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 percent 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 ip 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 ip 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, ip, respectively, in S. trifoliatus-treated animals). Furthermore, when administered ip 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.

5-HT3 receptors in selective animal models of cognition.

Role of 5-HT3 receptors in cholinergic hypofunctional models of cognitive impairment in the elevated plus maze model and a passive avoidance model is studied. Cognitive impairment was caused by scopolamine (1 mg/kg, ip) in mice and 5-HT3 ligands mCPBG (1 and 5 mg/kg, ip) and ondansetron (0.5 and 5 mg/kg, ip) were administered before the pre-learning phase to study the effects on acquisition, while post-learning administration was used to determine the effects on consolidation. Ondansetron improved acquisition and retention in cholinergic hypofunctional models while mCPBG potentiated selected impaired cognitive indices. The results indicate the role of 5-HT3 receptors in cognition and that an ideal evaluation of 5-HT3 ligands in cognition should distinguish true cognitive effects from locomotor, motivational and emotional effects.