Lidong Zhai

University of Alabama at Birmingham, Birmingham, Alabama, United States

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Publications (3)12.24 Total impact

  • Lidong Zhai · Scott W Ballinger · Joseph L Messina ·
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    ABSTRACT: Acute insulin resistance is common after injury, infection, and critical illness. To investigate the role of reactive oxygen species (ROS) in critical illness diabetes, we measured hepatic ROS, which rapidly increased in mouse liver. Overexpression of superoxide dismutase 2, which decreased mitochondrial ROS levels, protected mice from the development of acute hepatic insulin resistance. Insulin-induced intracellular signaling was dramatically decreased, and cellular stress signaling was rapidly increased after injury, resulting in the hyperglycemia of critical illness diabetes. Insulin-induced intracellular signaling, activation of stress (c-Jun N-terminal kinase) signaling, and glucose metabolism were all normalized by superoxide dismutase 2 overexpression or by pretreatment with antioxidants. Thus, ROS play an important role in the development of acute hepatic insulin resistance and activation of stress signaling after injury.
    Molecular Endocrinology 02/2011; 25(3):492-502. DOI:10.1210/me.2010-0224 · 4.02 Impact Factor
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    Lidong Zhai · Joseph L Messina ·
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    ABSTRACT: Injuries, hemorrhage, sepsis, burn, and critical illnesses all induce insulin resistance, and insulin resistance is strongly associated with advancing age. However, the effect of age on injury induced insulin resistance is not well studied. We performed surgical trauma in male rats of three different ages (3-, 6-, and 10-weeks old). Rats were either hemorrhaged to a mean arterial pressure of 35-40 mmHg and subsequently maintained at that pressure for up to 90 min, or maintained without hemorrhage as controls. Results indicate that insulin-induced intracellular signaling was diminished in liver and skeletal muscle of 6- and 10-week old rats following trauma and hemorrhage. In even younger rats, immediately post-weaning ( approximately 3 weeks of age), insulin signaling was lost in liver, but not in skeletal muscle. Glucocorticoids can play a role in the chronic development of insulin resistance. Our results demonstrate that corticosterone levels were increased in 6- and 10-week old animals following hemorrhage, but little change was measured in 3-week old animals. Blockade of glucocorticoid synthesis prevented the development of insulin resistance in skeletal muscle, but not in liver of 6- and 10-week old rats. Moreover, skeletal muscle glucocorticoid receptor levels increased dramatically between 3 and 6 weeks of age. These results indicate that trauma and hemorrhage-induced hepatic insulin resistance occurs at all ages tested. However, there is no development of insulin resistance following trauma and hemorrhage in skeletal muscle of post-weaning rats. In skeletal muscle of 6- and 10-week old rats, inhibition of glucocorticoid levels prevents the development of insulin resistance.
    Journal of Endocrinology 09/2009; 203(3):365-74. DOI:10.1677/JOE-09-0269 · 3.72 Impact Factor
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    ABSTRACT: It has long been known that injury, infections, and other critical illnesses are often associated with hyperglycemia and hyperinsulinemia. Mortality of critically ill patients is greatly reduced by intensive insulin therapy, suggesting the significance of reversing or compensating for the development of acute insulin resistance. However, the development of acute injury/infection-induced insulin resistance is poorly studied, much less than the chronic diseases associated with insulin resistance, such as type 2 diabetes and obesity. We previously found that insulin resistance develops acutely in the liver after trauma and hemorrhage. The present study was designed to begin to understand the first steps in the development of trauma and hemorrhage-induced acute hepatic insulin resistance in an animal model of injury and blood loss similar to traumatic or surgical injury and hemorrhage. We present novel data that indicate that hepatic insulin resistance increased dramatically with an increasing extent of hemorrhage. With increasing extent of blood loss, there were increases in serum TNF-alpha levels, phosphorylation of liver insulin receptor substrate-1 on serine 307, and liver c-Jun N-terminal kinase activation/phosphorylation. Exogenous TNF-alpha infusion increased c-Jun N-terminal kinase phosphorylation and insulin receptor substrate-1 serine 307 phosphorylation, and inhibited insulin-induced signaling in liver. Conversely, neutralizing TNF-alpha antibody treatment reversed many of the hemorrhage-induced changes in hepatic insulin signaling. Our data indicate that the acute development of insulin resistance after trauma and hemorrhage may have some similarities to the insulin resistance that occurs in chronic diseases. However, because so little is known about this acute insulin-resistant state, much more needs to be done before we can attain a level of understanding similar to that of chronic states of insulin resistance.
    Endocrinology 06/2008; 149(5):2369-82. DOI:10.1210/en.2007-0922 · 4.50 Impact Factor