 Within the ovaries, transmembrane G-protein coupled receptors (GPCRs) bind to LH in the bloodstream, and the signal is transduced to the interior of theca cells through the action of the second messenger cAMP and third messenger protein kinase A (PKA).Theca cells are then stimulated to produce testosterone, which is sent in a paracrine fashion to neighboring granulosa cells for conversion to estradiol.Hyperactivity of theca cells causes hyperandrogenism, and hypoactivity leads to a lack of estrogen.