StAR protein is increased by muscarinic receptor activation in human luteinized granulosa cells

Cultured human luteinized granulosa cells (GC) are a unique model to study regulation of the human corpus luteum, e.g. by local factors, including ace tylcholine (ACh). GC express functional ACh-receptors of the M1-type (M1R). Priming with the cholinergic agonist carbachol for 24 h, followed by a 24 h stimulation with human chorionic gonadotrophin (hCG), significantly incre ased progesterone levels (up to 2-fold), compared with hCG stimulation alon e. This is likely due to the effect of carbachol. observed after 24 h, to i ncrease the levels of steroid acute regulatory (StAR) protein, as found in Western blots. StAR protein was increased (2-10-fold), while P450 side chai n cleavage (SCC) enzyme was unaffected. Thus, one role of muscarinic recept or activation in human GC is regulation of StAR protein and, subsequently, progesterone production. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.