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1.
Neuroscience ; 248: 664-9, 2013 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-23811398

RESUMO

Reproductive success depends on a robust and appropriately timed preovulatory luteinizing hormone (LH) surge, which is induced by the activation of gonadotropin-releasing hormone (GnRH) neurons in response to positive feedback from increasing estrogen levels. Here we document an increase in postsynaptic GluR2-lacking Ca2+ -permeable AMPA-type glutamate receptors (CP-AMPARs) at synapses on GnRH neurons on the day of proestrus in rats, coincident with the increase in estrogen levels. Functional blockade of CP-AMPARs depressed the synaptic responses only on the day of proestrus and concomitantly attenuated the LH surge. Thus, the phasic synaptic incorporation of postsynaptic CP-AMPARs on GnRH neurons is involved in the generation of the LH surge.


Assuntos
Hormônio Liberador de Gonadotropina/metabolismo , Hormônio Luteinizante/sangue , Receptores de AMPA/fisiologia , Sinapses/fisiologia , Animais , Estrogênios/fisiologia , Feminino , Técnicas In Vitro , Neurônios/fisiologia , Ratos , Ratos Wistar , Reprodução
2.
Neurosci Lett ; 442(2): 114-7, 2008 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-18620021

RESUMO

Nicotinic cholinergic receptors play a role in cardiovascular regulation in the lower brain stem. Herein, we present evidence that l-3,4-dihydroxyphenylalanine (DOPA), a putative neurotransmitter in the central nervous system, is involved in the depressor response to microinjection of nicotine into the nucleus tractus solitarii (NTS). Microinjection of nicotine into the medial area of the NTS led to decreases in arterial blood pressure and heart rate in anesthetized rats. Mecamylamine, a nicotinic receptor antagonist, microinjected into NTS, blocked the depressor and bradycardic responses to nicotine. Nicotine-induced depressor and bradycardic responses were blocked by DOPA cyclohexyl ester (DOPA CHE), an antagonist for DOPA. DOPA CHE did not modify the action of carbachol on excitatory postsynaptic potential in rat cortical slices. These results suggest that endogenous DOPA is involved in nicotine-induced depressor responses in the NTS of anesthetized rats.


Assuntos
Sistema Cardiovascular/efeitos dos fármacos , Levodopa/análogos & derivados , Levodopa/antagonistas & inibidores , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Núcleo Solitário/efeitos dos fármacos , Animais , Pressão Sanguínea/efeitos dos fármacos , Carbacol/farmacologia , Agonistas Colinérgicos/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Técnicas In Vitro , Levodopa/farmacologia , Masculino , Mecamilamina/farmacologia , Microinjeções , Antagonistas Nicotínicos/farmacologia , Ratos , Ratos Wistar
3.
Neuropharmacology ; 50(8): 909-16, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16504219

RESUMO

L-3,4-dihydroxyphenylalanine (DOPA) is a neurotransmitter candidate. To map the DOPAergic system functionally, DOPA-induced c-Fos expression was detected under inhibition of central aromatic L-amino acid decarboxylase (AADC). In rats treated with a central AADC inhibitor, DOPA significantly increased the number of c-Fos-positive nuclei in the paraventricular nuclei (PVN) and the nucleus tractus solitarii (NTS), and showed a tendency to increase in the supraoptic nuclei (SON), but not in the striatum. On the other hand, DOPA with a peripheral AADC inhibitor elevated the level of c-Fos-positive nuclei in the four regions, suggesting that DOPA itself induces c-Fos expression in the SON, PVN and NTS. In rats treated with 6-hydroxydopamine (6-OHDA) to lesion the nigrostriatal dopamine (DA) pathway, DOPA significantly induced c-Fos expression in the four regions under the inhibition of peripheral AADC. However, under the inhibition of central AADC, DOPA did not significantly increase the number of c-Fos-positive nuclei in the four regions, suggesting that DOPA at least in part induces c-Fos expression through its conversion to DA. It was likely that the 6-OHDA lesion enhanced the response to DA, but attenuated that to DOPA itself. In conclusion, we proposed that the SON, PVN and NTS include target sites for DOPA itself.


