Dietary capsaicin reduces obesity-induced insulin resistance and hepatic steatosis in obese mice fed a high-fat diet.
Obesity-induced inflammation contributes to the development of obesity-related metabolic disorders such as insulin resistance, type 2 diabetes, fatty liver disease, and cardiovascular disease. In this study, we investigated whether dietary capsaicin can reduce obesity-induced inflammation and metabolic disorders such as insulin resistance and hepatic steatosis. Male C57BL/6 obese mice fed a high-fat diet for 10 weeks received a supplement of 0.015% capsaicin for a further 10 weeks and were compared with unsupplemented controls. Glucose intolerance was estimated by glucose tolerance tests. Transcripts of adipocytokine genes and the corresponding proteins were measured by reverse transcription-PCR and enzyme-linked immunosorbent assay, and macrophage numbers were determined by flow cytometric analysis. Transient receptor potential vanilloid type-1 (TRPV-1), peroxisome proliferator-activated receptor (PPAR)-alpha, and PPARgamma coactivator-1alpha (PGC-1alpha) mRNAs were also measured by RT-PCR, and PPARalpha luciferase assays were performed. Dietary capsaicin lowered fasting glucose, insulin, leptin levels, and markedly reduced the impairment of glucose tolerance in obese mice. Levels of tumor necrosis factor-alpha (TNFalpha), monocyte chemoattractant protein-1 (MCP-1), and interleukin (IL)-6 mRNAs and proteins in adipose tissue and liver decreased markedly, as did macrophage infiltration, hepatic triglycerides, and TRPV-1 expression in adipose tissue. At the same time, the mRNA/protein of adiponectin in the adipose tissue and PPARalpha/PGC-1alpha mRNA in the liver increased. Moreover, luciferase assays revealed that capsaicin is capable of binding PPARalpha. Our data suggest that dietary capsaicin may reduce obesity-induced glucose intolerance by not only suppressing inflammatory responses but also enhancing fatty acid oxidation in adipose tissue and/or liver, both of which are important peripheral tissues affecting insulin resistance. The effects of capsaicin in adipose tissue and liver are related to its dual action on PPARalpha and TRPV-1 expression/activation.
Department of Food Science and Nutrition, University of Ulsan, Ulsan, South Korea.
Ji-Hye
JH
Kang
Tsuyoshi
T
Goto
In-Seob
IS
Han
Teruo
T
Kawada
Young Min
YM
Kim
Rina
R
Yu
D052242:Adiponectin / Q000235:genetics / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001786:Blood Glucose / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology / Q000627:therapeutic use*; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D019587:Dietary Supplements; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D005434:Flow Cytometry; D015870:Gene Expression; D018149:Glucose Intolerance / Q000209:etiology / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D007249:Inflammation / Q000235:genetics; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood; D050356:Lipid Metabolism / Q000187:drug effects; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism; D047493:PPAR alpha / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
D052242:Adiponectin; D000893:Anti-Inflammatory Agents; D001786:Blood Glucose; D004041:Dietary Fats; D007004:Hypoglycemic Agents; D007328:Insulin; D020738:Leptin; D047493:PPAR alpha; D012333:RNA, Messenger; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D014280:Triglycerides; D002211:Capsaicin