An Experimental Study Of The Protective Effects Of Tetramethylpyrazine On Acute Kidneyinjury Induced By Sepsis

Sepsis, a systemic inflammatory response syndrome (SIRS) induced by infection, will likely lead to septic shock and multiple organ dysfunction syndrome, turning itself to be one of the main killers of those seriously-ill patients[1]. It has been reported that mortality rate induced by sepsis is 18% ~ 19% and that of severe sepsis is as high as 40% ~ 50%; the occurrence of sepsis is rising by 1.5% ~ 9% every year. At present, the pathophysiologic mechanism on how sepsis causes MODS is not clear. Therefore, exploring pathologic mechanism of sepsis to find a new approach has important values in decreasing the mortality rate of those infected victims. Kidney is the target organ vulnerable to attacks; in the early period of acute kidney injury (AKI), that glomerular filtration rate (GFR) declines, or that GFR is still normal but kidney has emerged histological or biological markers such as traumatic changes can also result in significant increase in mortality rate of sepsis victims[2].Tetramethylpyrazine (TMP), a type of alkaloid monomer extracted from the Umbelliferae chuanxiong, has been widely used in clinical treatment of acute and chronic renal failure[4], since it has many functions as inhibiting excessive inflammatory response, reducing formation of oxygen free radical, antagonizing Ca2+, steadying mitochondrial membrane potential[3], improving microcirculation, and resisting blood coagulation. This study was initiated with the establishment of the sepsis-induced AKI experimental models by LPS, and then followed by a series of experimental observations after the intervention of TMP: the edema kidney of laboratory animals, urine volume changes, cystatin C ( Cys C), von Willebrand factor (von Willebrand factor, vWF) measurement and renal pathology observed. In this process, the mechanism of sepsis-induced renal injury was investigated and the protective effects and probable mechanism of TMP on sepsis-induced renal injury was evaluated with the prospect of finding new and effective clinical therapies for the treatment of sepsis-induced renal injury.ObjectivesThe animal models of sepsis were established with rabbits. Then the water content, urine, cystatin C, von willebrand factor and renal pathology were observed, and the nosogenesis of AKI was explored in sepsis model. The protective effects and probable mechanism of TMP on acute kidney injury were evaluated, before and after the use of TMP as treatment.MethodsThirty-six New Zealand white rabbits were randomly divided into three groups: normal control group (Group C), sepsis model group (Group M) and TMP group (Group P),12 rabbits each group. Group M and P underwent the intravenous injection of lipopolysaccharide (LPS, 1 mg/kg), group C were injected equal amount of 0.9% NaCl (weight percentage), and group P were treated with TMP (60 mg/kg) immediately after LPS injected. Four hours after reaching the diagnostic criteria of sepsis [5-6], urine output, and blood cystatin C (Cys-C) concentration were measured. Kidney tissue was extracted after execution; pathological changes were observed after renal water content was detected, and vWF was determined by using immunohist- ochemistry .Results 1. The animal model of sepsis was established successfullyAfter LPS(1mg/kg) was injected into experimental animal (rabbit) through the vein, fever (rectal temperature rised 1℃), tachypnea and tachycardia emerged, heart rate (HR) and breathing frequency gradually increased over 20%. Sepsis model had been established.2. The water content in kidney tissue, fourth-hour urine and serum Cys-C were compared between the different groupsCompared with group M, the other two groups (C and P) were reported of lower water content in kidney tissue and serum Cys-C concentration (P <0.05), and the fourth-hour urine volume increased with statistical significance (P <0.01), group C and group P the difference was not statistically significant (P >0.01).3. Detection of renal vWFThrough vWF immunohistochemistry,in the light microscope, for group M, the stained part of vWF in glomerular capillary endothelial cells and renal interstitial capillary endothelial cells was found positive (++)。As to group P, vWF staining in renal interstitial and glomerular cells, capillary endothelial cells was comparatively low (+), and group C was not significantly different.4. Renal Histopathology4.1. HE staining performance Observed in the optical microscope, group M's glomerular had a small amount of fibrous tissue hyperplasia, accompanied by inflammatory cell infiltration, mainly lymphocytes; glomerular swelling was more obvious, whose structure was not clear, and hyperplasia and infiltration of the cells can give pressure to capillary loop cavity, causing capillary's narrowing or even occlusion, renal cysts'significant decrease and narrowing. For group P, edema was observed in glomerular tissue, but there was no change in glomerular fibrosis, no stenosis or occlusion in renal cysts.4.2. Electron Microscopy Observed in the electron microscope, group M's visceral glomerular filtration membrane portion of epithelial cells, foot process fusion, capillary endothelial cells and basement membrane can be seen between the small electron-dense material deposition; proximal tubular epithelial cell brush border surface of the micro - villi fracture, epithelial cells, mitochondria swelling, vacuolar degeneration and spike disappearance can be observed. Group P's glomerular filtration membrane of the visceral epithelial cells in the visible part of the foot process fusion, proximal tubular epithelial cells of a small amount of mitochondrial swelling can be seen, and vacuolar degeneration was not obvious.Conclusion1.The sepsis animal model was made successfully by injecting LPS (1mg/kg) into New Zealand white rabbits through intravenous injection.2.Sepsis can lead to AKI; the main situation at the early period is that glomerular filtration rate decreases, leading to increased Cys-C concentration in the blood, decreased urine output, injury of renal vascular endothelial cells and pathological changes in the structure.3.TMP can alleviate body's excessive inflammatory response and restore the functions of tissues and organs such as micro-circulation to prevent the furtherance of AKI, exerting preventive and therapeutic effects on sepsis-induced AKI.