| Obstructive jaundice (OJ) results in intestinal mucosal barrier dysfunction with consequent a series of complications, such as septicaemia and renal failure. However, the causes of renal function impairment during OJ are still unclear. The disturbance of renal hemodynamics caused by severe liver dysfunction may play an important role in renal function impairment. The characteristics of renal hemodynamics during OJ were as following: constriction of intrarenal blood vessels, redistribution of renal blood, diffluence of blood flowed from renal cortex to medulla, cortex ischemia, constriction of afferent glomerular arteriole and glomerular filtration rate (GFR) decreased.Heme oxygenase (HO) plays a critical role in attenuating the production of reactive oxygen species through its ability to degrade heme in an enzymatic process that leads to the production of equimolar amounts of carbon monoxide (CO) and biliverdin/bilirubin and the release of free iron. Clinical studies have shown that heme administration can precipitate acute tubular necrosis and that the HO system reduced tissue injury in the kidney. HO-1 is induced by oxidant stress, and a robust increase in HO-1 expression provides protection against oxidative insults. Heme degradation products, CO, biliverdin/bilirubin and iron/ferritin, possess potent antioxidant properties and anti-apoptotic effects.Resveratrol (3, 4, 5-trihydroxystilbene), a polyphenolic compound found in mulberries, grapes and red wine has been reported to exhibit a wide range of biological actions that include antioxidant effect, anti-carcinogenesis, anti-in?ammatory effects and antioxidant properties via inducing the expression of HO-1.Objective: To investigate the effect and its possible mechanism of resveratrol on renal injury induced by bile duct ligation (BDL) in rats. Methods: Obstructive jaundice rats were induced wistar rats by BDL. Kidneys in all groups were harvested at fixed time points: 1wk, 2wk after operation or sham operation. Sixty rats were randomized to five groups: rats with sham operation, rats with BDL, rats with BDL and treated with vehicle, rats with BDL and treated with resveratrol 10 mg/kg and 20 mg/kg. The renal tissue changes of BDL rat were examined by pathology and electron microscope observation. Assay endotoxin levels of plasma in endpoint chromogenic TAL method. The 24 hour urine and serum of rats were used for determining the creatinine clearance rat (Ccr), malonaldehyde (MDA) and superoxide dismutase (SOD) were measured. The renal apoptotic index was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end- labeling (TUNEL). HO-1 protein expression in the kidney was determined by Western blot, HO-1 mRNA expression in the kidney was determined by real-time PCR. And the distribution of HO-1 and tight junction protein ZO-1 and occludin in the kidney was assessed immunohistochemistically.Results:⑴Serum liver function levels of rats established the BDL rats.⑵Renal pathological changes staining by HE shown that there was edematus in renal tubule epidermis in 1 wk BDL rats and was worse in 2 wk.⑶Irregular thickening of glomerular basement membrane, mesangial expansion and fusion of foot processes were observed at 1 wk and was worse more at 2 wk by electron microscope.⑷The endotoxin levels of plasma in sham operation, 1 wk and 2 wk BDL rats were 0.15±0.29, 0.44±0.14 and 0.53±0.03. The plasma endotoxin at 1 wk and 2 wk significantly increased with sham operation (P<0.05).⑸The Ccr were significantly decreased in 2 wk group rats, the urinary albumin excretory rates were increased in 1 wk and 2 wk group rats.⑹MDA in 1 wk and 2 wk sham operation, 1 wk and 2 wk BDL rats were 1.83±0.79, 2.39±0.96,3.88±0.23 and 4.82±0.16. 1 wk and 2 wk significantly increased with sham operation(P<0.05), SOD at 1 wk and 2 wk significantly decreased with sham operation (P<0.05).⑺The protein ZO-1 and occludin in kidney of rats by immunohistochemistry assay: Expression of ZO-1 protein (optical density, OD) in sham operation and 2 wk BDL rats were 0.17±0.00 and 0.10±0.02, 2 wk significantly increased with sham operation. However, there was no statistical difference of ZO-1 protein between the sham operation and 1 wk BDL rats, and that of treated with resveratrol at 2 wk increased with BDL at 2 wk; Expression of occludin protein (OD) in sham operation and 2 wk BDL rats were 0.14±0.01 and 0.09±0.02, the expression of occludin at 2 wk significantly increased with sham operation. However, there was no statistical difference of occludin protein between the sham operation and 1 wk BDL rats, and that of treated with resveratrol at 2 wk increased with BDL at 2 wk.⑻Immunohistochemical analysis: It was found that in the kidney of the 2 wk BDL rat, the numbers of HO-1 positive cells were increased. Expressions of HO-1 protein (optical density) in sham operation, 1 wk and 2 wk BDL rats were (0.07±0.00), (0.08±0.01) and(0.14±0.01), 2 wk significantly increased with 1 wk or sham operation. However, there was no statistical difference of HO-1 protein between the sham operation and 1 wk BDL rats (P=0.18).⑼Western blot analysis: HO-1 expression in sham operation, and 2 wk BDL rats were (0.25±0.07) and (0.63±0.06), the expression of HO-1 at 2 wk significantly increased with 1 wk or sham operation. However, there was no statistical difference of HO-1 protein between the sham operation and 1 wk BDL rats (P=0.61).⑽Real-time PCR analysis: HO-1 mRNA expression in sham operation, 1 wk and 2 wk BDL rats were (1.00±0.00), (1.05±0.03) and (3.76±0.77), the expression of HO-1 mRNA at 2 wk significantly increased with 1 wk or sham operation. However, there was no statistical difference of HO-1 mRNA between the sham operation and 1 wk BDL rats (P=0.97).Conclusions:⑴The mechanism of renal injury induced by BDL in rats includes endotoxemia, oxidative stress, apoptosis.⑵The protein ZO-1, occludin of the renal epithelial cell are decreased in the obstructive jaundice rats.⑶The protein and mRNA of HO-1 in the kindey of obstructive jaundice rats is increased. ⑷Resveratrol has the beneficial effect on renal injury by BDL in rats via inducing the expression of HO-1. |
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