Assuntos
Descarboxilases de Aminoácido-L-Aromático/metabolismo , Sistema Nervoso Central/efeitos dos fármacos , Dopaminérgicos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Levodopa/farmacologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Animais , Benserazida/farmacologia , Contagem de Células/métodos , Interações Medicamentosas , Inibidores Enzimáticos/farmacologia , Lateralidade Funcional , Hidrazinas/farmacologia , Imuno-Histoquímica/métodos , Masculino , Feixe Prosencefálico Mediano/lesões , Atividade Motora/efeitos dos fármacos , Oxidopamina/toxicidade , Ratos , Ratos Sprague-Dawley
4.
Neuroscience ; 136(2): 593-9, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16226386

RESUMO

We have reported in the past that female rats fed a powdered diet showed better spatial learning and memory functions than female rats a fed pelleted diet. In the present study, we examined the effects of feeding with powdered diet on acetylcholine release in the hippocampus in both sexes of rats. After weaning (3 weeks of age), rats were fed either standard pelleted diet or powdered diet, and after maturation (9-12 weeks of age), they were used in an in vivo microdialysis study, in which no eserine (a cholinesterase inhibitor) was added to the perfusate. The dialysate was collected from the dorsal hippocampus at 20-min intervals under freely moving conditions for more than 24 h. Acetylcholine in the dialysate was measured by high performance liquid chromatography. As we reported previously, the acetylcholine release showed a clear daily rhythm in both sexes, and males showed significantly greater acetylcholine release in the hippocampus than females in rats fed pelleted diet. Conversely, in rats fed powdered diet, no sex difference in the acetylcholine release was observed, since feeding with powdered diet significantly increased the acetylcholine release only in females. To further examine the number of cholinergic neurons in the medial septum and horizontal limb of the diagonal band of Broca, immunocytochemistry for choline acetyltransferase was performed in both sexes of rats fed either standard pelleted diet or powdered diet. However, neither sex nor feeding conditions affect the number of choline acetyltransferase immunoreactive cells in the areas. These results suggest that powdered diet after weaning enhances spontaneous acetylcholine release in the hippocampus in female rats without changes in the number of cholinergic neurons in the areas. It is possible that this effect of feeding contributes to improve the performance in spatial learning and memory functions in female rats fed powdered diet.


Assuntos
Acetilcolina/metabolismo , Dieta , Hipocampo/metabolismo , Animais , Colina O-Acetiltransferase/metabolismo , Cromatografia Líquida de Alta Pressão , Feixe Diagonal de Broca/metabolismo , Feminino , Hipocampo/química , Imuno-Histoquímica , Masculino , Microdiálise , Neurônios/metabolismo , Gravidez , Ratos , Septo do Cérebro/metabolismo , Caracteres Sexuais , Desmame
5.
Neuroscience ; 132(2): 537-42, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15802204

RESUMO

To examine the sex difference in the 24-h profile of the acetylcholine (ACh) release in the hippocampus, in addition to the effects of housing conditions on this profile, we performed an in vivo microdialysis study in intact male and cycling female rats that had been living in large (diameter=35 cm) or small (diameter=19 cm) cylindrical cages. Each rat was individually housed in a cage for 4 days. On the day of the experiment, the dialysate was collected from the dorsal hippocampus at 20-min intervals and sequential blood samples were simultaneously obtained at 2-h intervals, under the freely moving condition for more than 24 h. ACh in the dialysates was measured by the high performance liquid chromatography system, while the corticosterone concentration in the serum was measured by radiostereoassay. Although the ACh release showed a clear daily rhythm in both sexes of rats, the amount of ACh released in female rats was significantly lower than that in males. Furthermore, the housing in the small cage significantly attenuated the ACh release during the dark phase in male rats, but not in female rats. Conversely, the serum corticosterone concentration showed a clear daily rhythm and the mean concentration of serum corticosterone in female rats was significantly higher than that in male rats. Housing in the small cage did not affect the corticosterone rhythm in either sex. These results reveal a sex difference in the 24-h profile of the ACh release, which suggests vulnerability of the cholinergic system in male rats depending on its housing conditions.


