The objective of this proposal is to elucidate the signaling pathways in GnRH neurons which constitute the clock for pulsatile GnRH release and that mediate the action of neurotransmitters. The investigator proposes to determine the relationship between intracellular and extracellular cAMP levels and GnRH secretion; to determine whether GT1 cells express cAMP gated cation channels and how they are regulated; to determine which isoforms of adenyl cyclase and phosphodiesterase are expressed in GT1 cells and how they are regulated, particularly isoforms that are regulated by PKA; and, to determine cAMP and GnRH secretion dynamics in GT1 cells stably expressing either the constitutively-active PDE-4D isoform or a dominant-negative PKA regulatory subunit. Finally, if effects are observed in the biochemical studies, the effector molecules will be targeted to GnRH neurons using transgenic approaches in order to determine their physiological significance.