Reactive oxygen species are involved in the signaling of equine sperm chemotaxis

Abstract

Sperm chemotaxis may facilitate the finding of the oocyte. Only capacitated spermatozoa can orient their movement by chemotaxis,which as well as capacitation, is regulated in part by the cAMP-PKA pathway. Reactive oxygen species (ROS) are produced duringsperm capacitation which is closely related to chemotaxis. Then, the ROS participation in the chemotactic signaling can be expected.Here we studied the role of ROS in the chemotaxis signaling of equine spermatozoa which produce high quantities of ROS because oftheir energy metabolism. The level of capacitated and chemotactic spermatozoa was increased with 0.1 and 0.2 mM hydrogenperoxide (H2O2), which was involved in the chemotactic signaling. By combining a concentration gradient of H2O2 with inhibitors/chelators of some of the signaling pathway elements, we showed that the activation of NOX (membrane NADPH oxidase) increasesthe intracellular ROS which activate the chemotaxis AMPc-PKA pathway. Our results provide evidence about the participation ofROS in the chemotactic signaling mediated by progesterone (P).