Curcumin mitigates lithium-induced thyroid dysfunction by modulating antioxidant status, apoptosis and inflammatory cytokines

Lithium is an integral drug used in the management of acute mania, unipolar and bipolar depression and prophylaxis of bipolar disorders. It has also been shown to reduce suicidal risk and short term mortality. Few experimental studies have demonstrated the thyroid toxicity caused by lithium as well as the possible protective effect of curcumin. Twenty four male albino rats were divided into three groups; group I (control group), group II received lithium carbonate daily for 6 weeks and group III received the same dose of lithium carbonate as group II concomitantly with curcumin for 6 weeks. The specimens were prepared for histopathological, immunohistochemical and biochemical examination. Lithium-induced thyroid dysfunction evidenced by the histopathological and immunohistochemical changes represented by detached cells and vacuolated cytoplasm of some follicular cells and highly significant increase in positive immunostained of thyroglobulin and caspase-3 respectively. Moreover, a significant decrease in serum free triiodothyonine (FT3), free thyroxine (FT4) concomitant with significantly increased thyroid stimulating hormone (TSH) and pro-inflammatory cytokines, and thyroid lipid peroxidation (MDA) and nitric oxide (NO) levels. Curcumin counteracted lithium-induced oxidative stress and inflammation as assessed by restoration of the antioxidant defenses and diminishing of pro-inflammatory cytokines and improvements in the degenerative changes of the thyroid gland. In conclusion, the present study provides evidence that curcumin exerts thyroprotective effects against lithium carbonate mediated by its antioxidant, anti-inflammatory and anti-apoptotic effect as indicated by caspase-3. This report also confers that the use of this drug should be justified for long treatment under direct medical supervision.