title: The effect of leptin, tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) production on insulin resistance in Otsuka Long-Evans fatty rats.
abstract: Adipocytokines and nitric oxide (NO) play important roles in type 2 diabetes; however, the regulatory mechanism has not been fully clarified. To investigate the role of adipocytokines and NO production on insulin resistance in type 2 diabetes, the LETO rats and the OLETF rats were fed a control diet or a high-fat diet for 4 weeks. After 4 weeks the blood levels of leptin, tumor necrosis factor-alpha (TNF-alpha), and NO were measured. As an indicator of insulin resistance, the homeostasis model assessment for insulin resistance (HOMA-R) was applied. Food intake in high-fat diet group rats was lower than in control diet group rats. The high fat diet increased body weight (BW), but did not significantly affect the HOMA-R and blood pressure (BP). Leptin and TNF-alpha levels were significantly higher in the OLETF rats than in the LETO rats, while NO levels did not change between the two groups. The high-fat diet elevated blood leptin levels, but not TNF-alpha and NO levels. The HOMA-R in the OLETF rats was correlated with leptin, but not with BP, BW, TNF-alpha or NO. NO showed an inverse correlation with BP. In conclusion, leptin, TNF-alpha, and NO may each regulate insulin sensitivity through their own unique pathways. The elucidation of the regulatory mechanism of adipocytokines and NO may give a clue to clarify the pathophysiology of insulin resistance.
authors.affiliation: Department of Endocrinology, Metabolism, and Diabetology, Kinki University School of Medicine.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ohno
authors.forename: Norihiko
authors.initials: N
authors.lastname: Aoki
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D001835:Body Weight; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D004435:Eating; D002149:Energy Intake; D006706:Homeostasis; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D020738:Leptin / Q000096:biosynthesis* / Q000097:blood; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D009929:Organ Size; D011897:Random Allocation; D051381:Rats; D020334:Rats, Inbred OLETF; D011919:Rats, Inbred Strains; D013599:Systole; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide