Hypothyroidism impairs antioxidant defence system and testicular physiology during development and maturation.

In the present study, effects of transient hypothyroidism (from birth to 30 days) and persistent hypothyroidism (from birth to 90 days) on testicular antioxidant defence system of mature rats were compared in order to know the role of hypothyroidism induced oxidative stress in testicular development and maturation. Rats were made hypothyroid by feeding lactating mothers and adult rats with 0.05% 6-n-propyl thiouracil (PTU) in drinking water. PTU treatment for 30 days or for 90 days to rats from birth resulted in a decrease in body weight at the age of 90 days in comparison to the controls. The testicular germ cell counts were significantly decreased in persistent hypothyroid rats whereas they were increased in the transient hypothyroid rats. However, a significant reduction in the number of live sperms in epididymis of both 30 day and 90-day PTU treated rats was noticed on 90 days of age. Mitochondrial lipid peroxidation (LPx) levels were decreased in transient hypothyroidism whereas LPx and protein carbonylation were elevated during persistent hypothyroidism in the testis. Reduced testicular superoxide dismutase (SOD), catalase and glutathione reductase (GR) and glutathione peroxidase (GPx) activities were marked during transient hypothyroidism. In contrast, an elevation in SOD (PMF) and catalase activities with a significant decline in GPx and GR activities was found following persistent hypothyroidism. Marked histological changes were observed in the testis of both experimental groups. These results suggest a direct regulatory role of thyroid hormone on testicular physiology and antioxidant defence system during development and maturation.