Neurochemical effects of exercise and neuromuscular electrical stimulation on brain after stroke: A microdialysis study using rat model

Treadmill exercise and neuromuscular electrical stimulation are common clinical approaches for stroke rehabilitation. Both animal and clinical studies have shown the functional improvements after these interventions. However, the neurochemical effects on the ischemic brain had not been well studied. This study aimed at evaluating the effects of treadmill exercise and neuromuscular electrical stimulation (NMES), and studying their effects during a 2-week training, on the levels of common neurotransmitters (aspartate, glutamate, taurine and gamma-aminobutyric acid (GABA)) in the hippocampus following transient focal cerebral ischemia. Either treadmill exercise or neuromuscular electrical stimulation was prescribed to the rats 24 h after cerebral ischemia whereas Control group remained in cages for 2 weeks. Microdialysis technique was used to collect dialysates from ipsilesional hippocampus in vivo. It was found that the glutamate level was increased significantly during treadmill exercise and then returned to baseline level. Both interventions did not trigger significant effects on aspartate and glutamate basal levels during the 2 weeks. The relatively high taurine level in Control groups may suggest that the interventions might suppress the taurine release in hippocampus. GABA and aspartate levels did not showed significant changes over the 2 weeks in all groups. These results provide insights to explain the neurochemical effects on the ischemic injured brain during the course of rehabilitation.