Pausinystalia yohimbe (P. yohimbe) was first discovered and used by tribes in West Africa, where it grows wild mostly in the Atlantic evergreen forest throughout West Africa from South-east Nigeria to Congo. P. yohimbe bark extract is commonly used as an aphrodisiac among men and for the treatment of erectile dysfunctions. More recently, due to infertility more men have resorted to using P. yohimbe to improve chances of having baby. However, there are no studies on the effects of P. yohimbe on sperm motility and movement characteristics. This study examined its effects on reproductive organs, sperm production and motility in rats.Fifteen male Sprague Dawley (SD) rats were divided into 3 groups of 5 rats. Group A was the control while groups B and C served as the test groups. Group A received 0.5ml of normal saline daily while groups B and C received orally 150mg/kg and 300mg/kg body weights of aqueous extracts of P. yohimbe respectively for 4 weeks. Serum samples obtained from the rats were assayed for reproductive hormones (Testosterone, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and Estradiol (E2)). Testes, Seminal Vesicles and the Prostates were removed for histology, while sperm count, motility and vitality were done using sperm from the caudal epididymis and vas deference.Mean percentage change in body weights of groups B and C were significant when compared to control group A. There was significant reduction in sperm motility and concentration in the test groups, but none in sperm vitality. Serum hormonal levels of Testosterone, FSH, LH and E2 were not significantly different from the control. However, there was a significant reduction in testosterone / E2 ratio in the test groups. Degenerative changes were observed in the testes, prostate and seminal vesicles.Prolonged use of P.yohimbe adversely affects the testes, male accessory glands, sperm concentration and motility. This may lead to reduced reproductive functions and male infertility. Keywords: P. yohimbe, Accessory glands, Testis, Sperm motility, Sperm concentratio
