Four Effects of Exogenous Insulin on Food Intake

Abstract

After a subcutaneous injection of bovine insulin into the rat, at first there is an augmentation of the satiety produced by nutrient eaten immediately before injection. Later, with large enough doses, as has been commonly observed, feeding is elicited—perhaps simply by hastening the passage of satiety. A third type of effect is behavioural disruption, reducing food and water intake when food is withheld for an hour after injection and producing postural changes even when food is present. Fourth, repeated pairing of insulin injection with intake of water of a particular flavour (even when drunk over half an hour beforehand) depresses subsequent intake of water having that flavour, whether presented alone or together with water of another flavour which has been paired with control injections. The acquired discriminated intake change involves the initial acceptability of the flavour but changes in the inhibition of acceptability during an intake bout have not been excluded.