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Published on: January 10, 2014
Orofacial anti-hypernociceptive effect of citral in acute and persistent inflammatory models in rats
Bruna M Santos1, Wanderson S Santos2, Isabelly G Solon2
1Department of Basic and Oral Biology, Dental School of Ribeirão Preto, University of São Paulo, Avenida Do Café s/n, São Paulo, 14040-904 Ribeirão Preto, SP, Brazil; Department of General and Specialized Nursing Ribeirão Preto, College of Nursing - University of São Paulo, Ribeirão Preto, SP, Brazil.
Abstract:
Orofacial pain has significant psychological and physiological effects. Citral (3,7-dimethyl-2,6-octadienal) is the main component of Cymbopogon citratus (DC) Stapf, an herb with analgesic properties. Although citral has been considered a potent analgesic, its putative effects on orofacial pain are still unknown.
Objective:
The objective of this study is to test the hypothesis that citral modulates orofacial pain using two experimental models: formalin-induced hyperalgesia in the vibrissae area and during persistent temporomandibular hypernociception using Complete Freund's Adjuvant - CFA test.
Methods:
For the formalin test, citral (100 and 300 mg/kg, oral gavage) or its vehicle (Tween 80, 1 %) were given 1 h before the formalin injection subcutaneously (sc) into the vibrissae area. For the CFA model, we analyzed the prophylactic (100 mg/kg of citral by oral gavage, 1 h before CFA injection) and the chronic therapeutic (citral treatment 1-hour post-CFA injection and daily post-CFA injection) effect of citral or its vehicle in animals treated with CFA for 8 days.
Results:
Citral caused a decrease in formalin-induced local inflammation and the time spent performing nociceptive behavior in a dose-dependent fashion. Similarly, prophylactic and therapeutic citral treatment decreased the CFA-induced persistent mechanical hypernociception in the temporomandibular area.
Conclusion:
Our data strengthen the notion that citral plays a powerful antinociceptive role by decreasing orofacial hypernociception in formalin and CFA models.
