| Objectives:Hyperglycaemia commonly occurs after trauma or surgical procedures. Dysfunction of glycometabolism promotes the development of infection and multi- organ dysfunction syndrome in trauma patients, so as to result in bad prognosis. As isletβ-cells play a key role in glycometabolism, it is quite important to study the insulin secretion functions of Isletβ-cells and the mechanisms of immunologic injury to the islet beta-cell by trauma. In this study we carried out experiments by means of models on normal rat and severely scalded endotoxemic rat, inspecting the islet functions in vivo by hyperglycemic clamp technique and isolating rat islets through digestion by collagenase, so as to observe the islet functions in vitro. Observations were also made on the expression of NF-кB gene of pancreatic islet and on the TNF-αand IL-1βvariations of serum inflammatory cytokines in hope to study the correlations between NF-кB genetic expression of islet and islet functional injuries and the possible molecular immunological injury mechanism, so as to provide theoretical and experimental basis for clinical prevention, therapy and the harm of traumatic hyperglycemia.Methods:Sprague-Dawley (SD) rats (n=72, w=250-300g) of either gender were randomly allocated into control groups (n=12) and experiment groups (n=60). Each group was housed in a separate cage and had free access to standard rat chow and water. The control animals underwent nothing. The experimental animals were subjected to model of full thickness scald at 30% TBSA by way of improved Walker& Mason Approach and to abdominal injection of endotoxin two hours later. The experiment rats at time points of 12h, 1d, 3d, 5d, and 7d (n=6×2) after the trauma and control rats(n=6×2) were consequently divided into two groups at random, which underwent experiments as follows:1. Control and experimental rats, fasted overnight, underwent blood sampling by carotid artery at time points of 12h, 1d, 3d, 5d, and 7d (n=6)after the trauma of scalded and endotomic rats. The samples were centrifuged to serums which were stored at -70℃, and TNF-αand IL-1βwere measured by ELISA. To assess beta-cell function in vivo, control and experimental rats underwent hyperglycemic clamp technique at all time points;2. Pancreatic tissues were extracted from fasted overnight control and experimental rats for uses in:⑴Isolation of pancreatic islets by collagenase digestion, which is followed by test of glucose& L-arginine stimulated insulin secretion aimed at observation of islet functions in vitro;⑵Preservation in 10% formalin, which is for use of HE staining and Immunohistochemical staining that is for observation of islet structural variation of pancreatic tissues and expressions of Ins and NF-κBP65 proteins;⑶Grinding of pancreatic tissues, of which the centrifuged supernatant liquor was preserved at -70℃and used for observation of variation of insulin contents in the pancreatic tissues.Results: 1. The status of setting up the severely scalded and endoxemia rats⑴By pathological section, pathological changes of scalded surface were in conformity to scaldⅢ○;⑵Compared with normal control group, the level of glucose and insulin in serum were significantly increased at all time-points in scald group﹙p﹤0.05﹚.2. The pancreatic islet functions of severely scalded and endotoxemic rats⑴The functions of scalded groups , determined by hyperglycemic clamp technique and HOMA-βindex, was decreased at all time-points in comparison to the control group in vivo.⑵The function of isolated islets from scalded groups , compared with normal control group's, was decreased after scald in vitro (p﹤0.05).3. There were increase in the contents of insulin in the experiment groups'pancreatic tissue contrast with control groups'(P<0.01) . But the contents of insulin relative to blood sugar were decrease in the experiment groups contrast with normal groups.4. The gene expression of NF-кB in rat pancreatic islet was increase significantly in experiment groups contrast with normal groups (P<0.01).The level of TNF-αand IL-1βin serum were increase obviously in scald group contrast with normal group (P<0.01). 5. There is a significant negative correlation between the level of TNF-αor IL-1βand beta-cell function in vivo﹙p﹤0.05﹚and between the positive rate of NF-κB protein and beta-cell function in vitro﹙p﹤0.01﹚.Conclusions:1. The severely scalded and endoxemia rat exerts dysfunction of Insulin secretion in Isletβ-cells.2. Over expression of NF-кB gene and high level of TNF-αand IL-1βplays a key role in the Islet dysfunctional injuries to severely scalded and endotoxemic rats.
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