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(180) THE RAT SPERM ACROSOME: EFFECTS OF CARBOHYDRATE AND NON-CARBOHYDRATE AGONISTS. Bendahmane, Malika1, Zeng, Haitao1, Tulsiani, Daulat1, 1 Depts. of Obstetrics & Gynecology and Cell Biology, Nashville, TN ABSTRACT- Capacitated acrosome-intact mouse spermatozoa interact with natural [soluble zona pellucida (ZP) and progesterone (P4)] and synthetic [neoglycoproteins (ngps) and calcium (Ca2+)-ionophore] agonists, prior to the initiation of a Ca2+-dependent signal transduction cascade. The net result is the fusion of the sperm plasma membrane overlying the outer acrosomal membrane and exocytosis of acrosomal contents. This step is believed to be a prerequisite that enables the acrosome-reacted spermatozoon to penetrate the ZP and fertilize the egg. Although rat is one of the most commonly used laboratory animals, very little is known about the chemical nature of agonists that induce the AR in this species. The lack of this information is primarily due to the fact that the rat sperm acrosome is a relatively thin structure. Thus, it is difficult to assess its status in this species. In this report, we have used Coomassie Brilliant Blue dye staining procedure of Larson and Miller to assess the status of the rat sperm acrosome by light microscopy. The procedure is highly reproducible and has allowed us to examine the effects of carbohydrate (ngps and mouse ZP) and non-carbohydrate (P4 and Ca2+-ionophore) agonists on capacitated spermatozoa. Data presented in this report demonstrate that several ngps, solubilized mouse ZP, P4 and Ca2+ionophore induce the AR in rat spermatozoa in vitro. Furthermore, we demonstrate that whereas CaM antagonists blocked P4-induced AR in a dose-dependent manner, most of the inhibitors used had no significant effect on the Ca2+ionophore-induced (non-physiological) AR. The last results, in conjunction with our studies in the mouse spermatozoa, suggest that similar reagents can block sperm function in multiple species. Supported by grants HD 25869 and HD34041 from NIH. KEY WORDS: capacitation, rat sperm acrosome, progesterone, neoglycoproteins |
