支链氨基酸代谢在糖肽类和环脂肽类抗生素产量提高与组分优化中的应用

摘要：糖肽类和环脂肽类抗生素具有很好的抗菌活性,临床上广泛用于治疗多重耐药菌导致的严重感染。大部分糖肽类和 环脂肽类抗生素均含有带支链结构的脂肪酸侧链,侧链结构差异是导致这两类抗生素发酵组分多样性的主要原因。支链脂肪酸 侧链的合成起始于支链氨基酸分解代谢,调控支链氨基酸代谢对于定向合成含有特定脂肪酸侧链的糖肽类和环脂肽类抗生素具 有重要作用。本文从糖肽类和环脂肽类抗生素中脂肪酸侧链的生源途径、外源添加支链氨基酸对糖肽类和环脂肽类抗生素产量 和组分的影响,内部改造支链氨基酸代谢途径对糖肽类和环脂肪肽类抗生素产量和组分的影响3方面进行了综述。     

Regulation of microbiota–GLP1 axis by sennoside A in diet-induced obese mice

Sennoside A (SA) is a bioactive component of Chinese herbal medicines with an activity of irritant laxative, which is often used in the treatment of constipation and obesity. However, its activity remains unknown in the regulation of insulin sensitivity. In this study, the impact of SA on insulin sensitivity was tested in high fat diet (HFD)-induced obese mice through dietary supplementation. At a dosage of 30 mg/kg/day, SA improved insulin sensitivity in the mice after 8-week treatment as indicated by HOMA-IR (homeostatic model assessment for insulin resistance) and glucose tolerance test (GTT). SA restored plasma level of glucagon-like peptide 1 (GLP1) by 90% and mRNA expression of Glp1 by 80% in the large intestine of HFD mice. In the mechanism, SA restored the gut microbiota profile, short chain fatty acids (SCFAs), and mucosal structure in the colon. A mitochondrial stress was observed in the enterocytes of HFD mice with ATP elevation, structural damage, and complex dysfunction. The mitochondrial response was induced in enterocytes by the dietary fat as the same responses were induced by palmitic acid in the cell culture. The mitochondrial response was inhibited in HFD mice by SA treatment. These data suggest that SA may restore the function of microbiota–GLP1 axis to improve glucose metabolism in the obese mice.     

Branched-chain amino acids increase the seizure threshold to picrotoxin in rats.

During infusion of branched-chain amino acids (BCAAs) in humans, changes in ventilatory drive, appetite, and sleep have been reported. The mechanism by which BCAAs exert their effects on CNS remains unclear. Picrotoxin is a proconvulsant drug, acting as an antagonist on the GABA-benzodiazepine receptor complex. Twenty rats were randomized to receive either an IP injection with 4% BCAAs (300 mg/kg; 8 ml/kg) (n = 10) or placebo (saline 8 ml/kg) (n = 10). The mean latency time from injection to onset of seizures was recorded as an indication of the seizure threshold. Latency time was significantly longer for BCAAs than for placebo, 11.2 (+/- 1.9) vs. 8.3 (+/- 1.8) min. Thus, a BCAA injection increased the seizure threshold to picrotoxin (p < 0.03). This suggests that BCAA infusion may exert effects on the GABA-benzodiazepine receptor complex.     

小檗碱——抗能量代谢紊乱的新机制药物（英文）

Berberine(BBR)is a natural compound isolated from Coptis chinensis and for decades an over-the-count medicine in China for bacterial-caused diarrhea.We have identified BBR to be an effective drug in treating hyperlipidemia as well as hyperglycemia.Clinical studies showed that oral administration of BBR caused significant reduction of blood cholesterol,LDL-c,triglyceride,as well as glucose and HbA1c in patients with hyperlipidemia or T2D.A small%of patients have minor and transient side-effect in the GI system.The cholesterol-lowering effect was associated with the ERK mediated LDLR m RNA up-regulation;the glucose-lowering effect mainly resulted from PKD-mediated insulin receptor expression as well as activation of AMPK.The clinical efficacy of BBR were verified by a large number of independent clinical groups in and outside China.For BBR absorption mechanism,we showed that BBR was first converted into dh BBR by nitroreductase in the gut microbiota,promoting BBR enter into intestinal well,where it was oxidized back to BBR,and then got into blood.Our recent study showed that BBR could also promote gut microbiota pathways to make SCFAs(such as butyrate),which entered blood and reduced blood lipids and glucose,suggesting a newly identified MOA of BBR.BBR is now in clinical trial in China.We consider it a multiple-target drug for metabolic disorders in clinic.     

