The Effect of Caffeine on Guinea Pig Epididymal Spermatozoa: Motility and Fertilizing Capacity

Abstract

Guinea pig epididymal spermatozoa, when taken from different segments of the epididymis, are known to differ markedly in their in vitro motility, metabolism and morphology. In this report, the fertilizing capacity of epididymal spermatozoa isolated from proximal and distal segments and treated with caffeine was tested. Twenty six guinea pig sows were inseminated 16–26 h after parturition with isolated epididymal spermatozoa. In 15 cases the spermatozoa were treated with caffeine (10 mM), and 11 cases served as controls. Sperm characteristics (mean ± SE) were: proximal sperm; concentration 48 ± 3.9 millions/ml, vitality 94 ± 0.9%, motility 42 ± 5.3%. Distal sperm: concentration 161 ± 21 million/ml, vitality 94 ± 0.9% and motility 86 ± 3.0%. Caffeine increased significantly the motility of proximal spermatozoa (by 59.5%). These suspensions of spermatozoa were used for intraperitoneal artificial insemination. The impregnation rate of untreated proximal sperm was zero (0 out of 4), compared with 83% (5 out of 6) for the caffeine treated sperm. The impregnation rate of untreated distal segment sperm was 42.8% (3 out of 7) compared with 100% (9 out of 9) for caffeine treated sperm.