CAPSAICIN SENSITIVITY IS ASSOCIATED WITH THE EXPRESSION OF THE VANILLOID (CAPSAICIN) RECEPTOR (VR1) MESSENGER-RNA IN ADULT-RAT SENSORY GANGLIA

A vanilloid receptor (VR1) has recently been cloned and shown to be a target for capsaicin, the excitotoxic component of capsicum peppers (C aterina, M.J., Schumacher, M.A., Tominaga, M., Rosen, T.A,, Levine, J. D. and Julius, D., Nature, 389 (1997) 816-824). The effects of capsaic in appear to be selective for a subset of sensory neurones which inclu des polymodal nociceptors. The present study describes the distributio n of VRI mRNA, together with measurements of capsaicin sensitivity, in sensory nerve ganglia of different embryological origins and a single sympathetic ganglion, the superior cervical ganglion (SCG). In situ h ybridisation revealed the expression of VRI mRNA in small-to-medium-si zed neurones of the dorsal root, trigeminal and vagal ganglia. No hybr idisation signal was observed in the SCG neurones. This pattern of exp ression correlated with capsaicin sensitivity measured by whole-cell v oltage clamp where, in similar sized cells, over 80% of neurones from dorsal root and vagal ganglia were capsaicin sensitive, but all SCG ne urones were insensitive to capsaicin. (C) 1998 Elsevier Science Irelan d Ltd. AII rights reserved.