Increased plasma and pituitary prolactin concentrations in adult male rats with selective elevation of FSH levels may be explained by reduced testosterone and increased estradiol production.

摘要: The roles of testosterone and estradiol in regulating prolactin concentrations were studied acutely castrated adult male rats receiving subcutaneous Silastic® implants the sex steroids. Testosterone was administered increasing doses, from subphysiologic to intact levels, both alone combination with a small, single dose estradiol. study designed assess whether change relative rates steroid production could account for an increase PRL release absence other testicular factors. At very low levels plasma testosterone, FSH LH indistinguishable castrate controls. As concentration increased, suppressed progressively levels. When coadministered small estradiol, combined effects produced midcastrate level but maintained normal similar selective observed men germinal aplasia. Although controls, replacement by capsule increased dose-related manner so that, at physiologic elevated two-fold (P< 0.01), achieved alone. Pituitary also doses values remained within range measured different depending on dose. With replacement, when selectively four-fold 0.01) compared controls (P < 0.01). A smaller pituitary content noted toward midphysiologic values, fell progressively, above 0.05). It concluded that modulate secretion factors, greatest effect is seen testosterone-estradiol ratio reduced, producing concentration. These results are dysfunction associated concentrations. precise mechanism these changes remain be elucidated.