Mechanisms of hormone action: luteinizing hormone receptors and second-messenger pathways.

The binding of luteinizing hormone/chorionic gonadotropin (LH/CG) to its receptor leads to an orderly cascade of events leading to activation of cytoplasmic effector molecules. The mechanism of action of LH includes stimulation of multiple signal transduction effector systems, including adenylyl cyclase (AC) and inositol phospholipid-specific phospholipase-C (PLC). These effector systems operate by activating families of protein kinases (PKs) which regulate cell metabolism, secretion, gene induction, cellular proliferation and differentiation. The signaling pathways activated by LH interact or cross-talk with the signaling pathways activated by growth factors. The diversity of cellular signaling mechanisms elicited by LH and the potential for interactions with signals generated by growth factors may allow fine tuning of cellular responses during the process of follicular development, ovulation, and corpus luteum formation.