Attenuation of Persistent Pain and Hyperalgesia by Spilanthus acmella. Flowers in Rats

Abstract

The effectiveness of Spilanthes acmella. Murr. (Compositae) flowers against continuous inflammatory pain and its antihyperalgesic potential were investigated in vivo.. Rats were administrated a cold-water extract (CWE) in three different doses: 500, 1000, or 1500 mg/kg given orally. Pain reduction was measured with the formalin test of nociception and carrageenan-induced thermal hyperalgesia test. In the formalin test, the CWE significantly (p < 0.05) impaired the number of paw lickings and the time spent on paw licking in both early and late phases. In the carrageenan hyperalgesia test, CWE markedly and significantly (p < 0.05) prolonged the hot-plate response latency from h up to 6 h after treatment. The CWE possessed antihistamine activity (determined by histamine wheal test) and inhibited prostaglandin synthesis (as judged from the impairment of frequency of spontaneous contraction in isolated dioestrous rat uterus) activities but had no membrane stabilization effect (in heat-induced rat erythrocyte hemolysis test) or antioxidant activities. It is concluded that CWE of S. acmella. flowers possess antinociception activity against persistent pain and antihyperalgesic activity, possibly by inhibiting prostaglandin synthesis, interrupting nociception transmission, and exerting antihistamine activity.

Keywords:

• Antihyperalgesia
• antinociception
• continuous pain
• Spilanthus acmella