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Background and Aims: Moderate physical exercise, dietary restriction as well as enriched environment in separate studies have been reported to delay some of the adverse effects of aging on brain function, parallel to an increase in brain-derived neurotrophic factor (BDNF). In order to elucidate these influences in a comparative setting, we examined the tissue concentrations of BDNF in the cerebral parietotemporal cortex of old Sprague-Dawley rats. Methods: Male Sprague-Dawley rats were divided randomly into six groups, living from 5 months (baseline group BL) up to 23 months of age as follows: voluntary running in wheels (RW), food restricted by feeding to pair weight with RW animals (PW), forced running on treadmills (TM), and sedentary controls with ad libitum access to food, either housed individually (S1) or in groups of 4 animals (S4). BDNF concentrations were determined by a commercially available ELISA. Results: We found higher BNDF concentrations in the 5 months old animals than in the 23 months old animals of group S1. The old sedentary group S4 showed significantly higher BNDF concentrations in comparison with the old individually caged groups RW, TM, PW and S1. Their BNDF concentrations were even higher than those of the young baseline group. Conclusions: Our data suggest that housing and social interactions have more influence on BDNF concentrations in the cerebral parietotemporal cortex of aging Sprague-Dawley rats than physical exercise and food restriction.

Spatial learning and memory decline with ageing in humans as well as rats. We examined the influence of different interventions on male Sprague Dawley rats with respect to learning ability and memory at the age of 5, 10 and 18 months. The intervention and control groups were: (RW) voluntary exercise in running wheels, (PW) sedentary, food restricted (by about 25%) to keep them at pair weight with RW, (S1) sedentary, fed ad libitum, (TM) forced training in a treadmill, and, (S4) sedentary, fed ad libitum. The animals in all groups were housed individually except those in group S4, which were housed four in each cage. The ability of learning and memory was determined in the Morris water maze. The results showed a significantly better learning ability when young in comparison with their ability when having grown older. At the age of 18 months, the performance was significantly better in the subgroups which had received training also at the age of 10 months compared to the subgroups receiving their first training. None of the various interventions had any significant effect on these functions. Repeated training seems to be the best intervention with respect to retaining learning ability and memory.