Effect of decreased BCAA synthesis through disruption of <Emphasis Type="Italic">ilvC</Emphasis> gene on the virulence of <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis>

Streptococcus pneumoniae (pneumococcus) is responsible for significant morbidity and mortality worldwide. It causes a variety of life-threatening infections such as pneumonia, bacteremia, and meningitis. In bacterial physiology, the metabolic pathway of branched-chain amino acids (BCAAs) plays an important role in virulence. Nonetheless, the function of IlvC, one of the enzymes involved in the biosynthesis of BCAAs, in S. pneumoniae remains unclear. Here, we demonstrated that downregulation of BCAA biosynthesis by ilvC ablation can diminish BCAA concentration and expression of pneumolysin (Ply) and LytA, and subsequently attenuate virulence. Infection with an ilvC mutant showed significantly reduced mortality and colonization in comparison with strain D39 (serotype 2, wild type), suggesting that ilvC can potentiate S. pneumoniae virulence due to adequate BCAA synthesis. Taken together, these results suggest that the function of ilvC in BCAA synthesis is essential for virulence factor and could play an important role in the pathogenesis of respiratory infections.     

胰岛素抵抗小鼠肠道菌群与FGF21的相关性研究

目的研究糖耐量正常人粪菌液移植(fecal bacteria transplantation,FMT)对胰岛素抵抗(insulin resistance,IR)小鼠肠道菌群的影响及其与成纤维细胞生长因子21(fibroblast growth factor 21,FGF21)的相关性,探究肠道菌群影响IR的可能机制。方法采用高脂饮食建立IR模型,筛选30只建模成功的小鼠随机分成3组:IR组、IR+二甲双胍(Met)组、IR+粪菌液移植(FMT)组,及空白对照(Control)组,每组10只。给药8周,记录第8周小鼠的体质量、空腹血糖;采用RT-qPCR检测粪样中靶标菌的数量,肝脏、结肠、回肠中FGF21及其受体mRNA表达水平。结果①与Control组比较,IR组小鼠体质量和空腹血糖升高,肝脏、结肠和回肠中FGF21/β-Klotho/FGFR1/FGFR4 mRNA表达降低,粪样中Bacteroides、B.sartorii降低,P.distasonis、M.schaedleri、R.gnavus升高,Met、FMT干预后上述指标均逆转。②FGF21的表达与FBG、P.distasonis、M.schaedleri、R.gnavus呈负相关,与Bacteroides、B.sartorii呈正相关。结论FMT可增加FGF21的表达量和调节肠道菌群,且二者密切相关,可能是FMT改善胰岛素抵抗的重要机制之一。     

Clinical significance and potential role of trimethylamine N-oxide in neurological and neuropsychiatric disorders

In the past three decades, research on the gut microbiome and its metabolites, such as trimethylamines (TMA), trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), bile acids, tryptophan and indole derivatives, has attracted the attention of many scientists and industrialists. Among these metabolites, TMAO is produced from dietary choline, phosphatidylcholine, carnitine, and betaine. TMAO and other gut metabolites, such as TMA and SCFAs, reach the brain by crossing the blood–brain barrier (BBB) and are involved in brain development, neurogenesis, and behavior. Gut-microbiota composition is influenced by diet, lifestyle, antibiotics, and age. Several studies have confirmed that altered TMAO levels contribute to metabolic, vascular, psychiatric, and neurodegenerative disorders. This review focuses on how altered TMAO levels impact oxidative stress, microglial activation, and the apoptosis of neurons, and may lead to neuroinflammation, which can subsequently result in the development of psychiatric, cognitive, and behavioral disorders.     

Effects of the Combination of Evogliptin and Leucine on Insulin Resistance and Hepatic Steatosis in High-Fat Diet-Fed Mice

In this study, we aimed to investigate the effects of 8 weeks of treatment with a combination of evogliptin and leucine, a branched-chain amino acid, in mice with high-fat diet (HFD)-induced diabetes. Treatment with evogliptin alone or in combination with leucine reduced the body weight of the mice, compared to the case for those from the HFD control group. Long-term treatment with evogliptin alone or in combination with leucine resulted in a significant reduction in glucose intolerance; however, leucine alone did not affect postprandial glucose control, compared to the case for the mice from the HFD control group. Furthermore, the combination of evogliptin and leucine prevented HFD-induced insulin resistance, which was associated with improved homeostasis model assessment for insulin resistance, accompanied by markedly reduced liver fat deposition, hepatic triglyceride content, and plasma alanine aminotransferase levels. The combination of evogliptin and leucine increased the gene expression levels of hepatic peroxisome proliferator-activated receptor alpha, whereas those of the sterol regulatory element-binding protein 1 and stearoyl-CoA desaturase 1 were not altered, compared to the case in the HFD-fed mice (p<0.05). Thus, our results suggest that the combination of evogliptin and leucine may be beneficial for treating patients with type 2 diabetes and hepatic steatosis; however, further studies are needed to delineate the molecular mechanisms underlying the action of this combination.     

