|Lipman Ruth D|
|Smith Donald E|
Submitted to: Clinical Experimental Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1994
Publication Date: N/A
Citation: Interpretive Summary: Young rats fed a restricted number of calories from a diet that provides adequate nutrition have a longer lifespan than rats allowed to consume as many calories as desired. Many of the age-associated changes which occur are diminished or delayed in rats which have been continually calorically restricted from their youth. However, there are data suggesting that weight loss in older individuals may increase their risk of mortality. This study was designed to examine whether caloric restriction instituted in fully mature rats would be beneficial. The median lifespan for rats fed ad libitum with those rats in which caloric restriction was imposed in adulthood did not demonstrate a significant difference. This data may suggest that there may be a level of maturity or stage in the aging process after which caloric restriction no longer increased longevity.
Technical Abstract: Caloric restriction initiated in young mice and rats results in increases in mean and median lifespan. When calorie restriction is implemented in older animals an increase in lifespan is still observed, however the magnitude of the increase is not as great as that observed in animals calorie restricted since they were young. Here we report the results of a study in which calorie restriction was initiated in mature, older rats. Survival rates and terminal pathology were characterized and compared between a cohort of 17 continually ad libitum fed Long Evans rats and a cohort of 18 Long Evans rats which were gradually introduced to 33% restriction in diet consumption at 18 months of age. No difference in the median lifespan was observed between the two groups. This data may suggest that there may be a level of maturity or a stage in the aging process after which caloric restriction no longer increases longevity.