فهرست نشریات علمی دسترسی آزاد ایران

. Thirty-five adult male Wistar rats were used. Hypothyroidism was induced by administering CBZ (30 mg/kg/day, p.o.) for 22 days and confirmed via significant reductions in serum triiodothyronine (T₃) and thyroxine (T₄) and an elevation in thyroid-stimulating hormone (TSH). Subsequently, hypothyroid rats were divided into groups receiving either vehicle, Brazil nut powder (9.42 g/kg/day, p.o., providing ~290 µg Se/kg/day), or levothyroxine (20 µg/kg/day, p.o.) for 30 days, alongside healthy controls. Brazil nut supplementation significantly ameliorated the hypothyroid state, as evidenced by the restoration of serum T₃ and T₄ levels and the normalization of TSH in treated animals (HBN group). This effect was comparable to that achieved with levothyroxine. Importantly, CBZ-induced hypothyroidism led to a significant depletion of selenium levels in both serum and thyroid tissue. Brazil nut treatment effectively restored these selenium reserves. Immunohistochemical analysis revealed severe suppression of thyroid peroxidase (TPO) enzyme expression in hypothyroid rats, which was markedly improved by both Brazil nut and levothyroxine interventions. The findings demonstrate that Brazil nut supplementation effectively counteracts CBZ-induced hypothyroidism, normalizes thyroid hormone profiles, restores systemic and tissue selenium status, and enhances the immunohistochemical expression of the key thyroid enzyme TPO. These results suggest that Brazil nut, via its high bioavailable selenium content and associated antioxidant properties, represents a promising nutritional adjunct for managing hypothyroidism and mitigating associated oxidative stress and selenoprotein impairment.