RESUMO
Ontogenic and sexual differences have been described in the regulation of anterior pituitary hormone release. In the present experiments we studied basal release and the effect of a depolarizing concentration of K+ on in vitro gonadotropin and prolactin release from anterior pituitaries of male and female rats at 12, 20 and 28 days of age. Basal release of LH and FSH increased with age, values obtained from female glands being significantly higher than those obtained from male glands. K(+)-induced release of LH did not present differences among ages, although the response in females was always greater than that in age-matched males. If K(+)-induced release of LH was considered in relation to basal release, infantile 12-day-old rats of both sexes, had a significantly greater sensitivity to the effect of K+ in comparison to older ages, as has been described for the LH-releasing effect of LHRH and of other stimuli. K(+)-induced FSH release was maximal in females at 20 days of age, and in males at 28 days of age. Percentage increase relative to basal values, induced by K+ was also greatest at 12 days in both sexes, although values from female glands were significantly higher than those from males. Basal and K(+)-induced prolactin release increased significantly with age in both sexes. Basal prolactin release was greater in females than in males at 28 days of age, and no other sexual difference was evidenced.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Envelhecimento/fisiologia , Hormônio Foliculoestimulante/metabolismo , Hormônio Luteinizante/metabolismo , Adeno-Hipófise/metabolismo , Potássio/farmacologia , Prolactina/farmacologia , Análise de Variância , Animais , Feminino , Técnicas In Vitro , Cinética , Masculino , Adeno-Hipófise/efeitos dos fármacos , Adeno-Hipófise/crescimento & desenvolvimento , Radioimunoensaio , Ratos , Ratos Sprague-Dawley , Caracteres SexuaisRESUMO
The ontogeny of diazepam's endocrine effects in male and female rats, and of 3H-diazepam binding in the hypothalami of both sexes was studied. Diazepam inhibited basal prolactin levels in 38 day-old male rats and, if prolactin levels were stimulated by Haloperidol the inhibition occurred in 28 day-old males, indicating that the hypoprolactinemic effect of the drug could be evidenced earlier if prolactin titers were high. The prolactin inhibition in females did not reach statistical significance at any studied age. Diazepam significantly released LH only in male rats at 12 days, showing thus, a period of special sensitivity of LH release to the drug. Benzodiazepine-hypothalamic binding sites increased in number from birth to puberty, reaching a plateau at 20 days of age. No sexual differences or changes in affinity were found throughout the studied period. These results suggest that the maturation of diazepam's hypoprolactinemic effect could be partially related to the increase in hypothalamic binding sites, whereas the sexual differences observed in diazepam's endocrine actions could be due to sexual differentiation of endocrine control mechanisms.
Assuntos
Diazepam/farmacologia , Hipotálamo/metabolismo , Prolactina/metabolismo , Receptores de GABA-A/biossíntese , Animais , Sítios de Ligação , Diazepam/metabolismo , Feminino , Haloperidol/farmacologia , Hipotálamo/efeitos dos fármacos , Hormônio Luteinizante/sangue , Hormônio Luteinizante/metabolismo , Masculino , Prolactina/sangue , Ratos , Ratos Endogâmicos , Receptores de GABA-A/análise , Caracteres Sexuais , Maturidade Sexual , Tireotropina/sangue , Tireotropina/metabolismoRESUMO
In adult female rats born from Streptozotocin-diabetic mothers, blood glucose measured under basal conditions or 30 min after glucose administration was similar to controls; however at 180 min 50% of offspring from diabetics was moderately hyperglycemic whereas 100% of controls were normoglycemic. The time of vaginal opening, and after maturity, the number of rats with regular estrous cycles was in the range of controls. After ovariectomy, control rats receiving estradiol showed a sharp increase of serum LH at 4 pm following progesterone treatment at 10 am, while rats born from diabetic mothers failed to modify serum LH. Estradiol receptors in cell nuclei and cytosolic progestin receptors were determined in anterior pituitary, hypothalamus and preoptic area of rats subjected to a 4-day estradiol treatment. Changes were statistically significant in the hypothalamus only, in that rats born from diabetic mothers showed reduced induction of progestin receptors coupled to increased binding of (3H)-estradiol in cell nuclei. These findings bring support for a hypothalamic defect in rats born from diabetic mothers, the reduction of hypothalamic progestin receptors being reflected in the reduced sensitivity to the positive feedback action of progesterone to release LH.