RESUMO
The present investigations were designed to assess the effect of the serotoninergic system on luteinizing hormone (LH) and LH-releasing hormone (LH-RH) secretion in female rats aged 14 and 30 days. The administration of 5-hydroxytryptophan (5-HTP; 75 mg/kg i.p.) increased hypothalamic serotonin (5-HT) concentrations in both age groups, and did not affect hypothalamic norepinephrine (NE) concentrations or release. Serum LH levels were raised by 5-HTP in 14-day-old, but not in 30-day-old rats. Basal and KCl- (28 mM) stimulated LH-RH release by incubated hypothalamic fragments was significantly enhanced when 5-HTP was injected previously to 14-day-old animals. In 30-day-old rats, 5-HTP treatment did not modify basal LH-RH release, and decreased the KCl-stimulated LH-RH output. Similarly, the addition of 5-HT (10(-7) M) to superfused hypothalamic fragments enhanced basal LH-RH release in 14-day-old rats and blocked the increment in LH-RH release evoked by KCl in 30-day-old rats. The present results show that in 14-day-old female rats, the serotoninergic system (activated in vivo by 5-HTP treatment, or in vitro by 5-HT addition) exerts a stimulatory effect on LH-RH, and thus, on LH release. On the contrary, in 30-day-old animals, stimulated LH-RH secretion was inhibited by 5-HT. Apparently, the hypothalamic NE system is not implicated in this response. The participation of this changing effect of 5-HT on LH-RH/LH release at the onset of puberty is postulated.
Assuntos
Hormônio Liberador de Gonadotropina/metabolismo , Hormônio Luteinizante/metabolismo , Serotonina/fisiologia , 5-Hidroxitriptofano/farmacologia , Animais , Feminino , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Metiltirosinas/farmacologia , Cloreto de Potássio/farmacologia , Ratos , Ratos Endogâmicos , alfa-MetiltirosinaRESUMO
1. Rats submitted to starvation or water deprivation showed a decrease in LH and prolactin serum levels. 2. 5-HT was increased without changes in DA and NA in cerebral cortex of starved rats. 3. Neurotransmitters did not change in hypothalamus of starved rats but water deprivation decreased NA and increased 5-HT.
Assuntos
Monoaminas Biogênicas/farmacologia , Desidratação/metabolismo , Hipotálamo/fisiologia , Hormônio Luteinizante/sangue , Prolactina/sangue , Inanição/metabolismo , Animais , Peso Corporal , Química Encefálica/efeitos dos fármacos , Masculino , Ratos , Serotonina/metabolismoRESUMO
1. Acute or chronic treatment with ethanol modify the monoamine levels in epididymis (body, tail) and prostate, without changes in head epididymis and seminal vesicle of male rats. 2. The prostate seems to be the most affected in acute treatment while the epididymis body is altered after prolonged exposure to ethanol.