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The LH secretory response of gonadotropes to GnRH varies during the estrous cycle of the rat. The increased secretion of estrogens during the 24-48 h before the preovulatory surge of LH secretion and the enhanced quantities of progesterone secreted acutely during the surge elevate the responsiveness of hypophysial gonadotropes to GnRH. However, the cause of(More)
The mechanisms of GnRH-induced desensitization of LH secretion are poorly understood. Protein kinase C (PKC) and protein kinase A (PKA) desensitize some receptors of the 7-membrane type, and the GnRH receptor has consensus phosphorylation sites for PKC in the first and third intracellular loops, and a site for PKA in the first intracellular loop. In the(More)
The classical mode of luteinizing hormone (LH) secretory desensitization in the rat appears after 3-6 h of continuous in vitro administration of gonadotropin (GnRH). A second mode has been reported to occur very rapidly (< 2 min) after the onset of GnRH administration, and to reverse within 3 min after its withdrawal. Here, the existence of a third mode of(More)
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