Effects of capsaicin on visceral smooth muscle: a valuable tool for sensory neurotransmitter identification.
Studying the visceral effects of the sensory stimulant capsaicin is a useful and relatively simple tool of neurotransmitter identification and has been used for this purpose for approximately 25 years in the authors' and other laboratories. We believe that conclusions drawn from experiments on visceral preparations may have an impact on studies dealing with the central endings of primary afferent neurons, i.e. research on nociception at the spinal level. The present review concentrates on the effects of capsaicin--through the transient receptor potential vanilloid receptor type 1 (TRPV1) receptor--on innervated gastrointestinal, respiratory and genitourinary smooth muscle preparations. Tachykinins and calcitonin gene-related peptide (CGRP) are the most widely accepted transmitters to mediate "local efferent" effects of capsaicin-sensitive nerves in tissues taken from animals. Studies more and more frequently indicate a supra-additive interaction of various types of tachykinin receptors (tachykinin NK(1), NK(2), NK(3) receptors) in the excitatory effects of capsaicin. There is also evidence for a mediating role of ATP, acting on P(2) purinoceptors. Non-specific inhibitory actions of capsaicin-like drugs have to be taken into consideration while designing experiments with these drugs. Results obtained on human tissues may be sharply different from those of animal preparations. Capsaicin potently inhibits tone and movements of human intestinal preparations, an effect mediated by nitric oxide (NO) and/or vasoactive intestinal polypeptide.
Barthó
Lorand
L
Department of Pharmacology and Pharmacotherapy, Division of Pharmacodynamics, University Medical School of Pécs, Pécs, Hungary. lorand.bartho@aok.pte.hu
Benkó
Rita
R
Patacchini
Riccardo
R
Pethö
Gabor
G
Holzer-Petsche
Ulrike
U
Holzer
Peter
P
Lázár
Zsofia
Z
Undi
Sarolta
S
Illényi
Laszlo
L
Antal
Andras
A
Horváth
Ors-Peter
OP
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology*; D002490:Central Nervous System / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009411:Nerve Endings / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology; D010146:Pain / Q000378:metabolism / Q000503:physiopathology; D011955:Receptors, Drug / Q000502:physiology; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D015320:Tachykinins / Q000502:physiology; D014566:Urogenital System / Q000187:drug effects / Q000502:physiology; D014781:Viscera / Q000187:drug effects* / Q000502:physiology
D011955:Receptors, Drug; D015320:Tachykinins; D009569:Nitric Oxide; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin