Effects of cotinine on sperm motility, membrane function, and fertilizing capacity in vitro

We evaluated the effect of cotinine on sperm fertilizing capacity in vitro. Human spermatozoa were washed and re-suspended in medium containing albumi n and various concentrations of cotinine (0, 100, 200, 400, or 800 ng/ml). After an 8-h incubation period, sperm motility, hypoosmotic swelling test ( HOST) outcome, and the percentage of hyperactivated spermatozoa were assaye d. Aliquots of spermatozoa were then processed for the zona-free hamster oo cyte sperm penetration assay (SPA) or hamster ooplasmic injections. Spermat ozoa exposed to concentrations of cotinine equal to 400 or 800 ng/ml demons trated significantly smaller outcomes for all of the above with the excepti on of after hamster ooplasmic injections, where high cotinine concentration s did not affect sperm viability or sperm capacity to undergo decondensatio n and activate hamster oocytes. It appears that cotinine concentrations of 400 or 800 ng/ml exert a detrimental effect on sperm motility, membrane fun ction, and the ability to undergo capacitation. In addition, the current fi ndings suggest that smokers with a high seminal plasma cotinine concentrati on who participate in assisted reproduction programs may be treated with in tracytoplasmic sperm injections (ICSI) rather than conventional in vitro fe rtilization (IVF) trials.