The effects of body-weight supported treadmill training on the expression of glutamate and glycine in the synaptic inputs to motor neurons in the lumbar spinal cord of spinally transected rats.

Following a complete spinal cord transection, stepping generation depends on the circuitry and neurotransmitters within the lumbar cord. Excitatory and inhibitory neurotransmitters, glutamate and glycine, respectively, are important in generating weight-bearing stepping after complete transection. In this study, 10 rats received a complete transection at 5 days of age. 5 of these rats were trained on a robotic treadmill at 4 weeks of age everyday for 4 weeks whilst 5 were left untrained. Analyses of the lumbar cord showed a trend towards increases in glutamate and glycine vesicle transporters around motor neurons in trained transected rats versus untrained. Kinematic analyses showed that stepping patterns of trained rats were more similar to that of intact rats and this was not observed in untrained rats. These results suggest that stepping pattern restoration in transected rats involves remodelling of lumbar cord circuitry and that this remodelling may involve glutamate and glycine neurotransmitter systems.