study of taste effectiveness of cycloheximide as a repellent to rats

In the present study, the electrical responses of the taste nerve and the lingual nerve of a rat to cycloheximide applied on the tongue were analyzed to determined the taste effectiveness of this chemical. The residue of cycloheximide on the tongue after rinsing with water was also measured to evaluate the possible effective period of this chemical. In addition, the residual effect of previously applied cycloheximine on the drinking behavior of the rat when fed with quinine hydrochloride solution was also determined. Results obtained are as follows : cycloheximide applied to the tongue induces obvious response in the whole chorda tympani, and the bitter-sensitive unit fiber within the whole chorda tympani was specially sensitive to cycloheximide. However, when higher concentrations of this chemical was used, nerve response to the 2nd trial was not elicited, and the response recovery of the nerve to this chemical varied depending on its concentration. Even after rinsing the tongue surface with water, the previously applied cycloheximide still remained, suggesting a firm binding of cycloheximide with the sites of bitter taste receptors in the tongue. Responses of the lingual nerve to mechanical and thermal stimuli applied to the tongue did not change at all even after application of cycloheximide.The present results indicate that the repellency of cycloheximide to rat is primarily attributed to the sense of taste transmitted through the bitter-sensitive unit fiber in the taste nerve and to its long lasting effect on the bitter taste receptors of the tongue.