高脂饮食对大鼠胰岛素抵抗及氧化损伤指标的影响及意义

目的建立胰岛素抵抗(IK)大鼠模型并观察氧化应激指标的变化。方法将SD大鼠随机分为正常对照组(NC)及高脂饮食组(HFD),分别予普通饮食及高脂饮食6周,用高胰岛素正常血糖钳夹技术评价胰岛素敏感性;检测总抗氧化能力(TAOC)、超氧化物歧化酶(SOD)、丙二醛(MDA)等氧化应激指标,同时检测血总胆固醇(TC)、甘油三酯(TG)、游离脂肪酸(FFA)及胰岛素(Ins)水平。结果与NC组相比,HFD组的大鼠体重、血压、血糖、胰岛素水平明显高于NC组(P<0.05),而钳夹试验的结果显示IR组的葡萄糖输注率(GIR)低于NC组;HFD组出现明显的血脂代谢异常,TC、TG及FFA均高于NC组;HFD组MDA高于NC组,但TAOC和SOD却低于NC组。结论持续6周高脂饮食可成功复制胰岛素抵抗大鼠模型,IR状况下机体存在明显的氧化损伤。     

PPAR gamma agonists partially restores hyperglycemia induced aggravation of vascular dysfunction to angiotensin II in thoracic aorta isolated from rats with insulin resistance.

Altered vascular responses to various vasopressors in animal models of insulin resistance (IR) and diabetes have been well documented. However, the precise mechanisms about vascular responses in IR with or without frank hyperglycemia (prediabetic state) are not available. Moreover, recently the role of peroxisome proliferators activated receptor-gamma (PPAR gamma) has been linked to influence the vascular responses in hypertensive and diabetic state. Hence, the present study was conceived to determine the role of hyperglycemia on angiotensin II (Ang II) mediated vascular responses in the high fat diet (HFD) induced insulin resistance either with mild or frank hyperglycemia [induced by injection of low dose streptozotocin (STZ) to HFD fed rats (HFD+STZ)]. In addition, insulin-sensitizing agent such as rosiglitazone and pioglitazone were also studied on biochemical and vascular responses. Ang II-induced contractions were studied isometrically in thoracic aortic rings isolated from 4 weeks of normal pellet diet (NPD) fed control, HFD and HFD+STZ fed insulin resistant rats. Specific binding of Ang II receptors were carried out using radioligand ([(3)H]-Ang II) binding studies. After 4 weeks of HFD feeding, rats exhibited characteristics features of insulin resistance such as mild hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypercholesterolemia and hypertension; whereas HFD+STZ treated rats showed all above parameters along with frank hyperglycemia. Maximal contractile response (E(max)) to Ang II is increased in HFD fed rats as compared to control rats. Moreover, E(max) values are further elevated in HFD+STZ group where the frank hyperglycemia was induced by low dose of streptozotocin. Rosiglitazone (5 mg kg(-1), p.o.) and pioglitazone (10 mg kg(-1), p.o.) treatment significantly lowered the plasma glucose, triglycerides, insulin and cholesterol levels in insulin resistance rats. In addition, it also restored the elevated systolic, mean arterial, diastolic blood pressure and attenuated the enhanced contractile responses to Ang II in thoracic aortic rings obtained from both HFD and HFD+STZ treated rats. Specific binding of [(3)H]-Ang II is upregulated in HFD-fed and HFD+STZ treated rats. Treatment with pioglitazone and rosiglitazone significantly decreased the AT(1)R specific binding in HFD fed rats. Our results indicate the role of hyperglycemia in the elevation of Ang II induced vascular responses in thoracic aorta isolated from insulin resistant rats and PPAR gamma agonists can attenuate these responses.     

