INFLUENCE OF CALORIC-INTAKE ON AGING AND ON THE RESPONSE TO STRESSORS

Reducing the food intake of rodents to well below that of ad libitum f ed animals increases the life span. This action, which gerontologists often refer to as the antiaging action of dietary restriction (DR), is due to the slowing of the aging processes. DR also maintains most phy siological processes in a youthful state and delays the occurrence and /or slows the progression of age-associated disease processes. This an tiaging action of DR results from the reduced intake of calories. Redu ction of the body fat content does not play a causal role in the antia ging action of DR, nor does reduction in the metabolic rate. Alteratio ns in the characteristics of carbohydrate metabolism and of oxidative metabolism in response to DR have been found that are of such a nature that they could, at least in part, underlie the antiaging action. Sev eral theories have recently been proposed in regard to the mechanisms responsible for the antiaging action of DR, but none has been tested b y rigorously designed studies. Of these theories, the one that seems m ost promising is based on the fact that DR protects rats and mice of a ll ages against the damaging actions of acute stressors. This protecti ve action against stressors may play a major role in the antiaging act ion of DR.