Increased carbohydrate consumption induced by neonatal administration of monosodium glutamate to rats

Using two different experimental feeding paradigms, patterns of diet selection were examined in rats given monosodium glutamate (MSG) as neonates. In both Experiment 1 and Experiment 2, rats received subcutaneous injections of either 4 mg/g MSG or distilled water on alternate days from Day 3 to Day 19 postnatally. As previously reported, MSG-treated rats were shorter and had a greater mean Lee Index of obesity than vehicle-injected control animals. When provided with a choice of separate sources of the three macronutrients, protein, fat and carbohydrate, MSG-treated rats comsumed significantly more carbohydrate and less protein than vehicle-injected controls. Similarly, MSG-treated animals given access to a carbohydrate (32% sucrose) solution in addition to a standard laboratory diet (ground Purina Laboratory Chow) took in a significantly greater proportion of their daily caloric intake from the carbohydrate solution than did controls. The pattern of diet selection in MSG-treated animals is contrasted with patterns of diet selection in animals with other forms of experimental obesity.