The turnover of brain monoamines after total hepatectomy in rats infused with branched chain amino acids.

Abstract

AbstractThe metabolism of monoamines in the brain of rats in fulminant hepatic failure was studied after administration of branched chain amino acids (BCAA). Male Sprague‐Dawley rats were exposed to a total hepatectomy or a sham operation and infused intravenously for 5 hours with a 10% glucose solution alone or 10% glucose + 0.24 mol/l BCAA (0.08 mol/l of each valine, leucine, and isoleucine). Thirty minutes before decapitation, a decarboxylase inhibitor (NSD 1015®), blocking the conversion of 5‐hydroxytryphtophan (5‐HTP) to 5‐hydroxytryptamine (5‐HT), and dihydroxyphenylalanine (DOPA) to dopamine (DA), was injected intraperitoneally. The concentrations of 5‐HTP, 5‐HT, and 5‐hydroxyindoleacetic acid (5‐HIAA) were analyzed by high‐performance liquid chromatography, DOPA, DA, and norepinephrine (NE) by a radio‐enzymatic method in 8 different regions of the brain and spinal cord. The concentrations of 5‐HTP were increased in the brains of hepatectomized rats, indicating an increased synthesis rate of the indoleamines. After administration of BCAA to hepatectomized rats, the synthesis rate was decreased to normal or, in some brain regions, even to subnormal values. The brain and spinal cord concentrations of DOPA and DA were unchanged in hepatectomized rats compared to sham‐operated animals, indicating an unchanged turnover of the catecholamines. The levels of NE in the diencephalon and in the spinal cord were decreased after hepatectomy. The level of consciousness was not influenced by the BCAA infusions.It is concluded that BCAA infusion may normalize brain indoleamine synthesis in hepatectomized rats, whereas the catecholamine synthesis and the level of consciousness are unaffected by the BCAA administration.