Inhibitory action of taurine on motoneuron of frog spinal cord

Using the sucrose gap method, the effect of taurine on the spinal cord of the bullfrog was investigated. Taurine inhibited the spontaneous potential and the ventral root reflex potential elicited by the stimulation of the dorsal root. The excitability of motoneuron did not necessarily diminish following taurine application. Taurine inhibited the responses induced by excitatory neurotransmitter candidates such as, glutamate and substance P, in a concentration dependent manner in the preparation, where the neurotransmission was abolished by Ca2+-deprivation and/or Mg2+-supplement. From these results, the depressant action of taurine on the electrical activities in the frog spinal cord may be interpreted, in part, by the inhibition of the response evoked by excitatory transmitter at postsynaptic site.