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PubMed2006

Laminar organization of the early developing anterior hypothalamus.

The bHLH-PAS transcription factor SIM1 is required for the development of neurons of the anterior hypothalamus (AH). In order to dissect this developmental program, we compared gene expression in the AH of E12.5 Sim1(+/+) and Sim1(-/-) littermates using an oligonucleotide-based microarray. Our analysis identified 48 genes that were downregulated and 8 genes that were upregulated. We examined the expression pattern of 10 of the identified genes--Cart, Cbln1, Alcam, Unc-13c, Rgs4, Lnx4, Irx3, Sax1, Ldb2 and Neurod6--by in situ hybridization in E12.5 embryos. All of these genes are expressed in domains that are contained within that of Sim1 and their expression is changed in Sim1(-/-) embryos as predicted by the microarray analysis. Classical dating studies have established that the hypothalamus follows an "outside-in" pattern of neurogenesis, with neurons of the lateral hypothalamus being born before the medial ones. Analysis of the genes identified in this microarray study showed that the developing AH is characterized by different layers of gene expression that most likely correspond to distinct waves of neurogenesis. In addition, our analysis suggests that Sim1 function is required for the production or the survival of postmitotic neurons as well as for correct positioning of AH neurons.

Animals↗
PubMed2006

Development of a real-time (Q) PCR assay to measure variation in expression of prolactin receptor mRNA in the hypothalamus and pituitary gland during late embryogenesis in turkeys and chickens.

Changes in levels of PRLR mRNA in the pituitary gland and hypothalamus of chickens and turkeys from embryonic day (ED) 15 and ED21 to 1 day post-hatch, respectively, were measured by real-time PCR. In both species, PRLR mRNA increased from low levels during the last week of ED to reach maxima at the peri-hatch period. Similarly, circulating levels of PRL also increased during this interval and were highly correlated with levels of the PRLR mRNA in both the pituitary gland and hypothalamus. This suggests that PRL was up-regulating its receptor. In support of this, stimulation of the turkey pituitary gland with VIP on ED24 resulted in a 4- and 3-fold increase in PRL and PRLR, respectively. Since VIP had no direct effect on the levels of PRLR transcript in the hypothalamus, it is likely that VIP is acting indirectly through increased PRL to up-regulate the number of receptors.

Animals↗
PubMed2003

Estrogen increases messenger RNA and immunoreactivity of aryl-hydrocarbon receptor nuclear translocator 2 in the rat mediobasal hypothalamus.

We examined the effect of estrogen on the expression of aryl-hydrocarbon receptor (AhR) and two types of AhR nuclear translocator (Arnt1 and Arnt2) mRNAs in the hypothalamus of ovariectomized rats. Northern blotting demonstrated that, in the mediobasal hypothalamus, a subcutaneous injection of 20 microg estradiol benzoate (E(2)) significantly increased the expression of Arnt2 mRNA, but induced no significant changes in the expression of AhR and Arnt1 mRNAs. The expression of Arnt2 mRNA was significantly increased at 4, 24, and 72h after the injection. Immunocytochemical study revealed that the number of Arnt2 immunoreactive cells was also significantly increased at 72h after the injection. Conversely, in the preoptic area, injection of E(2) did not cause significant changes in the expression of any of the three mRNAs. These observations suggest that estrogen regulates Arnt2 expression in the mediobasal hypothalamus and modulates the toxic action of dioxins in rats.

Animals↗
PubMed2000

Estrogen receptors and aromatase activity in the hypothalamus of the female frog, Rana esculenta. Fluctuations throughout the reproductive cycle.

