‘Safety Valve’ Effect of Excess Dietary Amino-acids and Protein on Food Intake in Hyperphagic Rats

Abstract

IMBALANCES in amino-acids and excessively high-protein content of the diet (66 per cent or more) depress food intake and retard growth in rats. It has been suggested that resulting metabolic disturbances affected the mechanism of regulation of food intake. The fact that in some instances administration of insulin counteracts the growth-retarding effect of leucine excess was taken as supporting this view¹. Going one step further, it has been suggested that blood amino-acid patterns played a crucial part in the mechanism of satiety and the regulation of food intake^2,3. The experiments presented here were designed to show whether excess or imbalanced amino-acid and protein intake do, in fact, act on the mechanism regulating food intake or whether they limit food intake by acting through other structures. Inasmuch as it has been shown that the ventromedial hypothalamic area regulates food intake, that is, adjusts food intake to energy output⁴, apparently by inhibiting constantly activated lateral ‘feeding centres’⁵ and exercising some measure of control over gastric contractions⁶, the animals used were ten female albino rats (Charles River strain) the ‘satiety’ centres of which had been destroyed by electrocoagulation of the ventromedial area.