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STUDIES ON LIPID AND CARBOHYDRATE METABOLISM IN THE RAT
Author(s) -
Hoffmann Choo C,
Carroll KF,
Goldrick RB
Publication year - 1972
Publication title -
australian journal of experimental biology and medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0004-945X
DOI - 10.1038/icb.1972.23
Subject(s) - insulin , meal , carbohydrate , medicine , endocrinology , carbohydrate metabolism , biology , lipid metabolism , zoology , pancreas , metabolism , chemistry
Summary Male Wistar rats were maintained from the age of 4 weeks on one of four feeding programmes— ad libitum feeding with chow with or without the addition of glucose to the drinking water, or meal feeding with restricted or unrestricted quantities of chow—to evaluate the effects of diet on body composition and metabolism. In rats fed ad libitum on chow, the percentage of water in the carcass decreased, the percentages of ash and protein rose, but there was no change in the percentage of lipid during growth. The addition of glucose to the drinking water caused a moderate elevation of the percentage of lipid and a corresponding decrease in the percentage of water in the carcass during the first 2 weeks. Unrestricted meal feeding for only 2 hours per day caused the percentage of lipid in the carcass to increase during growth. This effect of meal feeding was abolished by caloric restriction. Both the body weight and the weight of the epididymal fat pad proved to be unreliable indices of the percentage of lipid in the carcass. The weight of the pancreas was directly proportional to body weight. The concentration of preformed insulin in the pancreas was elevated by unrestricted meal feeding and by supplementing the diet with glucose. The rate of insulin secretion in vitro by the pancreas m the presence of physiological (1 mg/ml) or high (5 mg/ml) concentrations of glucose was directly proportional to the concentration of preformed insulin in the tissue. The rate of insulin secretion in vitro of tissues from rats in the post‐absorptive phase was also directly proportional to the total weight of the rat. In meal‐fed rats, which were in the late post‐absorptive phase when sacrificed, the concentration of plasma insulin was directly proportional to body weight, the total insulin content of the pancreas and the rate of insulin secretion in vitro. These findings suggest that both dietary factors and total body mass determine the supply of insulin and the basal plasma insulin concentration. The insulin responses in vivo to intravenous glucose and the hypoglycaemic effect of intravenous insulin were found to be affected by the age of the rats and the method of feeding, but in a highly variable manner.