THE VARIABLE EFFECTS OF 2'-DEOXYADENOSINE ON HUMAN SPERM MOTILITY ANDHYPERACTIVATION IN-VITRO

The response of human sperm motility and hyperactivation to the stimul ant 2'-deoxyadenosine (2'-DEA) was studied in vitro using computer-ass isted sperm motion analysis. A total of 20 randomly selected individua ls with normal sperm counts as defined by the World Health Organizatio n were chosen and their migration-separated spermatozoa exposed to a r ange (0.1-10.0 mM) of concentrations of 2'-DEA. The straight line velo city (VSL) was increased above control values only at 0.1 mM, while th e curvilinear velocity (VCL) and lateral head displacement (ALH) were increased significantly at all concentrations. Linearity of progressio n (LIN), on the other hand, declined with increasing concentration of 2'-DEA. These changes were related to a significant increase in the nu mber of spermatozoa exhibiting hyperactive-like motion. There was, how ever, considerable intra-individual variability in the response to 2'- DEA. In some individuals VCL and ALH exhibited little or no response t o 2'-DEA, whilst in others an increase above the control of 50-55% occ urred. The maximum response for VCL and ALH occurred at 2.5 mM 2'-DEA. Individuals showed greater variability in the percentage of spermatoz oa exhibiting hyperactivity in response to 2'-DEA, with increases rang ing from 76 to 948% of the control value, although the maximum respons e was also most commonly seen at 2.5 mM 2'-DEA. The diversity of respo nse to 2'-DEA emphasizes the importance of tailoring doses to the indi vidual rather than employing one concentration for all. Further tests on a subgroup of the individuals examined the longevity of spermatozoa in response to 24 h of continued exposure to 2'-DEA. Prolonged exposu re to 0.1 mM 2'-DEA continued to enhance VSL, while higher concentrati ons produced detrimental effects on all other motion characteristics i ncluding hyperactivation.