Cellular mechanism underlying leptin‐induced anion secretion of rat epididymal epithelial cells

Abstract

AbstractBackgroundA large number of studies have shown that leptin plays an important role in the regulation of fertility via the hypothalamus‐pituitary‐gonad axis. However, its peripheral function in epididymis was still elusive.ObjectiveThe purpose of this study was to determine the pro‐secretion effect of leptin on the rat epididymal epithelium.Materials and methodsIn the present study, real‐time quantitative polymerase chain reaction, western blot, and immunohistochemical analysis were employed to detect the expression pattern of leptin receptors in rat epididymis. The pro‐secretion effect of leptin on epididymal epithelial cells was measured by short‐circuit current, and the prostaglandin E2 and cyclic adenosine monophosphate level was evaluated by enzyme‐linked immunosorbent assay.ResultsWe verified that the leptin receptor was located on the epididymal epithelium, with a relatively high expression level in corpus and cauda epididymis. Ussing chamber experiments showed that leptin stimulated a significant rise of the short‐circuit current in rat epididymal epithelial cells, which could be abolished by the specific leptin receptor antagonist peptide Allo‐aca, or by removing the ambient Cl− and HCO3−. Furthermore, the leptin‐stimulated short‐circuit current response could be abrogated by blocking the apical cystic fibrosis transmembrane regulator or the basolateral Na+‐K+‐2Cl− cotransporter. Our pharmacological experiments manifested that interfering with the prostaglandin H synthase‐2‐prostaglandin E2‐EP2/EP4‐adenylate cyclase pathways could significantly blunt the cystic fibrosis transmembrane regulator‐mediated anion secretion induced by leptin. The enzyme‐linked immunosorbent assay demonstrated that leptin could induce a substantial increase in prostaglandin E2 release and cyclic adenosine monophosphate synthesis of primary cultured rat cauda epididymal epithelial cells. Our data also suggested that JAK2, ERK, and PI3K‐dependent phosphorylation may be involved in the activation of prostaglandin H synthase‐2 and the subsequent prostaglandin E2 production.ConclusionsThe present study demonstrated the pro‐secretion function of leptin in rat epididymal epithelium via the activation of cystic fibrosis transmembrane regulator and Na+‐K+‐2Cl− cotransporter, which was dependent on the paracrine/autocrine prostaglandin E2 stimulated EP2/EP4‐adenylate cyclase pathways, and thus contributed to the formation of an appropriate microenvironment essential for sperm maturation.