Experimental hepatic encephalopathy: changes in the binding of gamma-aminobutyric acid.

Two populations of receptors for gamma-aminobutyric acid, one with low- and the other with high-affinity characteristics, are detectable in frozen, thawed, Triton-treated synaptic membrane preparations from normal brain. It is now reported that membrane preparations from rats with mild galactosamine-induced hepatic encephalopathy show an increase in the number of low- and high-affinity gamma-aminobutyric acid binding sites, whereas those from rats with severe encephalopathy show only high-affinity binding sites. Thus, hepatic encephalopathy appears to involve partial degeneration of the gamma-aminobutyric acid-containing presynaptic nerve terminals.