| IntroductionSepsis, ischemia - reperfusion injury, and multiorgan dysfunction are responsible for significant human morbidity and mortality despite the use of antibiotics, vasoactive agents, and anti - cytokine therapies. These injuries appear to be mediated in part by the response of the immune system to an infectious agent, ischemic insult, or other severe stress. A potential approach to this problem is to make use of a natural defense mechanism called " the stress response," which is characterized by a transient down - regulated synthesis of nonvital cellular proteins and increased production of endogenous protective factors known as heat shock proteins ( HSPs) that act to allow proper refolding of proteins denatured by the incipient injury. The member of the HSP family thought to play a vital role in cellular protection is HSP70. The induction of HSPs to improve outcome in human disease has not been exploited because induction agents utilized in the laboratory are themselves toxic and not clinically relevant.Traditionally considered a nonessential amino acid, glutamine ( Gin) now appears to be a conditionally essential nutrient during serious injury or illness. In good health , Gin is the most abundant amino acid in plasma and skeletal muscle, but circulating and tissue concentrations fall precipitously after injury, surgery, or infection. Extensive research in animal models of illness/injury demonstrates that Gin -supplementation improves survival and may modulate immune function. However, the mechanism of Gins protection in these patients remains unclear.Recent study found that Gin was a potent inducer of HSP in vitro. Moreover, Gin may also play a role in the regulation of the inflammatory response.Thus, we hypothesized that Gin would decrease cytokine release, reduce end - organ injury, and enhance HSP expression in multiple tissues of a rat model of lipopolysaccharide (LPS) - induced sepsis.Materials and Methods1. Animals and groupingEighteen adult male Wistar rats (weight range 250 to 300g) were randomly divided into 3 groups.(1) lipopolysaccharide - treated group( LPS) :The rats were anesthetized with amobarbital (66mg/kg, ip), then were given LPS (5mg/kg) and lactated Ringer (25ml/kg) via the lateral tail vein.( 2) Glutamine - treated group( Gin) :Gin was prepared as a 3% solution dissolved in lactated Ringer (LR) immediately before administration. After given LPS, rats were administrated with Gin (0.75g/kg) via the lateral tail vein by using a syring pump at a rate of 0.5ml/min.( 3 ) Control group ( C) :The rats were given saline alone as previously described.2. Measurements(1) Tumor necrosis factor - a( TNF - a): Blood was drawn from lateral tail vein for analysis of cytokine levels at 0, 2, 4, and 6 h post- LPS insult.(2)HSP70 detection; After completion of treatment and/or injury regimens, multiple tissues were harvested from killed rats. HSP70 were detected by immunohistochemistry ( SABC) , anti - HSP70 sera was 1; 100 dilution, color was developed with DAB. HSP70 location and content were examined by Metamorph / DP10 / BX51 image analyzer.(3) Tissue pathology evaluation: Rats were sacrificed with amo-barbital (lOOmg/kg) 6 h post - LPS administration. Organs (lung, liver, and ileum) were then removed, fixed in phosphate -buffered formalin, and embedded in paraffin. Histological sections were then stained with hematoxylin and eosin and reviewed.3. StatisticsResults are presented as means ?SE. HSP70 densitometry measurements were compared by using ANOVA and the Student' s t - test where applicable. Results were considered significant at a value of p <0.05.Result1. Plasma TNF - a concentrationGin treatment resulted in marked attenuation of TNF - a expression at 2 h post - LPS injection( p < 0. 005 ) . 2. HSP70 detectionGray gradients of HSP70 in group Gin were much lower than those of group LPS ( p < 0. 005 ) , as suggests that HSP70 content of group Gin was higher than that of group LPS.3. Tissue pathology evaluat...
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