The Expression And Meaning Of Urinary Kidney Injury Molecular-1 In Rat Model Of Acute Kidney Injury Induced By Glycerol

Objective: This experiment is to provide some experimental evidence to the early clinical diagnosis of the acute kidney injury by observing the expression and meaning of urinary kidney injury molecular-1 in rat model of acute kidney injury induced by glycerol.Methods: Sixty healthy Sprague-Dawley male rats were randomly divided into two groups:①control group (saline group,n=30);②model group (glycerol group, n=30). According to the time of injection, each of the two groups was divided into 5 subugroups(0-3h, 3-6h, 6-24h, 24-48h, 48-72h subugroups), every subugroup contained 6 rats. The rats did not drink and eat for 24 hours before the experiment, and weighing and recording the weight, the model group were injected 50﹪glycerol saline into the hind limbs muscle with the injected dose of 10ml/kg. The control group were injected 0.9﹪saline into the hind limbs muscle with the injected dose of 10ml/kg. The urine of the rats were collected respectively, and the urine samples were centrifuged for 10 minutes (3000r/min)to remove debris which were kept in -20℃to preserve. 4ml blood was draw from the inferior vena cava of each rat under the anesthesia of the intraperitoneal injection of 20﹪urethane with the dose of 5ml/kg. The blood samples were centrifuged for 10 minutes (3000r/min), and the supernate were preserved in -20℃. Rats were killed after being blooded. Both kidneys were removed and observed the changes of the color and size. To observe the pathology morphological changes of the kidneys, they were stripped the renal capsule, split longitudinally, and were kept in 10﹪formalin solution to fixed and stained with hematoxylin-eosin. The experimenter assayed the expressions of the urinary kidney injury molecule-1 by ELISA, the urinaryβ-N-acetyl-glucosaminidase by colorimetric method, the blood urea nitrogen by diacetylmonoxime method, and the serum creatinine by picric acid method.Results: 1. After the glycerol being injected, the injected muscles of rats in the model group were dropsical obviously, the bodies hair were yellow, and the rats were unresponsive and refused to diet and water. Dark red urine appeared after one hour, and the urine reduced compared with the control group. There was no adverse reaction occurred to the control group, the urine is normal.2. Urinary kidney injury molecule-1, urinaryβ-N-acetyl-glucosaminidase, the serum creatinine and the blood urea nitrogen test results:①The model group: urinary kidney injury molecule-1 level in 3h, 6h, 24h, 48h, 72h periods is significantly higher than the control group (P<0.01)at same time point, and increases progressively with time, each subugroup differences have the statistical significances (P<0.01); Urinaryβ-N-acetyl-glucosaminidase levels in 6h, 24h, 48h, 72h periods is significantly higher than the control group (P<0.01)at same time point, and the levels increase progressively with time in the 6h, 24h, 48h periods, while decrease in the 72h time period compared with the 48h time period, the differences have the statistical significances(P<0.05); The serum creatinine levels in 24h, 48h, 72h periods are significantly higher than the control group(P<0.01) at same time point; and the level increase progressively with time in the 24h, 48h periods, while decrease in the 72h time period compared with the 48h time period, the differences have no statistical significances (P>0.05); The blood urea nitrogen levels in 48h, 72h periods are significantly higher than the control group(P<0.01) at same time point, while decrease in the 72h time period compared with the 48h time period, and the differences have no statistical significances(P>0.05); The control group: the differences of urinary kidney injury molecule-1, urinaryβ-N-acetyl-glucosaminidase, the serum creatinine and the blood urea nitrogen levels has no statistical significance (P>0.05)at each time point.②All the differences have the statistical significances (P<0.01)between the 4 indexes which are the ratios (i.e. multiple) of the control group to the model group at the same time period. The average rank is: urinary kidney injury molecule-1 (18.00)>urinaryβ-N-acetyl-glucosaminidase(9.00)>the blood urea nitrogen (8.40)>the serum creatinine(6.60). The increase of urinary kidney injury molecule-1 among them is maximal.③The levels of urinary kidney injury molecule-1 was positively correlated with urinaryβ-N-acetyl-glucosaminidase(r=0.983,P<0.01), the serum creatinine(r=0.965,P<0.01)and the blood urea(r=0.763,P<0.01) respectively.3. The dynamic variations of kidney histomorphology:①macroscopic observation: the model group: the kidneys are larger and edematous; the color of the kidneys shade into atropurpureus. The control group: the appearances of the kidneys are normal, and the insides are soft and ruddy while being split longitudinally.②Optical microscopic observation: the model group: in the early time, the glomeruli are swelling mildly, the renal capsule space are widened, part of the cytoplasm are dyed red, and particles are swelling and hydropic degeneration in proximal convoluted tubule epithelial cells, cast formations can be seen in distal convoluted tubules, and the renal interstitium are slightly congestive. As time goes on, the glomeruli are swelling significantly, the tubular epithelial cells are disintegration and necrosis, and a large number of protein casts and cellular casts constituted of mass necrotic and exfoliated tubular epithelial cells are formed in the distal tubules. However, after 72 hours, the casts in the tubular lumens gradually dissolve and disappear, and regenerative epithelial cells can be seen in the intermittent injury sites of tubules. The structures of glomerulus and tubules are normal in the control group.Conclusions: 1. Through the acute renal injury rats induced by glycerol, urinary kidney injury molecule-1 can be earlier expressed than urinaryβ-N-acetyl- glucosaminidase, the blood urea nitrogen, and the serum creatinine. It can reflect the acute kidney injury early and sensitively. It will provide some experimental evidence to the early detection and clinical diagnosis of the acute kidney injury.2. The increasing of urinary kidney injury molecule-1 expression in the 72h time period, the lysis and disappearance of the casts in the tubular lumens, and the regeneration of the epithelial cells in the intermittent injury sites of tubules declares that urinary kidney injury molecule-1 may be involved in the repair process of renal injury.3. The dynamic variations of kidney histomorphology on acute kidney injury rats induced by glycerol: the glomeruli swelling are ingravescent, the renal capsule space are widened, the tubular epithelial cells are disintegration and necrosis, and a large number of protein casts and cellular casts are formed in the tubules. After 72 hours, the casts in the tubular lumens gradually dissolve and disappear, and regenerative epithelial cells can be seen in the intermittent injury sites of tubules.