Lipogenesis by hepatocytes of rats with hypothalamic obesity

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 muatoms 3H per 100 mg liver protein per hour, and in cells from VMN lesioned rats 25 to 80 muatoms 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.