However, we found that chicken essence had protective effects and suggested that these effects were partially correlated to carnosine, which is a histamine precursor compound abundant in chicken essence and plays important roles on central histaminergic system. Moreover, the activity of 5-HT, another anxiety related important neurotransmitter, was also indicated to be regu lated by chicken essence. Xu and Sim(1997) found that chicken essence markedly increased the level of 5-hydroxyindoleacetic acid(5-HIAA), a main metabolite 5-HT, in cerebrospinal fluid. This result reflected the influence chicken essence on cerebral 5-HT metabolism. However, whether amino acids in chicken essence such as taurine, aspartate, glutamate, and glycine directly partici- pate in regulation of 5-HIAA level still remains unknown