黄连素抑制FSP27基因表达改善2型糖尿病地鼠内脏白色脂肪组织胰岛素抵抗的研究

摘要：目的 研究黄连素（BBR）对2型糖尿病（T2DM）中国地鼠内脏白色脂肪组织（VWAT）中脂肪特异蛋白27（FSP27）和PR结构域蛋白16 （PRDM16）信号通路基因mRNA表达的影响并探讨相关机制。方法 以高脂饮食诱导肥胖胰岛素抵抗（OIR）地鼠模型,然后给予小剂量链脲菌素建立T2DM地鼠模型,对照组喂以普通饲料。造模完成后随机分成对照组、OIR组、肥胖T2DM组和T2DM BBR组。BBR治疗9周后,应用实时定量PCR方法检测各组地鼠VWAT中FSP27和PRDM16信号通路及其靶基因的mRNA表达改变。结果 与对照组相比,OIR组和肥胖T2DM组地鼠VWAT中PRDM16、CtBP-1、CtBP-2、C/EBPβ、PPARγ、PGC1α、PGC-1β及棕脂组织特异基因UCP-1、Cidea、Elovl3、PPARα及Acox、Cpt1和Acadm的mRNA表达降低,而FSP27和白脂组织特异基因Resistin、MEST和Serpina3k的mRNA表达增加。BBR治疗降低肥胖T2DM组地鼠VWAT中FSP27的表达而增强PRDM16信号通路效应,诱导棕脂组织特异基因mRNA的表达,诱导VWAT棕色化基因表型,改善脂诱性胰岛素抵抗。结论 BBR降低FSP27表达而增加PRDM16的表达与其诱导VWAT棕色化的分子机制相关,有助于增强产热耗能, 改善VWAT的异常脂代谢,改善FIVWATIR,恢复VWAT的功能。     

Sarsasapogenin improves adipose tissue inflammation and ameliorates insulin resistance in high-fat diet-fed C57BL/6J mice

Insulin resistance is a major cause of type 2 diabetes and metabolic syndrome.Macrophage infiltration into obese adipose tissue promotes inflammatory responses that contribute to the pathogenesis of insulin resistance.Suppression of adipose tissue inflammatory responses is postulated to increase insulin sensitivity in obese patients and animals.Sarsasapogenin(ZGY)is one of the metabolites of timosaponin AIII in the gut,which has been shown to exert anti-inflammatory action.In this study,we investigated the effects of ZGY treatment on obesity-induced insulin resistance in mice.We showed that pretreatment with ZGY(80 mg·kg^?1·d^?1,ig,for 18 days)significantly inhibited acute adipose tissue inflammatory responses in LPS-treated mice.In high-fat diet(HFD)-fed obese mice,oral administration of ZGY(80 mg·kg^?1·d^?1,for 6 weeks)ameliorated insulin resistance and alleviated inflammation in adipose tissues by reducing the infiltration of macrophages.Furthermore,we demonstrated that ZGY not only directly inhibited inflammatory responses in macrophages and adipocytes,but also interrupts the crosstalk between macrophages and adipocytes in vitro,improving adipocyte insulin resistance.The insulin-sensitizing and anti-inflammatory effects of ZGY may result from inactivation of the IKK/NF-κB and JNK inflammatory signaling pathways in adipocytes.Collectively,our findings suggest that ZGY ameliorates insulin resistance and alleviates the adipose inflammatory state in HFD mice,suggesting that ZGY may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.     

Long-lasting partnership between insulin resistance and endothelial dysfunction: role of metabolic memory

Background and Purpose

The persistence of deleterious effects of hyperglycaemia even after glucose normalization is referred to as ‘metabolic memory’. However, similar persistent effects of the metabolic consequences of a high fat diet (HFD) have not been described.

Experimental Approach

Rats were given a normal pellet diet (NPD) or a HFD for 3 months. The animals from the HFD group were then returned to the NPD to observe the long-term effects of insulin resistance. Endothelial dysfunction was assessed by carbachol-mediated vasorelaxation and eNOS phosphorylation.

Key Results

As expected, HFD consumption resulted in insulin resistance and endothelial dysfunction. Phosphorylation of eNOS at S1177 was decreased in HFD rats, compared with that in the NPD group. Rats on 3 months of HFD showed glucose intolerance and impaired insulin sensitivity and were then switched back to NPD (REV group). Levels of cholesterol and triglyceride, and adiposity returned to normal in REV rats. However, endothelium-dependent vascular responses to carbachol which were impaired in HFD rats, continued to be impaired in REV rats. Similarly, decreased eNOS phosphorylation after HFD was not improved after 1 or 6 months of REV.

