The Effect Of Hyperglycemia On Progression Of Hepatic Fibrosis In Rats

Objective: Hepatic fibrosis is characterised by intrahepaticconnective tissue hyperplasia. With collagen primarily the extracellularmatrix （ECM） protein synthesis, degradation and sedimentary imbalanceis the main mechanism of liver fibrosis. An important enzymes involvedin ECM protein catabolism is the matrix metalloproteinases （MMPs）,including interstitial collagenase MMP-1, which can degrade typeⅠandtypeⅡcollagen of ECM. MMPs are regulated specifically by tissueinhibitors of matrix metalloproteinaseses （TIMPs）. TIMP-1/MMP-1system has an important role in hepatic fibrosis. Diabetes is a commonmetabolic disease and hyperglycemia is important manifestations ofdiabetes. The current researches indicate hyperglycemia have a noticeableeffect on the liver fibrosis. In this research, we established rat model withdiabetes and liver fibrosis, observed the effect of hyperglycemia on liverfibrosis, further revealed the mechanisms of liver fibrosis withhyperglycemia, and provided the experimental evidence and bases forclinical treatment of diabetes-related liver fibrosis. Methods:60healthymale SD rats were randomized divided into four groups: the normalcontrol group, the diabetes group, the liver fibrosis group and doublemodel group,15rats in each group. Rats in diabetes group and doublemodel group were intraperitoneal （i.p.） injected with35mg/kgstreptozocin （STZ）.48hours later, rats model with diabetes were identified as successful model if blood sugar was higher than16.7mmol/L.After a week,rats in liver fibrosis group and double model group wereestablished with subcutaneous injection of40%CCL₄peanut oil solution0.4ml/kg first time,every3days after then subcutaneous injection40%CCL₄peanut oil0.2ml/kg twice weekly, eight weeks. Rats in the controlgroup were injected with citrate and peanut oil solution of equal volume.After the final injection of CCL₄, blood of heart was collected. Alanineaminotransferase （ALT）, glutamic-oxaloacetic transaminase （AST）,albumin （ALB） and Albnmin/Glonmin （A/G） in the serum were detectedby automated biochemical detector. Hepatic fibrosis indexes, such ashyaluronic acid （HA）, layer-attached proteins （LN）, Procollagentype-Ⅲ（PⅢNP）, Ⅳ type collagen （C-Ⅳ）, were detected by chemiluminescentmethod. The hepatic tissue of every group rats for hema-toxylin and eosin（H&E） stain to decetct liver cell necrosis and degeneration and degree offibrosis，with Van Gieson （VG） stain to observe hyperplasia of collagenlevels in liver tissue and with immunohistochemical method for detectionof PAI-1protein. The level of mRNA expression of α-SMA, MMP-1andTIMP-1were detected by Quantitative Real-Time polymerase chainreaction （PCR）. Results:1. Compared with the control group anddiabetes group, ALT and AST of serum were increased significantly in theliver fibrosis group and double model group （P<0.05）; ALB and A/G ofserum were decreased in the liver fibrosis group and double model group（P<0.05）; the serum ALT and AST levels in the double model group were higher than in the liver fibrosis group （P<0.05）.2. Compared with thecontrol group and diabetes group, HA, LN, PⅢNP, C-Ⅳ of serum in theliver fibrosis group and double model group were increased significantly（P<0.05）; the levels of HA and C-Ⅳ of serum in the double model groupwere higher than in the liver fibrosis group （P<0.05）.3. Score of liverfibrosis in the double model group was higher than that of liver fibrosisgroup （P<0.05）.4. The expression of PAI-1protein in the liver fibrosisgroup and double model group was increased obviously in contrast to thecontrol group and diabetes group （P<0.05）; the expression of PAI-1protein in the double model group was higher than that of liver fibrosisgroup （P<0.05）.5. The expression of α-SMA mRNA in the liver fibrosisgroup and double model group was increased obviously in contrast to thecontrol group and diabetes group（P<0.05）; the expression of α-SMAmRNA double model group was increased as compared with that of liverfibrosis group （P<0.05）.6. The expression of TIMP-1/MMP-1mRNA inthe liver fibrosis group and double model group was significantly higherthan that of the control group and diabetes group （P<0.05）; the expressionof TIMP-1/MMP-1mRNA in the double model group rats was increasedcompared to liver fibrosis group （P<0.05）.Conclusion:1. Hyperglycemiacan promote and enhance liver fibrosis, mainly in the decrease of liverfunction, the increase of serum fibrosis index levels and the exacerbationof liver collagen hyperplasia.2. Hyperglycemia can promote liver HSCactivation, proliferation and increase the expression of PAI-1protein, thus increasing TIMP-1and inhibiting MMP-1level.3. Hyperglycemiaaggravate liver fibrosis occurrence, and can up-regulate the ratio ofTIMP-1; MMP-1to increase the ECM deposits.