EFFECT OF GLYCERYL TRINITRATE ON SPERM MOTILITY AND LIPID-PEROXIDATION IN NORMOZOOSPERMIC MEN

The objective of this study was to assess the in-vitro effects of the nitric oxide substrate glyceryl trinitrate (GTN) on sperm motility and membrane lipid peroxidation. Nitric oxide (NO) can impair sperm motil ity, possibly by an alteration of cyclic nucleotide levels. NO may als o be protective against lipid peroxidation. Semen samples from nine no rmospermic men were prepared by a swim-up technique. Each specimen was divided into four aliquots, one of which was the control sample. The other three had 10(-6), 10(-8) or 10(-10) M GTN added. Sperm motility was then analysed over 180 min using a Hamilton Thorn motility analyse r. Lipid peroxidation was assessed by measuring media malondialdehyde (MDA) levels at 180 min. Compared with control, the following measurem ents were reduced (p < 0.05) over the first 10(-6) M GTN aliquots only : mean path velocity (reduced by 14-15%), curvilinear velocity (reduce d by 12-21%), straight-line velocity (reduced by 18-19%) and percentag e of hyperactivated spermatozoa (reduced by 38-43%). MDA levels and he ad movement parameters were comparable amongst all aliquots (p > 0.05) . The depressant effects of GTN on sperm motility appeared to be trans ient and reversible. The effects observed may be due to NO generated b y GTN, or to GTN itself. This suggests that NO may have a role in vivo as a physiological inhibitor of sperm motility. The addition of GTN d id not appear either to cause sperm membrane damage or to protect the spermatozoa from lipid peroxidation.