Assuntos
Acetilcolina/metabolismo , Hipocampo/metabolismo , Abrigo para Animais , Caracteres Sexuais , Córtex Suprarrenal/metabolismo , Análise de Variância , Animais , Ritmo Circadiano/fisiologia , Corticosterona/sangue , Feminino , Masculino , Microdiálise/métodos , Ratos , Ratos Wistar
6.
J Neuroendocrinol ; 16(2): 99-104, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14763995

RESUMO

Alkylphenols, such as p-nonylphenol (NP) and 4-tert-octylphenol (OP) and bisphenol A (BPA) are thought to mimic oestrogens in their action, and are called endocrine disrupters. We examined whether these endocrine disrupters affected progesterone receptor (PR) mRNA expression in the adult female rat neocortex. In one experiment, at 12.00 h, ovariectomized rats were given a subcutaneous injection of 10 mg of NP, 10 mg of OP or 10 mg of BPA, or sesame oil alone as control. Twenty-four hours after injection, the left side of the frontal cortex, parietal cortex and temporal cortex was collected. In a second experiment to study the time-course of the effects of BPA on PR mRNA, the ovariectomized rats were given a subcutaneous injection of 10 mg of BPA and killed 0, 6, 12 and 24 h after injection. In addition to the frontal cortex and temporal cortex, the occipital cortex was also collected. Northern blotting revealed that, in the first experiment, injection of NP, OP or BPA significantly increased PR mRNA expression in the frontal cortex but not in the parietal cortex. In the temporal cortex, BPA significantly decreased PR mRNA, but NP and OP produced no significant changes. The second experiment revealed that, in the frontal cortex, BPA induced a significant increase in PR mRNA expression at 6 h after injection, which lasted until 24 h after injection. In the temporal cortex, PR mRNA expression was significantly decreased 6 h after injection of BPA and was still significantly low 24 h after injection. No significant change was observed in the occipital cortex. These results suggest that, even in adult rats, endocrine disrupters alter the neocortical function by affecting the PR system, although the physiological significance of PR in the affected area is unknown.


Assuntos
Córtex Cerebral/metabolismo , Poluentes Ambientais/toxicidade , Estrogênios não Esteroides/toxicidade , Fenóis/toxicidade , Receptores de Progesterona/metabolismo , Animais , Compostos Benzidrílicos , Northern Blotting , Estrogênios/agonistas , Feminino , Lobo Frontal/metabolismo , Ovariectomia , Lobo Parietal/metabolismo , RNA Mensageiro/análise , Ratos , Ratos Wistar , Receptores de Progesterona/genética , Lobo Temporal/metabolismo , Fatores de Tempo , Distribuição Tecidual
7.
J Neuroendocrinol ; 15(2): 134-40, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12535155

RESUMO

Recently, we reported that bisphenol A (BPA), an endocrine disrupter, increased progesterone receptor (PR) mRNA in the preoptic area (POA) in adult ovariectomized rats. In the present study, we examined whether BPA also induced expression of PR proteins in both the POA and the ventromedial hypothalamic nucleus (VMH), and whether those proteins were involved in the induction of sexual behaviour. Two weeks after ovariectomy, rats received a subcutaneous (s.c.) injection of BPA, 17 beta-oestradiol or vehicle. Twenty-four hours after the injection, the rats were killed and their tissues were examined by immunocytochemistry. Some rats that received a s.c. injection of BPA, E2 or vehicle alone on the day before were injected with progesterone at 15.00 h and examined for sexual behaviour 5-7 h later. As expected, injection of 10 microg E2 significantly increased the number of PR immunoreactive cells in both the POA and the VMH compared to the number after injection of vehicle alone. In both the POA and the VMH, injection of BPA at a dose of 10 mg also significantly increased the number of PR immunoreactive cells compared to the number after injection of sesame oil alone. Furthermore, BPA induced a dose-dependent increase in the number of PR immunoreactive cells in both the POA and the VMH, demonstrating that the number of PR cells was significantly increased by as little as 100 microg of BPA. Ovariectomized (OVX) rats that were primed with 10 mg of BPA, followed by 1 mg of progesterone, displayed mainly rejection behaviour, but not lordosis as typically observed in OVX rats primed with E2 followed by progesterone. The present study suggests that BPA influences reproductive functions, including sexual behaviour even in adulthood, by altering the PR system in the hypothalamus.


