The antiemetic interaction of Delta9-tetrahydrocannabinol when combined with tropisetron or dexamethasone in the least shrew

5-HT3 receptor antagonists (e.g. tropisetron) combined with dexamethasone are effective for the acute phase of cisplatin (CIS)-induced emesis. This study determined the possible additive or synergistic antiemetic efficacy of Delta9-THC when combined with tropisetron or dexamethasone (DEX). Delta9-THC (0-10 mg/kg i.p.) was injected in combination with tropisetron (0-5 mg/kg i.p.) or dexamethasone (0-20 mg/kg i.p.) prior to CIS (20 mg/kg i.p.) in the least shrew, and the induced emesis was recorded for 60 min. CIS-induced vomiting was dose-dependently and significantly attenuated by individual administration of Delta9-THC (59-97% reductions) and tropisetron (79-100% attenuation), but not dexamethasone (26-40%), although a trend (p