Conclusions and Implications

Our data indicate that returning to NPD did not improve the insulin sensitivity or the endothelial dysfunction induced by HFD. Although some biochemical parameters responsible for insulin resistance and endothelial dysfunction were normalized, molecular and vascular abnormalities, involving NO, persisted for several months, highlighting the long-lasting effects of metabolic memory.     

内质网应激对Nrf2抗氧化系统调控与高脂诱导的胰岛素抵抗发病机理研究

目的：探讨内质网应激对氧化还原平衡作用及其诱导胰岛素抵抗机制信号机理。方法随机将30只C57BL／6J小鼠分为低脂饲料对照组（LFD组,n＝10）和高脂饲料模型组（HFD组,n＝20）,14周后,经葡萄糖耐量试验（IPGTT）确定胰岛素抵抗模型成功后,HFD 组随机选出10只开始进行4-PBA药物干预（HFD＋PBA 组,n ＝10）,持续1周后检测小鼠葡萄糖耐量（IPGTT）、肌肉和肝脏及相应组织线粒体中丙二醛（ MDA）含量;Western blot检测肌肉和肝脏组织中胰岛素信号、内质网应激信号和Nrf2内源性抗氧化系统相关蛋白的表达。结果4-PBA干预组胰岛素抵抗明显减轻,PTEN蛋白受到抑制从而上调胰岛素信号（ PKB Ser473）;4-PBA干预组MDA水平明显下降,Nrf2系统信号增强;高脂组Keap1蛋白明显上调,而4-PBA干预则减弱这一变化。结论内质网应激造成氧化应激并通过上调 PTEN蛋白和抑制 Nrf2抗氧化系统参与胰岛素抵抗。     

Crucial roles of Nox2-derived oxidative stress in deteriorating the function of insulin receptors and endothelium in dietary obesity of middle-aged mice

Background and Purpose

Systemic oxidative stress associated with dietary calorie overload plays an important role in the deterioration of vascular function in middle-aged patients suffering from obesity and insulin resistance. However, effective therapy is still lacking.

Experimental Approach

In this study, we used a mouse model of middle-aged obesity to investigate the therapeutic potential of pharmaceutical inhibition (apocynin, 5 mM supplied in the drinking water) or knockout of Nox2, an enzyme generating reactive oxygen species (ROS), in high-fat diet (HFD)–induced obesity, oxidative stress, insulin resistance and endothelial dysfunction. Littermates of C57BL/6J wild-type (WT) and Nox2 knockout (KO) mice (7 months old) were fed with a HFD (45% kcal fat) or normal chow diet (NCD, 12% kcal fat) for 16 weeks and used at 11 months of age.

Key Results

Compared to NCD WT mice, HFD WT mice developed obesity, insulin resistance, dyslipidaemia and hypertension. Aortic vessels from these mice showed significantly increased Nox2 expression and ROS production, accompanied by significantly increased ERK1/2 activation, reduced insulin receptor expression, decreased Akt and eNOS phosphorylation and impaired endothelium-dependent vessel relaxation to acetylcholine. All these HFD-induced abnormalities (except the hyperinsulinaemia) were absent in apocynin-treated WT or Nox2 KO mice given the same HFD.

Conclusions and Implications

In conclusion, Nox2-derived ROS played a key role in damaging insulin receptor and endothelial function in dietary obesity after middle-age. Targeting Nox2 could represent a valuable therapeutic strategy in the metabolic syndrome.     

黄连素对2型糖尿病地鼠内脏脂肪组织RIP140调控通路基因mRNA表达的影响

目的：研究黄连素（BBR）对肥胖2型糖尿病（OT2DM）中国地鼠内脏白色脂肪组织（VWAT）中受体相互作用蛋白140（Receptor-interacting protein 140,RIP140）/PR结构域蛋白16 （PR domain containing 16,PRDM16） 信号通路基因mRNA表达的影响及相关机制。方法：以高脂饮食诱导肥胖胰岛素抵抗（OIR）地鼠模型,然后给予小剂量链脲菌素（STZ）建立OT2DM地鼠模型。造模完成后随机分成对照组、OIR组、OT2DM组和OT2DM BBR治疗组。BBR治疗9周,应用real-time RT-PCR技术检测各组地鼠VWAT中RIP140/PRDM16信号通路基因mRNA表达改变。结果：模型地鼠VWAT中RIP140、PKCε、PRMT1、Exportin1和白脂组织特异基因Resistin和Serpina3k的mRNA表达增加,而PRDM16、CtBP-1、CtBP-2、C/EBPβ、PPARγ、PGC-1α、PGC-1β、Gyk、GPDH、AQP7、GLUT4及棕脂组织特异基因UCP-1、Cidea、Elovl3和PPARα的mRNA表达降低。BBR治疗抑制VWAT中RIP140调控通路,诱导PRDM16信号通路,诱导棕脂组织特异基因mRNA的表达,抑制白色脂肪选择性基因的表达,诱导VWAT棕色化,改善脂诱性胰岛素抵抗（FIIR）。结论：RIP140/PRDM16信号通路参与BBR诱导VWAT棕色化的分子机制。     