Assuntos
Estrogênios não Esteroides/farmacologia , Hipotálamo/metabolismo , Fenóis/farmacologia , Receptores de Progesterona/metabolismo , Comportamento Sexual Animal/efeitos dos fármacos , Animais , Anticorpos , Compostos Benzidrílicos , Relação Dose-Resposta a Droga , Feminino , Hipotálamo/efeitos dos fármacos , Ovariectomia , Progesterona/farmacologia , Ratos , Ratos Endogâmicos WF , Receptores de Progesterona/imunologia
8.
Neuroscience ; 113(1): 109-14, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12123689

RESUMO

GABA is a potent regulator of gonadotropin-releasing hormone neurons in the hypothalamus. To determine the profile of GABA release in the medial preoptic area where the gonadotropin surge generator resides, an in vivo microdialysis study was performed in cyclic female rats. The microdialysis samples were collected and sequential blood samples (150 microl each) were also obtained, at 1-h intervals. During estrus and diestrus 1, GABA release in the medial preoptic area was relatively low. A small increase in the GABA release began in the afternoon of diestrus 1 and attained its peak in the morning of diestrus 2, but declined in the afternoon of that day. The GABA release markedly increased from late in the night of diestrus 2 through the morning of proestrus, when it attained its peak, and thereafter it declined sharply until the critical period of proestrus. A distinct preovulatory luteinizing hormone surge was observed in the afternoon of proestrus in all proestrous rats. From these results we suggest that the preovulatory elevation of the GABA release from the night through to the morning of proestrus, followed by a sharp decline, is closely associated with the onset of the preovulatory luteinizing hormone surge in cyclic female rats. The present study is the first to report the 4-day profile of GABA release in the medial preoptic area during the estrous cycle.


Assuntos
Ciclo Estral/metabolismo , Área Pré-Óptica/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Ritmo Circadiano , Diestro/metabolismo , Estradiol/sangue , Ciclo Estral/sangue , Estro/metabolismo , Feminino , Hormônio Luteinizante/sangue , Microdiálise , Proestro/metabolismo , Radioimunoensaio , Ratos , Ratos Endogâmicos , Ratos Wistar
9.
J Neuroendocrinol ; 14(6): 486-91, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12047723

RESUMO

Butyl benzyl phthalate (BBP) and bisphenol A (BPA), termed endocrine disrupters, are known to mimic oestrogen in their actions, and therefore there is concern about their effect on reproductive functions. Since it is reported that the inhibitory action of oestrogen on the pulsatile secretion of luteinizing hormone (LH) is enhanced under insulin-induced hypoglycaemia, whether this also applies to BBP and BPA was examined in the present study. In adult ovariectomized (OVX) rats, the pulsatile LH secretion 24 h after subcutaneous injection of 10 mg BBP (BBP-treated), 10 mg BPA (BPA-treated) or 100 ng 17beta-oestradiol (E2-treated), all of which were dissolved in sesame oil, was not changed significantly compared to that after the injection of sesame oil only. Furthermore, in oil-treated OVX rats, the pulsatile LH secretion immediately after intravenous injection of insulin (1.0 U) was not changed compared to that after saline injection. In BBP-treated OVX rats, the injection of insulin (1.0 U) significantly decreased the number of LH pulses as in E2-treated OVX rats. The injection of insulin did not significantly affect the amplitude of LH pulses in BBP-, BPA- and E2-treated OVX rats. The results indicate that the oestrogenic action of BBP is significantly enhanced by insulin-induced hypoglycaemia and thus the pulsatile LH secretion is inhibited. We suggest that weak oestrogenic endocrine disrupters may become harmful to reproductive functions even in adult female rats, if acting under a low energy state.


Assuntos
Glândulas Endócrinas/efeitos dos fármacos , Hipoglicemia/induzido quimicamente , Hipoglicemia/metabolismo , Insulina , Hormônio Luteinizante/metabolismo , Ovariectomia , Ácidos Ftálicos/farmacologia , Animais , Compostos Benzidrílicos , Estradiol/farmacologia , Estrogênios não Esteroides/farmacologia , Feminino , Injeções Intravenosas , Insulina/administração & dosagem , Insulina/farmacologia , Hormônio Luteinizante/antagonistas & inibidores , Fenóis/farmacologia , Fluxo Pulsátil , Ratos
10.
Neuroscience ; 110(2): 301-8, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11958871

