Molecular mechanisms of human sperm chemotaxis mediated by progesterone

TEVES, ME; GUIDOBALDI, HA; UÑATES, DR; MISKA, W; SANCHEZ, R; GIOJALAS, LC

MADRID, ESPAÑA

Simposio; 10th International Symposium on Spermatology; 2006

Sperm chemotaxis is a cell transport mechanism that guides spermatozoa up an attractant concentration gradient in order to facilitate the gamete encounter. Recently, very low concentrations of Progesterone (the main steroid of the egg microenvironment), have been showed to induce a chemotactic response in human and rabbit spermatozoa. The aim of this work was to use the chemotactic response mediated by Progesterone as an experimental model to study the molecular events that take place during the mammalian sperm chemotaxis. Since calcium (Ca++), adenylate cyclase (AC), guanylate cyclase (GC) and protein kinase A (PKA) are involved in the chemotactic response of other cellular systems, we assayed their participation in the chemotactic response mediated by Progesterone. Capacitated human spermatozoa were incubated with different concentrations of either an intracellular Ca++ chelator (BAPTAAM), an inhibitor of AC (2´,5´-Dideoxyadenosine), an inhibitor of GC (LY-83,583), or an inhibitor of PKA (KT 5720). Then, the sperm chemotactic response to Progesterone (10-11 M) was evaluated by videomicroscopy and computer image analysis. The results showed a statistically significant inhibition of the Progesterone-mediated chemotaxis at 100 ìM BAPTA-AM, 300 ìM 2´,5´-Dideoxyadenosine, 30 ìM LY-83,583 and 100 ìM KT 5720 (p<0.05 vs. in the absence of inhibitors). The molecular mechanism of human sperm chemotaxis mediated by a physiological chemoattactant like Progesterone is described here for the first time, whereas the AC, GC, intracellular calcium and PKA are, apparently, involved.