Abstract
Attempts were made to find out whether hyperprolactinemia has an effect on the hypothalamo-pituitary response to estrogen feedback and LHRH stimulation. Adult female rats of Wistar strain were ovariectomized and received subcutaneous injection of 20μg estradiol benzoate (EB) 3-4weeks later (day-0). A second injection of 20μg EB, when administered at noon on day-3, induced a highly significant increase in serum LH (p<0.001 vs. basal values), but not FSH, estimated at 1800h on the same day. This EB-promoted LH release was not altered by pretreatment with rat PRL (5μg/day), which was administered subcutaneously daily in the morning (1100h) between day-1 and day-3. No statistical difference in the serum LH concentration was found when compared with the values for the control animals pretreated with 0.9% saline alone.
Serum gonadotropins 15min after LHRH administration (100ng/100g BW) in 32-day-old female rats were not statistically different between the animals pretreated with 5μg PRL, which was given subcutaneously daily (at 0800h) for 3days, and the controls pretreated with 0.9% saline. These results suggest that an acute increase in serum PRL may not exert a negative effect on the gonadotropin release induced by estrogen feedback and LHRH stimulation.
