Effects of litter size and diet composition on the development of some lipogenic enzymes in the liver and brown adipose tissue of the rat.

Male Sprague-Dawley rats were reared in litters of nine (normal litters) or 18 pups, and the dams were fed either a low fat (control) or a high fat diet. Offspring from each litter size and diet group were separated from the mothers on postnatal d 30, subdivided into two groups each, and fed either the control or the high fat diet until postnatal d 77. Hepatic glucose-6-phosphate dehydrogenase, malic enzyme and ATP-citrate lyase activities in the offspring from large litters were elevated during the early stages of weaning but later lagged behind enzyme activity of the normal litters. Brown adipose tissue enzymes also surged earlier in rats from large litters but did not fall below the values attained by the normal litters until postnatal d 32. Enzyme activities on postnatal d 77 revealed that large litter size and high fat feeding during or after weaning were associated with diminished hepatic enzyme activities. Hepatic glucose-6-phosphate dehydrogenase and ATP-citrate lyase activities also showed significant positive interaction between litter size and diet composition after weaning. Large litter size was also associated with diminished brown adipose tissue enzymes in the mature rats, but the composition of the weaning diet did not independently exert long-lasting changes in this tissue. Nevertheless, there was a positive interaction between litter size and diet composition during and after weaning. The data suggest that neonatal undernourishment can exert a long-term influence on the metabolic profiles of the animal, and that diet plays a role in modulating this influence.