Characterization of vanilloid receptors in the dorsal horn of pig spinal cord.
Specific [3H]resiniferatoxin binding is thought to represent the postulated vanilloid (capsaicin) receptor. We have previously characterized [3H]resiniferatoxin binding to membranes from rat and pig dorsal root ganglia, which contain the cell bodies of capsaicin-sensitive primary afferent neurons. We now demonstrate specific binding of [3H]resiniferatoxin to particulate preparations from pig dorsal horn, which contains the central nerve endings of the capsaicin-sensitive primary afferent neurons. The Kd was 0.27 +/- 0.03 nM; the Bmax was 370 +/- 40 fmol/mg protein. Vanilloids of the capsaicin class (capsaicin, piperine, zingerone) and resiniferatoxin class (tinyatoxin, 12-deoxyphorbol 13-phenylacetate 20-homovanillate) inhibited binding with affinities consistent with their relative in vivo potencies. Given the interest in vanilloids as potential non-narcotic analgesic agents, this binding assay affords an attractive approach for characterization of structure-activity relations at spinal vanilloid receptors.
Szallasi
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Molecular Mechanisms of Tumor Promotion Section, National Cancer Institute, NIH, Bethesda, MD 20892.
Blumberg
P M
PM
D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D002211:Capsaicin / Q000031:analogs & derivatives / Q000378:metabolism; D004224:Diterpenes / Q000378:metabolism*; D066298:In Vitro Techniques; D010703:Phorbol Esters / Q000378:metabolism; D011869:Radioligand Assay; D013116:Spinal Cord / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine
D004224:Diterpenes; D010703:Phorbol Esters; C024353:resiniferatoxin; D002211:Capsaicin