Anti-nociceptive effect and mechanism of madecassic acid / 中国药科大学学报

ABSTRACT

@#Abstract: To date, the investigation of the functional composition of Centella asiatica (L.) Urban has been mainly focused on the triterpenoid saponins, with little research on the other compositions. The acetic acid-induced writhing, Eddy's hot plate and formalin tests were employed to investigate the anti-nociceptive effects of madecassic acid (MA). The experiment was divided into normal control group, acetylsalicylic acid (ASA) group, and the MA groups of low (10 mg/kg), medium (20 mg/kg) and high (40 mg/kg) dosage. Meanwhile, the anti-nociceptive effect of MA on the acetic acid and formalin-induced nociceptive models in the absence and presence of NAL (naloxone hydrochloride) was evaluated. To have an insight into the anti-nociceptive mechanisms of MA, the capsaicin- and glutamate-induced paw licking tests were also employed to evaluate the involvement of the vanilloid and glutamatergic systems, respectively. Results showed that MA exhibited good anti-nociceptive activity in the acetic acid-induced writhing test and the second phase of formalin test; the anti-nociceptive effect of MA in both the acetic acid and formalin-induced nociception was not effectively removed by NAL; MA (20 mg/kg and 40 mg/kg) effectively reduced the duration of biting/licking the capsaicin-injected paw with inhibition rates of 29.5% and 64.4%, respectively; MA (20 mg/kg and 40 mg/kg) distinctly shortened the time spent in biting/licking the glutamate-injected paw by 30.9% and 56.1%, respectively. In summary, MA induces significant peripheral anti-nociceptive effect, and the anti-nociceptive activities probably involve the modulation of glutamatergic systems and vanilloid systems (TRPV1) instead of the opioidergic system.