Lack of effect of hypothyroidism on rat liver regeneration.

Thyroid hormone has been postulated to be important for liver regeneration. In the present studies liver regeneration in hypothyroid male rats treated with methimazole was compared to euthyroid rats. At 5 days after 70% partial hepatectomy liver weight was significantly less in the hypothyroid rats, but total hepatic DNA and protein were the same in the hypothyroid and euthyroid rats and RNA was significantly greater in the hypothyroid rats. These results indicate that liver regeneration is nearly normal in hypothyroid rats, despite the fact that whole body growth has ceased due to the hypothyroidism. Since both thyroid and growth hormones are low in hypothyroid rats, these results suggest that neither thyroid nor growth hormones are required for liver regeneration.