Anxiolytic effects of kava extract and kavalactones in the chick social separation-stress paradigm.

Piper methysticum extract (kava kava) possesses numerous therapeutic properties, but it is unknown which of its principle constituents (kavalactones) subserve such effects. This experiment sought to characterize the putative anxiolytic properties of P. methysticum extract and its six principle kavalactones in the chick social separation-stress paradigm. Eight-day-old chicks received intraperitoneal injections of either vehicle, chlordiazepoxide (5.0 mg/ml per kg), P. methysticum extract (containing 30% kavalactones), kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, or desmethoxyyangonin (30 mg/ml per kg for kava compounds) 30 min prior to being tested in the presence of two conspecifics or in isolation for a 3-min observation period. Latency to adopt a ventral recumbent posture to index sedation, number of vocalizations to index separation distress, and a composite pain score (in response to 50 microliters 0.10% formalin injection into the plantar surface of the foot) to index stress-induced analgesia served as dependent measures. Both chlordiazepoxide and P. methysticum extract attenuated separation-induced distress vocalizations and stress-induced analgesia. Dihydrokavain attenuated separation-induced distress vocalizations. These findings suggest that the anxiolytic effects of P. methysticum extract may be mediated, in part, by dihydrokavain.