The Combinatory Effects of Diet and Exercise on BDNF Gene Expression

Brain Derived Neurotrophic Factor (BDNF) plays a critical role in the synaptic activity and plasticity of mature neurons and regulates the formation and maintenance of memory. Furthermore, human and mouse BDNF levels were found to be altered in psychiatric diseases. Actually, BDNF signaling not only contributes to the pathophysiology of depression, but also is important for the therapeutic effects of antidepressants. On the other hand, exercise induces beneficial responses in the brain, many of which are mediated through induction of BDNF expression. Moreover, BDNF expression was shown to be enhanced under select dietary conditions. However the exact mechanisms for these inductions have been elusive. The aim of the present work was to explore the effect of combining different diets with exercise on BDNF expression in the brain. First, C57BL/6 mice were divided into 6 groups based on the diet they received (standard versus high protein versus high fat) and whether they were provided with a running wheel to exercise during 28 days or not. Results showed that high protein diets induced BDNF expression and that combining this diet with voluntary exercise had an additive effect on BDNF expression. In contrast, a high fat diet attenuated the positive effects of exercise on BDNF expression. In a second experiment, the effect of dietary leucine (1.5% or 3%) was tested in mice exposed to the same 28‐day voluntary exercise paradigm as the first experiment. Results showed that supplementation with 1.5% leucine significantly induced BDNF in the brain, and this effect was additive with exercise as well. Future work will investigate whether the effect found is restricted to leucine or may be extended to other branched chain amino acids such as isoleucine or valine. The present results enrich our understanding of how exercise and different diets coordinate to induce BDNF gene expression and may be used in identifying novel therapeutic targets for depression.