Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA210

Poster Communications

Purinergic Signaling in Testicular Peritubular Cells

L. Kenzler1, F. Brüntgens1, J. Spehr1, D. Fleck1, M. Spehr1

1. Dept. of Chemosensation, RWTH Aachen University, Aachen, Germany.

Generation of spermatozoa is the most fundamental process for male fertility. However, the underlying physiological processes are still largely unknown. Seminiferous tubules represent the functional units of the testis. Their wall is composed of extracellular matrix proteins and flat smooth-muscle-like cells, the testicular peritubular cells. These cells are ideally positioned to serve multiple paracrine functions and thus contribute to spermatogenesis. We recently identified ATP-sensitive P2 receptors in peritubular cells (1), adding them to the complex testicular purinergic signaling network (2, 3). Here, we investigate ATP-dependent signaling mechanisms in both human and mouse testicular peritubular cells (HTPCs and MTPCs, respectively) utilizing electrophysiological and live cell imaging techniques in both primary cultures and acute in situ preparations. Electrophysiological investigation of HTPCs reveal ATP-induced currents that show strong rectification and moderate desensitization. Together with ivermectin-mediated current potentiation, our data suggest expression of P2X4 receptors in HTPCs. In MTPCs (C57BL/6J), electrophysiological recordings reveal similar ATP-induced currents with moderate desensitization. On-going experiments aim to identify the underlying P2X receptor isoforms. Moreover, Ca2+ imaging in acute seminiferous tubule slices reveals ATP-induced cytosolic Ca2+ transients in MTPCs. Signals are dose-dependent with an activation threshold of 1 μM, supporting functional expression of P2X receptors. When examining the source of ATP-induced Ca2+ signals by either buffering extracellular Ca2+ or by depletion of internal Ca2+ stores, Ca2+ signals are significantly reduced under buffering condition and abolished by store depletion. Together, this research provides insight into physiological signaling mechanisms in both HTPCs and MTPCs. In the long-term, our data will help to elucidate mechanisms that regulate germ cell development and might identify reasons for male infertility.

Where applicable, experiments conform with Society ethical requirements