Acta physiologica Scandinavica. Supplementum
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Acta Physiol Scand Suppl · Jan 1995
Autoradiographic visualization and pharmacological characterization of vanilloid (capsaicin) receptors in several species, including man.
Sensory neurons sensitive to vanilloids (the paradigm of which is capsaicin, the pungent principle in hot peppers) were visualized by [3H]resiniferatoxin (RTX) autoradiography in several species, including man. Vanilloid binding sites were detected in somatic (trigeminal and dorsal root) and visceral (nodose) sensory ganglia, peripheral (vagal and sciatic) nerves, dorsal horn of the spinal cord, as well as in nuclei in the central nervous system receiving sensory input, such as the nucleus of the solitary tract (containing vagal afferents) and the spinal trigeminal nucleus. Twenty four hrs after ligation of the vagal or the sciatic nerves, a strong accumulation of specific RTX binding sites was observed proximal to the ligature, implying anterograde intraaxonal receptor transport from the nodose and dorsal root ganglia, respectively, to the periphery. ⋯ In conclusion, specific binding of [3H]RTX provides a unique tool to visualize vanilloid receptors and to study their pharmacology. A heterogenous vanilloid receptor system is emerging with types/subtypes, and marked species-related differences. The interaction of protons and neuroleptics at vanilloid receptors may provide a rational basis to explain their actions on on primary sensory neurons.