Dose-dependent effects of glutamate in pyridoxine-induced neuropathy.

In order to explore the effects of glutamate in a pyridoxine megadose-induced neuropathy, rats were received glutamate either 0.5 or 1 g/kg/day orally with or without pyridoxine 0.8 g/kg/day intraperitoneally for 14 days. The animal's motor coordination, the muscle power and the thermal threshold were observed daily. The nerve conduction velocity was measured at day 0 and day 15 of the treatment. Glutamate either 0.5 or 1 g/kg/day appeared to have no effect on motor coordination, the nerve conduction velocity and the muscle power score compared with control. However, the thermal response latency was significantly decreased (from day 9) in animals treated with 1 g/kg/day glutamate. In pyridoxine-induced neuropathy rats, glutamate 0.5 g/kg/day significantly decreased the effects of pyridoxine on the sciatic nerve conduction velocity, the muscle power score and the motor coordination. Interestingly, glutamate at a dose of 1 g/kg/day worsened the neurotoxic effects cause by pyridoxine.