Nitric oxide modulates ATP-evoked currents in mouse Leydig cells

Testosterone synthesis within Leydig cells is a calcium-dependent process. Intracellular calcium levels are regulated by different processes including ATP-activated P2X purinergic receptors, T-type Ca(2+) channels modulated by the luteinizing hormone, and intracellular calcium storages recruited by a calcium-induced calcium release mechanism. On the other hand, nitric oxide (NO) is reported to have an inhibitory role in testosterone production. Based on these observations, we investigated the interaction between the purinergic and nitrergic systems in Leydig cells of adult mice. For this purpose, we recorded ATP-evoked currents in isolated Leydig cells using the whole cell patch clamp technique after treatment with L-NAME (300 μM and 1 mM), L-arginine (10, 100, 300, and 500 μM), ODQ (300 μM), and 8-Br-cGMP (100 μM). Our results show that NO produced by Leydig cells in basal conditions is insufficient to change the ATP-evoked currents and that extra NO provided by adding 300 μM L-arginine positively modulates the current through a mechanism involving the NO/cGMP signaling pathway. Thus, we report an interaction between the nitrergic and purinergic systems in Leydig cells and suggest that Ca(2+) entry via the purinergic receptors can be regulated by NO.