The Role and Study of Mitochondrial Impairment and Oxidative Stress in Cholestasis.
TL;DR: An animal model of cholestasis is described, and the techniques for liver mitochondria isolation, evaluating mitochondrial indices of functionality, and assessing biomarkers of oxidative stress in the liver tissue are outlined.
Abstract: The blockage of bile flow, cholestasis, could lead to serious clinical outcomes, including severe liver injury. Accumulation of the cytotoxic molecules, such as bile acids, during cholestasis, not only impairs liver function, but also affects other organs, including the kidneys. Although the precise mechanisms of cytotoxicity and organ injury in cholestasis are far from clear, oxidative stress and its subsequent events seem to play a central role in this complication. Oxidative stress acts as a signaling path which could finally lead to cell death and organ injury. At the cellular level, mitochondria are major targets affected by cytotoxic molecules. Mitochondrial impairment could lead to severe outcomes, including cellular energy crisis and release of cell death mediators from this organelle. Therefore, targeting oxidative stress and mitochondrial dysfunction might serve as a therapeutic point of intervention against cholestasis-associated organ injury. In this protocol, an animal model of cholestasis is described, and the techniques for liver mitochondria isolation, evaluating mitochondrial indices of functionality, and assessing biomarkers of oxidative stress in the liver tissue are outlined.
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TL;DR: Evaluated pathologic effects of cholestasis-associated reproductive toxicity in male and female rats is restrictedly coupled with severe oxidative stress and mitochondrial impairment.
48 citations
TL;DR: It was found that the PARP-1 inhibitor, NA (50 and 100 mg/kg, i.p), significantly mitigated cholestasis-induced renal injury and indicated a pathogenic role for PARp-1 overexpression in CN.
32 citations
TL;DR: It was found that NAC treatment significantly mitigated biomarkers of oxidative stress and alleviated tissue histopathological changes in cirrhotic rats, representing NAC as a potential protective agent with therapeutic capability in cholestasis and its associated complications.
Abstract: Cholestasis is a multifaceted clinical complication. Obstructive jaundice induced by bile duct ligation (BDL) is known as an animal model to investigate cholestasis and its associated complications...
30 citations
Cites methods from "The Role and Study of Mitochondrial..."
...For this purpose, animals were anesthetized (10mg/kg of xylazine and 70mg/kg of ketamine, i.p), a midline incision was made through the linea alba, and the common bile duct was localized, doubly ligated, and cut between two ligatures (Heidari & Niknahad, 2019)....
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30 Sep 2020
TL;DR: Tau treatment significantly decreased oxidative stress and improved mitochondrial function in the heart tissue of cirrhotic animals, providing clues for the involvement of mitochondrial impairment and oxidative stress in the pathogenesis of heart injury in BDL rats.
Abstract: Cirrhosis-induced heart injury and cardiomyopathy is a serious consequence of this disease. It has been shown that bile duct ligated (BDL) animals could serve as an appropriate experimental model to investigate heart tissue injury in cirrhosis. The accumulation of cytotoxic chemicals (e.g., bile acids) could also adversely affect the heart tissue. Oxidative stress and mitochondrial impairment are the most prominent mechanisms of bile acid cytotoxicity. Taurine (Tau) is the most abundant non-protein amino acid in the human body. The cardioprotective effects of this amino acid have repeatedly been investigated. In the current study, it was examined whether mitochondrial dysfunction and oxidative stress are involved in the pathogenesis of cirrhosis-induced heart injury. Rats underwent BDL surgery. BDL animals received Tau (50, 100, and 500 mg/kg, i.p.) for 42 consecutive days. A significant increase in oxidative stress biomarkers was detected in the heart tissue of BDL animals. Moreover, it was found that heart tissue mitochondrial indices of functionality were deteriorated in the BDL group. Tau treatment significantly decreased oxidative stress and improved mitochondrial function in the heart tissue of cirrhotic animals. These data provide clues for the involvement of mitochondrial impairment and oxidative stress in the pathogenesis of heart injury in BDL rats. On the other hand, Tau supplementation could serve as an effective ancillary treatment against BDL-associated heart injury. Mitochondrial regulating and antioxidative properties of Tau might play a fundamental role in its mechanism of protective effects in the heart tissue of BDL animals.
26 citations
Cites background or methods from "The Role and Study of Mitochondrial..."
...Based on a previously reported protocol, the changes in the light scattering of isolated mitochondria samples at λ = 540 nm was used as an estimate of the mitochondrial swelling and permeabilization [47, 62, 76]....
