Diacylglycerol species as messengers and substrates for phosphatidylcholine re-synthesis during Ca2+-dependent exocytosis in boar spermatozoa

Abstract

We have investigated pathways of lipid metabolism in spermatozoa and generation of various metabolites with potential messenger functions during exocytosis stimulated with A23187/Ca2+. Stimulation of boar spermatozoa resulted in a considerable rapid increase in saturated/unsaturated 1,2‐diacylglycerol (1,2‐SU‐DAG) and, concomitantly, a substantial reduction in disaturated 1,2‐diacylglycerol (1,2‐DS‐DAG), and in phosphatidylcholine (PC). These changes preceded the onset of exocytosis. Phosphatidic acid was sometimes generated in parallel, but usually rose later, suggesting that 1,2‐SU‐DAG may be formed directly by phospholipase C action. Lipid changes observed in stimulated spermatozoa that have been prelabelled with several lipid precursors ([14C]palmitic acid, [14C]glycerol, [14C]choline, or [14C]arachidonic acid) suggested the existence of a unique process involving the utilization of the high basal levels of 1,2‐DS‐DAG to form 1,2‐SU‐DAG, with the latter being subsequently employed to replenish the PC pool. An ensuing generation of lysoPC and arachidonic acid, which paralleled the occurrence of exocytosis, revealed that the newly synthesized PC was hydrolyzed by phospholipase A2. The highest levels of 1,2‐SU‐DAG, minimum levels of 1,2‐DS‐DAG, and the regeneration of the PC pool were tightly coupled to the beginning of visible exocytosis. These results suggest that changes in these lipid metabolites may be fundamental processes during acrosomal exocytosis occurring in response to physiological agonists. Mol. Reprod. Dev. 48:95–105, 1997. © 1997 Wiley‐Liss, Inc.

Sperm Lipid Markers of Male Fertility in Mammals

“…The most important function of DAG in sperm is its participation in the acrosome reaction. Diacylglycerols have been reported to be engaged in membrane fusion during acrosomal exocytosis [174][175][176], which is consistent with previous studies in other cell types [177][178][179]. In particular, PC-derived DAG is thought to be related to AR exocytosis in boars [176].…”

“…Diacylglycerols have been reported to be engaged in membrane fusion during acrosomal exocytosis [174][175][176], which is consistent with previous studies in other cell types [177][178][179]. In particular, PC-derived DAG is thought to be related to AR exocytosis in boars [176]. Another study revealed that DAGs promoted intraacrosomal calcium efflux and triggered exocytosis of permeabilized human sperm [180].…”

Involvement of Protein cAMP‐dependent Kinase, Phospholipase A2 and Phospholipase C in Sperm Acrosome Reaction of Chinchilla lanigera

“…The stimulation with different inducers showed an increase in DAG concentration in human sperm treated with progesterone, calcium ionophore A23187 and ZP (Roldan and Murase ), in mouse (O'Toole et al. ), in ram (Roldan and Harrison ) and in boar (Vázquez and Roldan ).…”

“…The negative control represents SAR (13.9%). Results are expressed as the mean AE SEM of 5 experiments with different animals A23187 and ZP(Roldan and Murase 1994), in mouse(O'Toole et al 1996), in ram(Roldan and Harrison 1992) and in boar (V azquez andRoldan 1997).…”

α/β-Hydrolase D16B Truncation Results in Premature Sperm Capacitation in Cattle

“…This included lower levels of diacylglycerol (DAG) and sphingomyelin (SM) and higher levels of phosphatidylcholine (PC) and ceramide (Cer). Since these lipids have been shown to play a major role in capacitation, we hypothesized that the variant-induced altered sperm membrane composition is causative for infertility [ 29 , 30 , 31 , 32 ].…”