Effect of 4-week electroacupuncture intervention on "Browning" of white fat in rats and its mechanism

Abstract

Objective: To investigate the effects of 4-week electroacupuncture intervention on "Browning" of white fat in rats, and to explore its molecular mechanisms. Methods: Twenty-four 8-week-old male SD rats were randomly divided into sedentary group (Sed), aerobic exercise group (Exe) and electroacupuncture group (ElA), 8 rats in each group. Exe group used 65% Max oxygen uptake intensity treadmill exercise, 1 h/d,6 d/w, while the ElA group used electric acupuncture to stimulate "zusanli" and "tianshu" points, 20 min/d,6 d/w, and the weight of rats was recorded every week. After 4 weeks of intervention, blood samples were collected from the apex and abdominal aorta. The wet weight of scapular fat and perirenal fat of rats was detected and the body fat and the serum levels of Irisin were determined. What's more, the expressions of adenosine 5'-monophosphate activated protein kinase-α (AMPKα), phosphorylation of adenosine 5'-monophosphate activated protein kinase-α (p-AMPKα), peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α), fibronectin type III domain containing 5 (FNDC5) and uncoupling protein (UCP1) and brown adipose tissue lipid droplets in rats were detected. Results: Compared with the Sed group, the weight gain of rats in the Exe and ElA groups was decreased significantly from the second week. After 4 weeks, the body weight and body fat of the Exe and ElA groups were decreased significantly (P＜0.01), while there was no significant difference between the Exe and ElA groups (P＞0.05). ②After 4 weeks of intervention, the white fat wet weight of ElA group and Exe group was significantly was reduced (P＜0.05 or P＜0.01). ③The serum levels of Irisin in Exe and ElA groups were significantly increased (P＜0.05), and the expressions of p-AMPKα/AMPKα, PGC-1α, FNDC5 in the gastrocnemius and the expressions of UCP1 in white fat and brown adipose tissue of Exe and ElA groups were increased (P＜0.05). ④The area of lipid droplets in white and brown adipose tissue of Exe and ElA groups was significantly reduced (P＜ 0.01). Conclusion: 4 weeks of electroacupuncture intervention can effectively control the weight of rats and induce "browning" of white fat, and its effect was similar to aerobic exercise, which may be release Irisin through the AMPKα-PGC-1α-FNDC5-Irisin signaling pathway, and then "crosstalk" with adipose tissue, up-regulate the expression of UCP1, and induce "browning" of white adipose tissue.