Uneven distribution of lipids and fatty acids between head and tail in rat spermatozoa

ORESTI GM; AYUZA ARESTI PL; FURLAND NE; AVELDAÑO MI

Rosario, Argentina

Congreso; XLII Reunión Nacional de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2006

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Spermatozoa are structurally and functionally polarized cells. The aim of this work was to study how lipids are distributed between sperm tails and heads. Rat spermatozoa isolated from cauda epididymidis were subjected to ultrasound and these two parts were purified using sucrose density gradients. The cholesterol / phospholipid (PL) ratio was twice larger in the head than in the tail. The head showed a choline / ethanolamine glycerophospholipid (CGP, EGP) ratio larger than the tail, both PL being richer in plasmalogens in the head than the tails. The tails contained virtually all of the cardiolipin, and the heads virtually all of the sphingomyelin (SM) that can be isolated from the cells. The fatty acid composition of all PL also differed between parts. The main head and tail PL polyunsaturated fatty acids (PUFA) were 22:4n-9 and 22:5n-6, respectively, the former being a major PUFA of the head CGP, and the latter of tail CGP. EGP were rich in 22:5n-6 in both parts. An important part of the head CGP 22:4n-9 was associated to plasmenylcholine. Head sperm SM was characterized by a large proportion of very long chain PUFA, the main one being 28:4n-6. The lipid and fatty acid regionalization, unusual for a single cell, associates specific lipids with physiological events distinctive of the head or the tail of spermatozoa.