Effect of forced treadmill exercise on long-term potentiation (LTP) in the dentate gyrus of hippocampus in male rats

Introduction: Previous studies indicate that exercise influences cognitive function. Nevertheless, considering that exercise in animal study can be voluntary, or forced, effects of exercise (specially forced exercise) on learning and memory abides as a matter of controversy. The present study aimed to investigate the effects of treadmill exercise on LTP in the dentate gyrus of rats. Methods: The exercise program that is used was a moderate exercise consisting of treadmill running at 17 m/min and 0-degree inclination for 40 min/day, 7 days/week, for 12 weeks. Field excitatory postsynaptic potentials (fEPSP) were recorded in dentate gyrus (DG) after stimulation (by 400 Hz titanization) of Perforant pathway. Results: The indices of responses including amplitude of population spike and slope of excitatory postsynaptic potential were significantly smaller in exercise group with respect to control group. But the stimulus-response curves in DG area measured before induction of LTP, had no significant difference between the groups. Conclusion: The present results suggest that alternative stress due to electrical shock in order to motivate the animal to run in treadmill exercise, affect synaptic transmission and impairs LTP induction in DG. Therefore, these experiments indicate that chronic treadmill exercise can decline learning and memory.