Abstract
Introduction. Although new biological effects of lithium salts are being constantly discovered, they are still used as nephrotoxins. Recently, experimental data have appeared on regenerative and protective properties of short-term lithium administration in various kidney pathologies. The paper aimed to evaluate ultrastructural organization of the kidney proximal tubule cells in peripheral tumor growth and lithium carbonate peroral administration. Materials and methods. The study was carried out on CBA male mice (n=20). We formed four groups, 5 animals each: “control”, “control + lithium”, “tumor” and “tumor + lithium.” To stimulate tumor growth in the thigh muscle tissue, we used a cell line of hepatocellular carcinoma-29. Lithium carbonate was administered per os at a dose of 125 mg/kg of body weight every other day, starting from day 3 after inoculation of tumor cells. Animals were sacrificed on day 30 of tumor development, and kidney fragments were collected for electron microscopy. Results. We compared and analyzed ultrastructural organization of the apical and perinuclear zones as well as autophagic structures of the kidney proximal tubule cells. The animals with peripheral tumor growth showed decreased numerical density of endosomes and dense apical tubules as well as decreased volume density of the granular endoplasmic reticulum and mitochondria. In these animals, we also revealed increased volume density of autolysosomes in the cytoplasm of the epitheliocytes. The intact animals that received lithium carbonate demonstrated an increase in the volume density of free polysomal ribosome complexes. The animals that developed tumors and were administered lithium carbonate showed a growth in both numerical density of dense apical tubules and the volume density of autophagic structures. Conclusion. Peroral administration of lithium carbonate to intact animals every other day for 30 days did not cause any destructive changes to the kidney proximal tubule cells. The administration of lithium carbonate to animals with peripheral tumor growth had a protective effect on the ultrastructural organization of the kidney proximal tubules cells (probably due to autophagy activation). Keywords: peripheral tumor, lithium carbonate, renal proximal tubules, ultrastructure, endocytosis, autophagy