ABSTRACT
Pausinystalia yohimbe (P. yohimbe) is a member of the family Rubiaceae and an important medicinal tree that was discovered and used by tribes in West Africa. It is commonly used as an aphrodisiac among men and for treatment of erectile dysfunction. Little or nothing is known scientifically on the safety of P. yohimbe crude extract on reproductive hormones and histology of both testes and ovaries. It is against this backdrop that this research was carried out; to evaluate the hormonal and histopathological effect of P. yohimbe bark extract on male and female Wistar rats. This was achieved by examination of reproductive hormones including testes and ovaries of Wistar rats. The animals were acquired and kept in a serene environment and allowed to acclimatize for 2 weeks prior to experimentation. Plant material (stem bark) was obtained from ring-road market, Benin City, Edo state which was identified and authenticated by a taxonomist prior to use. It was dried and crushed into uniform powder and maceration extraction method was used with water as the solvent. Forty-two adult albino rats were used for this study. Ten rats (five males and five females) were used to determine the acute toxicity of P. yohimbe bark extract while the remaining thirty-two rats were randomly allocated into eight groups and divided into two batches (1 and 2). Rats in batch 1 were divided into 4 groups with Group A serving as control while Groups B, C, and D were administered 100 mg/kg, 200mg/kg, and 400mg/kg of the extract respectively for one month (30days). Rats in batch 2 were treated similarly, but for a period of two months (60 days). At the end of the treatment period, serum hormonal assay for reproductive hormones (Testosterone, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estradiol (E2), Progesterone and Prolactin) plus tissue histology of the testes and ovaries were carried out using standard laboratory methods. The results showed that serum hormonal levels of testosterone, FSH, LH and E2 were not significantly different from the control. However, there was a significant reduction (p<0.05) in prolactin and progesterone when compared to the control. Degenerative changes were also observed in the ovaries and testes of treated rats. In conclusion, prolonged use of P. yohimbe adversely affects the testes, ovaries, and some reproductive hormones (prolactin and progesterone) in this study, which may impair fertility of the rats in the long run. Therefore, further studies should be done to elaborate on the mechanism of this plant extract.
