The immunoexpression of CuZnSOD, MnSOD and catalaze in testes of hypothyroid rats

Abstract

Although the mammalian testis has for many years been regarded as an organ unresponsive to thyroid hormones, their role in cell proliferation and differentiation during spermatogenesis was recently established. It was shown that thyroid hormones affect both immature and adult testes in sense of their involvement in spermatic cells differentiation and survival through metabolic regulation and that both, hyper- and hypothyroidism are associated with increased oxidative stress in semen. Hence, we addressed the effect of hypothyroidism on CuZnSOD, MnSOD and catalase immunoexpression in rat testes. Two-month-old male Wistar rats were fed with standard pelleted food ad libitum. The rats were divided into two groups. Hypothyroidism was induced by 0.04% methimazole in drinking water for 21 days while animals that drank tap water served as control. Isolated testes were examined by immunohistochemistry on 2 μm semi-fine sections using antibodies against CuZnSOD, MnSOD and catalase respectively. The immunopositive reaction for all examined antioxidant enzymes was visible in seminiferous tubule of both, control and hypothyroid groups. CuZnSOD-positive reaction in both groups was observed solely in the spermatids and the hypothyroid group showed stronger CuZnSOD immunoexpression compared to control. In contrast, MnSOD immunopositivity was detected in spermatogonia, spermatocytes and spermatids in both groups. Compared to other analyzed antioxidant enzymes, MnSOD immunoexpression is slightly reduced in the methimazole-treated group compared to control, particularly in spermatogonia. Catalase immunopositivity was visible all through the seminiferous tubules from the basal lamina to the lumen, around and within the cells in both groups. In contrast to control, the hypothyroid group showed more prominent catalase immunopositivity, especially in early spermatogonial stages. It is interesting that spermatocytes nuclei in the hypothyroid group appeared catalase-positive. Our results clearly showed that cell and stage-specific CuZnSOD, MnSOD and catalase immunoexpression in the rat testes were changed in hypothyroidism and may contribute to altered spermatic characteristics.