Indole Amines and Amino Acids in Various Brain Regions after Infusion of Branched Chain Amino Acids into Hepatectomized Rats

Abstract

This study was designed to determine regional changes of amino acids and indole amines in the brain and possible interactions between amino acids and indole amines 18 h after hepatectomy in rats. Hepatectomy and glucose infusion alone resulted in a profound increase of most large neutral amino acids (LNAA) in plasma and in the brain except for the branched-chain amino acids (BCAA), which maintained normal or somewhat lower values in plasma. Hepatectomy and infusion of glucose combined with BCAA sharply reduced the plasma and brain amino acid concentrations of other LNAA. Simultaneously the concentrations of serotonin and 5-hydroxyindoleacetic acid were decreased in all brain regions. In both groups of hepatectomized rats there were regional variations of the amino acid and the indole amine concentrations in the brain, but the response to BCAA infusion was generally the same in all brain regions. No difference in survival between the 2 groups could be found.

Increased serotoninergic and noradrenergic activity in hepatic encephalopathy in rats with thioacetamide—induced acute liver failure

“…Unchanged levels of dopamine and of its metabolites DOPAC and HVA suggest an undisturbed synthesis and release of this neurotransmitter. Similar observations were made in some (8, 191, but not in all, models of HE (13). The reason for these conflicting findings is unknown but may be explained by the different models of HE studied.…”

Concentrations of 3,4‐Dihydroxyphenylalanine and Catecholamines and Metabolites in Brain in an Anhepatic Model of Hepatic Encephalopathy

“…The increases of DOPA and DA content could perhaps be attributed to the increase in plasma and tissue tyrosine content reported by us (Tyce et al ., 1981) and by others (Jonung et al ., 1985) . Although it has been calculated (Carlsson and Lindqvist, 1978) that tyrosine hydroxylase is ---75% saturated with tyrosine at the concentration of tyrosine normally present in brains of control rats and thus changes in tyrosine concentration would be unlikely to influence greatly the concentra- tions of DOPA or DA in brain, the converse has sometimes been shown to occur .…”

“…Concentrations of amines in the striatum, a region of the brain with low dopamine ß-hydroxylase activity, were little changed after hepatectomy, suggesting that inhibition of dopamine-,6-hydroxylase might be a significant factor in other regions of the brain in hepatectomized rats. Compounds that accumulate in tissues or plasma of animals after hepatectomy, or in patients in hepatic coma, and that are known to inhibit dopamine-ß-hydroxylase, include histidine (Mans et al ., 1982;Jonung et al, 1985) and the mercaptans (Zieve, 1987) . Methanethiol content is also increased in brains of rats in hepatic coma and in blood of cirrhotic patients (McClain et al ., 1980), and, although it has not been specifically tested for in vitro inhibition of dopamine-/3-hydroxylase, the chemical structure would suggest that it would indeed inhibit this enzyme .…”

Releases of Norepinephrine and Dopamine in Ventriculocisternal Perfusions in Hepatectomized and Laparotomized Rats

“…As pointed out by Basile et al (1991), neurotransmitter systems are obvious targets for investigating changes in CNS function and may have a role in the pathogenesis of hepatic encephalopathy. Decreased concentrations of norepinephrine (NE) and increased concentrations of dopamine (DA) in brain are characteristic in rats at 12-24 h after total hepatectomy (Tyce et al, 1967;Tyce and Owen, 1979;Herlin et al, 1982Herlin et al, , 1983Jonung et al, 1985;Bugge et al, 1986;Yurdaydin et al, 1990;Hadesman et al, 1995). However, changes in concentrations of NE or DA may result from alterations in several processes including synthesis, release, uptake, metabolism, or storage.…”