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Melatonin administration to pituitary-grafted male and female rats resulted in a marked decrease of previously high plasma prolactin levels, while an increase in prolactin levels was observed in sham-operated controls. The latter effect was significant only in males. Treatment with melatonin did not modify basal LH hormone levels or LH responses to(More)
This work was designed to investigate the effects of cyclosporine on prolactin secretion by an ectopically grafted heterologous pituitary gland, and on the hypothalamic content of norepinephrine, dopamine and serotonin. The administration of cyclosporine prevented the augmentation in plasma prolactin levels which occurred following an ectopic graft of a(More)
To study the possible role of prolactin on growth regulation pituitary grafted rats of different ages and their sham-operated controls have been used. After the transplant operation of one pituitary gland from a litter-mate donor on day 5 or on day 30 of life, a marked prolactin increase has been observed. This increase has been immediate in 30 day-old rats(More)
Treatment of adult male rats with ethanol for a period of six weeks resulted in a numerical but not significant increase in plasma prolactin levels together with a reduction in plasma luteinizing hormone (LH) levels. Although basal plasma testosterone (T) levels were not affected in ethanol-treated animals, testicular weight was reduced and seminiferous(More)
Melatonin influences prolactin (PRL) secretion through unknown mechanisms. This work was undertaken to study the effects of melatonin administration on PRL secretion in pituitary-grafted male rats. Melatonin administration 5 hours before dark resulted in a marked decrease of previously high basal plasma PRL levels in pituitary-grafted rats, whereas a marked(More)
Effects of cyclosporine (CyA) on ovarian function and the possible role of prolactin in mediating these effects were examined in young female rats. The animals were sham-operated or rendered hyperprolactinemic by transplanting pituitary glands under the renal capsule. Cyclosporine prevented the increase in plasma prolactin levels in grafted rats. However,(More)
Recent evidence suggests that increased plasma prolactin (PRL) levels could be modifying the synthesis and release of catecholamines (CA) from the adrenal medulla. In order to study this possibility, female rats bearing an anterior pituitary gland, from a litter-mate donor, under the right kidney capsule since day 30 of life and their sham-operated controls(More)
It was recently reported that anterior pituitary tissue transplanted to an ectopic site contains measurable amounts of dopamine and noradrenaline. To examine the possibility of local catecholaminergic control of prolactin secretion from ectopic pituitaries, pituitary grafted and sham-operated female rats were submitted to several pharmacological treatments(More)
The effects of melatonin treatment and pituitary transplants on serum total and free cholesterol levels, cholesterol esterification index, phospholipid levels and prolactin, thyroid-stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) levels were examined in rats. Male rats were grafted an anterior pituitary under the kidney capsule or were(More)
In order to study the possible role on prolactin secretion of the catecholamines present in ectopic pituitaries, female rats bearing an anterior pituitary graft under the kidney capsule since day 30 of life and their sham-operated controls, were sacrificed at 1, 2, 4, 7, 15, 30, 45 and 60 days after the operation. Data obtained showed a significant increase(More)