Evaluation of reproductive toxicity of hypothyroidism and levothyroxine in male rats

Male infertility is a prevalent public health concern that may arise from numerous conditions, including hypothyroidism. Although conclusive research on the impact of hypothyroidism on male infertility is lacking, the detrimental effects of hypothyroidism on the male reproductive system have been a prominent topic of discourse. L-T4 is commonly utilized in the management of hypothyroidism. Considering that L-T4 is a chronically administered hormone-based therapy, it is important to examine its effects on the male reproductive system. This study showed that hypothyroidism was developed in rats with low T3 and T4 levels and elevated TSH levels. The administration of L-T4 led to the normalization of thyroid hormone concentrations. Hypothyroid rats demonstrated reduced sperm concentration and an increased prevalence of morphologically abnormal sperm. Additionally, serum concentrations of LH, FSH, SHBG, testosterone, and inhibin B were markedly reduced in comparison to the control group. Following L-T4 treatment, sperm concentration and the percentage of abnormal sperm exhibited different results compared to the control group, although FSH levels remained diminished and SHBG, LH, testosterone, and inhibin B levels continued to be significantly decreased compared to controls. Moreover, hypothyroid rats had reduced GSH levels and raised MDA levels, indicating elevated oxidative stress. No notable variations in GSH and MDA levels were observed following L-T4 therapy in comparison to the control group. In conclusion, PTU-induced hypothyroidism resulted in reproductive toxicity in male rats, and substantial abnormalities in these parameters persisted even after L-T4 treatment compared to the control group.