aLaboratory of Advanced Animal and Marine Bioresources Graduate School of Bioresources and Bioenvironmental Sciences Kyushu University, Fukuoka 812–8581, Japan
bFANCL Research Institute 12–13, Kamishinano, Totsuka-ku, Yokohama Kanagawa 244–0806, Japan
cDepartment of Animal and Poultry Sciences Virginia Polytechnic Institute and State University Blacksburg, VA 24061-0306, USA.
*For correspondence: Telefax: 81-92-642-2953; E-mail: furuse@brs.kyushu-u.ac.jp
**Present address: Laboratory of Animal Science, Department of Agrobiological Science, Faculty of Agriculture, Ehime University, Matsuyama 790–8566, Japan.
To elucidate the central effect of three essential amino acids viz. tryptophan, methionine and lysine on stress responses, each amino acid (0.8 μmol) or saline was administered i.c.v. just before exposure to social separation stress. The social separation stress increased spontaneous activity and vocalization of chicks, but these responses were attenuated by the i.c.v. injection of tryptophan, but not methionine or lysine. In conclusion, centrally administered tryptophan may be effective in attenuating anxiety induced by a psychological stressor.
DL-tryptophan, L-methionine, L-lysine, intracerebroventricular injection, neonatal chick, social separation stress
