidine was elevated 5-10-fold compared to controls, whereas the Vmax was approximately the same. Under this condition, the Km was calculated as high as 0.5-2.2 mM (depending on phosphorylating conditions), while controls had a Km of 0.1-0.3 mM (depending on the initial phosphorylating states). Addition of rabbit muscle (type I), bovine heart (type II) or rat cerebellum (types I and II) inhibitor of protein kinase A, to the phosphorylating mixture, abolished the difference in Km between control and ATP.Mg-treated HisDC. Moreover, rat cerebellum protein kinase A inhibitors increased Vmax to above the control level; while 20 mM NaF (inhibitor of phosphoprotein phosphatase) decreased Vmax to approximately one half of that of the controls. These data indicate that HisDC activity in the hypothalamus and the lungs, but not in the stomach, is affected in oppositely by protein kinase A and phosphoprotein phosphatases.

Animals↗
PubMed1992

Opioid inhibitory control of the ruminant stomach motility: functional importance of the hypothalamus.

In conscious sheep, Leu-enkephalin (10 and 20 micrograms.kg-1) administered into the third cerebral ventricle caused a psychosedative action and a significant inhibition of the frequency of rumen contractions. The amplitude of the first rumen contractions, following immediately after the end of the Leu-enkephalin's infusion (at a dose of 20 micrograms) and the average amplitude of primary rumen contractions were also significantly inhibited. The hypothalamic isolation prevented both the inhibitory effect of Leu-enkephalin on the rumen motility and the drug induced psychosedative action. In contrast, Leu-enkephalin (20 micrograms.kg-1), significantly enhanced phasic contractions of the rumen after hypothalamic isolation. However the hypothalamic isolation did not prevent Leu-enkephalin induced inhibition of the mean amplitude of rumen contractions, but this inhibition was not significant (NS). The character of the histopathological changes induced by the isolation of the hypothalamus showed descending degenerative changes of the neuronal pathways connecting the hypothalamus to the pons and lower to the medulla. These results do suggest that the isolation of the hypothalamus causes the degeneration of the descending inhibitory opioid pathways connecting the hypothalamus to the gastric centers of the medulla and point act out the functional importance of descending tonic opioid inhibitory control of ruminant forestomach motility.

Animals↗
PubMedDate not supplied

Renin mRNA concentration in rat hypothalamus is decreased by enalapril.

1. Renin mRNA is expressed in several extrarenal tissues, including brain. The aim of the present study was to quantify renin mRNA in the hypothalamus in response to a low NaCl diet and angiotensin converting enzyme inhibitor treatment, both of which are well-known stimuli of renin mRNA in kidney. 2. Groups of six Sprague-Dawley rats were given either a normal diet, low NaCl chow (0.04% NaCl), enalapril (0.25 mg/mL in drinking water), or low NaCl + enalapril, for 7 days. Renin mRNA in the hypothalamus was quantified by a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) technique. 3. Renin mRNA concentration in the hypothalamus of rats receiving a normal diet was 52 +/- 3 S.E. fg/microgram total RNA. Low NaCl had no effect (57 +/- 7), whereas values were significantly lower in rats treated with enalapril, either given alone (38 +/- 2; P = 0.002) or combined with a low NaCl diet (33 +/- 4; P = 0.003). 4. In conclusion, we have quantified renin mRNA in the rat hypothalamus and shown that it can be suppressed significantly by enalapril. This response is opposite to that seen in the kidney after enalapril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Male faces and odours evoke differential patterns of neurochemical release in the mediobasal hypothalamus of the ewe during oestrus: an insight into sexual motivation?

During behavioural oestrus female sheep, like females of many species, become both attracted to and sexually receptive towards males, whereas at other times they will avoid them. The mediobasal hypothalamus is the main site for the feedback action of sex steroids to induce sexual behaviour in the sheep and in previous studies we have shown that noradrenaline and serotonin are released in this region during sexual interactions with males. The current study investigated whether such changes are specific to interactions with males and if visual or olfactory cues or somatosensory stimulation during mating are critical. In vivo microdialysis sampling was carried out in the mediobasal hypothalamus of ovariectomized ewes submitted to artificial oestrous cycles. Release of monoamines and amino acid transmitters was first measured in animals during and after oestrus when they were exposed to interactions with either males or females or presentation of food. Noradrenaline concentrations only increased significantly when the females were in oestrus and interacted with males irrespective of whether intromissions were permitted. Females were then exposed to visual (faces) or odour (a home pen) cues from males or to the males themselves. Slide images of male faces increased concentrations of amines, glutamate and GABA during early oestrus, when females spent most time looking at them. During late oestrus noradrenaline, glutamate and GABA concentrations also increased in response to the male faces but no transmitter changes were seen during the luteal phase or at any time where the females were exposed to female faces, or inverted male faces. Exposure to male odour produced a lower increase in noradrenaline concentrations when females were in early oestrus but marked increases 20 and 30 min after exposure to male odours in late oestrus. No other transmitters were affected. Exposure to a male and mating with him when females were in early or late oestrus produced increased noradrenaline concentrations similar to those seen with face stimuli alone although other neurotransmitters were unaffected. These results show that noradrenaline, and to a lesser extent dopamine, serotonin, glutamate and GABA release in the mediobasal hypothalamus, can be modulated specifically in the oestrous female by sensory information coming from the male during oestrus. The differential effects of male cues during early and late oestrus suggest their involvement in (i) proceptive or anticipatory sexual responses shown by the female to male cues, and (ii) receptive sexual responses, and suggest that the mediobasal hypothalamus plays a key role in the integration of hormonal action on sexual motivation and processing of sensory information during oestrus.

Animals↗