title: Capsaicin desensitization in vivo is inhibited by ruthenium red.
abstract: The effect of systemic administration of Ruthenium Red on the excitatory and desensitizing effect of capsaicin was investigated in rats. Ruthenium Red was injected s.c. 30 min before capsaicin was administered. The excitatory effect of capsaicin on corneal, perivascular and visceral afferents was not influenced by treatment with Ruthenium Red. However, determination of the neuropeptide content and evoked neuropeptide release in peripheral organs and dorsal spinal cord 48 h after treatment showed that Ruthenium Red attenuated the 'desensitizing' effect of capsaicin at peripheral, but not at central, endings of primary afferents. On the other hand, a capsaicin-elicited autonomic reflex mediated by visceral afferents was still obtained in 9 of 14 rats that had received Ruthenium Red and capsaicin. The results indicate that a single dose of Ruthenium Red, which does not reduce the acute excitatory effect of capsaicin, reduces the desensitizing effect of capsaicin on peripheral endings of primary afferents in vivo. This long-lasting protective effect of Ruthenium Red suggests that it is possible to pharmacologically differentiate between the acute and chronic effects of capsaicin.
authors.affiliation: Department of Experimental and Clinical Pharmacology, University of Graz, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Amann
authors.forename: J
authors.initials: J
authors.lastname: Donnerer
authors.forename: C A
authors.initials: CA
authors.lastname: Maggi
authors.forename: S
authors.initials: S
authors.lastname: Giuliani
authors.forename: E
authors.initials: E
authors.lastname: DelBianco
authors.forename: E
authors.initials: E
authors.lastname: Weihe
authors.forename: F
authors.initials: F
authors.lastname: Lembeck
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007279:Injections, Subcutaneous; D009411:Nerve Endings / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D009479:Neuropeptides / Q000378:metabolism / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012430:Ruthenium Red / Q000494:pharmacology*; D013373:Substance P / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D001743:Urinary Bladder / Q000294:innervation / Q000378:metabolism
chemical_list: D009479:Neuropeptides; D012430:Ruthenium Red; D013373:Substance P; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin