Age-associated reduction in pineal beta-adrenergic receptor density is prevented by life-long food restriction in rats.

At 28 months of age (old rats), male Fisher 344 rats which had been fed 40% of the ad libitum food intake since they were 6 months old, had a similar beta-adrenergic receptor density (Bmax) in their pineal gland as young, 3-month-old rats. In contrast, old rats which had been fed ad libitum for the same period had approximately 50% of the Bmax value compared to that of young rats. The beta-receptor density of cerebral cortical tissue and the beta-receptor affinity (Kd) of both the cortex and the pineal gland did not decline with age and was not affected by food restriction. The reduction in pineal beta-receptor density with age may be casually related to the concurrent age-associated decline in pineal production of melatonin.