Treadmill exercise counteracts the suppressive effects of peripheral lipopolysaccharide on hippocampal neurogenesis and learning and memory

New neurons are continuously generated in hippocampal subgranular zone throughout life, and the amount of neurogenesis is suggested to be correlated with the hippocampus-dependent function. Several extrinsic stimuli are known to modulate the neurogenesis process. Among them, physical exercise has advantageous effects on neurogenesis and brain function, while inflammation shows the opposite. Herein we showed that a moderate running exercise successfully restored the peripheral lipopolysaccharide (LPS)-impaired neurogenesis in the dentate area. LPS treatment obstructed neuronal differentiation, but not proliferation. Exercise training facilitated both the proliferation of the neural stem cells and their differentiation into neurons. Interestingly, exercise replenished the LPS-reduced levels of brain-derived neurotrophic factor and its receptor, TrkB, and rescued the LPS-disturbed performance in water maze; while the LPS-elicited up-regulation of tumor necrosis factor-alpha and interleukin-1 beta remained unaltered. In conclusion, our findings suggest that running exercise effectively ameliorates the LPS-disturbed hippocampal neurogenesis and learning and memory performance. Such advantageous effects of running exercise are not due to the alteration of inflammatory response, but possibly by the restoring the LPS-lessened brain-derived neurotrophic factor signaling pathway.