Effects Of Dexamethasone On Adrenal Insufficiency In Rat With Sepsis At Early Stage

Objective: Sepsis, septic shock, and ensuing multiple organ dysfunction syndrome serve as the most common causes of the death of critically ill patients. According to many literature reports, with the exacerbation of sepsis, several organs such as liver, kidneys, gut, heart and the function of endothelial cells would be successively influenced as well as adrenal function under such condition. Marik reported that the total morbility of relatived adrenal insufficiency of critically ill patients was 30%~40%, while septic shock patients was 60%. However, few definite studies both home and abroad have reported that whether the corresponding changes of morphologic-functional status exsisted following the occurance of organ dysfunction.Plasma cortisol levels excreted by adrenal cortex can be extremely high in strong stress response to sepsis and shock, but not enough for severity of illness. The ectogenic glucocorticoids (GC) may act on each lay of hypothalamic-pituitary-adrenal axis (HPAA) making the level of blood plasma higher and accordingly serve the inner throtting action on stress response, allowing the organism to protect critically ill patients though many mechanisms. But for different diseases, the timing, dosage and duration of glucocorticoid are quite different. This study observes the effects of dexamethasone with the same dosage (low-dose) at different time to tumour necrosis factor-α(TNF-α) and interleukin-6(IL-6) in serum of the rats with early stage of sepsis complicating adrenal insufficiency. And looking forward to providing favorable exparimental evidence for the clinical treatment of sepsis and sepsis shock, this study will also judge whether HPAA has structural changes and their places by way of the ultrastructural difference of hypothalamus, pituitary and adrenal.Methods: The animal model used cecal ligation and puncture (CLP) to replicate and adopted the low-dose adrenocorticotropic hormone (ACTH) stimulated test to evaluate adrenal function of sepsis animals. 155 healthy male wistar rats with weight 250~300g were chosen and divided into five groups on random: (1) control group (n=10); (2) sham group (n=25): only cut open the celiac without CLP;(3) model group (n=50): only CLP; (4) prevention group (n=50): injected 10mg/kg dexamethasone into the abdominal cavity before CLP; (5) treatment group (n=20): injected 10mg/kg dexamethasone into the abdominal cavity 7 hours after CLP. The 2nd,3rd and 4th group set up five time points of 2h, 4h, 6h, 8h and 12h, each of which had 10 rats( sham group had 5 rats), and the 5th group only had 2 time points of 8h and 12h. All the rats were all injected ACTH (0.8μg/kg) into the abdominal cavity 6 hours after CLP. Before injection and 30min later, collected blood samples from arteria carotis communis catheter as T0, T30. Blood serum was stored in -70℃and detected cortisol with radioimmunoassay(RIA). At the same time, all the rats of each group were collected blood samples according to time points (except control group ), blood serum was also stored in -70℃and the TNF-αand IL-6 levels in serum were detected with ELISA (enzyme linked immunosorbent assay). In addition, two normal rats raised under the same environment as well as two rats of model, prevention and treatment groups at 12h were chosen on random and fixed with aorta perfusion. And hypothalamus, pituitary and adrenal were taken to be electron microscopic section to observe the ultramicrostructure changes of tissues. Data were presented as?x±s and analyzed with two group t-test using SPSS 11.5 statistical program. A level of P<0.05 was considered to be statistically significant.Results1 Effects of dexamethasone on cortisol levels in blood serum of rats.The levels of T0 of model, prevention and treatment groups were respectively higher than that of control and sham groups; And the levels of T0 of prevention group was higher than that of model and treatment groups respectively.The levels ofΔT (T30-T0) of control and sham groups were higher than that of model, prevention and treatment groups; While there was no statistical significance to differencite the levels ofΔT of model, prevention and treatment groups. 2 Effects of dexamethasone on levels of TNF-αand IL-6 in blood serum of rats.The level of TNF-αin blood serum of model group reached the peak 2 hours after CLP and then descended gradually. While the level of IL-6 elevated after CLP,and the peak appeared later than TNF-α. In model group, except 8h, the levels of TNF-αand IL-6 in blood serum were higher obviously than that of other four groups, and there is no stasistical significance to summarize the differences between TNF-αand IL-6 in the model and treatment groups at 8h; The levels of TNF-αin prevention group at 8h and 12h were lower than that of treatment group(p<0.01) and were not higher than that of sham group(p<0.05).3 The changes of ultramicrostructure of hypothalamus, pituitary and adrenal cortex.In the groups of model, prevention and treatment, paraventricular nucleus cells, pituitary ACTH cells and adrenocortical fascicular zone of rats respectively presented the histological changes of lipid droplets lossing and myelin bodies as well as the mitochondrial tracheid crista and intima partly or completely dissolved and disappeared. Besides, the histological changes of adrenal were more obvious than hypothalamus and pituitary, especially model group.Conclusion: This study observed the effects of dexamethasone with the low-dose at different time to TNF-αand IL-6 in blood serum of the rats with early stage of sepsis complicating adrenal insufficiency, and judged whether HAPP has structural changes following insufficiency of function by observing electron microscopic sections of hypothalamus, pituitary and adrenal. Some conclusions were as follows:1 The rats had adrenal insufficiency at early stage of sepsis.2 The levels of TNF-αand IL-6 in serum of rats with sepsis complicating adrenal insufficiency evidently ascended.3 The prevention application of hormone of low-dose could make the level of T0 ascend, but had no evident effect on ACTH stimulate test.4 low-dose hormone replacement therapy could effectively descend the levels of TNF-αand IL-6 in serum. Besides, the result of early application would be better.5 When sepsis occurs, hypothalamus, pituitary and adrenal gland would have metabolic structural changes with the most distinct manifestation of adrenal cortex, which might serve as one of causes producing adrenal insufficiency.