Capsaicin and nicotine both activate a subset of rat trigeminal
ganglion neurons.
Liu, L., and S. A. Simon.
Departments of Neurobiology and Anesthesiology
APStracts 2:0449C, 1995.
Nicotine and capsaicin produce many similar physiological responses
that include pain, irritation, and vasodilation. To determine whether
neuronal nicotine acetylcholine receptors (nAChRs) are present on
capsaicin-sensitive neurons, whole-cell patch clamp recordings were
performed on rat trigeminal ganglion cells. It was found that about
20% of the total number of neurons tested were activated by both 100
[mu]M nicotine and 1 [mu]M capsaicin. Other subsets of neurons were
activated by only one of these compounds, whereas a fourth subset was
not activated by either compound. At -60 mV, the magnitude of the
capsaicin-activated currents was about three times larger than the
magnitude of the nicotine-activated currents. The current-voltage
relationship of the nAChRs exhibited marked rectification such that
for voltages >/= 0 mV, the current was essentially zero. In contrast,
the current-voltage relationship of the capsaicin-activated current
was ohmic from +/- 60 mV. These data indicate the existence of
subsets of capsaicin-sensitive afferent neurons.
Received 4 October 1995; accepted in final form 1 December 1995.
APS Manuscript Number C603-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95