[Effect of Electroacupunctrue Stimulation at "Fenglong"(ST 40) on Expression of SREBP-1 c in Non-alcoholic Fatty Liver Disease Rats].

OBJECTIVE: To observe the effect of electroacupuncture(EA) stimulation at "Fenglong"(ST 40) on expression of sterol regulatory element binding protein-1 c(SREBP-1 c) in non-alcoholic fatty liver disease(NAFLD) rats, so as to reveal its mechanism underlying improving NAFLD. METHODS: Male SD rats were randomly divided into normal diet group, high-fat diet group, ST 40 manual acupuncture (MA) group, ST 40 EA group and "Zusanli"(ST 36) EA group(n=12 in each group). Apart from the normal diet group, rats in other groups were fed with high-fat diet to replicate NAFLD model. ST 40 MA group was treated with filiform needling for 20 min, EA (4 Hz/20 Hz, 5 mA) was applied to bilateral acupoints of ST 40 and ST 36 respectively for 20 min in the ST 40 EA group and ST 36 EA group, once a day for 4 weeks. The pathological changes of hepatic tissue were observed by HE staining. The contents of serum free fatty acid (FFA), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected by colorimetry. The expression of SREBP-1 c mRNA and protein in the hepatic tissue were detected by reverse transcription-polymerase chain reaction(RT-PCR) and Western blot, respectively. RESULTS: HE staining showed that hepatocytes disorganized with diffuse bullous fat vacuolar changes in rats of the high-fat diet group, and small vesicle steatosis appeared in the ST 40 MA group. The liver cells arranged orderly and the steatosis decreased in the ST 40 EA group and ST 36 EA group. The contents of FFA, ALT, AST in serum and the expression levels of SREBP-1 c mRNA and protein in the hepatic tissue were significantly higher in the high-fat diet group than in the normal diet group(P<0.01), while significantly lower in the MA and EA groups than in the high-fat diet group(P<0.01). Furthermore, the effects of treatment in the ST 40 EA group were better than those in the ST 40 MA group(P<0.01, P<0.05). The FFA contents in serum and the expression levels of SREBP-1 c mRNA and protein were decreased in the ST 40 EA group in comparison with the ST 36 EA group(P<0.05). CONCLUSIONS: EA at ST 40 and ST 36 have a positive regulating effect on NAFLD rats, which may be related to down-regulating the expression of SREBP-1 c mRNA and protein in hepatic tissue, improving the endoplasmic reticulum stress and regulating lipid metabolic disorder, so as to relieve the inflammatory injury in hepatic tissue, and ST 40 works better.

Mitochondrial expression and activity of P-glycoprotein under oxidative stress in outer blood-retinal barrier.

AIM: To investigate the role of oxidative stress in regulating the functional expression of P-glycoprotein (P-gp) in mitochondria of D407 cells. METHODS: D407 cells were exposed to different ranges of concentrations of H2O2. The mitochondrial location of P-gp in the cells subjected to oxidative stress was detected by confocal analysis. Expression of P-gp in isolated mitochondria was assessed by Western blot. The pump activity of P-gp was evaluated by performing the efflux study on isolated mitochondria with Rhodamine 123 (Rho-123) alone and in the presence of P-gp inhibitor (Tariquidar) using flow cytometry analysis. The cells were pretreated with 10 mmol/L N-acetylcysteine (NAC) for 30min before exposing to H2O2, and analyzed the mitochondrial extracts by Western blot and flow cytometry. RESULTS: P-gp was co-localized in the mitochondria by confocal laser scanning microscopy, and it was also detected in the mitochondria of D407 cells using Western blot. Exposure to increasing concentrations of H2O2 led to gradually increased expression and location of P-gp in the mitochondria of cells. Rho-123 efflux assay showed higher uptake of Rho-123 on isolated mitochondria in the presence of Tariquidar both in normal and oxidative stress state. H2O2 up-regulated P-gp in D407 cells, which could be reversed by NAC treatment. CONCLUSION: H2O2 could up-regulate the functional expression of P-gp in mitochondria of D407 cells, while antioxidants might suppress oxidative-stress-induced over-expression of functional P-gp. It is indicative that limiting the mitochondrial P-gp transport in retinal pigment epithelium cells would be to improve the effect of mitochondria-targeted antioxidant therapy in age-related macular degeneration-like retinopathy.