Influence of dark deprivation on the ultrastructure and mitochondrial apparatus of rat hepatocytes

Abstract

Background
 Melatonin (MT) is a hormone with a wide range of biological activities. The diversity of biological regulatory effects inherent in MT involves this hormone in the formation of adaptive reactions and in the pathogenesis of various diseases. А decrease оf MT secretion due to exposure to light at night is observed in a significant proportion of people. A number of previous studies have shown that melatonin deficiency, causes significant changes in the structure of the liver of laboratory animals. The state of ultrastructural features of hepatocytes, and in particular their mitochondria, under conditions of dark deprivation remains poorly understood.
 Aim of study
 To study the ultrastructural features of liver hepatocytes of male Wistar rats under conditions of 21-day dark deprivation.
 Materials and methods
 The study was performed on 40 male Wistar rats, divided into 2 groups. Group 1 was kept under a fixed light regime. Group 2 was kept under dark deprivation conditions. Liver samples, were analyzed using a transmission electron microscope. Micromorphometric methods were used to assess the mitochondrial apparatus of hepatocytes. Statistical processing of the results were performed in the GraphPad Prism v8.41 program (USA).
 Results
 In hepatocytes of rats of II group, dark deprivation causes a transformation in the shape of the nuclei, accompanied by swelling of the cytoplasm and the presence of a significant number of lipid-containing vacuoles. Mitochondria are characterized by pronounced hyperplasia, size polymorphism, high electron density, and disordered cristae orientation. In the cytoplasm, the phenomenon of shedding of ribosomes from the endoplasmic reticulum is observed. The number of glycogen granules is significantly reduced. The studied micromorphometric parameters of mitochondria are significantly reduced relative to the control.
 Conclusion
 The study suggests that melatonin deficiency, resulting from dark deprivation, leads to a number of significant ultrastructural changes in hepatocytes, especially their mitochondrial apparatus.