Effect of premature weaning to different diets on the subsequent response to a dietary change.

Rats were weaned prematurely (day 18 postnatally) to a high-fat, high-carbohydrate or Purina Chow diet until aged 30 days. They were then fed the Purina Chow diet until aged 43 or 68 days. For a further 2 days they then received a high-fat diet. They were compared with rats weaned on day 30 to the Purina Chow diet. Adipose tissue of rats weaned prematurely to the high-carbohydrate diet or Purina Chow showed higher activities of phosphoenolpyruvate carboxykinase, malic enzyme and fatty acid synthetase than the same tissue from normally weaned rats or rats fed the high-fat diet from 18 to day 30. Prematurely weaned rats also have a higher level of blood cholesterol on day 45 after 2 days on the high-fat diet.