Lipogenesis by Hepatocytes of Rats with Hypothalamic Obesity

Abstract

Hepatocytes were prepared from livers of rats with bilateral lesions of the ventromedial hypothalamic nucleus (VMN lesioned) and sham-operated control rats. The incorporation of tritium labeled water and ¹⁴C glucose and lactate into lipids was studied. Endogenous tritium incorporation into fatty acids in controls ranged from 7-20 µatoms ³H per 100 mg liver protein per hour, and in cells from VMN lesioned rats 25 to 80 µatoms per 100 mg/hour. In both types of cells addition of glucose had no effect on tritium incorporation, but the addition of lactate, pyruvate or alanine stimulated it 30-60%. There was little difference in the labeling of glycerol by the two groups. In cells from fasted refed control or lesioned rats, tritium incorporation was greatly increased and was equal in both groups. Incorporation of glucose carbon in VMN lesioned rats was three to ten times that of controls, but the contribution of glucose carbon to fatty acid synthesis was small.

It is concluded that lipogenesis is greatly enhanced in isolated hepatocytes of rats which have been subjected to ventromedial hypothalamic destruction.

Key words

Lipogenesis - Hepatocytes - Hypothalamic Obesity - Rat