It is well known that certain actions of androgen are mediated through in situ aromatization to estrogen in neural target tissues. This study was undertaken to investigate androgen utilization in the hypothalamus of the female frog, Rana esculenta, through a quantification of estrogen receptors and aromatase activity during the reproductive cycle. 3H-estradiol-binding molecules were present in both the cytosol and the nuclear extract of the hypothalamus. These molecules bound specifically 3H-estradiol with high affinity (Kd 10(-10) M) and low capacity (cytosol: 1.2+/-0.4 fmol/mg protein; nuclear extract: 7.9+/-0.6 fmol/mg protein). Aromatase activity was detected in the microsomal fraction of the hypothalamus using a sensitive in vitro radiometric assay. Both aromatase activity and nuclear estrogen receptor binding fluctuated in synchrony throughout the reproductive cycle. Western blot analysis of aromatase protein revealed one immunoreactive band with a molecular weight of approximately 56 kDa. In contrast to aromatase enzyme activity, the relative levels of aromatase protein changed little during the reproductive cycle suggesting that post-translational mechanisms may be involved in regulating estrogen synthesis in the frog brain. A possible role for estrogens in the modulation of the reproductive behavior in this species is suggested.

Animals↗
PubMed2000

Electroconvulsive seizures modulate levels of thyrotropin releasing hormone and related peptides in rat hypothalamus, cingulate and lateral cerebellum.

We have studied the neuroanatomic extent of electroconvulsive (ECS)-responsive prepro-TRH and TRH-related gene expression and its possible interaction with forced swimming. Young adult male Wistar rats were treated in a 2x2 Latin square protocol of swimming, no swimming, three daily ECS or sham ECS. Sixteen different brain regions were dissected and immunoreactivity measured for TRH (pGlu-His-Pro-NH(2)); TRH-Gly, a TRH precursor; Ps4, a prepro-TRH-derived TRH-enhancing decapeptide, and EEP (pGlu-Glu-Pro-NH(2)). ECS, in addition to elevating TRH-immunoreactivity (TRH-IR), TRH-Gly-IR, Ps4-IR and EEP-IR levels in the limbic regions, as we have previously reported, also significantly increased Ps4-IR levels in hypothalamus, posterior cingulate and lateral cerebellum, and increased TRH-Gly-IR levels in hypothalamus. Interestingly, the combination of ECS and swimming significantly reduced the levels of TRH-Gly-IR in the anterior cingulate compared to the sham ECS-no swim group. The combined use of high-pressure liquid chromatography and the EEP radioimmunoassay (RIA) revealed that pGlu-Tyr-Pro-NH(2) and/or pGlu-Phe-Pro-NH(2) occur in amygdala, anterior cingulate, frontal cortex, entorhinal cortex, lateral cerebellum and striatum and make a substantial contribution to the EEP-IR and TRH-IR. We conclude that ECS can alter the expression and secretion of TRH-related peptides in the hypothalamus, cingulate and lateral cerebellum. Such effects have not previously been reported in these limbic and extra-limbic regions which are increasingly implicated in the autonomic, behavioral and volitional changes which accompany severe depression and its treatment.

Animals↗
PubMed2001

Raphe region mediates changes in cutaneous vascular tone elicited by stimulation of amygdala and hypothalamus in rabbits.

Raphe pallidus/parapyramidal neurons control cutaneous vasoconstriction induced by noxious stimuli. To determine whether they mediate forebrain-induced cutaneous vasoconstriction, we assessed changes in ear pinna blood flow elicited by electrical stimulation of amygdala and hypothalamus before and after injection of muscimol into the raphe/parapyramidal region. We compared ear flow with simultaneously recorded mesenteric flow. Experiments were performed in rabbits anesthetized with urethane (1.25-1.5 g/kg), paralysed and mechanically ventilated. Amygdala stimulation reduced skin conductance from 0.32+/-0.06 to 0.10+/-0.02 cm/s per mmHg (P<0.05, n=9), without effect on mesenteric conductance. Hypothalamic stimulation caused vasoconstriction in both cutaneous and mesenteric beds (conductances fell from 0.27+/-0.05 to 0.05+/-0.02 cm/s per mmHg and from 0.27+/-0.06 to 0.14+/-0.04 cm/s per mmHg (P<0.05, n=9), respectively). Muscimol microinjection (5 nmol in 100 nl) to raphe/parapyramidal region eliminated amygdala- and hypothalamus-induced skin vasoconstriction (pre-stimulus conductance 0.42+/-0.13 and 0.41+/-0.11 cm/s per mmHg, post-stimulus 0.41+/-0.12 and 0.39+/-0.10 cm/s per mmHg, respectively), but not hypothalamically-induced mesenteric vasoconstriction (pre-stimulus 0.29+/-0.06, post-stimulus 0.16+/-0.03 cm/s per mmHg, P<0.05, n=8). The latter was strongly attenuated by bilateral injection of muscimol to the rostral ventrolateral medulla. Data suggest that descending hypothalamo-spinal and amygdala-spinal pathways constricting the cutaneous vascular bed relay in the raphe/parapyramidal area. A relay in the rostral ventrolateral medulla contributes substantially to mesenteric vasoconstriction elicited from the hypothalamus.

