ABSTRACT
<p><b>OBJECTIVE</b>To examine the abilities of theanine and houpu extracts (HE) to reverse behavioral indexes (separation vocalization, stress-induced analgesia and activity).</p><p><b>METHOD</b>7-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).</p><p><b>RESULT</b>In 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.</p><p><b>CONCLUSION</b>These 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.</p>