Background
Aging negatively affects adult hippocampal neurogenesis, and exercise attenuates the age-related reduction in adult hippocampal neurogenesis. In the present study, we used senescent mice induced by D-galactose to examine neural stem cells, cell proliferation, and neuronal differentiation with or without exercise treatment. D-galactose (100 mg/kg) was injected to six-week-old C57BL/6 J mice for 6 weeks to induce the senescent model. During these periods, the animals were placed on a treadmill and acclimated to exercise for 1 week. Then treadmill running was conducted for 1 h/day for 5 consecutive days at 10-12 m/min for 5 weeks.
Conclusion
These results suggest that treadmill exercise attenuates the D-galactose-induced reduction in neural stem cells, cell proliferation, and neuronal differentiation by enhancing the expression of pCREB and BDNF in the dentate gyrus of the hippocampus.
Results
Body weight and food intake did not change significantly after D-galactose administration with/without treadmill exercise, although body weight and food intake was highest after treadmill exercise in adult animals and lowest after treadmill exercise in D-galactose-induced senescent model animals. D-galactose treatment significantly decreased the number of nestin (a neural stem cell marker), Ki67 (a cell proliferation marker), and doublecortin (DCX, a differentiating neuroblast marker) positive cells compared to those in the control group. In contrast, treadmill exercise significantly increased Ki67- and DCX-positive cell numbers in both the vehicle- and D-galactose treated groups. In addition, phosphorylated cAMP-response element binding protein (pCREB) and brain derived neurotrophic factor (BDNF) was significantly decreased in the D-galactose treated group, whereas exercise increased their expression in the subgranular zone of the dentate gyrus in both the vehicle- and D-galactose-treated groups.