Abstract
A method for quantitative measurement of cold sensation evoked by menthol was studied by the discharge of cold fibres in the lingual nerve and the scrotal nerve in response to the application of menthol to the tongue and the scrotum in rats.
1. The evoked responses of cold fibres from the lingual nerve and the scrotal nerve increased linearly with increasing the concentration of menthol in log scale.
However, at a higher concentration of menthol the evoked response decreased; >10-4g/ml in the tongue, >10-3g/ml in the scrotum.
2. The sensitivity of cold fibres in the scrotal nerve to menthol was approximately 1/10 of that of cold fibres in the lingual nerve.
The latency of onset response of cold fibres to menthol was longer in the scrotal nerve than in the lingual nerve.
3. The responses of cold fibres to menthol were decreased by ethanol or surfactant (triethanolamine alkyl sulfates) in comparison with the control responses.
In short, the results demonstrate that this electrophysiological method in rat may be useful for quantitative measurement of cold sensation evoked by menthol.
