Presence of platelet-activating factor in squirrel monkey (Saimiri boliviensis) spermatozoa: seasonal differences.

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphoryl-choline) (PAF) is a potent signaling phospholipid which has pleiotropic biological properties in addition to platelet activation. PAF has been detected in the spermatozoa in a number of species. The concentration of PAF is inversely related to human spermatozoa quality. There are no reports on the presence of PAF in nonhuman primate spermatozoa. Therefore, the primary objective of this study was to determine if PAF is present in the spermatozoa from the squirrel monkey (which is a seasonal breeder). A second objective was to determine if PAF levels change from the breeding to the nonbreeding season. Endogenous lipids were extracted from mature Bolivian squirrel monkeys (Saimiri boliviensis) spermatozoa and assayed for the presence of PAF by [125I] radioimmunoassay. PAF was detected in all samples assayed. PAF levels were significantly higher (P < 0.01) during the breeding season (mean: 3.58 ng/10(6) spermatozoa) than the nonbreeding season (mean: 0.76 ng/10(6) spermatozoa). The data demonstrate that PAF is present in squirrel monkey spermatozoa, with higher levels found during the breeding season. Additional studies are warranted to elucidate the role of PAF in spermatozoa function.