Menthol: a natural analgesic compound.
Menthol, after topical application, causes a feeling of coolness due to stimulation of 'cold' receptors by inhibiting Ca++ currents of neuronal membranes. Since Ca++ channel blockers are endowed with analgesic properties, the aim of the present study was to investigate the potential antinociceptive effect of menthol. (-)-Menthol produced a dose-dependent increase in the pain threshold in the mouse hot-plate (3-10 mg kg(-1) p.o.) and abdominal constriction (3-10 mg kg(-1) p.o.; 10 microg per mouse intracerebroventricularly (i.c.v.)) tests. The antinociceptive effect of (-)-menthol was antagonised by the unselective opioid antagonist naloxone and by the selective kappa-antagonist nor-NBI. Conversely, CTOP (mu-antagonist), 7-benzylidenenal-trexone (delta(1) antagonist) and naltriben (delta(2) antagonist) did not prevent (-)-menthol antinociception. In both tests, (+)-menthol (10-50 mg kg(-1) p.o.; 10-30 microg per mouse i.c.v.) was unable to modify the pain threshold. These results indicate that (-)-menthol is endowed with analgesic properties mediated through a selective activation of kappa-opioid receptors.
Galeotti
Nicoletta
N
Department of Pharmacology, Viale G. Pieraccini 6, University of Florence, I-50139, Florence, Italy.
Di Cesare Mannelli
Lorenzo
L
Mazzanti
Gabriela
G
Bartolini
Alessandro
A
Ghelardini
Carla
C
D019342:Acetic Acid; D000284:Administration, Oral; D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D008297:Male; D008610:Menthol / Q000494:pharmacology*; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects; D004856:Postural Balance / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects
D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D008610:Menthol; D019342:Acetic Acid