Amygdala↗
PubMed2002

Long-term effects of St. John's wort and hypericin on monoamine levels in rat hypothalamus and hippocampus.

Hypericum perforatum L. (St. John's wort) is one of the leading psychotherapeutic phytomedicines and, because of this, great effort has been devoted to clarifying its mechanism of action. Chronic effects of St. John's wort and hypericin, one of its major active compounds, on regional brain amine metabolism have not been reported yet. We used a high-performance liquid chromatography system to examine the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine, Hypericum extract or hypericin on regional levels of serotonin (5-HT), norepinephrine, dopamine and their metabolites in the rat brain. We focused our interest on the hypothalamus and hippocampus, as these brain regions are thought to be involved in antidepressant drug action. Imipramine (15 mg/kg, p.o.), Hypericum extract (500 mg/kg, p.o.), and hypericin (0.2 mg/kg, p.o.) given daily for 8 weeks significantly increased 5-HT levels in the hypothalamus (P<0.05). The 5-HT turnover was significantly lowered in both brain regions after 8 weeks of daily treatment with the Hypericum extract (both P<0.05). Consistent changes in catecholamine levels were only detected in hypothalamic tissues after long-term treatment. Comparable to imipramine, Hypericum extract as well as hypericin significantly decreased 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the hypothalamus (P<0.01). Our data clearly show that long-term, but not short-term administration of St. John's wort and its active constituent hypericin modify levels of neurotransmitters in brain regions involved in the pathophysiology of depression.

Animals↗
PubMed2002

Lesion induced new neuron incorporation in the adult hypothalamus of the avian brain.

Cell loss in most adult vertebrate brain regions is thought to be irreversible. Here, we explore the effects of electrolytic lesions on the induction of cell proliferation and newborn neurons in the ventromedial nuclei (VMN) of the hypothalamus in young and adult ring doves. The hypothalamus does not normally recruit new neurons. Bromodeoxyuridine (BrdU) and tritiated thymidine ([3H]Thy) were used to identify cells born before and after bilateral electrolytic lesions. Hu and NeuN were used to identify neurons. TUNEL test for apoptosis and 3A7 antibodies were used to identify morphological changes of pre-existing cells. Lesions produced significantly more newborn cells in the subventricular zone (SVZ). The rate of cell proliferation peaked at 7-14 days postlesion. A fraction of these newborn cells were neuronal precursor and began to migrate away along the radial glial fibers 2 weeks after lesion. During this period, the outer area of the lesion site was marked with massive apoptosis and re-expression of radial glial-like fibers. In birds that survived 5 months, we found newly differentiated neurons in the outer area of the lesion site. We conclude that electrolytic lesion can invoke neuronal recruitment in the adult hypothalamus. We further suggest that lesion-induced apoptosis and re-expression of developmental mechanisms might be involved in the recruitment process.

Animals↗
PubMed2003

Localization of angiotensin II (AT1)-receptor-immunoreactive fibres in the hypothalamus of rats: angiotensin II-sensitive tanycytes in the ependyma of the third ventricle?

