title: Citronellol reduces orofacial nociceptive behaviour in mice - evidence of involvement of retrosplenial cortex and periaqueductal grey areas.
abstract: Citronellol (CT) is a monoterpenoid alcohol present in the essential oil of many medicinal plants, such as Cymbopogon citratus. We evaluated the antinociceptive effects of CT on orofacial nociception in mice and investigated the central pathway involved in the effect. Male Swiss mice were pretreated with CT (25, 50 and 100 mg/kg, i.p.), morphine (5 mg/kg, i.p.) or vehicle (saline + tween 80 0.2%). Thirty minutes after the treatment, we injected formalin (20 μl, 2%), capsaicin (20 μl, 2.5 μg) or glutamate (40 μl, 25 μM) into the right limb. For the action in the CNS, ninety minutes after the treatment, the animals were perfused, the brains collected, crioprotected, cut in a criostate and submitted in an immunofluorescence protocol for Fos protein. CT produced significant (p < 0.01) antinociceptive effect, in all doses, in the formalin, capsaicin and glutamate tests. The immunofluorescence showed that the CT activated significantly (p < 0.05) the olfactory bulb, the piriform cortex, the retrosplenial cortex and the periaqueductal grey of the CNS. Together, our results provide first-time evidence that this monoterpene attenuates orofacial pain at least, in part, through an activation of CNS areas, mainly retrosplenial cortex and periaqueductal grey.
authors.affiliation: Department of Physiology, Federal University of Sergipe, Aracaju, SE, Brazil.
authors.forename: Renan G
authors.initials: RG
authors.lastname: Brito
authors.forename: Priscila L
authors.initials: PL
authors.lastname: Santos
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Prado
authors.forename: Marília T
authors.initials: MT
authors.lastname: Santana
authors.forename: Adriano A S
authors.initials: AA
authors.lastname: Araújo
authors.forename: Leonardo R
authors.initials: LR
authors.lastname: Bonjardim
authors.forename: Márcio R V
authors.initials: MR
authors.lastname: Santos
authors.forename: Waldecy
authors.initials: W
authors.lastname: de Lucca Júnior
authors.forename: Aldeídia P
authors.initials: AP
authors.lastname: Oliveira
authors.forename: Lucindo J
authors.initials: LJ
authors.lastname: Quintans-Júnior
mesh_terms: D000080462:Acyclic Monoterpenes; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005157:Facial Pain / Q000188:drug therapy*; D005455:Fluorescent Antibody Technique; D008297:Male; D051379:Mice; D039821:Monoterpenes / Q000008:administration & dosage / Q000494:pharmacology*; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology; D010487:Periaqueductal Gray / Q000187:drug effects / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism
chemical_list: D000080462:Acyclic Monoterpenes; D000700:Analgesics; D039821:Monoterpenes; D016760:Proto-Oncogene Proteins c-fos; D009020:Morphine; C007078:citronellol