Electric stimulation of ears accelerates body weight loss mediated by high-fat to low-fat diet switch accompanied by increased white adipose tissue browning in C57BL/6\u2009J mice

Szu-Han Chen,Ching-Liang Hsieh,Pei-Min Chao,Hsiao-Chien Chen

doi:10.1186/s12906-018-2388-1

Abstract

BackgroundWeight reduction frequently occurs in patients receiving vagus nerve stimulation (VNS) therapy. Therefore, we hypothesized that during dietary intervention for weight loss, auricular electric stimulation (AES), an alternative of VNS, accelerates weight loss by increasing white adipose tissue (WAT) browning and increases energy expenditure.MethodsC57BL/6J male mice were fed a high-fat diet for 5 wk. to induce obesity, then switched to a low-fat diet for 5 wk. and allocated into 3 groups to receive 2 Hz electric stimulation on ears, electrode clamps only, or nothing (AES, Sham and Ctrl, respectively).ResultsSwitching to a low-fat diet reduced body weight progressively in all 3 groups, with the greatest reduction in the AES group. In accordance with a mild decrease in feed intake, hypothalamus mRNA levels of Npy, AgRP tended to be reduced, while Pomc tended to be increased by AES. Mice in the AES group had the highest concentrations of norepinephrine in serum and inguinal WAT, and expression levels of uncoupling protein-1 (UCP-1) and tyrosine hydroxylase in inguinal WAT. Furthermore, their subcutaneous adipocytes had multilocular and UCP-1+ characteristics, along with a smaller cell size.ConclusionAES, by increasing WAT browning, could be used in conjunction with a low-fat diet to augment weight loss in addition to suppressing appetite.

Highlights

Weight reduction frequently occurs in patients receiving vagus nerve stimulation (VNS) therapy
Effects of auricular electric stimulation (AES) on weight reduction As expected, body weight was linearly increased by a high-fat diet, whereas switching to a low-fat diet caused a rapid decrease in body weight at the 2nd wk., followed by less rapid declines, irrespective of AES or not (Fig. 1b)
When body weight change (Δ) were calculated and expressed as cumulative weight loss from baseline, there was a trend of AES > Sham>Ctrl across the 5-wk weight reduction period, with a difference (AES vs. Ctrl, P < 0.05) at the last week (Fig. 1c)

Summary

Introduction

Weight reduction frequently occurs in patients receiving vagus nerve stimulation (VNS) therapy. We hypothesized that during dietary intervention for weight loss, auricular electric stimulation (AES), an alternative of VNS, accelerates weight loss by increasing white adipose tissue (WAT) browning and increases energy expenditure. Obesity is a worldwide epidemic and is causally linked with many chronic diseases [1]. Adherence to the principle of weight reduction, namely eating less and exercising more, Electrical stimulation of the vagus nerve (VNS), approved by the Food and Drug Administration (FDA) for treating refractory epilepsy and resistance depression, is known to cause weight loss [2,3,4,5,6].

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