Effect of hypothyroidism on the testes in mature rats and treatment with levothyroxine and zinc.

This study was performed to investigate the effect of propylthiouracil (PTU) on rat testis, and to compare the results of the different treatment regimens of levothyroxine and zinc. Twenty sexually mature Wistar albino rats were subjected to PTU for 14 days intraperitoneally to make them hypothyroidic. The effect of PTU on testicular function was assessed histopathologically after unilateral orchiectomy on day 15, and treatment was evaluated by measuring serum thyroid-stimulating hormone (TSH), T3, T4, and zinc levels on days 0, 7, and 15. The rats were then divided into five groups which were given levothyroxine and/or zinc treatment for 15 days. Orchiectomies were repeated on day 30, and specimens were evaluated histopathologically. Although serum T3, T4 and zinc levels decreased, serum TSH levels increased in PTU-treated rats, and the difference to the control group was statistically significant (P < 0.001). Maturation arrest of spermatogenesis, a reduced number of Sertoli and Leydig cells, a decreased tubular diameter, interstitial oedema, and thickening of basal membrane were observed in hypothyroidic testicles. After treatment, testicular histology and spermatogenesis gradually recovered in all groups with hypothyroidism, but maximum improvement was achieved in the levothyroxine + zinc sulphate replacement group, indicating a possible role of zinc in testicular function.