Increased sensitivity to the negative feedback effects of testosterone induced by hyperprolactinemia in the adult male rat

Endocrinology
A S McNeillyH M Fraser

Abstract

High plasma levels of PRL induced by transplants of two donor pituitaries under the kidney capsule of adult male rats resulted in a prolonged suppression of plasma levels of LH and FSH although testosterone levels were maintained within normal limits. Castration of rats with pituitary transplants resulted in a normal though delayed rise in serum levels of both LH and FSH to levels equivalent to those in normal castrated controls. This increase in gonadotropin levels occurred in spite of maintenance of elevated PRL levels. Two experiments were carried out in which testosterone was restored after castration by Silastic testosterone-containing implants of various lengths (Exp 1:60, 30, and 10 mm; Exp 2: 30, 20, 10, 5, and 2 mm). In both experiments 60- and 30-mm testosterone implants prevented the postcastration rise in LH and FSH in both control and hyperprolactinemic rats. However, although the shorter testosterone implants delayed this rise in control rats, levels of LH and FSH increased by 4 days and were not significantly different from castrated rats without testosterone implants by 15 days after castration. In contrast, this rise in gonadotropins was abolished or considerably delayed by the shorter implants in hyperprolacti...Continue Reading

Citations

Jan 1, 1986·Journal of Steroid Biochemistry·H CohenJ Bertrand
Jan 1, 1988·Journal of Steroid Biochemistry·S P KalraW R Crowley
Jun 16, 2005·Pharmacology, Biochemistry, and Behavior·Andrea GogosMaarten van den Buuse
Mar 25, 2000·The Journal of Steroid Biochemistry and Molecular Biology·E DíazB Díaz
Dec 17, 2003·Behavioral Neuroscience·Andrea Gogos, Maarten van den Buuse
Feb 1, 1996·International Journal of Andrology·C CaraniP Marrama
Jan 1, 1984·Archives of Andrology·I MastrogiacomoM Chini
Oct 4, 2007·American Journal of Physiology. Endocrinology and Metabolism·Valencia L WilliamsAmeae M Walker

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