Effect of tamoxifen on testosterone concentration and sperm count in adult male rats

Introduction: Tamoxifen is a nonstroidal antiestrogen prescribed for treatment of breast cancer. The aim of this study was to investigate the effect of tamoxifen on testosterone level in the serum and sperm count in the epididymis of adult male Wistar rats. Methods: Three groups of rats received 200, 400 and 600 mu g/kg body weight tamoxifen dissolved in solvent (60% ethanol in physiological solution) for 30 consecutive days. The sham group received the solvent and controls did not receive any drug or solvent. 1, 12 and 36 days after treatment, serum testosterone was measured by radioimmunoassay and sperm numbers in the epididymis were counted. Results: Results showed that testosterone concentration in the serum and sperm count in the epididymis significantly decreased in groups which received tamoxifen compared with the control group. The most profound effects were observed in the first samplings of the group which received 600 mu g/kg tamoxifen. Conclusion: These findings indicate that tamoxifen decreases the fertilization ability in adult male rats in a dose dependent manner and this effect disappears after a period of time.