Nitric oxide modulates ATP-evoked currents in mouse Leydig cells

Abstract

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 Ca2+ 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 Ca2+ entry via the purinergic receptors can be regulated by NO.

Androgen Deficiency and Phosphodiesterase Type 5 Expression Changes in Aging Male: Therapeutic Implications

“…An interaction between the nitrergic and purinergic systems seems to exist in LCs. In fact, recently, it has been shown that basal NO production in LCs changes the adenosine triphosphate (ATP)-evoked currents and that extra NO modulates the current through a mechanism involving the NO/cGMP signaling pathway (22).…”

Nitric oxide-induced lipophagic defects contribute to testosterone deficiency in rats with spinal cord injury

“…One study showed that NO neither increased cGMP production nor modified cyclic adenosine monophosphate (cAMP) production, but alternatively, directly inhibited the cytochrome P450 enzyme family (25,26), which catalyzed several critical reactions during testosterone synthesis. In contrast, another study reported that NO critically elevated cGMP levels, which in turn blocked LH-modulated ATPevoked Ca 2+ currents required for testosterone synthesis (27,28). Interestingly, NO inhibited autophagy via complex inhibitory effects on JNK1/Bcl-2/Beclin 1 and IKK/AMPK/TSC2 pathways (39).…”

“…Nitric oxide (NO) is an important member of reactive oxygen species. Although physiological levels are required for testis function (21)(22)(23)(24), high NO concentrations can inhibit LC steroidogenesis; mechanisms inhibiting the cytochrome P450 enzyme family (25,26) or depressing NO/cyclic guanosine monophosphatec (cGMP) signaling to impair ATP-evoked Ca 2+ currents (27,28) have been suggested. NO is generated by oxidizing L-arginine to L-citrulline via NO synthases (NOSs), which constitute three isoforms: neuronal NOS (nNOS or NOS1), inducible (iNOS or NOS2), and endothelial (eNOS or NOS3) (29).…”