The response of adult rats weaned prematurely and normally to starvation.

Male rats were weaned normally (NW; day 30 after birth) or prematurely (PW; day 18) to a Purina Chow diet. Serum cholesterol levels and the activities of some enzymes of fatty acid and glucose metabolism were determined when the animals were 6 and 10 months old and, in the older group, also after 2 days of starvation. Blood cholesterol levels rose with age and at 10 months were higher in PW than NW rats. This difference disappeared after starvation. Hepatic pyruvate kinase (PK) activity was the same in fed NW and PW animals but was significantly higher in starved PW than NW rats. Hepatic phosphoenolpyruvate carboxykinase (PEPcK) activity was lower in NW than in PW rats, but this difference disappeared on starvation. In white fat, starvation caused a fall in PEPcK activity in both groups. In general, the effect of starvation did not accentuate the differences between the two groups. However, PEPcK activity in white fat increased with age about fourfold.