Does Protein Kinase C Mediate Pituitary Actions of Gonadotropin-Releasing Hormone?*

Part of the fascination in studying the interaction of GnRH with its target cell, the pituitary gonadotrope, is the number of end points that are regulated. GnRH provokes the release of two gonadotropins, LH and FSH, as well as regulates gonadotrope responsiveness, GnRH receptor number, and gonadotropin biosynthesis (translation and posttranslational events) and gene expression. Clearly, the complexity of these events, whether viewed from their temporal relationships or from the loci involved in these cellular actions, is one of the reasons that identification of messenger molecules and paths has been such a challenging goal. This, coupled with the clinical and veterinary significance of this releasing hormone, are reasons that the goal of understanding GnRH action has attracted the attention of many laboratories. It is well established that calcium plays a central role in many cellular actions of GnRH.