A high ratio of dietary n-3/n-6 polyunsaturated fatty acids improves obesity-linked inflammation and insulin resistance through suppressing activation of TLR4 in SD rats.
Dietary ratios of n-3/n-6 polyunsaturated fatty acids (PUFAs) have been implicated in controlling markers of metabolic disorders, including obesity, insulin resistance (IR), inflammation, and lipid profiles, which are also presumed to be partly related to type 2 diabetes mellitus (T2DM). However, molecular mechanisms of the different PUFAs related to metabolic disorders have not been systematically addressed. The present study aimed to investigate the impact of dietary n-3/n-6 PUFA ratios on obesity and IR and, further, to determine the underlying mechanisms. For 16 weeks, 32 SD male rats, randomly divided into four groups (n = 8 per group), received one of the following diets: normal chow, high saturated fatty acid (SFA), high n-3/n-6 PUFA ratio (1∶1, PUFA¹:¹), or low n-3/n-6 PUFA ratio (1∶4, PUFA¹:⁴). Following the experimental diet period, metabolic parameters related to obesity and IR were measured. Compared to SFA diet-fed rats, PUFA¹:¹ diet-fed rats exhibited decreased body and visceral fat weight, lowered blood lipids, and improved glucose tolerance and insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of circulating pro-inflammatory cytokines, including tumor necrosis factor α, interleukin-6, and C-reactive protein. Moreover, the TLR4 protein and mRNA levels were markedly down-regulated by PUFA¹:¹ compared with SFA; however, PUFA¹:⁴ diet-fed rats failed to exhibit these changes. Cumulatively, our data highlight a role for a PUFA¹:¹ diet in the prevention of obesity and related metabolic disorders by suppressing the activation of TLR4, a critical modulator of pro-inflammatory cytokines.
Department of Nutrition and Food Hygiene and the Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi'an 710032, China.
Han-Qiang
HQ
Liu
Ya
Y
Qiu
Ying
Y
Mu
Xian-Jiao
XJ
Zhang
Lu
L
Liu
Xiang-Hong
XH
Hou
Lei
L
Zhang
Xiao-Na
XN
Xu
Ai-Ling
AL
Ji
Rui
R
Cao
Rui-Hua
RH
Yang
Feng
F
Wang
D000818:Animals; D002097:C-Reactive Protein / Q000378:metabolism; D004041:Dietary Fats / Q000494:pharmacology / Q000627:therapeutic use*; D015536:Down-Regulation; D005227:Fatty Acids / Q000494:pharmacology; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology / Q000627:therapeutic use*; D043371:Fatty Acids, Omega-6 / Q000494:pharmacology*; D018149:Glucose Intolerance / Q000188:drug therapy; D007249:Inflammation / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D007333:Insulin Resistance; D015850:Interleukin-6 / Q000097:blood; D050152:Intra-Abdominal Fat / Q000378:metabolism; D008055:Lipids / Q000097:blood; D008297:Male; D009765:Obesity / Q000150:complications / Q000178:diet therapy* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D015431:Weight Loss / Q000187:drug effects
D004041:Dietary Fats; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D015850:Interleukin-6; D008055:Lipids; D012333:RNA, Messenger; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein
C-reactive protein; CRP; DHA; EPA; H&E; HOMA-IR; IKK-β; IL-6; IR; IRS; ITT; Insulin resistance; IκB kinase β; LPS; MyD88; NF-κB; PCR; PUFAs; Polyunsaturated fatty acids; Pro-inflammatory cytokines; Rat; SFA; T2DM; TC; TG; TIR domain-containing adaptor inducing interferon β; TLR; TNF-α; TRAM; TRIF; TRIF-related adaptor molecule; Toll-like receptor-4; docosahexanoic acid; eicosapentaenoic acid; hematoxylin and eosin; homeostasis model assessment of insulin resistance; insulin receptor substrate; insulin resistance; insulin tolerance test; interleukin-6; lipopolysaccharide; myeloid differentiation factor-88; nuclear factor κB; polymerase chain reaction; polyunsaturated fatty acids; saturated fatty acid; toll-like receptor; total cholesterol; triglycerides; tumor necrosis factor α; type 2 diabetes mellitus