Scanning the hypothalamus of rats for receptor binding sites of the octapeptide hormone angiotensin II (ANG II), we observed ANG II-sensitive fibres in the ventrolateral hypothalamus. The ANG II (AT(1))-receptor-immunoreactive processes originate from cells-probably tanycytes-embedded in the base and the ventrolateral walls of the third ventricle and reach into the retrochiasmatic area, the ventrolateral hypothalamus and the median eminence.

Angiotensin II↗
PubMed2003

Postnatal neurogenesis in the vasopressin and oxytocin-containing nucleus of the pig hypothalamus.

The vasopressin and oxytocin-containing nucleus (VON) of the pig hypothalamus demonstrates dramatic postnatal growth in nucleus size, both volume and neuron number, during puberty, and continues to increase in size in the adult sexually mature female pig throughout its reproductive prime. This study was designed to show that postnatal neurogenesis is responsible for the VON growth that occurs between adolescence and maturity. Recently divided neurosecretory cells of the hypothalamus were identified in adolescent and mature non-lactating female pigs using a sequential immunohistochemistry double-labeling technique with monoclonal mouse antibodies to detect vasopressin and proliferating cell nuclear antigen (PCNA), a protein associated with the S phase of the cell cycle. A computer-assisted image-analysis system was used to assess nucleus volume and neuron counts. The VON of the mature dry sows was significantly larger in volume and number of vasopressin neurons than the VON of the adolescent pigs. Double-labeled cells were noted in the VON of both adolescent and mature dry sows, but the number and proportion of double-labeled cells was significantly higher in adolescent pigs. Our results indicate the presence of neurons containing PCNA in the VON of the pig hypothalamus. This suggests that mitosis of neurogenic precursors plays a role in the growth of the nucleus.

Aging↗
PubMed2003

Neuropeptide Y and lipid increase apolipoprotein AIV gene expression in rat hypothalamus.

Apolipoprotein AIV (apo AIV) is a circulating signal released from intestinal cells in response to lipid feeding and contributes to the anorectic effect of a lipid meal. We have demonstrated that apo AIV is also synthesized in the hypothalamus, and that hypothalamic apo AIV gene expression is regulated physiologically. Neuropeptide Y (NPY) is a hypothalamic neuropeptide with broad regulatory actions in the central nervous system. In the present studies, the effects of intracerebroventricular (i.v.t.) administration of NPY and of intraduodenal lipid infusion on hypothalamic apo AIV gene expression were determined using competitive RT-PCR in fasted rats. I.v.t. injection of NPY alone significantly increased apo AIV mRNA levels in the hypothalamus in a dose-dependent manner. Intraduodenal infusion of lipid also stimulated the gene expression of hypothalamic apo AIV, but no further significant increment occurred when i.v.t. injection of NPY was combined with lipid infusion. These results suggest that NPY and lipid may regulate apo AIV gene expression in the rat hypothalamus.

Analysis of Variance↗
PubMed1997

Localization of angiotensin-converting enzyme, angiotensin II, angiotensin II receptor subtypes, and vasopressin in the mouse hypothalamus.

The hypothalamic angiotensin II (Ang II) system plays an important role in pituitary hormone release. Little is known about this system in the mouse brain. We studied the distribution of angiotensin-converting-enzyme (ACE), Ang II, Ang II receptor subtypes, and vasopressin in the hypothalamus of adult male mice. Autoradiography of binding of the ACE inhibitor [125I]351A revealed low levels of ACE throughout the hypothalamus. Ang II- and vasopressin-immunoreactive neurons and fibers were detected in the paraventricular, accessory magnocellulary, and supraoptic nuclei, in the retrochiasmatic part of the supraoptic nucleus and in the median eminence. Autoradiography of Ang II receptors was performed using [125I]Sar1-Ang II binding. Ang II receptors were present in the paraventricular, suprachiasmatic, arcuate and dorsomedial nuclei, and in the median eminence. In all areas [125I]Sar1-Ang II binding was displaced by the AT1 receptor antagonist losartan, indicating the presence of AT1 receptors. In the paraventricular nucleus [125I]Sar1-Ang II binding was displaced by Ang II (Ki = 7.6 X 10(-9)) and losartan (Ki = 1.4 X 10(-7)) but also by the AT2 receptor ligand PD 123319 (Ki = 5.0 X 10(-7)). In addition, a low amount of AT2 receptor binding was detected in the paraventricular nucleus using [125I]CGP42112 as radioligand, and the binding was displaced by Ang II (Ki = 2.4 X 10(-9)), CGP42112 (Ki = 7.9 x 10(-10)), and PD123319 (Ki = 2.2 x 10(-7)). ACE, Ang II, and AT1 as well as AT2 receptor subtypes are present in the mouse hypothalamus. Our data are the basis for further studies on the mouse brain Ang II system.

