Effect of Sapindus trifoliatus on hyperalgesic in vivo migraine models

Phytotherapies have offered alternative sources of therapy for migraine and gained much importance in prophylactic treatment. Sapindus trifoliatus is a medium-sized deciduous tree growing wild in south India that belongs to the family Sapindaceae. The pericarp is reported for various medicinal properties. A thick aqueous solution of the pericarp is used for the treatment of hemicrania, hysteria or epilepsy in folklore medicine. We have investigated the antihyperalgesic effects of the lyophilized aqueous extract of S. trifoliatus in animal models predictive of experimental migraine models using morphine withdrawal-induced hyperalgesia on the hot-plate test and on 0.3% acetic acid-induced abdominal constrictions in adult male Swiss albino mice. The extract significantly (N = 10, P < 0.05) increased the licking latency in the hot-plate test when administered i.p. at 10 mg/kg (6.70 +/- 0.39 s in saline control vs 18.76 +/- 0.96 s in S. trifoliatus-treated animals) and significantly (N = 10, P < 0.001) reduced the abdominal constrictions when administered i.p. at 2 and 10 mg/kg (40.20 +/- 1.36 in saline control vs 30.20 +/- 1.33 and 23.00 +/- 0.98 for 2 and 10 mg/kg, i.p., respectively, in S. trifoliatus-treated animals). Furthermore, when administered i.p. at 20 and 100 mg/kg, the extract significantly (N = 10, P < 0.05) inhibited the apomorphine-induced climbing behavior in mice (climbing duration 15.75 +/- 5.0 min for saline control vs 11.4 +/- 1.28 and 3.9 +/- 1.71 min for 20 and 100 mg/kg, respectively, in S. trifoliatus-treated animals). In receptor radioligand-binding studies, the extract exhibited affinity towards D2 receptors. The findings suggest that dopamine D2 antagonism could be the mechanism involved in the antihyperalgesic activity of the aqueous extract of S. trifoliatus.