OBJECTIVE: To study the protective effect of electroacupuncture (EA) at "Biao"-acupoints, "Fenglong"(ST40) and "Zhongwan"(CV12), used for treating symptoms of the disease, and "Ben"-acupoints, "Zusanli"(ST36) and "Guanyuan"(CV4), for treating the root cause of the disease on oxidative stress injury of renal mitochondria through SIRT1/PGC-1α signal pathway in rats with diabetic nephropathy (DN).
METHODS: A total of 33 male Wistar rats were randomized into normal (=10), model (=12) and EA (=11) groups.The DN model was established by feeding the rats with high-sugar and high-fat diet for 6 weeks combined with streptozotocin (STZ, 35 mg/kg, i.p.). EA (4 Hz/60 Hz, 1 mA)was applied to ST36-ST40 and CV4-CV12 for 15 min, once every other day for 8 weeks. The rats' body weight was recorded, urine in 24 hours (24-h UP) was collected to measure the urine protein level, and the fasting blood glucose (FBG) level detected by using a glucometer. The levels of serum glycosylated hemoglobin (HbA1c), creatinine (Scr) and urea nitrogen (BUN) were assayed using immunoturbidi-metry, picric acid method and urease method, respectively, and those of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) detected using an automatic biochemical analyzer. The kidney tissue was collected for assaying the activity of superoxide dismutase (SOD) with xanthine oxidase method, glutathione (GSH) activity with dithio-dinitrobenzoic acid method, catalase （CAT） activity with ammonium molybdate spectrometric method, and malondialdehyde (MDA) content with thiobarbituric acid method. Histopathological changes of the kidney tissue were observed by microscope after hematoxylin-eosin staining (HE), periodate Schiff staining (PAS) and Masson staining, separately, and its subcellular structure was observed under transmission electron microscopy. The expression levels of renal SIRT1 and PGC-1α mRNAs and proteins were detected by quantitative real-time PCR and Western blot, and the immunoactivity of renal α-smooth muscle actin (α-SMA), and immunofluorescence density of renal collagen Ⅰ (Col Ⅰ), collagen Ⅳ(Col Ⅳ) and fibronec-tin (FN) detected by immunohistochemistry and immunofluorescence assay, respectively. n n n
RESULTS: Compared with the normal group, the levels of FBG, HbA1c, BUN, Scr, 24-h UP, TG, TC, LDL-C, MDA, α-SMA, Col Ⅰ, Col Ⅳ and FN proteins were significantly increased (<0.01), and the levels of body weight, HDL-C, SOD, GSH, CAT, SIRT1 and PGC-1α mRNAs and proteins were decreased in the model group (<0.01,<0.05). In comparison with the model group, the levels of FBG, HbA1c, BUN, Scr, 24-h UP, TG, TC, LDL-C and MDA, and the expressions of α-SMA, Col Ⅰ, Col Ⅳ and FN proteins were markedly down-regulated (<0.05,<0.01), and those of body weight, HDL-C, SOD, GSH, CAT, and the expressions of SIRT1 and PGC-1α mRNAs and proteins significantly up-regulated (<0.01,<0.05) in the EA group. HE staining showed mesangial dilatation, glomerular hypertrophy and mesangial matrix accumulation; PAS staining showed an increase of the glomerular extracellular matrix deposition; and Masson staining displayed an enhancement of glomerular fibrosis and interstitial space expansion; and electron microscope revealed foot process fusion, basement membrane thickening and organelle injury in the rat's kidney of the model group, which were relatively milder in the EA group. P P P P P P P
CONCLUSION: EA of ST36-ST40 and CV4-CV12, "Biao-Ben" acupoints combination, can alleviate oxidative stress and mitochondrial dysfunction in DN rats, which may be associated with its functions in up-regulating SIRT1/PGC-1α signaling, and decreasing renal fibrosis.
