Compensation of the age-related decline in hippocampal muscarinic receptor density through daily exercise or underfeeding.

A decline in muscarinic receptor density of the hippocampus during aging has been previously observed. In the present investigation, the physiological treatments of underfeeding (every-other-day feeding) and exercise (daily treadmill running), initiated at 3 months or 10 months of age, compensated for this age-related decline in hippocampal muscarinic receptor density in F344 rats. Muscarinic receptor density in aged rats, 27 or 24 months of age, was maintained to levels comparable to rats 12 or 10 months of age, respectively. In addition, with the protocols used in this study, underfeeding appeared to be more effective than exercise in muscarinic receptor upregulation.