Efeito de Arrabidaea chica Verlot na dor neuropática pós-traumática em ratos

Abstract

Neuropathic pain (NP) is caused by an injury or disease of the somatosensory nervous system, which affects about 8% of the world population. Its management is considered a great challenge because its complexity and the absence of specific medication. In the search for new therapies, Arrabidaea chica Verlot, popularly known as carajirú and pariri, whose anti-inflammatory properties are scientifically proven, appears in this scenario. This study aimed to evaluate the efficacy of ethanolic extract and fractions of Arrabidaea chica (A. chica) in an experimental model of NP, induced by sciatic nerve compression in rats (Rattus norvegicus). The extract (EEAC) was obtained from dried leaves of the plant extracted by maceration with ethanol, followed by solvent fractionation of different polarities to obtain hexane (FH), chloroform (CF), ethyl acetate (FAE) and butanolic (FBU). The phytochemical approach of the fractions was performed by high performance liquid chromatography to identify the presence of the main compounds in AED and CF. To investigate the effect of EEAC and fractions on NP, behavioral tests were performed to evaluate the degree of thermal hyperalgesia, mechanical allodynia and locomotor activity, as well as the determination of the serum concentration of the enzymes catalase, superoxide dismutase (SOD), glutathione peroxidase and cytokine IL-1β. The treatment was performed daily, orally, with EEAC (500 mg/kg) and fractions (1mg / kg) for 10 to 15 days. Gabapentin was used as the standard drug in the experiments. The evaluation of thermal hyperalgesia showed that EEAC significantly increased the pain perception threshold by 48.3% at the end of treatment. Considering mechanical allodynia, the rats treated with the EEAC showed a significant decrease of 48.6% and those treated with the CF and FAE showed improvement of 49.5% and 46.9%, respectively, in allodynia. Regarding locomotor activity (Rotarod), the animals treated with EEAC and fractions showed a significant improvement in gait, reestablishing normal pattern score. In the behavioral evaluation of weight-bearing, the groups treated with CF, FAE and FBU presented nociceptive threshold increase at all times evaluated. On the 15th day, they induced an increase of 73.7%, 41.4% % and 43.1% in nociceptive threshold. The evaluation of the systemic antioxidant effect of the fractions showed that there were a reduction of 88.1% in catalase concentration, with both FC and FBU, and a reduction of SOD activity by CF (85%), FH (70%), FAE 60%) and FBU (34%). However, there was no change in the serum concentration of glutathione peroxidase. FAE, FBU, FH and CF also reduced cytokine IL-1β, with inhibition of 57.8%, 51.4%, 51.2% and 24.7%, respectively. In conclusion, the results of this study suggest that ethanolic extract of A. chica and its fractions present therapeutic potential for the treatment of neuropathic pains and/or as adjuvant in the conventional treatment of them.