Efeito antinociceptivo do geraniol (trans-3,7-dimetilocta-2,6-dien-1-ol) associado à codeína na região orofacial em camundongos

Abstract

The prospect of obtaining new alternatives for the pharmacological therapy of orofacial pain drives the investigation of products of natural origin with antinociceptive action associated with an opioid analgesic. Thus, the aim of this study was to investigate the activity of geraniol associated with codeine in the modulation of orofacial nociception,

and possible depressant effect at the CNS level. This study is characterized as non- clinical, controlled and triple-blind. An experimental model of nociception in mice was

adopted: formalin test,....For each test performed, six animals per group were treated, 30 minutes before the beginning of the experiment, by the intraperitoneal route (ip), according to the following experimental groups: a) geraniol 50 mg/kg + codeine 30 mg/kg; b) geraniol 50 mg/kg + codeine 15 mg/kg; c) geraniol 50 mg/kg + codeine 7.5 mg/kg; d) geraniol 50mg/kg; e) codeine 30 mg/kg (positive control); f) 0.9% sodium chloride (negative control). The analysis of the nociceptive behavior of the animals was performed after the injection of glutamate (20 μl, 25μM), capsaicin (20μl, 2.5μg) and formalin (20μl, 20%) in the right upper lip (paranasal) region of the animal. As a behavioral parameter, the time in seconds of friction of the referred region by the hind or front paws was considered. The results showed that in the glutamate test, geraniol and codeine in concentrations of 50 mg/kg and 30 mg/kg presented a reduction of 54.2% in the friction time, this same dose inhibited in 66.7% the nociception in the test of capsaicin (p<0.005). In the formalin test, the association at the same dose was able to reduce nociception by 86% (p<0.005). In order to investigate a possible myorelaxant and neurotoxic activity that could interfere with the results, the rota-rod test was also performed, where no such effects were observed. Therefore, from these experimental data, it can be suggested that there is a possible synergism of geraniol associated with codeine in orofacial antinociceptive activity.