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

Rationale: Piper methysticum extract (kava kava) possesses numerous therape utic properties, but it is unknown which of its principle constituents (kav alactones) subserve such effects. Objectives: This experiment sought to cha racterize the putative anxiolytic properties of P. methysticum extract and its six principle kavalactones in the chick social separation-stress paradi gm. Methods: Eight-day-old chicks received intraperitoneal injections of ei ther vehicle, chlordiazepoxide (5.0 mg/ml per kg). P. methysticum extract ( containing 30% kavalactones), kavain, dihydrokavain, methysticin, dihydrome thysticin, yangonin, or desmethoxyyangonin (30 mg/ml per kg for kava compou nds) 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 recum bent posture to index sedation, number of vocalizations to index separation distress, and a composite pain score (in response to 50 mul 0.10% formalin injection into the plantar surface of the foot) to index stress-induced an algesia served as dependent measures. Results: Both chlordiazepoxide and P. methysticum extract attenuated separation-induced distress vocalizations a nd stress-induced analgesia. Dihydrokavain attenuated separation-induced di stress vocalizations. Conclusions: These findings suggest that the anxiolyt ic effects of P. methysticum extract may be mediated, in part, by dihydroka vain.