Farnesol: antinociceptive effect and histopathological analysis of the striatum and hippocampus of mice.

Farnesol, a sesquiterpene alcohol, has been shown to have antioxidant and anti-inflammatory properties. Recent studies have found that antioxidant compounds may exert a certain protective effect against neurotoxicity. The objective of this study was to evaluate the antinociceptive activity of farnesol (FAR) and its neurotoxic effects on the brains of adult mice. In this study, two mouse models of analgesia were used to evaluate FAR at doses of 50, 100, and 200 mg/kg, injected intraperitoneally (i.p.). In the acetic acid-induced writhing test, a significant decrease was found in the number of contortions in the FAR-treated mice at doses of 50, 100, and 200 mg/kg. FAR was also found to inhibit the licking response in the injected paw at doses of 100 and 200 mg/kg (i.p.) in the first (0-5 min) and second phases (15-30 min) of the formalin test. To evaluate neurotoxic effects, Swiss mice were treated with 0.9% saline (i.p., control group), 0.05 Tween 80 dissolved in 0.9% saline (i.p., vehicle group), and FAR 50, 100, or 200 mg/kg, i.p. Following treatment, all groups were observed for 72 h. In the FAR 200-mg group, 16% of the animals suffered brain injury that affected 12% of the area of the hippocampus. No lesions were found in the hippocampal and striatal regions of the brain in any of the animals treated with the 50 and 100 mg/kg doses of FAR. In conclusion, FAR exerts an antinociceptive effect with no significant neurotoxicity in the brains of adult mice.

Analgesic effect of hydroalcoholic extract of Cissampelos sympodialis Eichl leaves / Efecto analgésico del extracto hidroalcoholico de las hojas de Cissampelos sympodialis Eichl

Cissampelos sympodialis Eichl is a species of the family Meniespermaceae known as “Milona”, which extracts showed low toxicity and several pharmacological activities as anti-inflammatory, anti-allergic or anti-depressive. In the present study two classic analgesia models in mice were used to evaluate the hydroalcoholic extract of C. sympodialis leaves (HAECs) at doses of 50, 100 and 200 mg/kg, i.p. In the test of writhing by acetic acid HAECs- treatment induced a significant reduction in the number of abdominal contortions in a dose-dependent manner (p <0,05). In the formalin test, HAECs-200 mg/kg induced a significant inhibition of the second phase (15-30 minutes) (p <0,05). Results suggest that the HAECs presented outlying antinociceptive peripheral activity probably related with the alleged anti-inflammatory proprieties of extracts of this plant.

Existen varios estudios que evidencian que la Cissampelos sympodialis posee atividad anti-inflamatoria, antialérgica, antidepresiva y de baja toxicidad. Este estudio evaluó los efectos de la administración intraperitoneal, del extracto hidroalcohólico de hojas de cissampelos sympodialis (EHACS), en las dosis de 50, 100 y 200 mg/Kg, en modelos de analgesia en camumdongos. En el modelo de las contracciones inducidas por el ácido acético (0,85 por ciento) fue encontrada una reducción en el número de contracciones proporcional a las dosis usadas (p<0,05). En el test de la reacción al formaldeído las dosis utilizadas no presentaron efecto significante en la primera fase del test (0-5 minutos). Sin embargo, la dosis de 200mg/Kg presentó una significante inhibición en la segunda fase (15 – 30 minutos) del test (p<0,05). Los resultados mostraron que el EHACS presentó una actividad antinociceptiva periférica probablemente relacionada con la alegada actividad anti-inflamatoria.

Antinociceptive activity of (-)-carvone: evidence of association with decreased peripheral nerve excitability.

(-)-Carvone is a monoterpene ketone that is the main active component of Mentha plant species like Mentha spicata. This study aimed to investigate the antinociceptive activity of (-)-carvone using different experimental models of pain and to investigate whether such effects might be involved in the nervous excitability elicited by others monoterpenes. In the acetic acid-induced writhing test, we observed that (-)-carvone-treated mice exhibited a significant decrease in the number of writhes when 100 and 200 mg/kg was administered. It was also demonstrated that (-)-carvone inhibited the licking response of the injected paw when 100 and 200 mg/kg was administered (i.p.) to mice in the first and second phases of the formalin test. Since naloxone (5 mg/kg, s.c.), an opioid antagonist, showed no influence on the antinociceptive action of (-)-carvone (100 mg/kg), this suggested nonparticipation of the opioid system in the modulation of pain induced by (-)-carvone. Such results were unlikely to be provoked by motor abnormality, since (-)-carvone-treated mice did not exhibit any performance alteration on the Rota-rod apparatus. Because the antinociceptive effects could be associated with neuronal excitability inhibition, we performed the single sucrose gap technique and observed that (-)-carvone (10 mM) was able to reduce the excitability of the isolated sciatic nerve through a diminution of the compound action potential amplitude by about 50% from control recordings. We conclude that (-)-carvone has antinociceptive activity associated with decreased peripheral nerve excitability.