The Synergy Effect of Low-Intensity Exercise Training and Caloric Restriction on BDNF in Rat Hippocampus

Abstract

PURPOSE: Recent studies have suggested that exercise training and caloric restriction have beneficial effects on brain function, including the improvements of cognitive function by the promotion of brain-derived neurotrophic factor (BDNF) expression in the hippocampus. In addition, the level of oxidative stress might be involved in the mechanism to explain these effects. The purpose of this study was to investigate the synergy effects between 12-week low-intensity exercise training and caloric restriction on BDNF expression and the level of oxidative stress in rat hippocampus. METHODS: Twenty-six, 7 week-old male Wistar rats were randomly divided into the following 4 groups: 1) sedentary control (Con, n=7); 2) exercise (Ex, n=6); 3) caloric restriction (CR, n=7); and 4) exercise training and caloric restriction (ExCR, n=6). Ex and ExCR underwent treadmill running at 10 m/min, 5° slope, 30 min/day, 5 days/week. Although Con and Ex were fed ad libitum over time, CR and ExCR consumed 40 % less food compared with Con. Forty-eight hours after the termination of the 12-week intervention, rats were sacrificed and the hippocampus was quickly dissected for measurement of BDNF and 4-hydroxy-2-nonenal (4-HNE) contents, and serum total antioxidant capacity (TAC) were also assessed. RESULTS: 4-HNE contents in Ex and CR were significantly increased compared with Con (p<0.05, respectively). However, these elevation was not observed in ExCR. On the other hand, no changes were observed in the alteration of serum TAC among 4 groups. Hippocampal BDNF contents was significantly increased in Ex compared with Con (p<0.05), whereas the exercise-induced elevation in BDNF was completely suppressed by a combination with caloric restriction. Furthermore, we found a significant relationship between hippocampal BDNF and 4-HNE contents (p<0.05), suggesting the hypothesis that oxidative stress is essential for the expression of BDNF in the hippocampus. CONCLUSION: Our findings indicate that optimal stimulus of oxidative stress induced by low-intensity exercise training contributes to BDNF expression in hippocampus. However, it is conceivable that exercise training combined with caloric restriction might not have a synergy effect on hippocampal BDNF expression.