DOES THE INTEGRATED LEVEL OF ALL PLASMA NUTRIENTS CONTROL DAILY FOOD-INTAKE

Studies on two different types of one-way crossed-intestines rats have shown that daily food intake is controlled by either endogenous gut signals or absorbed nutrients and their metabolic consequences, or both. If the amount of incoming ingested food is metered somewhere in the body, this could only occur in the gut or liver. The capacity of the liver to determine the amount of water-soluble nutrient absorbed was assessed by portacaval shunt and found to be inadequate. Infusion of nutrients directly into the bloodstream show that plasma nutrients provide part of the signal that inhibits daily food intake, but that endogenous gut signals must play some role. Insulin, an important hormone in the movement of plasma nutrients into cells, was found to stimulate food intake at low infusion doses. IV nutrients raise the level of plasma nutrients and lower daily food intake, while insulin, which inhibits the release of endogenous fuels and moves exogenous fuels into cells, lowers plasma nutrients and stimulates daily intake. Thus, the integrated level of all plasma nutrients may be a major controller of daily food intake.