Effect of maternal malnutrition during pregnancy and lactation on hepatic protein metabolism in the infant rat: biochemical and ultrastructural studies

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Abstract
Diets containing 18, 6, and 3.5% protein were fed ad libitum to pregnant rats during the last week of gestation and continued throughout the period of lactation. Evaluation of hepatic protein metabolism in the progeny of these well-fed and malnourished mothers showed that both the dietary protein level of maternal diet and the litter size in which the young rats were suckled were of crucial importance. Between days 2 and 21, body weight, liver weight, and liver contents of RNA, DNA, and protein increased 6.8-, 7.2-, 5.5-, 3.7-, and 7.6-fold, respectively, in young rats suckled in groups of nine by mothers fed 18% protein. Comparative values in rats raised in litter sizes of 13 to 15 by adequately fed mothers were 4.3, 3.6, 3.1, 1.8, and 3.9, respectively. During the same time interval, liver weight and liver contents of nucleic acids and proteins increased one- to twofold in the young (litter size 5 to 8) of malnourished mothers fed 3.5% protein. At weaning, the livers of the malnourished suckling rats showed marked disorganization of the cytoplasmic organelles as exemplified by the breakdown of the granular endoplasmic reticulum into short, often dilated fragments and vesicles, with loss of the usual parallel stacking of the granular membranes. Such morphologic equivalent of impaired protein synthesis correlated well with the biochemical findings of reduced liver contents of nucleic acids and proteins, disaggregation of polyribosomes (n > 2) into slow sedimenting monomeric and dimeric ribosomes, and reduced as well as distorted hepatic free amino acid pool.