Evidence suggests that regular exercise can protect against learning and memory impairment in the presence of insults such as sleep deprivation. The dentate gyrus (DG) area of the hippocampus is a key staging area for learning and memory processes and is particularly sensitive to sleep deprivation. The purpose of this study was to determine the effect of regular exercise on early-phase long-term potentiation (E-LTP) and its signaling cascade in the presence of sleep deprivation.Experimental design
Rats were exposed to 4 weeks of regular treadmill exercise then subsequently sleep-deprived for 24 h using the modified multiple platform model before experimentation. We tested the effects of exercise and/or sleep deprivation using electrophysiological recording in the DG to measure synaptic plasticity; and Western blot analysis to quantify the levels of key signaling proteins related to E-LTP.Measurements and results
Regular exercise prevented the sleep deprivation-induced impairment of E-LTP in the DG area as well as the sleep deprivation-associated decrease in basal protein levels of phosphorylated and total α calcium/calmodulin-dependent protein kinase II (P/total-CaMKII) and brain-derived neurotrophic factor (BDNF). High frequency stimulation (HFS) to the DG area was used to model learning stimuli and increased the P-CaMKII and BDNF levels in normal animals: yet failed to change these levels in sleep-deprived rats. However, HFS in control and sleep-deprived rats increased the levels of the phosphatase calcineurin. In contrast, exercise increased BDNF and P-CaMKII levels in exercised/sleep-deprived rats.Conclusions
Regular exercise appears to exert a protective effect against sleep deprivation-induced spatial memory impairment by inducing hippocampal signaling cascades that positively modulate basal and stimulated levels of key effectors such as P-CaMKII and BDNF, while attenuating increases in the protein phosphatase calcineurin.