Differential involvement of rat sperm choline glycerophospholipids and sphingomyelin in capacitation and the acrosomal reaction.
Rat spermatozoa main lipid classes and their fatty acids were studied to assess their possible changes in capacitation and the acrosomal reaction (AR), induced in vitro. Capacitation-associated protein tyrosine phosphorylation, and the efflux of 30% of the total cholesterol from gametes to the medium, took place concomitantly with the release of a similar percentage, i.e., a larger amount, of the total phospholipid, mostly after hydrolysis of the major choline glycerophospholipids (CGP). Main medium lipid metabolites after capacitation were lyso-CGP and polyenoic fatty acids typical of CGP (22:4n-9, 22:5n-6), as free fatty acids (FFA). The AR, induced by a calcium ionophore, resulted in further phospholipid loss, but the produced metabolites remained in the gametes. CGP decrease in AR accounted for some additional FFA and lyso-CGP, but mostly for (22:5n-6-rich) diglycerides. Hydrolysis of sphingomyelins (SM) to ceramides also occurred, mostly affecting species with very long chain polyenoic fatty acids. Quantitatively, CGP and SM were the lipid classes decreasing the most after capacitation and AR, respectively. The massive cholesterol and phospholipid loss from the gametes during capacitation is thus associated with protein phosphorylation, a function that has been located to the sperm tail. The lipid metabolites produced during AR, by accumulating in the gamete heads, could be implicated in sperm-oocyte interactions.
Zanetti
Samanta R
SR
Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina.
Monclus
María de los Ángeles
Mde L
Rensetti
Daniel E
DE
Fornés
Miguel W
MW
Aveldaño
Marta I
MI
D020101:Acrosome Reaction / Q000502:physiology*; D000818:Animals; D002518:Ceramides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D050356:Lipid Metabolism / Q000502:physiology; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013075:Sperm Capacitation / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism*
D002518:Ceramides; D005227:Fatty Acids; D010713:Phosphatidylcholines; D010743:Phospholipids; D013109:Sphingomyelins; D002784:Cholesterol