Information Tetrahydroberberine (Canadine) is an isoquinoline alkaloid with micromolar affinity fordopamine D2(antagonist, pKi = 6.08) and5-HT1A(agonist, pKi = 5.38) receptors but moderate to no affinity for other relevant serotonin receptors. Targets D2 receptor ; 5-HT1A 6.08(pKi); 5.38(pKi) In vivo Oral administration of THB not only resulted in significantly accelerated gastric emptying of normal rats in a bell-shaped relationship, with a maximal efficacy at a dose of 30 μg/kg, but also restored the delayed gastric emptying caused by apomorphine, which might be mediated by an antidopaminergic effect.