Role of cAMP in histamine-dependent regulation of Leydig cell proliferation and esteroidogenesis

MONDILLO, C; PAGOTTO, R; MONZÓN, C; BESIO MORENO, M; PIGNATARO, OP

Congreso; SISTAM, The First South American Spring Symposium in Signal Transduction and Molecular Medicine; 2010

Recently, our group reported a novel biological activity of HA in the testis: the dual concentration-dependent regulation of Leydig cell (LC) steroidogenesis via H1 and H2 receptors. In the present study, we used the MA-10 cell line as an experimental model to evaluate the potential role of HA as modulator of LC proliferation, as well as its mechanism of action. We assessed cell proliferation by using tritiated thymidine incorporation and MTS assays. Both HA and amthamine (A, H2 agonist) stimulated LC proliferation after 24 hours. Given that H2 couples to the adenylate cyclase (AC) system in LC, we studied the effect of a 24-hour treatment with forskolin (FSK, direct stimulator of AC) or db-cAMP (permeable analogue of cAMP). Both compounds inhibited cell proliferation in a concentration-dependent manner. We then measured intracellular cAMP levels at various times after stimulation with HA, A or FSK. While HA and A raised cAMP levels transiently, FSK induced a sustained elevation. Interestingly, a short treatment (15 minutes) with db-cAMP stimulated cell proliferation, and addition of a phosphodiesterase inhibitor 15 minutes after HA or A led to inhibition of cell proliferation. These results suggest that HA stimulates MA-10 LC proliferation via H2 activation and a transient increase in cAMP levels. Grants: ANPCYT, CONICET, UBA and F Roemmers.