| Objectives:The antioxidant mechanism of carnosine is mainly focused on its ability of clearing ROS and reacting with aldehydes. The current experiment used restraint stress induced oxidative stress model in mice to simulate psychological stress induced oxidative stress status, which is the commonest encountered by humans. The improving effects of carnosine was investigated by regulation of production of free radicals. It aimed to provide further scientific evidences for the research of anti-oxidative mechanisms of carnosine.Method:Kun Ming (KM) mice loaded with restraint stress were induced by fixed in the restraint cage for 18h. Animals were randomly divided into normal group, restraint stress group, Vc group (200 mg·kg-1), carnosine (100 mg·kg-1) and carnosine (200 mg·kg-1) and there are 7 mice in each group. The alanine aminotransferase (ALT) activity in plasma was firstly determined to ensure the liver injury model was successfully built up, then malondialdehyde (MDA) and oxygen radical absorbance capacity (ORAC) value in liver. We also determined the level of antioxidants and antioxidase such as glutathione (GSH) content, superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities. Since mitochondrion is the main source of free radical, we researched protective effect of carnosine on impaired liver through changes of mitochondrial function. We observed mitochondrial function through optical microscope, detected the respiratory chain complex, F0F1-ATPase activities through spectrophotometry instrument. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect the changes of the expression of liver succinate dehydrogenase (SDHA-SDHD) through measured mitochondria membrane potential through the Flow Cytometer. And then generation rate of Reactive Oxygen Species (ROS) was determined by automated multifunction microplate reader, content of ATP, ADP in mice liver were determined by Reproducible High-performance Liquid Chromatography (RP-HPLC) finally.Result:Our experiments showed that 18 h restraint stress could serious oxidative stress and induced liver injury, with an increase in plasma ALT activity. Meanwhile, we observed increased MDA levels and lowered ORAC values in liver of restraint stress mice compared with normal mice. Carnosine was oral administrated to mice for 7d, which markedly decreased ALT activity, and protect the liver injury induced by oxidative stress. In addition, carnosine could effectively increase the ORAC value, GSH content, SOD and GSH-PX in mice liver with MDA levels significantly reduced. At the same time, carnosine improved mitochondrial function: mitochondrial membrane potential, the activities of respiratory complexs, F0F1-ATPase activities and the expression of related gene through scavenging ROS and inhibiting its generation. ATP and ADP in mitochondria were also involved in the protective effect of carnosine.Conclusion:Carnosine plays an important role in improving restraint stress induced oxidative stress status, it maybe related to its effects on clearing excess free radicals and maintaining the inner antioxidant and oxidant balance to achieve the goal of protecting mitochondrion. Other possible mechanisms of carnosine on mirochondrion regulations include increasing mitochondrial respiratory chain enzymes activity, recovering F0F1-ATPase activity, balancing energy metabolism status of mitochondrion, etc. The inhibition of excess free radicals production might also be one of the important anti-oxidant mechanisms of carnosine. |
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