Angiotensin II↗
PubMed1998

Altered number of diaphorase (NOS) positive neurons in the hypothalamus of rats with heart failure.

Recently, we have demonstrated a decreased neuronal isoform of nitric oxide synthase (nNOS) message in the hypothalamus of rats with heart failure (HF). The purpose of this study was to determine the changes in NADPH-diaphorase (a commonly used marker for neuronal NOS activity) positive neurons in specific hypothalamic sites of rats with HF. After a standard histochemical protocol, NOS positive neurons were measured in paraventricular nucleus (PVN), supraoptic nucleus (SON), median preoptic area (MePO), subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT) and lateral hypothalamus (LH) of rats with coronary artery ligation (HF group; n=8) and sham-operated control rats (n=9). A total of 4 months after coronary ligation, the rats in the HF group displayed infarcts greater than at least 35% of the left ventricular wall (n = 8). Sham-operated rats had no observable damage to the myocardium. Rats with HF had a significantly lower number of NOS positive cells in the PVN (36% less) compared to sham rats. The number of NOS positive cells remained unaltered in the SON, MePO and LH in rats with HF. Conversely there was an increased number of NOS positive cells in the SFO (42% greater) and OVLT (100% greater). These data support the conclusion that the NO system within the hypothalamus involved in controlling autonomic outflow is altered during HF and may contribute to the elevated levels of vasopressin and sympatho-excitation commonly observed in HF.

Animals↗
PubMed1998

Cholecystokinin B receptors in the periaqueductal gray potentiate defensive rage behavior elicited from the medial hypothalamus of the cat.

Defensive rage behavior is mediated over a descending pathway from the medial hypothalamus to the dorsolateral midbrain periaqueductal gray (PAG) where further integration of this response takes place. The present study sought to determine the roles of CCK-A and CCK-B receptor activation in the PAG in modulating defensive rage behavior. The 'hissing' component of the defensive rage response was used throughout the experiment as the measure of defensive rage behavior. The basic design of the experiment involved placement of monopolar electrodes into the medial hypothalamus from which defensive rage could be elicited and cannula electrodes into the dorsal PAG for purposes of identifying defensive rage sites in this region and for microinjections of CCK compounds into these sites at a later time. Microinjections of the selective CCK-B receptor antagonist, LY288513 (1.05, 4.2, 17.0 nmol/0.25 microliter), into the PAG suppressed the hissing response in a dose- and time-dependent manner. Microinjections of the CCK-B agonist, pentagastrin, (0.5 and 1.0 nmol/0.25 microliter) facilitated the occurrence of defensive rage behavior. Moreover, administration of LY288513 (17 nmol/0.25 microliter) 55 min prior to pentagastrin (1.0 nmol/0.25 microliter) delivery blocked the facilitatory effects of pentagastrin. Administration of the CCK-A antagonist, PD140548 (34 nmol/0.25 microliter), into the PAG failed to alter response latencies for defensive rage behavior. In contrast, microinjections of the CCK-B antagonist, LY288513 (4.2, 17.0 nmol/0.25 microliter), facilitated the occurrence of predatory attack behavior elicited from the lateral hypothalamus. This finding demonstrates the specificity of the effects of CCK-B receptor blockade upon hissing. A combination of immunocytochemical and retrograde tracing procedures using microinjections of Fluoro-Gold (8%, 6 microliters) into the PAG were employed to identify the possible loci of CCK neurons that project to the PAG. The data revealed that neurons labeled for both CCK and Fluoro-Gold were located in the dorsolateral aspect of the midbrain tegmentum, identifying this region as a source of CCK inputs to the PAG. Overall, the findings demonstrate that CCK-B receptors in the PAG potentiate defensive rage behavior and likely suppress predatory attack.