RESUMO

Pituitary adenylate cyclase-activating peptide is densely distributed in the suprachiasmatic nucleus, which functions as the circadian pacemaker. A receptor for pituitary adenylate cyclase-activating peptide, denoted as PAC(1), exists in six variant forms. We used reverse transcriptase-polymerase chain reaction to identify the PAC(1) variants that are expressed in the suprachiasmatic nucleus. Dominant variant forms of PAC(1) in the suprachiasmatic nucleus were PAC(1)short, PAC(1)hip, and PAC(1)hop1. By in situ hybridization, we examined 24-h profiles of mRNAs for the identified receptor variants in the suprachiasmatic nucleus in constant darkness and during the light-dark cycle. In constant darkness there were clear circadian rhythms in PAC(1)short mRNA with a peak at circadian time 4 but no rhythmicity was observed in PAC(1)hip mRNA or PAC(1)hop1 mRNA. In light-dark cycles, on the other hand, PAC(1)hip mRNA displayed a bimodal rhythm with troughs at zeitgeber time 4 and 16 but PAC(1)hop1 mRNA stayed constant during the day. These results suggest that PAC(1) splice variants are differentially regulated in the rat suprachiasmatic nucleus.


Assuntos
Processamento Alternativo/genética , Ritmo Circadiano/genética , Neurônios/metabolismo , RNA Mensageiro/genética , Receptores do Hormônio Hipofisário/genética , Núcleo Supraquiasmático/metabolismo , Animais , Northern Blotting , Hibridização In Situ , Masculino , Neurônios/citologia , Estimulação Luminosa , Isoformas de Proteínas/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores de Polipeptídeo Hipofisário Ativador de Adenilato Ciclase , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Núcleo Supraquiasmático/citologia
11.
Biochem Biophys Res Commun ; 288(4): 780-5, 2001 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-11688975

RESUMO

Ghrelin, an endogenous growth hormone (GH) secretagogue, is shown to increase food intake, which action is similar to that of orexin, also a hypothalamic peptide. Since orexin suppresses pulsatile LH secretion in ovariectomized (OVX) rats, the present study was undertaken to investigate whether ghrelin also suppresses LH secretion. Effects of intracerebroventricularly injected ghrelin (0.1 nmol/0.3 microl) were examined in OVX rats treated with a small dose of 17beta-estradiol (E(2)). After ghrelin injection, pulsatile LH secretions which were ongoing in these E(2)-treated OVX rats were significantly suppressed for about 1 h, whereas GH secretion increased, peaking at 30 min. The main parameter suppressed by ghrelin was the pulse frequency, not the pulse amplitude, suggesting the hypothalamus as the site of ghrelin action. This study provides evidence that ghrelin acts not only in the control of food intake but also in the control of LH secretion.


Assuntos
Hormônio Luteinizante/metabolismo , Ovariectomia , Hormônios Peptídicos , Peptídeos/administração & dosagem , Peptídeos/farmacologia , Análise de Variância , Animais , Estradiol/farmacologia , Feminino , Grelina , Hormônio do Crescimento/sangue , Injeções Intraventriculares , Hormônio Luteinizante/sangue , Radioimunoensaio , Ratos , Ratos Wistar
12.
Neurosci Res ; 41(3): 251-5, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11672838

RESUMO

To determine whether estrogen has an effect on clock genes in the suprachiasmatic nucleus (SCN), we examined the effect of estrogen on the expression of Cry1 and Cry2 mRNAs in the SCN of female rats. Ovariectomized rats were injected with 20 microg 17beta-estradiol at zeitgeber time (ZT) 6 and ZT 18 and killed 24 h after the treatment. Northern blot revealed that the expression of Cry2 mRNA was significantly decreased in the SCN of estrogen-treated rats at both time points [correction]. But estrogen did not affect Cry1 mRNA levels in the SCN at any ZT. These results suggested that Cry1 and Cry2 mRNAs in the SCN were differently regulated by estrogen.


