Hippocampal PGC-1α-mediated positive effects on parvalbumin interneurons are required for the antidepressant effects of running exercise

Running exercise was shown to have a positive effect on depressive-like symptoms in many studies, but the underlying mechanism of running exercise in the treatment of depression has not been determined. Parvalbumin-positive interneurons (PV+ interneurons), a main subtype of GABA neurons, were shown to be decreased in the brain during the depression. PGC-1 alpha, a molecule that is strongly related to running exercise, was shown to regulate PV+ interneurons. In the present study, we found that running exercise increased the expression of PGC-1 alpha in the hippocampus of depressed mice. Adult male mice with PGC-1 alpha gene silencing in the hippocampus ran on a treadmill for 4 weeks. Then, depression-like behavior was evaluated by the behavioral tests, and the PV+ interneurons in the hippocampus were investigated. We found that running exercise could not improve depressive-like symptoms or increase the gene expression of PV because of the lack of PGC-1 alpha in the hippocampus. Moreover, a lack of PGC-1 alpha in the hippocampus decreased the number and activity of PV+ interneurons in the CA3 subfield of the hippocampus, and running exercise could not reverse the pathological changes because of the lack of PGC-1 alpha. The present study demonstrated that running exercise regulates PV+ interneurons through PGC-1 alpha in the hippocampus of mice to reverse depressive-like behaviors. These data indicated that hippocampal PGC-1 alpha -mediated positive effects on parvalbumin interneurons are required for the antidepressant actions of running exercise. Our results will help elucidate the antidepressant mechanism of running exercise and identify new targets for antidepressant treatment.