alpha-Tocopherol in human spermatozoa and seminal plasma: relationships with motility, antioxidant enzymes and leukocytes.

The chain-breaking antioxidant alpha-tocopherol has not been reported to be present in mammalian spermatozoa, unlike other cell types where it contributes to cell integrity and function. Semen samples obtained from 36 male partners of infertile couples during infertility investigations were analysed for alpha-tocopherol content of seminal plasma and spermatozoa, and the superoxide dismutase and glutathione peroxidase activities of spermatozoa were determined concomitantly with routine semen analysis. A wide range of alpha-tocopherol concentrations was detected in human spermatozoa (85 +/- 51 ng/10(8) spermatozoa, range 10-245). The concentration of alpha-tocopherol in spermatozoa was not found to be significantly related to the concentration or the total amount of alpha-tocopherol in seminal plasma. The percentage of motile spermatozoa was significantly related to sperm alpha-tocopherol content (r = 0.84, P < 0.001). alpha-tocopherol concentration and superoxide dismutase and glutathione peroxidase activities of spermatozoa were significantly elevated when the semen samples contained < 10(6) leukocytes/ml (mean +/- SD, 94 +/- 53 compared with 54 +/- 29 ng/10(8) spermatozoa, P < 0.02, 1.15 +/- 0.41 compared with 0.77 +/- 0.30 IU/10(8) spermatozoa, P < 0.02 and 60 +/- 26 compared with 30 +/- 14 spermatozoa mlU/10(8) spermatozoa, P < 0.005 respectively). From these results, it is suggested that alpha-tocopherol might play a role in association with antioxidant enzymes, for preserving the functional competence of spermatozoa subjected to an oxidative attack.