Phospholipids of the Plasma Membrane and Outer Acrosomal Membrane during in vitro Capacitation and Acrosome Reaction of the Goat Spermatozoa

摘要

The Plasma Membrane (PM) and Outer Acrosomal Membrane (OAM) were prepared simultaneously from fresh, capacitated and acrosome reacted spermatozoa using discontinuous sucrose density gradient centrifugation. The gross amount of lipids in PM was doublethan that found in OAM. Phospholipids accounted for 58 & 42 percent; Cholesterol 30 & 28; Cholesterol esters 6 &8 and glycerides 6 & 10 percent of the total lipids in the PM and OAM respectively. The respective cholesterol/phospholipid ratio was 0.66 and1.01. The OAM was rich in cardiolipin (27%) compared to PM (9%) which had higher proportion of other phospholipids like phosphatidyl choline (43%). The contents of phosphatidyl Inositol (PI); Phosphatidyl ethanolamine (PE) and sphingomyelin (SPM) were almost similar in the two membrane preparations. The phospholipid composition of the membranes showed distinct changes during capacitation and induction of AR of the capacitated spermatozoa by Ca~(+2) as agonist. PC & Pl increased in PM during capacitation. The percent levels of lysophosphatidyl choline (LPC) increased (4 Vs 15 & 7 Vs 18) while the PC level decreased (33 Vs 20 and 24 Vs 15) during AR in the PM and OAM respectively. The PI levels were also found to decrease during acrosome reaction in both the membranes. SPM contents showed however, an increasing trend during capacitation & AR. The results are discussed in terms of the role of respective phospholipid during capacftation & AR.