Objective To investigate the effect of electroacupuncture (EA) on endothelial dysfunction related to high fat diet (HFD)-induced insulin resistance through the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signalling pathway.
Methods Twenty-four male Sprague-Dawley rats were fed a regular diet (Control group, n=8) or a HFD (n=16) for 12 weeks to induce an insulin resistance model. HFD-fed rats were divided into two groups that remained untreated (HFD group, n=8) or received electroacupuncture (HFD+EA group, n=8). EA was applied at PC6, ST36, SP6 and BL23. At the end of the experiment, fasting blood glucose (FBG), serum insulin (FINS), serum C-peptide (C-P) and homeostatic model assessment of insulin resistance (HOMA-IR) indices were determined. Pancreatic islet samples were subjected to histopathological examination. The thoracic aorta was immunostained with anti-rat insulin receptor substrate (IRS)-1, Akt and endothelial nitric oxide synthase (eNOS) antibodies. mRNA and protein expression of IRS-1, PI3K, Akt2 and eNOS in the vascular endothelium were determined by real-time PCR and Western blot analysis, respectively.
Results The bodyweight increase of the HFD+EA group was smaller than that of the untreated HFD group. Compared with the HFD group, the levels of FBG, FINS, C-P and HOMA-IR in the HFD+EA group decreased significantly (P<0.01). Histopathological evaluation indicated that EA improved pancreatic islet inflammation. The expression of endothelial markers, such as IRS-1, PI3K, Akt2 and eNOS, decreased in the HFD group, while EA treatment appeared to ameliorate the negative impact of diet.
Conclusion EA may improve insulin resistance and attenuate endothelial dysfunction, and therefore could play a potential role in the prevention or treatment of diabetic complications and cardiovascular disease through the PI3K/Akt signalling pathway.
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DL and WY contributed equally.
Contributors WY, NX, DL and JS conceived and designed the experiments. DL, ZL, HZ and XL performed the experiments. DL and RL analysed the data. DL, NX and WY wrote the paper. All authors read and approved the final version of the manuscript accepted for publication.
Funding National Natural Science Foundation of China (grant no. 81273845).
Competing interests None declared.
Ethics approval All research protocols were approved by the Experimental Animal Committee of Guangzhou University of Chinese Medicine (reference no. S2015019) and were conducted in accordance with local guidelines for animal welfare consistent with the National Institutes for Health ‘Guide for the Care and Use of Laboratory Animals’.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The authors are willing to share the data generated by this study. Please contact the corresponding author WY at firstname.lastname@example.org.