[A study on the gustatory effects of tetrodotoxin in rat (author's transl)].

Effects of tetrodotoxin (TTX) on neural responses of the chorda tympani to four basic taste stimuli were investigated electrophysiologically in rats. When the TTX (10 mg/ml) was applied directly to the tongue surface for 3 minutes, magnitude of the integrated responses of the chorda tympani was diminished to about 60% of that of the control response. This diminution of response was recovered within 30 minutes by degrees and the effect of the TTX was antagonized by guanylate. This result gives a suggestion that guanidyl group in the TTX may play an important role for the inhibitory actions to the responses of the chorda tympani. On the other hand, when the TTX (0.25 mg/100 g b. wt.) was applied intravenously, magnitude of the responses of the chorda tympani to four basic taste stimuli decreased gradually to 20 approximately 30% of that of the control responses within 60 minutes and did not recover more than 10 hours. This is assumed due to the blocking of the sodium pump of nerve fibers in the chorda tympani by the TTX.