Summary.
The increase of the brain levels of 5-hydroxyindoleacetic acid (5-HIAA) in hepatic encephalopathy (HE) suggests an increased turnover of serotonin (5-HT). To study the role of tryptophan on the increased brain 5-HT metabolism in HE, we attempted to monitor brain levels of tryptophan in rats with thioacetamide-induced acute liver failure by intravenous infu-sion of branched-chain amino acids (BCAA). The effect of this treatment on 5-HT synthesis and metabolism was investigated in five brain areas. BCAA-infusions (1 and 2 gm/kg/24 h) increased the ratio BCAA/aromatic amino acids in plasma two- and fourfold, respectively, and lowered both plasma and brain levels of tryptophan. At the higher BCAA-dose all parameters suggesting an altered brain 5-HT metabolism (increased brain levels of 5-HT and 5-HIAA, increased 5-HIAA/5-HT ratio) were almost completely normalized. These results provide further evidence for the role of tryptophan in the elevation of brain 5-HT metabolism and for a potential role of BCAA in the treatment of HE.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received December 17, 1997; accepted March 19, 1998
Rights and permissions
About this article
Cite this article
Herneth, A., Steindl, P., Ferenci, P. et al. Role of tryptophan in the elevated serotonin-turnover in hepatic encephalopathy. J Neural Transm 105, 975–986 (1998). https://doi.org/10.1007/s007020050106
Issue Date:
DOI: https://doi.org/10.1007/s007020050106