Dithiothreitol supplementation mitigates hepatic and renal injury in bile duct ligated mice: Potential application in the treatment of cholestasis-associated complications.

Cholestasis is a disorder characterized by impaired bile flow and accumulation of cytotoxic bile acids in the liver. On the other hand, oxidative stress and its deleterious consequences seem to have a significant role in cholestasis-induced organ injury. Hence, antioxidants and thiol-reducing agents could have potential protective effect against this complication. The current investigation was designed to evaluate the effect of dithiothreitol (DTT) as a safe and clinically applicable thiol-reductant in cholestatic animals. DTT is a dithiol compound which effectively reduces disulfide bonds in glutathione molecule or different proteins and preserves cellular redox environment. Bile duct ligated (BDL) mice were supplemented with DTT-containing drinking water (0.25% and 1% w: v) for 14 days. Blood, liver, kidney, and spleen samples were collected at scheduled time intervals (3, 7, and 14 days after BDL operation). Significant elevation in plasma biomarkers of liver and kidney injury was detected in BDL animals. Liver and kidney injury was also histopathologically evident by necrosis, inflammation, and fibrosis. Furthermore, high levels of reactive oxygen species in addition to lipid peroxidation, depleted glutathione reservoirs, and impaired tissue antioxidant capacity was detected in the liver and kidney of cholestatic animals. It was found that DTT supplementation (0.25% and 1% w:v) alleviated markers of oxidative stress in the liver and kidney. Moreover, liver and kidney histopathological changes and collagen deposition were markedly attenuated by DTT treatment. The beneficial effects of DTT administration in cholestasis and its associated complications might be linked to its ability for preserving cellular redox environment and preventing oxidative stress.

Mitochondria protection as a mechanism underlying the hepatoprotective effects of glycine in cholestatic mice.

Cholestasis is the stoppage of bile flow which could lead to serious clinical complications if not managed. Cytotoxic bile acids are involved in the pathogenesis of liver injury during cholestasis. There are no promising pharmacological interventions against cholestasis and its associated complications. This study examined the impact of glycine supplementation on liver mitochondria as a major target of bile acids-induced toxicity during cholestasis. Mice underwent BDL operation and received glycine (0.25% and 1% w:v in drinking water). Blood and liver samples were collected at scheduled time intervals (3, 7, and 14 days after BDL surgery). Plasma biomarkers of liver injury, along with markers of oxidative stress in the liver tissue were evaluated. Furthermore, liver mitochondria were isolated, and several mitochondrial indices were assessed. BDL-induced cholestasis was evident in mice as a significant elevation in plasma biomarkers of liver injury. Markers of oxidative stress were significantly increased in the liver of BDL animals. Liver injury was histopathologically evident by tissue necrosis, bile duct proliferation, hydropic changes, inflammation, and fibrosis. Furthermore, high level of reactive oxygen species, lipid peroxidation, depleted glutathione reservoirs, and impaired tissue antioxidant capacity were also detected in the liver of cholestatic mice. An assessment of liver mitochondrial function in BDL animals revealed an inhibition of mitochondrial dehydrogenases activity, collapse of mitochondrial membrane potential, mitochondrial swelling, and increase of reactive oxygen species (ROS), and lipid peroxidation (LPO). Furthermore, a significant decrease in mitochondrial ATP was detected in the liver mitochondria isolated from cholestatic animals. Glycine supplementation (0.25% and 1%) decreased mitochondrial swelling, ROS, and LPO. Moreover, glycine treatment improved mitochondrial membrane potential and restored liver mitochondrial ATP. On the other hand, it was found that glycine supplementation attenuated oxidative stress markers in the liver of BDL animals. Moreover, liver histopathological changes and collagen deposition were markedly mitigated by glycine treatment. The mechanisms for the beneficial effects of glycine administration in cholestatic animals might be linked to its ability for preserving cellular redox environment, preventing oxidative stress, and maintaining mitochondrial functionality.