Serotonin receptors in the brain following total hepatectomy in rats treated with branched-chain amino acids.

Serotonin concentrations and receptor binding characteristics were investigated in rats subjected to total hepatectomy, portacaval shunt (PCS) or sham-operation. The animals were infused for 5 hr with a 10% glucose solution or the same solution enriched with 0.24 M branched-chain amino acids (BCAA). Hepatectomized animals were in grade-two coma at the end of the experiment independent of infusion. Indoleamines in mesencephalon-pons and diencephalon were analyzed by high-pressure liquid chromatography with electrochemical detection. Serotonin receptors (5-HT1 and 5-HT2) were investigated in the cortex and hippocampus by radioligand binding studies using 3H-serotonin for analysis of 5-HT1-receptors and 3H-ketanserin for analysis of 5-HT2-receptors. Concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were significantly increased after hepatectomy compared with controls. Treatment with BCAA significantly decreased 5-HT and 5-HIAA levels in hepatectomized animals. The affinity and the number of binding sites for the 5-HT1 and 5-HT2 receptors were found to be similar in all groups. The present study indicates that PCS for 1 week and the anhepatic state for 5 hr in rats do not influence brain serotonin receptors in contrast to previous studies in pigs with liver ischemia or rabbits with galactosamine-induced liver damage. In addition, infusion of BCAA for 5 hr did not alter the binding characteristics.