ABSTRACT
The purposes of this study were to evaluate the anti-nociceptive effect of oral and topical administration of (-)-α-bisabolol (BISA) in rodent models of formalin- or cinnamaldehyde-induced orofacial pain and to explore the inhibitory mechanisms involved. Orofacial pain was induced by injecting 1.5% formalin into the upper lip of mice (20 µL) or into the temporomandibular joint (TMJ) of rats (50 µL). In another experiment, orofacial pain was induced with cinnamaldehyde (13.2 µg/lip). Nociceptive behavior was proxied by time (s) spent rubbing the injected area and by the incidence of head flinching. BISA (100, 200, or 400 mg/kg p.o. or 50, 100, or 200 mg/mL topical) or vehicle was administered 60 min before pain induction. The two formulations (lotion and syrup) were compared with regard to efficacy. The effect of BISA remained after incorporation into the formulations, and nociceptive behavior decreased significantly in all tests. The high binding affinity observed for BISA and TRPA1 in the molecular docking study was supported by in vivo experiments in which HC-030031 (a TRPA1 receptor antagonist) attenuated pain in a manner qualitatively and quantitatively similar to that of BISA. Blockers of opioid receptors, NO synthesis, and K+ ATP channels did not affect orofacial pain, nor inhibit the effect of BISA. In conclusion, BISA had a significant anti-nociceptive effect on orofacial pain. The effect may in part be due to TRPA1 antagonism. The fact that the effect of BISA remained after incorporation into oral and topical formulations suggests that the compound may be a useful adjuvant in the treatment of orofacial pain.
Subject(s)
Analgesics/pharmacology , Behavior, Animal/drug effects , Facial Pain/prevention & control , Nociception/drug effects , Nociceptive Pain/prevention & control , Sesquiterpenes/pharmacology , Temporomandibular Joint/drug effects , Acrolein/analogs & derivatives , Administration, Oral , Administration, Topical , Analgesics/administration & dosage , Analgesics/chemistry , Analgesics/metabolism , Animals , Binding Sites , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Compounding , Facial Pain/chemically induced , Facial Pain/physiopathology , Facial Pain/psychology , Formaldehyde , Male , Mice , Molecular Docking Simulation , Monocyclic Sesquiterpenes , Nociceptive Pain/chemically induced , Nociceptive Pain/physiopathology , Nociceptive Pain/psychology , Protein Binding , Protein Conformation , Rats, Wistar , Sesquiterpenes/administration & dosage , Sesquiterpenes/chemistry , Sesquiterpenes/metabolism , TRPA1 Cation Channel , TRPC Cation Channels/antagonists & inhibitors , TRPC Cation Channels/chemistry , TRPC Cation Channels/metabolism , Temporomandibular Joint/metabolism , Temporomandibular Joint/physiopathology , Transient Receptor Potential Channels/antagonists & inhibitors , Transient Receptor Potential Channels/chemistry , Transient Receptor Potential Channels/metabolismABSTRACT
The present study was designed to verify whether frutalin (FTL) affords gastroprotection against the ethanol-induced gastric damage and to examine the underlying mechanism(s). Gastric damage was induced by intragastric administration of 0.2 ml of ethanol (96%). Mice in groups were pretreated with FTL (0.25, 0.5 and 1 mg/kg; i.p.), cimetidine (100 mg/kg; p.o.), or vehicle (0.9% of NaCl, 10 mL/kg; p.o.), 30 min before ethanol administration. They were sacrificed 30 min later, the stomachs excised, and the mucosal lesion area (mm²) measured by planimetry. Gastroprotection was assessed in relation to inhibition of gastric lesion area. To study the gastroprotective mechanism(s), its relations to capsaicin-sensitive fibers, endogenous prostaglandins, nitric oxide, sulphydryls, ATP-sensitive potassium channels, adrenoceptors, opioid receptors and calcium channels were analyzed. Treatments effects on ethanol-associated oxidative stress markers GSH and MDA were measured in gastric tissue. FTL afforded a dose-unrelated gastroprotection against the ethanol damage. However, it failed to prevent the ethanol-induced changes in the levels of GSH and MDA. It was observed that the gastroprotection by FTL was greatly reduced in animals pretreated with capsazepine, indomethacin, L-NAME or glibenclamide. Considering the results, it is suggested that the FTL could probably be a good therapeutic agent for the development of new medicine for the treatment of gastric ulcer.