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...The mitochondrial capacity to capture the cationic fluorescent dye, rhodamine 123, was used to estimate mitochondrial depolarization [47, 62, 70-74]....
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...Thiobarbituric acid reactive substances (TBARS) were measured to assess the amount of lipid peroxidation in the heart tissue of BDL rats [47]....
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...This step was repeated at least three times using a fresh isolation buffer medium to increase the mitochondrial yield [47, 63, 64]....
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...Therefore, the amount of rhodamine 123 in the supernatant is increased [47, 62, 70-73]....
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TL;DR: The protective role of BET in the intestine of cirrhotic animals could be attributed to the effect of this compound on oxidative stress and its associated events in enterocytes.
24 citations
References
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TL;DR: A "two-hit" hypothesis is developed, in which Ca(2+) plus another pathological stimulus can bring about mitochondrial dysfunction, and the delicate balance between the positive and negative effects of Ca( 2+) and the signaling events that perturb this balance is highlighted.
Abstract: The mitochondrion is at the core of cellular energy metabolism, being the site of most ATP generation. Calcium is a key regulator of mitochondrial function and acts at several levels within the organelle to stimulate ATP synthesis. However, the dysregulation of mitochondrial Ca(2+) homeostasis is now recognized to play a key role in several pathologies. For example, mitochondrial matrix Ca(2+) overload can lead to enhanced generation of reactive oxygen species, triggering of the permeability transition pore, and cytochrome c release, leading to apoptosis. Despite progress regarding the independent roles of both Ca(2+) and mitochondrial dysfunction in disease, the molecular mechanisms by which Ca(2+) can elicit mitochondrial dysfunction remain elusive. This review highlights the delicate balance between the positive and negative effects of Ca(2+) and the signaling events that perturb this balance. Overall, a "two-hit" hypothesis is developed, in which Ca(2+) plus another pathological stimulus can bring about mitochondrial dysfunction.
2,265 citations
TL;DR: Up to 2% of the oxygen consumed by the mitochondrial respiratory chain undergoes one electron reduction, typically by the semiquinone form of coenzyme Q, to generate the superoxide radical, and subsequently other reactive oxygen species such as hydrogen peroxide and the hydroxyl radical.
797 citations
TL;DR: Reactive oxidant species likely contribute to both onset and progression of fibrosis as induced by alcohol, viruses, iron or copper overload, cholestasis, hepatic blood congestion and many if not all chronic disease processes affecting hepatic tissue.
606 citations
TL;DR: It is concluded that glycochenodeoxycholate causes a bioenergetic form of lethal cell injury dependent on ATP depletion analogous to thelethal cell injury of anoxia.
Abstract: Chenodeoxycholate is toxic to hepatocytes, and accumulation of chenodeoxycholate in the liver during cholestasis may potentiate hepatocellular injury. However, the mechanism of hepatocellular injury by chenodeoxycholate remains obscure. Our aim was to determine the mechanism of cytotoxicity by chenodeoxycholate in rat hepatocytes. At a concentration of 250 microM, glycochenodeoxycholate was more toxic than either chenodeoxycholate or taurochenodeoxycholate. Cellular ATP was 86% depleted within 30 min after addition of glycochenodeoxycholate. Fructose, a glycolytic substrate, maintained ATP concentrations at 50% of the initial value and protected against glycochenodeoxycholate cytotoxicity. ATP depletion in the absence of a glycolytic substrate suggested impairment of mitochondrial function. Indeed, glycochenodeoxycholate inhibited state 3 respiration in digitonin-permeabilized cells in a dose-dependent manner. After ATP depletion, a sustained rise in cytosolic free calcium (Cai2+) was observed. Removal of extracellular Ca2+ abolished the rise in Cai2+, decreased cellular proteolysis, and protected against cell killing by glycochenodeoxycholate. The results suggest that glycochenodeoxycholate cytotoxicity results from ATP depletion followed by a subsequent rise in Cai2+. The rise in Cai2+ leads to an increase in calcium-dependent degradative proteolysis and, ultimately, cell death. We conclude that glycochenodeoxycholate causes a bioenergetic form of lethal cell injury dependent on ATP depletion analogous to the lethal cell injury of anoxia.
254 citations
TL;DR: Key events are the activation and transformation of quiescent hepatic stellate cells into myofibroblast-like cells with the subsequent up-regulation of proteins such as α-smooth muscle actin, interstitial collagens, matrix metalloproteinases, tissue inhibitor of metallofiltration, and proteoglycans.
224 citations