Cellular distribution of lysosomal hydrolase activities in the regenerating rat liver

Content, pattern and metabolic processing of rat-liver gangliosides during liver regeneration

During rat liver regeneration, the ganglioside content and distribution undergo significant changes after partial hepatectomy; total liver gangliosides increase remarkably till the 4th day after surgery, thereafter progressively decreasing to reach the values of sham-operated controls at the 12th day. The qualitative pattern is characterized by the 95% relative increase of GD1a at the 4th day and the 40% relative decrease of GD1b. In order to investigate the processes of ganglioside penetration into cells, degradation and biosynthesis, radiolabelled GM1 ([Sph-3H] GM1) was administered. One day after hepatectomy the liver uptake and metabolism of exogenous ganglioside were significantly reduced. Three days post-surgery these parameters were restored to control values; however an increased radioactivity incorporation was found in GD1a, thus suggesting an enhancement of its biosynthesis around the 4th day. The data reported here suggest that in the first two days after partial hepatectomy, the ganglioside degradation is reduced with a consequent increase of ganglioside content; later on the catabolic routes normalize and some biosynthetic processes leading to GD1a are enhanced. GD1a seems to be a marker of a peculiar transition phase of liver regeneration.