小檗碱的故事（英文）

Berberine(BBR)is an alkaloid from plants like Coptis chinensis and is for many years an OTC drug in China for bacterial-caused diarrhea.We have identified BBR to be an effective drug in treating hyperlipidemia as well as hyperglycemia.Clinical studies showed that oral administration of BBR caused significant reduction of blood cholesterol,triglyceride as well as glucose in patients with hyperlipidemia and T2D,with no obvious side-effect.Mechanism studies have identified several molecular mechanisms involving in the mode of action of BBR.The cholesterol-lowering effect was associated with the extracellular-signalregulated kinase(ERK)mediated LDLR mRNA up-regulation;the glucose-lowering effect mainly resulted from the protein kinase D mediated InsR expression and the activation of AMPK.The observed reduction of triglyceride by BBR might reflect its synergistic effect on both sugar and lipid metabolism.The interaction between gut microbiota and BBR explained the molecular mechanism of BBR′s intestinal absorption.BBR concentrated in liver after oral administration with a level many times more than that in blood.At least three CYP450 subtypes were responsible for BBR phase-Ⅰ metabolism.Structure-activity relationship of BBR was analyzed,and the clinical advantage of BBR was demonstrated.We consider BBR a new medicine for metabolic disorders.     

AMPK-ULK1 mediated autophagy contributed to myocardial injury by BCAA with a ROS independent pathway

OBJECTIVE Leucine, isoleucin and valine,which are derived from the diet, are essential amino acids termed branched-chain amino acids(BCAA). BCAA promotes protein synthesis and has an anti-decomposition effect, which can prevent protein decomposition and muscle loss, and are important nutrients that are essential for normal growth and function of the cell and organism.However, researchers discovered that higher concentrations of BCAA were associated with increased risk of cardiovascular disease, and could promote oxidative stress. This work was designed to demonstrate that BCAA resulted in myocardial injury, and the role of autophagy and oxidative stress in BCAA inducing myocardial injury and possible mechanisms. METHODS Mice were randomly divided into two groups: the control(fed with the solvent, water); the BCAA group(fed with 2% BCAA solved in water), for successive 12 weeks. RESULTS BCAA feeding did not change body weight, diet consumption with significantly increased water uptake. For the mice fed with BCAA mixture water, the content of BCAA in the cardiac tissues was remarkably increased. The myocardial injury markers, including CK, CK-MB and LDH in serum or CRP and CTn-T in cardiac tissues,were obviously increased in the BCAA group. Severe myocardial fibrosis was observed in the BCAA group by Masson staining, accompanied with increased ROS and decreased SOD activity in the cardiac tissues, indicating that elevated BCAA levels cause severe myocardial fibrosis and oxidative stress in mice. Expression of both p-AMPK and p-ULK1 were significantly increased together with enhanced autophagy by detecting the autophagy markers(LC3) using Western blotting and LC3 immunofluorescence staining. Transmission electron microscopy displayed increased number of autophagosomes in the BCAA group. In vitro, BCAA 20 mmol · L~(-1) strikingly increased the ROS production and decreased cel viability in cultured H9C2 cells, which were reversed by the ROS scavenger N-acetyl-L-cysteine(NAC). In addition, BCAA 20 mmol·L~(-1) decreased cel viability in cultured H9C2 cel s also reversed either by the AMPK blockers(Compound C and STO-609) or the ULK1 inhibitor(SBI-0206965, siRNA-ULK1).Furthermore, blocking AMPK or ULK1 decreased the enhanced expression of p-AMPK/AMPK, p-ULK1/ULK1,and LC3-Ⅱ/LC3-Ⅰ induced by BCAA. CONCLUSION BCAA could induce myocardial injury by excessive ROS production and enhancement of autophagy via an AMPK-ULK1 pathway; inhibiting either ROS or autophagy could alleviate myocardial cell injury induced by BCAA.