Presence of platelet-activating factor in rhesus (Macaca mulatta) spermatozoa

Effect of sperm treatment with exogenous platelet-activating factor on the outcome of intrauterine insemination

OBJECTIVE

To evaluate the effect of sperm treatment with exogenous platelet-activating factor (PAF) on IUI clinical pregnancy rate.

DESIGN

Prospective randomized study.

SETTING

Assisted Reproduction Unit, 2nd Department of Obstetrics and Gynecology, University of Athens, Aretaieion Hospital, Athens, Greece.

SUBJECT(S)

Fifty-two couples with unexplained infertility, candidates for IUI.

INTERVENTION(S)

Sperm treatment with an exogenous mixture of PAF (final concentration, 10(-7) mol/L) in sperm-washing medium, direct swim-up technique of sperm preparation, a maximum of six IUI cycles per couple with or without PAF treatment.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate (pregnancies confirmed by ultrasonography per hundred cycles).

RESULT(S)

The overall clinical pregnancy rate after a maximum of six IUI cycles was significantly higher when sperm was treated with PAF compared with the rate after the direct swim-up technique (23.07% vs. 7.92%).

CONCLUSION(S)

Treatment of sperm with exogenous PAF might improve the clinical outcome of IUI in cases of unexplained infertility.

The significance of platelet-activating factor and fertility in the male primate: a review

Since its discovery nearly 30 years ago platelet-activating factor (PAF) has emerged as one of the more important lipid mediators known. PAF (1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) exists endogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signaling phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a significant role in reproduction and is present in the sperm of a number of primate species. PAF content in squirrel monkey sperm is significantly higher during the breeding season than the non-breeding season. PAF content in rhesus sperm has a significant relationship with sperm motility. PAF content in human sperm has a positive correlation with seminal parameters and pregnancy outcomes. The enzymes (lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present in primate sperm. PAF-acetylhydrolase may act as a "decapacitation factor". Removal of this enzyme during capacitation promotes PAF synthesis increasing primate motility and fertilization. PAF also plays a significant role in the fertilization process, enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilized with PAF-treated sperm. Exogenous PAF will also significantly improve primate artificial insemination pregnancy outcomes. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization thus suggesting the presence of receptors for PAF. The PAF-receptor is present on primate sperm, with altered transcript levels and distribution patterns on abnormal cells. Whereas, the exact mechanism of PAF in sperm function and reproduction is uncertain, its importance in normal primate fertility is substantial.

Relationship between platelet-activating factor concentration in rhesus monkey (Macaca mulatta) spermatozoa and sperm motility

Platelet-activating factor (PAF) is a potent signaling phospholipid that has been implicated in a number of biological activities. PAF concentration in primate spermatozoa has a positive correlation with fertility. While PAF is present in rhesus spermatozoa, there are no relational reports on its concentration and the cell's motility. The study objective was to determine if PAF concentration in rhesus spermatozoa was correlated with motility indices (percent motility and forward progression). Semen was collected from sexually mature males and cell counts, and percent motilities and forward progressions were recorded prior to PAF measurement by radioimmunoassay. Spermatozoa-derived PAF concentration ranged from a low of 0.9 picomoles/10(6) cells to a high of 13.0 picomoles/10(6) cells. The overall mean (+/-SEM) PAF concentration was 4.6 (+/-1.6) picomoles/10(6) spermatozoa. Regression analysis revealed a positive and significant relationship between PAF concentration in the spermatozoa and percent motility (R2 = 0.914; P < 0.01) as well as forward progression (R2 = 0.849; P < 0.05). A receiver-operator characteristic curve and the calculation of the probability that a positive forward progression will be predicted indicated a cutoff limit of 1.5 picomoles/10(6) cells for PAF concentration in rhesus sperm. Rhesus monkey spermatozoa motility was significantly greater (P < 0.01) in the high-PAF (> or =2 picomoles/10(6) cells) group (31.0 +/- 7.6) than in the low-PAF (<2 picomoles/10(6) cells) group (6.8 +/- 2.1). Rhesus monkey spermatozoa forward progression was significantly greater (P < 0.05) in the high-PAF (> or =2 picomoles/10(6) cells) group (3.0 +/- 1.0) than in the low-PAF (<2 picomoles/10(6) cells) group (0.7 +/- 0.3). The data demonstrate that PAF concentration in rhesus spermatozoa has a significant relationship with percent motility and the cell's forward progression. Determining PAF concentration in spermatozoa may be a significant predictor of fertility in the primate. Additional studies will elucidate the role of PAF in spermatozoa function and the significance PAF plays in primate fertility.

