The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
目的：探究低强度脉冲超声(Low-intensity pulsed ultrasound, LIPUS)对高脂饮食诱导的肥胖小鼠脂肪细胞肥大及脂肪组织代谢的影响及相关分子机制。方法：采用60%kcal高脂饲料进行食源性肥胖小鼠造模(高脂组,n=20),对照组小鼠食用10%kcal普通饲料(普食组,n=10)。喂食10周后依据体重匹配度随机选取10只高脂肥胖小鼠接受LIPUS辐照,辐照靶区为腹股沟脂肪垫,干预10周后收取小鼠全血,路径皮肤、肌肉,肝,脾,靶区及各内脏脂肪垫。称取小鼠体重、局部脂重,检测血脂来评估小鼠的整体和局部代谢水平；HE染色观察超声靶区脂肪细胞肥大情况；GPO-PAP酶法测定组织内甘油三酯含量；qPCR分析靶区成脂代谢转录因子(PPAR-γ和C/EBPα)、脂解酶转录因子(IRF4、FoxO1)、脂解酶(ATGL和HSL)和脂肪细胞因子(ADPN和LEP)基因mRNA水平；Western blot检测成脂分化调控因子(C/EBPα)、脂解酶(ATGL和HSL)和相关信号通路(PKA和ERK1/2)的蛋白水平,阐明LIPUS起效的可能机制；最后结合血液学指标和靶区组织HE(hematoxylin-eosin, HE)染色评估LIPUS的体内安全性。结果：LIPUS明显改善肥胖小鼠超声靶区脂肪细胞的肥大,下调成脂相关转录因子(PPAR-γ和C/EBPα)表达水平,上调脂解酶相关转录因子(IRF4、FoxO1)mRNA水平,促进脂解酶(ATGL和HSL)转录和翻译水平的表达,并通过激活PKA和ERK1/2使HSL磷酸化促进下游脂解水平。结论：LIPUS通过提高脂解水平,降低成脂相关调控分子表达,改善食源性肥胖小鼠脂肪细胞肥大。
Objective: The aim of this study was to investigate the potential effects and mechanisms of low-intensity pulsed ultrasound (LIPUS) on the metabolism of hypertrophic adipose tissue induced by high-fat diet. Methods: Twenty male mice fed a 60% kcal high-fat diet (HFD group) for 10 weeks as an obesity model, while ten fed a 10% kcal low-fat diet (NC group) as a negative control. Then selected 10 mice randomly matched body weight with HFD group for LIPUS treatment at inguinal fat depot as a LIPUS group. After 10 weeks LIPUS irradiation, the whole blood, skin, muscles and inguinal fat pads at LIPUS region, liver, spleen and representative visceral fat depots. We evaluated the effects of LIPUS on the prevention of a series of disorders through an analysis of plasma biochemical profile, body and fat pads mass, adipocytes size, triglyceride contents and associated genes and proteins expression in inguinal adipose depot. The mRNA expression levels of transcription factors for adipogenic differentiation (PPAR-γ and C/EBPα), transcription factors for ATGL (IRF4, FoxO1), lipolyases (ATGL and HSL) and adipokines (ADPN and LEP) genes in the target region were analyzed by qPCR. Additionally, Western blot was applied to detect the protein levels of C/EBPα, ATGL, HSL and related signaling pathways (PKA and ERK1/2). Furthermore, safety tests on LIPUS were conducted on the basis of complete blood counts and tissue sections at LIPUS site stained with hematoxylin-eosin. Results: LIPUS reduced local adipose hypertrophy at irradiation regions in obese mice through downregulating adipogenic differentiation related transcription factors and upregulating lipolytic enzymes expression and associated transcription factors. In addition, LIPUS stimulated lipolysis via activating PKA and ERK1/2 to phosphorylate hormone sensitive lipase. Conclusion: LIPUS diminishes local adipose tissue hypertrophy induced by high-fat diet through inhibiting adipogenic differentiation and encouraging lipolysis procedure.