A LOW-PROTEIN DIET AMELIORATES DISRUPTED DIURNAL LOCOMOTOR-ACTIVITY IN RATS AFTER PORTACAVAL ANASTOMOSIS

In previous studies we noted a disruption of the circadian locomotor a ctivity rhythm in rats after portacaval anastomosis (PCA). To examine whether this abnormality is related to factors that aggravate hepatic encephalopathy in humans, we studied the effect of dietary formulation and protein content on-body weight, locomotor activity, and entrainme nt to the light-dark cycle in rats after PCA or sham operation. Postop erative weight loss was prevented by pair-feeding with a purified liqu id diet. However, the behavioral abnormalities persisted in PCA rats f ed a high-protein diet, with a reduction in total activity and entrain ment to the light-dark cycle. These were ameliorated by a low dietary protein content. Since this treatment reduces the load of gut-derived nitrogenous substances that might alter brain metabolism, our data str engthen the hypothesis that the abnormal circadian activity patterns i n PCA rats may be part of the spectrum of hepatic encephalopathy.