SBNeC 2010
Resumo:B.069


Poster (Painel)
B.069Electrophysiological and Behavioral Evidences of (-)-α-Bisabolol Antinociceptive Effect
Autores:Aron de Miranda Henriques Alves (UFPB - Universidade Federal da Paraíba) ; Juan Carlos Ramos Gonçalves (UFPB - Universidade Federal da Paraíba) ; Fabrícia Costa Montenegro (UFPB - Universidade Federal da Paraíba) ; Reinaldo Nóbrega de Almeida (UFPB - Universidade Federal da Paraíba) ; Demetrius Antonio Machado de Araújo (UFPB - Universidade Federal da Paraíba)

Resumo

Objectives: (-)-α-Bisabolol is a sesquiterpene alcohol found as the major constituent of the German chamomile (Chamomilla recutita (L.) Rauschert) essential oil. Previous studies related that German chamomile and other (-)-α-bisabolol-rich plants showed significant antinociceptive activity in experimental models of pain. Therefore, the present work proposes to investigate the potential of this sesquiterpene as a novel antinociceptive agent by experimental models in vivo and its relation towards the reduction of nerve excitability. Methods and Results: For in vivo assays Swiss mice weighting 25-35g were used in the acetic acid-induced writhing and the formalin tests. Additionally, we used the single sucrose gap method adapted for mice sciatic nerve in order to assess eventual changes in the compound action potential (CAP) characteristics. In the acetic acid-induced writhing test it was observed, as compared with the control group, a significant decrease in the number of writhes, of about 55.8±11.2% and 89.3±20.1%, when 25 mg/kg and 50 mg/kg of (-)-α-bisabolol were administered i.p., respectively (P<0.05). It was also verified that (-)-α-bisabolol (50 mg/kg) inhibited about 36.2 ± 7.9% of the nociceptive response in mice on the first phase of the formalin test. On the second phase of this test (-)-α-bisabolol inhibited about 53.0±13.3% and 72.4±8.3% in mice treated with doses of 25 mg/kg and 50 mg/kg (i.p.), respectively. In the electrophysiological assays it was shown that (-)-α-bisabolol acts on peripheral nervous system reducing the CAP amplitude (Vcap) in a time-incubation and concentration-dependent manners, showing an IC50 of 9.0±0.1 mM. It was also observed that (-)-α-bisabolol (10 mM) promoted alterations in the velocity of CAP depolarization (DVcap), decreasing this parameter from 66.2±9.6 V/s to 30.7±6.8 V/s, which was similarly to lidocaine, a standard voltage-gated sodium channels blocker. Moreover, this sesquiterpene did not induce significant changes on the CAP repolarization phase, dissimilarly from 4-aminopyridine, a voltage-gated potassium channels blocker. Conclusion: We conclude that (-)-α-bisabolol has shown an antinociceptive-like effect, which might be associated, at least in part, with decreased peripheral neuronal excitability.


Palavras-chave:  (-)-α-Bisabolol, Antinociceptive effect, Sciatic nerve, Sucrose gap