OBJECTIVETo examine the abilities of theanine and houpu extracts (HE) to reverse behavioral indexes (separation vocalization, stress-induced analgesia and activity).

METHOD7-day-old chicks received IP injection of theanine and HE 30 min before being tested in the presence of three social companions or in isolation for 3-min observation period. Dependent measures were: a) Chicks were placed into an infrared ray device to calculate their spontaneous activities by a computer program b) record the separation vocalizations for every chick. c) In the experiment of stress-induced analgesia, 50 uL of formalin (0.1%) was injected into the plantar of the animal foot to index stress-induced analgesia (i. e. foot-lift frequency, foot-lift duration and peck frequency).

RESULTIn the experiments, isolated chicks exhibited more vocalizations (P < 0.01) and fewer pain-related behaviors than non-isolated chicks (P < 0.01). Theanine (12.5, 25, 50 mg x kg(-1)) and HE (25 mg x kg(-1)) decrease separately the tendency (dB) of the principal frequency (P < 0.05, P < 0.01); The stress induced analgesia can be reversed by theanine in 25, 50 mg x kg(-1). Both of the materials do not affect the spontaneous activities in this chick model without causing sedation.

CONCLUSIONThese results suggest that theanine and HE in the dosages may be useful in modulating anxiety states. They are seems no synergism in the chick model.