Alleviation of capsaicin-induced mechanical allodynia by Arbutus andrachne L. methanolic leaf extract in male rats

الملخص EN

Pain is one of the major health problems that impose huge social and economic burdens all over the world.

Mechanical allodynia is a symptom of pain defined as a painful sensation resulting from innocuous stimuli such as touch.

Currently available drugs have several side effects urging the need for new natural sources that alleviate mechanical allodynia.

This study investigated the effect of Arbutus andrachne L.

(a medicinal plant growing in Jordan) on capsaicin (Caps)-induced mechanical allodynia in male rats and the mechanism that underlie its effect.

Caps injection decreased paw withdrawal threshold (PWT) significantly compared to control group.

Mechanical allodynia was detected 30, 90 and 150 min after Caps injection to the plantar surface of the left hind paw of rats.

The intraplantar (ipl) injection of 100 |ig (but not 50 or 200 |ig) of A.

andrachne extract, ipsilaterally, prior to Caps injection increased PWT at all-time points similar to the anti-nociceptive effect in the positive group that was treated with 2.5% diclofenac sodium prior to Caps injection.

The ipsilateral pretreatment with the antagonists of transient receptor potential vanilloid-1 (TRPV1), cannabinoid receptor 1 (CB1) and peroxisome proliferator-activated receptor alpha (PPARa) reversed the activity of the leaf extract in contrast to the antagonists of PPARy and a2-adrenergic receptors.

In all groups, no effect was detected on the contralateral hind paw of animals at any time point.

In conclusion, A.

andrachne can be exploited as an antinociceptive agent.