Electroacupuncture combined with acarbose improves insulin sensitivity via peroxisome proliferator–activated receptor γ activation and produces a stronger glucose-lowering effect than acarbose alone in a rat model of steroid-induced insulin resistance

Abstract

Background: Previous studies have reported that electroacupuncture (EA) induces a glucose-lowering effect by improving insulin resistance (IR) and reduces plasma free fatty acid (FFA) levels in rats with steroid-induced insulin resistance (SIIR). In addition, EA can activate cholinergic nerves and stimulate endogenous opioid peptides to lower plasma glucose in streptozotocin-induced hyperglycemic rats. The aim of this study was to investigate the glucose-lowering effects of 15 Hz EA at bilateral ST36 in combination with acarbose (ACA). We hypothesized that EA combined with ACA would produce a stronger glucose-lowering effect than ACA alone. Methods: In this study, normal Wistar rats and SIIR rats were randomly divided into two groups: ACA and ACA + EA. To explore the potential mechanisms underlying the glucose-lowering effect, plasma FFA/insulin and insulin transduction signal pathway proteins were assayed. Results: Combined ACA + EA treatment had a greater glucose-lowering effect than ACA alone in normal Wistar rats (−45% ± 3% vs −19% ± 3%, p < 0.001) and SIIR model rats (−43% ± 2% vs −16% ± 6%, p < 0.001). A significant reduction in plasma FFA levels, improvement in homeostatic model assessment of IR (HOMA-IR) index (−48.9% ± 4.0%, p < 0.001) and insulin sensitivity index (102% ± 16.9%, p < 0.001), and significant increases in insulin receptor substrate 1, glucose transporter 4, and peroxisome proliferator–activated receptor γ protein expressions in skeletal muscle, were also observed in the ACA + EA group of SIIR rats. Conclusion: Combined EA and ACA therapy had a greater glucose-lowering effect than ACA monotherapy; this combined therapy could be more effective at improving IR in SIIR rats, which may be related to a reduction in plasma FFA levels and an elevation of insulin signaling proteins. Whether this combined therapy has an effect in type 2 diabetes mellitus (T2DM) patients still needs to be explored.