Assuntos
Proteínas de Drosophila , Estradiol/farmacologia , Proteínas do Olho , Flavoproteínas/genética , Células Fotorreceptoras de Invertebrados , RNA Mensageiro/metabolismo , Núcleo Supraquiasmático/metabolismo , Animais , Relógios Biológicos/efeitos dos fármacos , Relógios Biológicos/genética , Ritmo Circadiano , Criptocromos , Feminino , Ovariectomia , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G , Fatores de Tempo
13.
Neurosci Res ; 41(1): 25-32, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11535290

RESUMO

Expressions of Cry1 and Cry2 mRNA in the rat pineal gland were examined by Northern blot. The levels of Cry1 and Cry2 transcript had a marked circadian rhythm with peaks at circadian time (CT) 20 in constant darkness. But the amplitude of the Cry1 rhythm was higher than that of the Cry2 rhythm. Furthermore, a significant increase in Cry1 mRNA levels was caused by light pulse given at CT 16 but not at CT 4, but the expression of Cry2 was not significantly induced by light pulses given at either CT 4 or CT 16. These results suggest that Cry1 in the pineal gland is regulated by photic and circadian information but Cry2 is only regulated by circadian information.


Assuntos
Relógios Biológicos/genética , Ritmo Circadiano/genética , Proteínas de Drosophila , Proteínas do Olho , Flavoproteínas/genética , Regulação da Expressão Gênica/genética , Células Fotorreceptoras de Invertebrados , Glândula Pineal/metabolismo , RNA Mensageiro/metabolismo , Animais , Criptocromos , Masculino , Estimulação Luminosa , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G
14.
Neurosci Lett ; 309(1): 37-40, 2001 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-11489541

RESUMO

To determine the effects of ovarian steroid hormones on gap junction communication in the suprachiasmatic nucleus (SCN), we examined the effects of estrogen and/or progesterone on the expression of connexin-36 mRNA in the SCN and cerebral cortex (CX) of female rats. Ovariectomized adult rats were injected with 20 microg 17beta-Estradiol or sesame oil 48 h before sacrifice and further injected with 1.5 mg progesterone or sesame oil 24 h before sacrifice. Northern blot revealed that estrogen significantly increased the expression of connexin-36 mRNA in the SCN and this increase was inhibited by progesterone. On the other hand, the connexin-36 mRNA level in the CX was not affected by estrogen or progesterone. These results suggest that the gap junction with connexin-36 in the SCN is specifically regulated by ovarian steroid hormones of female rats.


Assuntos
Ritmo Circadiano/efeitos dos fármacos , Conexinas/genética , Estrogênios/farmacologia , Proteínas do Olho/genética , Junções Comunicantes/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Progesterona/farmacologia , Núcleo Supraquiasmático/efeitos dos fármacos , Animais , Relógios Biológicos/efeitos dos fármacos , Relógios Biológicos/fisiologia , Comunicação Celular/efeitos dos fármacos , Comunicação Celular/fisiologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Ritmo Circadiano/fisiologia , Estrogênios/metabolismo , Estro/metabolismo , Feminino , Junções Comunicantes/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Neurônios/metabolismo , Progesterona/metabolismo , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Núcleo Supraquiasmático/metabolismo , Proteína delta-2 de Junções Comunicantes
15.
Neuroendocrinology ; 74(2): 77-81, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11474214

RESUMO

Butyl benzyl phthalate (BBP) and bisphenol A (BPA), so-called endocrine disrupters, are known to mimic the action of estrogens: they are thus liable to influence reproductive functions. Since little is known about their action on gene expression in the adult hypothalamus, we examined the effects of these chemicals on the expression of estrogen-regulated mRNAs, i.e., progesterone receptor (PR) mRNA, preproenkephalin (PPE) mRNA and neurotensin (NT) mRNA, in the hypothalamus and pituitary of adult female rats. Two weeks after ovariectomy, rats were subcutaneously injected with 10 mg BBP, 10 mg BPA, or 10 microg 17 beta-estradiol (E(2)) in sesame oil, or with sesame oil alone as a control. Twenty-four hours after the injection, tissues including the preoptic area (POA), mediobasal hypothalamus (MBH) and anterior pituitary were collected. Northern blot revealed that injection of E(2) resulted in expected changes, i.e., significant increases in PR mRNA in the POA, MBH and anterior pituitary, and in PPE mRNA in the MBH. We also found that injection of BPA significantly increased PR mRNA in the POA and anterior pituitary, while injection of BBP increased PR mRNA in the POA and anterior pituitary, although the increase in the anterior pituitary was not significant. No significant effect of E(2), BPA, or BBP on NT mRNA in the POA was detected. The present study demonstrates that the two endocrine disrupters BPA and BBP can increase the expression of PR mRNA in the POA of adult ovariectomized rats.


