The effects of dark deprivation and chronic alcohol intoxication on the liver of rats

Abstract

BACKGROUND: Nighttime exposure to artificial lighting promotes epiphyseal melatonin deficiency and disrupts the circadian cycle of most body functions in mammals. Several studies have associated these factors with the development of many liver pathologies. A considerable lack of melatonin, along with a mismatch in the daily cycle of vital processes, increases the sensitivity of the liver to alcohol-induced damage and the severity of alcoholic illness. AIM: This study aimed to identify the combined effect of constant lighting and chronic alcohol intoxication (CAI) on the liver structure of both sexes of rats. MATERIALS AND METHODS: TThe study was conducted on 120 male and 80 female outbred Wistar rats aged 6 months. The trial lasted for 3 weeks. Four groups of rats of each sex were formed (control group, CAI group, dark deprivation group, and group exposed to both factors). Preparations stained with hematoxylin and eosin were evaluated. Sudan III staining was used to assess the severity of fatty degeneration, and the expression of Ki-67 and p53 as markers of proliferation and apoptosis, respectively, was measured immunohistochemically. RESULTS: Chronic alcohol intoxication and dark deprivation cause similar morphological changes in the livers of male and female rats, resulting in fatty degeneration, necrosis, and increased hepatocyte apoptotic activity. The combined effect of these factors causes more dramatic changes in the structure of the liver of males, resulting in the development of cirrhotic changes in 13.3% of them and toxic hepatitis in 20%, whereas only 5% of females show signs of alcoholic hepatitis. Increased Ki-67 expression in male hepatocytes is found only when CAI and dark deprivation are combined. However, in females, an increase in Ki-67 expression is observed both alone and when these factors are combined. CONCLUSION: The findings allow us to conclude that female rats adapt more successfully to the independent and combined effects of CAI and dark deprivation than male rats.