Action of food restriction on age-related changes in adipocyte lipolysis

The effects of aging and of food restriction at different times during life on rat adipocyte responses to glucagon and epinephrine were explored by studying hormone-stimulated lipolysis, hormone binding, and phosphodiesterase activity. The times of food restriction were: (a) from 6 weeks of age, (b) limited to early life, and (c) beginning in young adult life. Hormone-sensitive lipolysis is lost with age. Food restriction from 6 weeks of age prevents this loss, and food restriction started in adult life causes the recovery of this lipolysis. Hormone binding studies reveal that: (a) changes in glucagon-stimulated lipolysis parallel changes in glucagon binding; (b) glucagon binding and glucagon-stimulated lipolysis correlate inversely with cell size; (c) changes in epinephrine-stimulated lipolysis are not due to changes in beta-adrenergic binding; and (d) neither beta-adrenergic binding nor epinephrine-promoted lipolysis correlate with fat cell size. Phosphodiesterase activity is not influenced by diet, making it unlikely to be a postreceptor component lost with age.