Platelet-activating factor content in boar spermatozoa correlates with fertility

The objective of this study was to evaluate the level of platelet-activating factor [1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine; PAF] content in spermatozoa between two groups of boars that differ in farrow rate percentages. The boar farrow rate was defined as High if it was > or = 70% and Low if it was < 70%. Fresh, extended semen was collected from sexually mature boars and used in the PAF extractions. Platelet-activating factor was detected in all semen samples assayed. The amount of PAF detected in spermatozoa obtained from the High group ranged from 1.90 to 11.30 pM/10(6) cells. The level of PAF in the Low group ranged from 0.92 to 4.96 pM/10(6) cells. Regression analysis revealed a positive (R2 = 0.369) and significant (P = 0.021) relationship between PAF content in boar spermatozoa and farrow rate. Spermatozoa-derived PAF levels (mean +/- SEM) were significantly higher (P = 0.015) in the High-farrow group (6.75 +/- 1.25 pM/10(6) cells) than in the Low-farrow group (2.45 +/- 0.51 pM/10(6) cells). The PAF content in spermatozoa was significantly higher (P = 0.035) in the High-average (> or = 10.5/litter) number of piglets born group (5.78 +/- 1.24 pM/10(6) cells) than in the Low-average (< 10.5/litter) number of piglets born group (3.34 +/- 1.19 pM/10(6) cells). Additionally, PAF content in spermatozoa was significantly higher (P = 0.034) in the High-average (> or = 9/litter) number of piglets born alive group (6.82 +/- 1.35 pM/10(6) cells) than the Low-average (< 9/litter) number of piglets born alive group (3.00 +/- 0.87 pM/10(6) cells). The data demonstrate that PAF is present in boar spermatozoa and that levels are significantly higher in individuals with a high-farrow rate status and high-number of piglets born and born-alive.

Impact of blood serum insulin-like growth factor I on platelet-activating factor in bull spermatozoa

The objective of this study was to examine differences in platelet-activating factor [1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine; PAF] in spermatozoa between two lines of Angus beef cattle divergently selected for blood serum insulin-like growth factor I (IGF-I) concentration. Endogenous lipids were extracted from the spermatozoa and endogenous PAF content was determined by radioimmunoassay. The amount of PAF detected in spermatozoa obtained from high IGF-I bulls (n = 8) ranged from 0.145 to 3.571 pM/10(6) cells. The level of PAF extracted from spermatozoa obtained from low IGF-I- bulls (n = 5) ranged from 0.001 to 1.024 pM/10(6) cells. Polynomial regression analysis revealed a significant cubic relationship (R(2) = 0.374; F = 6.292; P < 0.05) between spermatozoa PAF content and blood serum IGF-I concentration. Spermatozoa-derived PAF levels (mean +/- SEM) were significantly higher (P < 0.05) in the high IGF-I group (1.90 +/- 0.39 pM/10(6) cells) than in the low IGF-I group (0.59 +/- 0.20 pM/10(6) cells). High IGF-I bulls have a greater than three-fold higher PAF content in their spermatozoa than low IGF-I bulls. The data demonstrate that not only is PAF present in bull spermatozoa but that levels are significantly higher in individuals with high serum IGF-I concentrations.