Abstract
Simple SummaryModern intensive production methods attract accusations of poor animal welfare due to long-term exposure to stressors including high temperature, persistent humidity and overcrowding. Stress can be defined as any condition that threatens the physiological homoeostasis and hypothalamic-pituitary-adrenal (HPA) axis responses that tend to restore the prior stable status of the organism. Uncontrollable and unpredictable sources of stress can cause various forms of damage to the liver, which is the central mediator of systemic iron balance. Iron, notably, is an essential element for maintaining health in virtually all organisms. We found that chronic variable stress can cause weight loss and disorders of the liver iron metabolism in rats, thereby triggering liver oxidative damage. Our results also suggest that the miR-181 family is a potential target for treating iron overload-associated diseases.It is well-known that hepatic iron dysregulation, which is harmful to health, can be caused by stress. The aim of the study was to evaluate chronic variable stress (CVS) on liver damage, hepatic ferrous iron deposition and its molecular regulatory mechanism in rats. Sprague Dawley rats at seven weeks of age were randomly divided into two groups: a control group (Con) and a CVS group. CVS reduces body weight, but increases the liver-to-body weight ratio. The exposure of rats to CVS increased plasma aspartate aminotransferase (AST), alkaline phosphatase (ALP) and hepatic malondialdehyde (MDA) levels, but decreased glutathione peroxidase (GSH-Px) activity, resulting in liver damage. CVS lowered the total amount of hepatic iron content, but induced hepatic Fe(II) accumulation. CVS up-regulated the expression of transferrin receptor 1 (TFR1) and ZRT/IRT-like protein 14 (ZIP14), but down-regulated ferritin and miR-181 family members. In addition, miR-181 family expression was found to regulate ZIP14 expression in HEK-293T cells by the dual-luciferase reporter system. These results indicate that CVS results in liver damage and induces hepatic Fe(II) accumulation, which is closely associated with the up-regulation of ZIP14 expression via the miR-181 family pathway.
Highlights
Iron is an essential nutrient for all living organisms, playing a vital role in a variety of integrative metabolic processes [1,2,3]
The liver weight remained unchanged between the groups (Figure 1B); stress was associated with a significantly increased ratio of liver weight to body weight (p < 0.01, Figure 1C)
This finding is consistent with accumulating evidence that suggests that both long-term dexamethasone and mild chronic intermittent cold exposure result in a reduction of feed intake and body weight in rats [22,36]
Summary
Iron is an essential nutrient for all living organisms, playing a vital role in a variety of integrative metabolic processes [1,2,3]. Dysregulation of iron homeostasis has been found in various chronic liver diseases, and this imbalance leads to iron toxicity and liver damage [5,6,7]. Mutations in transferrin receptor (TFR) 2 and hemochromatosis protein lead to severe hepatic iron deposition, lipid peroxidation, and portal fibrosis in mouse models of hereditary hemochromatosis [6]. Inhibition of hepatic hepcidin expression induces significant iron deposition and subsequent liver damage in patients with chronic hepatitis C virus infections [7]. The homeostasis of hepatic iron is, tightly regulated to prevent liver damage
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