The ameliorating effects of an enteral nutrient for
liver failure (SF-1008C), which is enriched with
branched-chain amino acids (BCAA) and includes few
aromatic amino acids (AAA), were investigated. The blood
ammonia, plasma and brain free
amino acids, intracerebral
amine concentrations and electroencephalogram were measured in portacaval shunted rats with 10%
ammonium acetate (3 ml/kg, i.p.) (PCS) as a model of
hepatic encephalopathy. The blood
ammonia and plasma free
amino acid concentrations in PCS rats were significantly increased in comparison to
sham-operated (
Sham) rats. Thus, the plasma BCAA/AAA ratio in PCS rats was appreciably reduced. Concomitant with the abnormal plasma
amino acid concentrations, the brain free
amino acid concentrations in PCS rats were markedly increased in comparison to the
Sham rats. Moreover, the intracerebral
tryptophan (Trp) and 5-hydroxyindol
acetic acid (5-HIAA) concentrations were significantly increased, and the intracerebral
dopamine (DA) concentration was significantly decreased in the PCS rats. The intracerebral
serotonin (5-HT) and
norepinephrine (NE) concentrations were, however, hardly changed. A smaller voltage for the electroencephalogram was used in the PCS rats than in the
Sham rats. Abnormal plasma and brain free
amino acid concentrations in PCS rats were normalized by
oral administration of
SF-1008C, and the low voltage electroencephalograms in the PCS rats were suppressed. On the other hand, abnormal plasma and brain free
amino acid concentrations in the PCS rats were hardly normalized by
oral administration of ED-AC, an elemental diet based on an
amino acid composition of
egg protein. These results suggest that
SF-1008C affects brain free
amino acids, intracerebral
amine concentrations and electroencephalogram by ameliorating abnormal plasma free
amino acid concentrations. Moreover, there is a highly significant correlation between the plasma BCAA/AAA ratio and the brain BCAA/AAA ratio, and this finding suggests that the plasma free
amino acid patterns reflect the brain free
amino acid patterns.