A significant elevation in total SOD and CAT activities in response to neonatal persistent hypothyroidism and a simultaneous decrease in total GPx, Se-D GPx (GPx-1 and GPx-4), and Se-I GPx in the PMF of testis in experimental group suggested that SOD and CAT have predominant role to fight oxidative stress than GPx in hypothyroid rats. The gene discussed is GPX1; the disease is hypothyroidism.