Acetic acid induced writhing method[10]

The acetic acid induced abdominal writhing is considered as a sensitive method with minimal noxious stimulus for anti-nociception study. The acid (0.6%v/v) in a dose of 10 ml/kg was injected i.p to mice, and the number of abdominal constrictions (writhings) during the following 15 min period was counted. Mice were treated with 7-methoxy coumarin (3 .5 and 7 mg/ kg p.o), or vehicle (1% Tween-80) 60 min prior to acetic acid challenge. The standard drug morphine (1 mg/kg s.c) was administered 30 min before acetic acid administration. Any significant reduction in the number of abdominal constrictions in any treatment group compared with vehicle treatment was considered as an anti-nociceptive response.

Results were expressed as mean ± S.E.M. of six animals per group.

The percent inhibition of abdominal constrictions produced by any treatment groups was calculated using the formula: (C-T / C) X 100.

C = Number of abdominal constriction in vehicle treated group.

T = Number of abdominal constriction in test group.