Assuntos
Estradiol/farmacologia , Fenóis/farmacologia , Ácidos Ftálicos/farmacologia , Área Pré-Óptica/efeitos dos fármacos , RNA Mensageiro/efeitos dos fármacos , Animais , Compostos Benzidrílicos , Encefalinas/biossíntese , Encefalinas/genética , Estrogênios não Esteroides/farmacologia , Feminino , Neurotensina/biossíntese , Neurotensina/genética , Ovariectomia , Área Pré-Óptica/metabolismo , Precursores de Proteínas/biossíntese , Precursores de Proteínas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores de Progesterona/biossíntese , Receptores de Progesterona/genética
16.
Neurosci Res ; 40(2): 141-6, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11377752

RESUMO

Gonadotropin-releasing hormone (GnRH) neurons are mainly located in the anterior preoptic area (aPOA) and gamma-aminobutyric acid (GABA) is known as a potent regulator of the GnRH neurons. To examine the development of the GABAergic system in the aPOA, immunocytochemistry of glutamic acid decarboxylase 67 (GAD(67)) was performed in immature (postnatal d16, d25 and d30) and mature (postnatal 10 weeks) male rats. All immunocytochemical procedures were simultaneously performed. In the lateral part of the aPOA, the detectable number of GAD(67)-immunoreactive cells was small in the d16 group, but significantly increased in the d25, d30 and mature groups, up to 2.7, 4.8 and 5.7 times the number in the d16 group, respectively. In the diagonal band of Broca (DBB), the number was also small in the d16 group, and significantly increased in the d25, d30 and mature groups upto 1.8, 2.2 and 2.8 times the number in the d16 group, respectively. However, in the cingulate cortex, no significant developmental change was observed. These results suggest that the development of the GABAergic system in the lateral aPOA and the DBB occurs before sexual maturation of male rats.


Assuntos
Glutamato Descarboxilase/metabolismo , Hormônio Liberador de Gonadotropina/metabolismo , Isoenzimas/metabolismo , Neurônios/enzimologia , Área Pré-Óptica/enzimologia , Área Pré-Óptica/crescimento & desenvolvimento , Maturidade Sexual/fisiologia , Ácido gama-Aminobutírico/biossíntese , Envelhecimento/fisiologia , Animais , Contagem de Células , Tamanho Celular/fisiologia , Giro do Cíngulo/citologia , Giro do Cíngulo/enzimologia , Giro do Cíngulo/crescimento & desenvolvimento , Imuno-Histoquímica , Masculino , Neurônios/citologia , Área Pré-Óptica/citologia , Ratos , Ratos Wistar , Diferenciação Sexual/fisiologia
17.
Neuroendocrinology ; 73(3): 157-65, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11307034

RESUMO

Although it has been assumed that synchronized firing of gonadotropin-releasing hormone (GnRH) neurons is necessary for pulsatile GnRH secretion, there is no clear evidence for this. In the present study we simultaneously recorded spontaneous action potentials from multiple cells. Immortalized GnRH neurons (GT1-7 cells) were cultured on a multi-electrode dish (MED) and action potentials recorded by an extracellular recording method. One to two weeks after the beginning of culture, spontaneous action potentials appeared, exhibiting bursts composed of 5-10 action potentials. Burst activity was intermittent and periodic with mean burst intervals of 13.3 s. Furthermore, burst activity was recorded almost simultaneously from several micro-electrodes, suggesting that electrical activities of GT1-7 cells were synchronized with each other. Periodic bursts were completely and reversibly blocked by 1-5 microM tetrodotoxin, indicating that voltage-dependent Na(+) channels are involved in their generation. gamma-Aminobutyric acid (GABA) given at a 10-microM concentration shortened inter-burst intervals, whereas 10 microM bicuculline lengthened them. Finally, the gap junctional blockers n-octyl alcohol (1 mM) and carbenoxolone (100 microM) reversibly blocked periodic burst activity. The present study provides direct evidence that the electrical activity of GT1-7 cells exhibits synchronous and periodic bursts composed of action potentials. In addition, endogenous GABA is involved in GT1-7 cells in determining burst frequency. Although the precise mechanism of synchronized burst activities needs to be clarified, gap junctional communications among GT1-7 cells are at least partially involved.


