Sex difference in pituitary cyclic AMP response to gonadotropin-releasing hormone

Z. Naor, U. Zor, R. Meidan, Y. Koch

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35 Scopus citations

Abstract

To examine the possible role of pituitary cyclic AMP in the mechanism of luteinizing hormone (LH) release, we studied the effects of gonadotropin-releasing hormone (GnRH) on pituitary cyclic AMP concentration and LH release in male and female rats at different ages. Incubation of pituitaries derived from immature or adult female rats for 20-240 min with GnRH (1-25 nM) results in a 6- to 33-fold augmentation of LH release without any increase in pituitary cyclic AMP level. Pituitaries derived from immature males responded to GnRH (1 nM) with an increase in LH release, but no change in cyclic AMP level was observed. Higher concentrations of GnRH (5-25 nM) induced augmented cyclic AMP accumulation in these animals, but this response was demonstrable only after 90 min of incubation, whereas significant stimulation of LH release occurred within 20 min. GnRH failed to stimulate cyclic AMP production in pituitaries from mature male animals castrated 10 days before collection of the glands although the stimulatory action of GnRH on LH release was not impaired by castration. Testosterone replacement restored the pituitary cyclic AMP response to GnRH stimulation. Incubation of pituitaries derived from immature male or female rats with a cyclic AMP derivative (8-bromoadenosine 3',5'-cyclic monophosphate; 1 mM) did not affect LH release, whereas the release of growth hormone was augmented. Because enhanced cyclic AMP prodution in response to GnRH stimulation occurs only in pituitaries derived from intact adult males, cyclic AMP cannot be regarded as the exclusive mediator of GnRH action on pituitary LH release.

Original languageEnglish
Pages (from-to)E37-E41
JournalAmerican Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology
Volume4
Issue number1
DOIs
StatePublished - 1978
Externally publishedYes

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