Correlation between electroencephalographic and biochemical indices in acute hepatic encephalopathy in rats

Changes in biochemical and electroencephalographic parameters were followed over time during the development of acute hepatic encephalopathy (HE) in two different experimental models. In the rat, (sub)acute liver failure was obtained either by ligation of the hepatic artery in previously portacaval-shunted animals or by intraperitoneal injection of a high dose of galactosamine (GALN). The EEG changes were characterized in both models by a significant increase in low-frequency activity of the EEG power density spectra: the so-called 'left shift'. This 'left shift' was significant in liver ischemia after 4-5 h and in GALN hepatitis after about 30 h. The changes in plasma biochemical indices also showed a great similarity in both models. The concentration of all measured plasma amino acids (except histidine and arginine in GALN hepatitis and arginine in liver ischemia), NH3 and ALAT were significantly increased during the development of (sub)acute HE. Correlation of the combined data of electroencephalographic and biochemical indices showed a significant (P less than 0.01) correlation between the 'left shift' and NH3, taurine, threonine, proline, alanine, methionine, cystathionine, phenylalanine, tryptophan, ornithine and histidine. It is concluded that EEG spectral analysis is a useful parameter for following the development of (sub)acute hepatic encephalopathy in relation to biochemical parameters.