Effects of capacitation and acrosome reaction on rat spermatozoa lipids and fatty acids

ZANETTI SR; MONCLUS MA; AVELDAÑO MI; FORNÉS MW

Rosario, Santa Fe, Argentina

Congreso; XLII Reunion Anual de la Soc. Argentina de Investigación en Bioquímica y Biología Molecular; 2006

Soc. Arg. de Investigación en Bioquímica y Biología Molecular

EFFECTS OF CAPACITATION AND ACROSOME REACTION ON RAT SPERMATOZOA LIPIDS AND FATTY ACIDS Zanetti SR#; Monclus MA§; Aveldaño MI# and Fornés§ MW IHEM, CONICET-UNC, 5500 Mendoza(§) e INIBIBB, CONICET-UNS, 8000 Bahía Blanca(#), Argentina. Mammalian spermatozoa must mature (capacitate) before they can undergo the acrosome reaction (AR) that enable them to fertilize an egg. The mechanisms underlying these events have not yet been fully elucidated. In this work we focused on their effects on the amounts and fatty acid composition of the main lipid classes of mature rat spermatozoa. Capacitation was assessed by protein tyrosine phosphorylation assay, and AR was induced by stimulation of spermatozoa with A23187/Ca2+ in the presence of albumin. Capacitation resulted in a significant loss of cholesterol. By contrast, sphingomyelin (SM), as well as ceramide (Cer) increased their proportions. The latter lipids increased additionally in acrosome-reacted spermatozoa as did the male germ-cell specific sulfogalactolipid (seminolipid), SM and Cer being richer than those of the starting cells in very long polyunsaturated fatty acids, both non-hydroxylated and 2-hydroxylated. Also a concomitant hydrolysis of glycerophospholipids (GPL), reflected in the generation of diacylglycerol, phosphatidic acid, and free arachidonic acid (20:4n-6) was seen during acrosome reaction. The lipid changes may work synergistically with protein phosphorylation to convert an initially stable to a fusion-competent membrane, capable of engaging in the AR.