Intracerebroventricular Injection of Tryptophan, but not Lysine or Methionine, Induces Sedative Effect during an Acute Stressful Condition in Neonatal Chicks

Abstract

Kurauchi, I., Asechi, M., Tachibana, T., Han, L., Hayamizu, K., Denbow, D.M. and Furuse, M. 2007. Intracerebroventricular injection of tryptophan, but not lysine or methionine, induces a sedative effect during an acute stressful condition in neonatal chicks. J. Appl. Anim. Res., 31: 25–28.

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.e. 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.

Keywords:

• DL-tryptophan
• L-methionine
• L-lysine
• intracerebroventricular injection
• neonatal chick
• social separation stress