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Alterations of Testicular Selenium-Dependent and Independent Glutathione Peroxidase Activities during Experimentally L-Thyroxine Induced Hyperthyroidism and n-Propyl Thiouracil Induced Hypothyroidism in Adult Rats

Dipak Kumar Sahoo

Hyper- and hypothyroidism states are known to alter testicular antioxidant defence parameters in adult as well as in immature rats. Glutathione peroxidases represent a family of enzymes which metabolizes toxic hydroperoxides and are, along with superoxide dismutase and catalase, part of the enzymatic antioxidant defenses to protect cells from free-radical-mediated attacks. In mammalian testis, total GPx activity is contributed by both Selenium-dependent glutathione peroxidases (Se-D GPxs) and the Se-independent glutathione peroxidaes (Se-I GPx). Due to persistent hypothyroidism, both Se-D-GPx and Se-I-GPx were reduced in adult testicular post-mitochondrial as well as in mitochondrial fraction (MF);while, during transient hypothyroidism, both Se-D-GPx and Se-I-GPx were reduced in adult testicular post-mitochondrial fraction (PMF) with only decrease in mitochondrial Se-D-GPx activity. However, both Se-dependent and Se-independent GPx activities elevated in adult testicular PMF of L-thyroxine treated (group- T4), T4 with vitamin E (group- T4+Vit.E), T4along with curcumin and vitamin E (group- T4+Cur+Vit.E)with only increase in SeD-GPx in T4 with curcumin (group- T4+Cur) treated rats. In case of MF, Sedependent GPx showed no alteration in response to curcumin and/or vitamin E treatment to T4 treated rats (groups-T4+Cur, T4+Vit.E and T4+Cur+Vit.E), however its level increased in T4 treated rats (group-T4). Se-independent GPx elevated significantly in response to T4 (group-T4), T4 with curcumin (group- T4+Cur), T4 with vitamin E (group- T4+Vit.E) and T4 along with curcumin and vitamin E (group- T4+Cur+Vit.E) treated rats respectively. Hence, hypothyroid as well as hyperthyroid states influencing testicular Se-D- and Se-I-GPx activities along with other antioxidant defence enzymes, might regulate testicular physiology and oxidative stress.