Topogenesis of glycogen distribution pattern in post-natal rat liver in reference to the activity-rest cycle

The present study, on immature rats, revealed that in the liver with exclusively diploid cell population (MD), the glycogen content was half of the adult level and the 24 h distribution pattern was reverse, i.e. highest in the evening and lowest in the morning. In these animals, in general, the protein content was high and did not show any circadian rhythm but incidentally showed a time dependent zonal distribution pattern. The low glucose-6-phosphatase activity reciprocates with low glycogen content. The relative number of cells per unit area showed a time dependent distribution pattern. The liver with equal distribution of diploid and tetraploid classes (MD:MT), attained the classical circadian rhythm of glycogen with high morning and low evening oscillation pattern. The TRIDENT measurements manifest the zonal distribution pattern with high values at the perilobular region (PL) and low at the centrolobular region (CL). The relative cell number study along the acinus demonstrated more number of cells around the PL region than that at CL region, indicating a variation in the cell size. Eventually, the protein content showed a circadian rhythm in this group, with high amount in the morning. The zonal distribution pattern always revealed the high content near the perilobular region. This could be due to more number of cells per unit area in this region. The glucose-6-phosphatase showed a circadian rhythm. The typical high glucose-6-phosphatase in the perilobular region could be further subzonated into small groups of high activity surrounded by lighter zones, thus establishing the heterogeneous function of liver parenchymal cells.