Therapeutic Effect of Scutellaria baicalensis on L-Thyroxine-Induced Hyperthyroidism Rats.

This study was performed to evaluate the anti-hyperthyroidal effects and action mechanism of Scutellaria baicalensis Georgi (SB), a medicinal herb, on levothyroxine (LT4)-induced hyperthyroidal rats.

Male Wistar rats were divided into five groups, namely, euthyroidal normal group (Normal), hyperthyroidism control group (Control), hyperthyroidism plus PTU-treated group (PTU) as a positive control, hyperthyroidism plus 400 mg/kg SB-treated group (SB400), and hyperthyroidism plus 800 mg/kg SB-treated group (SB800). The rats in groups other than Normal were injected with LT4 for 2 weeks to induce hyperthyroidism and then were administrated each treatment for 2 weeks. Clinical symptoms and biomarkers related to hyperthyroidism were examined, and the gene expressions related to the regulation of thyroid hormone were determined.Compared with the Control group, pulse rate, serum T3, T4, triglyceride, thyroid follicle size, and the deiodinase 1 (Dio1) gene expression were significantly reduced in the SB and PTU groups. Serum TSH and the thyroxine-binding globulin (Tbg) gene expression were significantly increased in the SB and PTU groups.These results suggest that SB might suppress T3, T4, and adrenergic activity by modulating Dio1 and Tbg expression, and therefore, SB could be an alternative therapy for hyperthyroidism.