Potato Aspartic Proteases (StAPs) exert cytotoxic activity on bovine and human spermatozoa

CESARI A; FALCINELLI AL; MENDIETA JR; PAGANO MR; MUCCI N; DALEO GR; GUEVARA MG

FERTILITY AND STERILITY

Año: 2007 vol. 88 p. 1248 - 1255

0015-0282

Objective: To evaluate the in vitro spermicidal activity of StAPs (Solanum tuberosum aspartic proteinases) on bovine and human sperm. Design: Controlled laboratory study. Setting: Three research laboratories at a University of biological science. Animal(s) and Donor(s): Frozen semen from five Aberdeen Angus bulls and six proven fertile men volunteers. Intervention(s): The effect of StAPs on sperm motility was studied in vitro by incubation of different concentrations of StAPs with sperm suspensions and motility was assessed by direct microscopic observation. Membrane integrity was analyzed by SYTOX green uptake after incubation with different StAP concentrations. The effect of StAPs was evaluated by human erythrocyte lysis, as a control in somatic cells. StAPs binding was monitored by fluorescence. Main Outcome Measure(s): Total and progressive sperm motility; HOS test and SYTOX green uptake as measure of membrane damage; FITC-labelled StAP binding by optical microscopy. Result(s): StAPs reduced sperm motility in a dose-dependent manner, and 25 ìM of StAP1 and 35 ìM of StAP3 abolished completely the progressive motility. StAPs were able to bind in the postacrosomal and midpiece region only in bovine sperm. Besides, StAPs also caused spermatozoa agglutination. In vitro cell toxicity was observed by a dose-dependent increase in HOS negative sperm and SYTOX green uptake both human and bovine spermatozoa, however no toxic effect was observed on erythrocytes. Conclusion(s): The spermicidal effect of StAPs involves plasma membrane permeabilization.