Assuntos
Hormônio Liberador de Gonadotropina/metabolismo , Neurônios/fisiologia , 1-Octanol/farmacologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Bicuculina/farmacologia , Carbenoxolona/farmacologia , Linhagem Celular Transformada , Relação Dose-Resposta a Droga , Eletrofisiologia , Antagonistas GABAérgicos/farmacologia , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/fisiologia , Neurônios/efeitos dos fármacos , Potássio/farmacologia , Tetrodotoxina/farmacologia , Fatores de Tempo , Ácido gama-Aminobutírico/farmacologia
18.
Neuroreport ; 12(5): 893-5, 2001 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-11303754

RESUMO

We examined the effect of axillary compounds on pulsatile secretion of serum luteinizing hormone (LH). Axillary compounds were collected from donor women in the follicular phase (FP) and the ovulatory phase (OP) and were treated with isopropyl alcohol (IPA). The recipient was not exposed to either axillary compounds or IPA for the first 4 h and was exposed to FP or OP compounds, or to IPA, during the next 4 h. The frequency of the LH pulse was increased by FP compounds and was decreased by OP compounds, but the LH pulse frequency was not changed by IPA. Therefore, in humans, pheromones may play a role in the modulation of the timing of ovulation by changing the frequency of pulsatile LH secretion.


Assuntos
Hormônio Luteinizante/metabolismo , Atrativos Sexuais/farmacologia , Adulto , Feminino , Fase Folicular/fisiologia , Humanos , Ovulação/fisiologia
19.
Neurosci Lett ; 297(2): 73-6, 2001 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-11121873

RESUMO

We previously reported that the restriction of environmental space attenuates spontaneous locomotor activity and hippocampal acetylcholine release. To examine the effect of the restriction of environmental space on spatial learning function, male rats were individually housed in a cylindrical large cage (diameter=35 cm) or small cage (diameter=19 cm) for 5 days. Eight-arm radial maze performance was examined to evaluate spatial learning and memory functions. The task was performed once a day between 21:00 and 22:00 h in the dark phase. Although all rats learned and performed the task, those in the small cage had lower scores and took more trial time than those in the large cage. These results suggest that the restriction of environmental space impairs spatial learning in the dark phase in rats.


Assuntos
Aprendizagem em Labirinto/fisiologia , Memória/fisiologia , Percepção Espacial/fisiologia , Acetilcolina/metabolismo , Animais , Escuridão , Ambiente Controlado , Hipocampo/metabolismo , Iluminação , Masculino , Ratos , Ratos Wistar
20.
Neurosci Res ; 38(1): 43-7, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10997577

RESUMO

We examined effects of gap junction blockers, octanol and halothane, on circadian rhythms in the release of arginine-vasopressin (AVP) and vasoactive intestinal polypeptide (VIP) in suprachiasmatic nucleus (SCN) slice cultures of the rat. Circadian rhythms in AVP and VIP release maintained when the SCN culture was treated with octanol for 42 h. However, the release of AVP and VIP showed no circadian rhythms after 7 days incubation with octanol or halothane. Circadian rhythmicity in the two peptide rhythms appeared after the removal of the drug from the culture medium. These findings suggested that the gap junction communication may be involved in intercellular coupling within each subpopulation of AVP or VIP neurons in the SCN.


Assuntos
Junções Comunicantes/metabolismo , Núcleo Supraquiasmático/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo , Vasopressinas/metabolismo , Animais , Comunicação Celular/efeitos dos fármacos , Ritmo Circadiano/efeitos dos fármacos , Meios de Cultivo Condicionados/química , Junções Comunicantes/efeitos dos fármacos , Halotano/farmacologia , Técnicas In Vitro , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Octanóis/farmacologia , Ratos , Ratos Wistar , Núcleo Supraquiasmático/citologia , Peptídeo Intestinal Vasoativo/análise , Vasopressinas/análise
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