Pre-Pubertal Caffeine Exposure Interfered with Sperm Development in Wistar Rats without Deleterious Effects on Reproductive Hormones

This study investigated the effects of caffeine, a constituent of widely consumed energy drinks and beverages, on the sperm characteristics and level of reproductive hormones in developing male rats. Forty pre-pubertal Wistar rats (25 – 28 days old), weighing between 50 – 60 g were assigned into 4 groups (n = 10). Three test groups were administered daily with 50 mgkg-1, 100 mgkg-1 and 200 mgkg-1 of caffeine for 14 days by gavage while the controls received equivalent volumes of distilled water used in dissolving caffeine. Five rats from each group were sacrificed 24 hours after the last administration of caffeine while the remaining five were monitored for further three weeks till they were all sexually matured. Caudal part of the epididymis were excised and the sperm count, morphology, motility and viability were determined. The concentration of testosterone and luteinizing hormone were determined in the serum using enzyme-linked immunosorbent assay. Data obtained were analyzed using one way ANOVA followed by Dunnett post hoc test for comparison with control. Alpha level was set at 0.05. The result showed a significant decrease in epididymal sperm motility and count at treatment doses of 50 mg/kg, 100 mg/kg and 200 mg/kg. The 200 mg/kg dose also showed a decrease in sperm viability. There was also an increase in the number of abnormal sperm at treatment doses of 50 mg/kg, 100 mg/kg and 200 mg/kg compared to the control. Serum testosterone and luteinizing hormone levels were not significantly altered following treatment; however, the luteinizing hormone level was significantly increased in the group which received 200 mg/kg of caffeine after recovery. The study concluded that prepubertal caffeine exposure interfered with epididymal sperm development in a dose dependent manner without significant effect on the synthesis of reproductive hormones

Key Words: caffeine, pre-pubertal Wistar rats, sperm count, sperm motility, sperm morphology, sperm viability, testosterone, luteinizing hormone.