Paper dels intercanviadors iònics en la capacitació espermàtica en mamífers

Abstract

The aim of this project is to compile a literature review of the physiological role of ion exchangers in mammalian sperm capacitation and to describe the differences among species. Ion channels, pumps, and transporters allow the passage of ions, solutes, and other molecules across the plasma membrane. Sperm cells have several ion channels in their membrane that play a crucial role in their physiological functions. After ejaculation, the activity of ion channels is essential for sperm capacitation and the acrosomal reaction, two essential processes to fertilize the oocyte. Sperm capacitation, which takes place along the female reproductive tract, involves biochemical and physiological modifications that allow sperm motility hyperactivation. Ca2+ and HCO3- ions activate soluble adenylate cyclase (sAC), which triggers activation of the cAMP/PKA signaling pathway. Flux regulation of ions such as K+, Na+, Cl-, H+ and, HCO3- influence intracellular pH (pHi) and membrane potential (Em). Several ion exchangers modulate these processes, showing differences in sperm membrane localization and activation mechanisms according to species in mammals. The main exchangers present in the sperm membrane are divided into Na+/H+ exchangers (NHE), Cl-/HCO3- exchangers and Na+/Ca2+ exchangers (NCX). The NHE exchangers identified in the sperm membrane are NHE1, NHE5, NHE8 (intracellular), sNHE, NHA1 and NHA2, and play an essential role in the regulation of pHi to maintain homeostasis during capacitation, for the activation of other channels and sperm hypermotility. It has been found two families of HCO3- exchangers, the SLC4 family (SLC4A1, SLC4A2) and the SLC26 family (SLC26A3, SLC26A6, SLC26A8), which are essential for sperm alkalinization and are involved in hyperactivation of sperm motility and exocytosis of the acrosome. NCX exchangers are involved in the inhibition of premature hyperactivation and the acrosomal reaction. Understanding the role of sperm ion exchangers during sperm capacitation is of interest for understanding the process of fertilization and the study of fertility