Effects of Antecedent Food Intake Pattern on Hepatic Lipogenesis

Liver slices of ATG obese mice, of rats trained to eat their 24-hour ration in 1 hour and of rats fed a high carbohydrate diet after a 48-hour period of fasting were incubated with acetate-1-C¹⁴ and with glucose-U-C¹⁴ and the extent of incorporation of the precursor label in the fat fraction was measured. Comparatively high rates of lipogenesis were observed in all three circumstances, the highest in the ‘refed’ group. A high positive correlation was found between initial glycogen content and lipogenic performance of the slices. A high rate of glucose absorption from the g.i. tract was noted in the ‘trained’ animals. A three to fourfold increase in TPN-linked hexose monophosphate shunt dehydrogenase activity was found in preparations from the livers of ‘refed’ rats. The problem of ‘supernormal’ lipogenesis is discussed in the light of recent studies on the ‘failure’ of lipogenesis associated with diabetes and carbohydrate deprivation and the possible significance of a fluctuating supply of TPNH as a central mechanism in the adaptation and de-adaptation of the lipogenic apparatus is reemphasized.