Antinoceptive effect of triterpenoid α,β-amyrin in rats on orofacial pain induced by formalin and capsaicin |
| |
Authors: | SA Holanda Pinto LMS Pinto MA Guedes GMA Cunha MH Chaves FA Santos VS Rao |
| |
Institution: | aDepartment of Physiology and Pharmacology, Post-Graduation Programme in Medical Sciences, Faculty of Medicine, Federal University of Ceara, POB 3157, Rua Cel Nunes de Melo-1127, Porangabussu, 60430-270 Fortaleza, Ceara, Brazil;bDepartment of Organic and Inorganic Chemistry, Federal University of Piaui, Teresina, Piaui, Brazil |
| |
Abstract: | The effects of α,β-amyrin, a pentacyclic triterpene isolated from Protium heptaphylum was investigated on rat model of orofacial pain induced by formalin or capsaicin. Rats were pretreated with α,β-amyrin (10, 30, and 100 mg/kg, i.p.), morphine (5 mg/kg, s.c.) or vehicle (3% Tween 80), before formalin (20 μl, 1.5%) or capsaicin (20 μl, 1.5 μg) injection into the right vibrissa. In vehicle-treated controls, formalin induced a biphasic nociceptive face-rubbing behavioral response with an early first phase (0–5 min) and a late second phase (10–20 min) appearance, whereas capsaicin produced an immediate face-rubbing (grooming) behavior that was maximal at 10–20 min. Treatment with α,β-amyrin or morphine significantly inhibited the face-rubbing response in both test models. While morphine produced significant antinociception in both phases of formalin test, α,β-amyrin inhibited only the second phase response, more prominently at 30 mg/kg, in a naloxone-sensitive manner. In contrast, α,β-amyrin produced much greater antinociceptive effect at 100 mg/kg in the capsaicin test, which was also naloxone-sensitive. These results provide first time evidence to show that α,β-amyrin attenuates orofacial pain atleast, in part, through a peripheral opioid mechanism but warrants further detailed study for its utility in painful orofacial pathologies. |
| |
Keywords: | Protium heptaphyllum α β -Amyrin Antinociception Orofacial pain Formalin Capsaicin |
本文献已被 ScienceDirect 等数据库收录! |
|