Animals↗
PubMed1998

Localization of ATP-gated P2X2 receptor immunoreactivity in the rat hypothalamus.

Previous pharmacological studies have indicated that ATP receptors may be involved in the regulation of physiological functions in hypothalamus. In the present study, the distribution of P2X2 receptor in the rat hypothalamus was studied with immunohistochemistry. It was shown that P2X2 immunoreactivity-positive neurons and nerve fibres were localized in many hypothalamic nuclei. Intense labelling of both neuronal cell bodies and nerve fibres was observed in the paraventricular nucleus, arcuate nucleus, retrochiasmatic area, periventricular nucleus, and the ventral part of tuber cinereum area. In supraoptic, circular, and ventral tuberomammillary nuclei the neuronal cell bodies were strongly positive, but few nerve fibres were positive. Axons with strong P2X2 immunoreactivity were found in the organum vasculosum of the lamina terminalis and median eminence. Some scattered positive neurons and nerve fibres were found in many hypothalamic nuclei including preoptic nucleus. The results of the present study demonstrated the existence of P2X receptors in hypothalamus, as a basis for detailed studies of the roles of P2X receptors in the regulation of hypothalamic functions.

Adenosine Triphosphate↗
PubMed1999

Rhythmicity of beta-endorphinergic neuronal activity in the mediobasal hypothalamus during pregnancy in the rat.

During the first half of gestation in the rat, prolactin (PRL) from the anterior pituitary gland exerts its luteotropic function on the ovary to stimulate progesterone secretion. During this period, beta-endorphin stimulates PRL secretion by regulation of dopaminergic neurons in the hypothalamus. During the second half, placental lactogens (PLs) take the place of PRL in maintenance of pregnancy, and initiate a negative feedback to suppress PRL secretion. However, the effect of PLs on beta-endorphinergic neurons is not known. The aim of this study was to examine the possibility that PLs suppress PRL secretion by inhibiting beta-endorphinergic neuronal activity. To accomplish this aim, we examined the changes in the neuronal activity of beta-endorphinergic neurons in the mediobasal hypothalamus, as measured by Fos immunoreactivity, after manipulating the levels of PRL and PLs during pregnancy. On day 4 of pregnancy, animals received either Rcho-1 cells in the lateral ventricle that secrete PLs or HRP-1 cells as controls. In a separate experiment on day 12, hysterectomy was performed to remove the intrinsic source of PLs. These rats received Rcho-1 cells, HRP-1 cells, or nothing. Intracerebroventricular (i.c.v.) injection of Rcho-1 into hysterectomized rats was done to examine the effect of PL replacement. Sham-hysterectomy was also performed as a control. Animals were sacrificed 2 days after each treatment at 0200 h, 1400 h, and 1800 h. Brains were used for dual immunocytochemistry of Fos/beta-endorphin. The neuronal activity of beta-endorphinergic neurons of HRP-1 i.c.v. injected animals showed a daily rhythm, with high levels at 0200 h and 1800 h, and a low level at 1400 h. These animals also exhibited two surges of PRL secretion on day 6 of pregnancy. This rhythmicity of beta-endorphinergic neurons was also observed in Rcho-1 i.c.v. injected animals, which showed very low and unchanging PRL levels. However, the magnitude of neuronal activity was reduced. On day 14 of pregnancy, all four experimental groups showed diurnal rhythms of beta-endorphinergic neurons. This rhythmicity occurred even though PRL was elevated at all three time points in the hysterectomized rats and very low in the Rcho-1 i.c.v. injected hysterectomized and sham-hysterectomized rats. Our results demonstrate that there is a diurnal rhythm of beta-endorphinergic neuronal activity in the mediobasal hypothalamus during pregnancy in the rat. PLs might reduce the neuronal activity of beta-endorphinergic neurons, but only during the first half of pregnancy, partially explaining the suppression of PRL surges.

