| Backgrounds:Renal ischemia reperfusion (IR) is an inevitable pathological process which commonly occurs during kidney transplantation and causes acute kidney injury. The most important pathophysiology of such injury is the following inflammation and tubular epithelial cell apoptosis. The cytoprotective properties of baicalin, a flavonoid glycoside isolated from traditional chinese drug Scutellaria baicalensis, have been verified in various diseases and widely accepted for clinical treatment. But it remained unclear whether it can protect kidney from IRI. This study aims to investigate the protective effect of baicalin against renal IRI in rats.Methods:Male Wistar rats weighing200-250g were used for this study. Rats were randomly divided into five group (n=6):(ⅰ) Sham group;(ⅱ) IR+saline group;(ⅲ) IR+baicalin (1mg/kg) group;(ⅳ) IR+baicalin (10mg/kg) group;(ⅴ) IR+baicalin (100mg/kg) group. Renal ischemia-reperfusion injury was induced by a45minutes clamping of left renal arteries with right nephrectomy. In treatment groups, baicalin diluted in sterile saline was injected intraperitoneally30minutes before surgery. Baicalin at doses of1,10,100mg/kg was applied. Sham-operated animals underwent the same surgical procedure without clamping. Rats were sacrificed24h after reperfusion. Serum creatinine and blood urea nitrogen were examined. HE staining and TUNEL staining were performed. Messenger RNA level of inflammatory factors (IL-1β, IL-6, TNF-α) was detected through real time PCR. Activity of caspase-3was evaluated by colorimetric assay. Expression of NF-κB, p-NF-κB, IκB, p-IκB, caspase-3, cleaved caspase-3, caspase-9, bcl-2and bax were evaluated by western blot.Results:Compared with IR group,10mg/kg B group and100mg/kg B group have better kidney function. Serum creatinine (47.17±6.05vs.79.67±8.71μmol/L, p<0.001;39.00±6.16vs.79.67±8.71μmol/L, p <0.001) and blood urea nitrogen (16.18±0.71vs.22.37±3.87mmol/l,p <0.01;12.15±0.78vs.22.37±3.87mmol/l, p<0.001) were significantly down-regulated. The HE staining showed significant alleviation of kidney injury after baicalin treatment:fewer urinary cylinder, milder inflammation and tubular edema. Higher concentration of baicalin leads to lower HE score which represent better protection (2.58±0.12vs.2.83±0.12, p<0.01;2.32±0.17vs.2.83±0.12, p<0.001). TUNEL assay showed less apoptosis of tubular epithelial cells in10mg/kg B group and100mg/kg B group (3.87±0.67vs.6.75±0.91, p<0.001;3.43±0.85vs.6.75±0.91, p<0.001). Level of IL-1β(19.03±0.95vs.55.35±4.12, p<0.001;12.27±1.50vs.55.35±4.12, p<0.001), IL-6(4.29±0.59vs.24.92±5.80, p<0.001;3.08±0.61vs.24.92±5.80, p<0.001), and TNF-α(1.67±0.23vs.18.73±4.49, p<0.001;1.75±0.41vs.18.73±4.49, p<0.001) mRNA was also down-regulated through real time PCR assay. Western analysis also provided evidences of anti-inflammation and anti-apoptosis evidences in these two groups. The p-NF-κB and p-IκB protein were decreased, which suggested the inhibition of NF-κB pathway. The caspase-3, cleaved caspase-3, caspase-9, bax protein were down-regulated and bcl-2protein was up-regulated, which suggested the inhibition of mitochondria mediated apoptosis.Conclusions:According to mentioned data, we came to a conclusion that baicalin has protective effects against rat kidney IRI. The protection is related to the anti-inflammation and anti-apoptosis effects of baicalin. As a key inflammatory pathway during kidney IRI, NF-κB pathway was significantly inhibited after baicalin treatment. Mitochondria mediated apoptosis was the dominant apoptosis pathway of tubular epithelial cells during kidney IRI which directly mediated kidney function loss. This pathway is inhibited after baicalin treatment. Thus, baicalin at doses of10and100mg/kg can attenuate renal ischemia reperfusion injury through inhibition of NF-κB mediated inflammation and mitochondria mediated tubular epithelial cell apoptosis. |
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