Short-term stimulation of lipogenesis by triiodothyronine in maintenance cultures of rat hepatocytes

Within 4 h following the addition of 3,3′,5 triiodo-L-thyronine to monolayer cultures of hepatocytes isolated from hypothyroid rats, a very distinct stimulation of fatty acid and cholesterol synthesis, measured as incorporation of either [1- 14C]acetate or [ 3H]H 2O into these lipid fractions, is observed. A smaller but significant increase in the rate of lipogenesis occurs in hepatocytes derived from euthyroid animals. These stimulatory effects of triiodothyronine are also observed in the presence of cycloheximide, indicating that the described early and direct stimulation of lipogenesis by the thyroid hormone is, at least in part, independent of protein synthesis.