Effect of the oral administration of branched chain amino acids on hepatic encephalopathy in the rat.

The aim of this study was to investigate the effect of oral administration of branched-chain amino acid (BCAA)-enriched diets after portacaval shunt (PCS) in rats. Fifty-one Sprague-Dawley male rats (200 gm) underwent PCS and 55 a sham operation. Half of the animals received BCAA 142 mg per day through a gastric tube; the other half underwent a sham procedure. Sleep disturbances were evaluated at 7, 14, and 28 days postoperatively by measurement of the excitability of the reticular brain-stem formation during the slow-wave sleep and paradoxical sleep. Animals were killed at the same intervals and liver/body weight ratio, plasma, and brain amino acids, brain norepinephrine, brain serotonin, 5-hydroxyindolacetic acid and histamine were measured. Each group of animals was matched with a similar group of sham-operated rats, i.e., receiving or not receiving BCAA. After PCS (as compared to sham-operated animals) a significant hyperexcitability of the reticular brain-stem formation was found during the slow-wave sleep. The liver/body weight ratio was significantly lower. Tryptophan (free tryptophan in the plasma), phenylalanine, tyrosine, and histidine increased in the plasma and the brain. Leucine and isoleucine were decreased in the plasma. After PCS, an initial decrease at 7 days postoperatively of brain norepinephrine and blockade of the intracerebral metabolism of tryptophan were observed. These changes were transient and progressively disappeared at 14 and 28 days postoperatively. Brain histamine remained at a very high level through the experiment. A good correlation was demonstrated between modification of the sleep disturbance and tryptophan (or 5- hydroxyindolacetic acid) and histamine brain levels.(ABSTRACT TRUNCATED AT 250 WORDS)