Analysis of Variance↗
PubMed1999

Neuropeptide Y induced inhibition of noradrenaline release in rat hypothalamus: role of receptor subtype and nitric oxide.

We aimed at characterizing the receptor subtype and the signaling pathway involved in the inhibitory effect of neuropeptide Y on the release of endogenous noradrenaline from rat hypothalamus. Slices of hypothalamus were stimulated with two trains of electrical pulses, and the release of noradrenaline and nitric oxide was measured. The electrical stimulation of hypothalamic slices induced a consistent release of both endogenous noradrenaline and NO. Neuropeptide Y inhibited concentration dependently the stimulated noradrenaline release. Similarly, agonists for neuropeptide Y Y1, Y2 and Y5 receptors inhibited noradrenaline release, albeit with a potency lower than neuropeptide Y. GW1229, a selective neuropeptide Y Y1 receptor antagonist counteracted the effect of neuropeptide Y, but not that of PYY-(3-36), an agonist active at neuropeptide Y Y5 and Y2 receptors. These results indicate that the inhibitory effect of neuropeptide Y is likely mediated by several receptor subtypes, including neuropeptide Y Y1, Y5 and possibly Y2 receptors. One microM NPY significantly enhanced NO release induced by the electrical stimulation. NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, abolished NO release and blocked the inhibitory effect of neuropeptide Y on noradrenaline release. We conclude that nitric oxide participates in the signaling pathway of neuropeptide Y in the rat hypothalamus.

Animals↗
PubMed2000

Distribution of estrogen receptor beta (ERbeta) mRNA in hypothalamus, midbrain and temporal lobe of spayed macaque: continued expression with hormone replacement.

This study used in situ hybridization (ISH) to examine the distribution of estrogen receptor beta (ERbeta) mRNA in hypothalamic, limbic, and midbrain regions of monkey brain and its regulation by estrogen (E) and progesterone (P). Monkey-specific ERbeta cDNAs were developed with human primers and reverse transcription and polymerase chain reaction (RT-PCR) using mRNA extracted from a rhesus monkey prostate gland. ERbeta 5' (262 bases) and 3' (205 bases) riboprobes were used in combination for ISH. Ovariectomized and hysterectomized (spayed) pigtail macaques (Macaca nemestrina; four per treatment group) were either untreated spayed-controls, treated with E (28 days), or treated with E plus P (14 days E+14 days E and P). Dense ERbeta hybridization signal was seen in the preoptic area, paraventricular nucleus, and ventromedial nucleus of the hypothalamus; the substantia nigra, caudal linear, dorsal raphe, and pontine nuclei of the midbrain; the dentate gyrus, CA1, CA2, CA3, CA4, and the prosubiculum/subiculum areas of the hippocampus. Expression in the suprachiasmatic region, supraoptic nucleus, arcuate nucleus, and amygdala was less intense. Image analysis of the dense areas showed no significant difference in the hybridization signal in individual regions of the hypothalamus, midbrain, or hippocampus between any of the treatment groups. However, P treatment decreased overall ERbeta signal in the hypothalamus and hippocampus when several different subregions were combined. The localization of ERbeta in monkey brain by ISH is in general agreement with that previously described in rodents. The presence of monkey ERbeta mRNA in brain regions that lack ERalpha should help to clarify the molecular mechanisms by which E acts in the central nervous system to influence hormone secretion, mood disorders, cognition, and neuroprotection.

Amygdala↗