Preliminary evidence that riluzole protects against glutamate-induced excitotoxicity at the crayfish neuromuscular junction
We investigated whether the drug riluzole, a glutamate antagonist, protects against glutamate-induced excitotoxicity at the crayfish neuromuscular junction. We measured the excitatory postsynaptic potential (EPSP) amplitudes of crayfish abdominal extensor muscles with intracellular microelectrodes while stimulating the motor neuron through suction micropipettes. We compared the EPSP amplitudes of crayfish muscle cells exposed to glutamate only with those exposed to both riluzole and glutamate, using EPSP amplitude as an indicator of the level of excitotoxicity. We did not observe a significant difference in percent change of EPSP amplitude between trials conducted with 10mM glutamate only and both 10mM glutamate and 50μM riluzole; however, we believe that this is because 10mM glutamate was insufficient to induce excitotoxicity. We observed a loss of EPSPs across three trials soon after the application of 20mM glutamate, which suggested that 20mM glutamate induced excitotoxicity. In trials with 20mM glutamate and 50μM riluzole we did not lose the EPSP and observed a strong EPSP amplitude for the duration of the trial, suggesting that riluzole likely protected against glutamate-induced excitotoxicity.