Circulating levels of apelin, glucagon-like peptide and visfatin in hypercholesterolemic–hyperhomocysteinemic guinea-pigs: their relation with NO metabolism

Abstract

The aim of this study was to determine the levels of regulatory peptides apelin, glucagon-like peptide (GLP-1) and visfatin in hypercholesterolemic and hyperhomocysteinemic state and to examine their relation with nitric oxide (NO) metabolism. 32 Male guinea pigs were divided into four groups and each group was fed as follows: (a) commercial chow, (b) cholesterol (chol)-rich diet, (c) methionine (meth)-rich diet, and (d) chol + meth-rich diet. Blood samples were drawn at the end of 10 weeks, and abdominal aorta was dissected for histopathological examination. Serum insulin, GLP-1, apelin, visfatin, and nitrotyrosine concentrations were measured by the manufacturer's kits based on ELISA; asymmetric dimethylarginine (ADMA) and arginine levels were measured by the high performance liquid chromatography. Homocysteine level was measured by the chemiluminescence immunoassay; glucose, total chol and triglyceride levels were measured by the autoanalyzer. The microscopic examination of aorta indicated varying degrees of vascular disturbance in chol- and chol + meth-fed groups. High levels of chol and homocysteine, accompanied with significantly low levels of apelin and GLP-1 were detected in the plasma. Visfatin, ADMA, and nitrotyrosine levels both in chol- and chol + meth-fed groups were significantly higher than those in control animals, whereas arginine and arginine/ADMA ratio were lower. This study indicated that circulating levels of apelin, GLP-1, and visfatin are markedly altered during the development of atherosclerotic changes in close association with chol, homocysteine, NO, and ADMA levels. The measurements of these peptides in serum may help for the diagnosis and follow-up of vascular dysfunction.

MCD diet-induced steatohepatitis is associated with alterations in asymmetric dimethylarginine (ADMA) and its transporters

“…This is consistent with the hypothesis that methyl groups in ADMA may be derived from the demethylation of methionine to homocyst(e)ine [21]. An increase in serum ADMA concentrations has also been found in pigs given a diet supplemented with methionine [22]. In our study, on the contrary, ADMA generation was not encouraged when using a diet deficient in methionine.…”

The Functional Effects of Visfatin on Human Left Internal Mammary Artery

“…[38][39][40] On the other hand, the elevation of circulating levels of visfatin during atherosclerosis is closely associated with decreased levels of NO. 41 Thus, visfatin seems to have a rather complex role in the regulation of contractile/relaxation responses to endogenous mediators, especially in NO release and bioavailability, in the cardiovascular system. These controversial results of visfatin are partly explained by different functions performed by both cytokine-like extrinsic PBEF and enzymatic intrinsic NAMPT activities.…”

Adipocytokines: Are they the Theory of Everything?

“…Insulin resistance &diabetes [11,12], psoriasis [88], vasoconstriction [156], atherosclerosis [142], coronary artery disease [144,145] [17], hyperlipidemia [25], IVDD [46], rheumatoid & osteoarthritis [66], joint damage in rheumatoid arthritis [67], atherosclerosis [157], diastolic hypertension [20] Abbreviations matrix proteolytic enzymes and their inhibitors) [44].…”

“…TNF-α, another adipocytokine, has been shown to induce impairment of nitric oxide-mediated vasodilatation in the small arteries found in the visceral fat of obese patients, which ends in vasoconstriction [156]. RBP4 (retinol-binding protein 4) serum level also, positively correlates with pro-atherogenic conditions [18], while visfatin is markedly elevated during atherosclerosis and its elevation was associated with decreased levels of L-arginine and nitric oxide [157] and associated with higher diastolic blood pressure [20]. Finally, adiponectin was found to lower serum triglyceride levels that lead to improving endothelial dysfunction [24]; higher adiponectin meant less atherosclerosis and vascular disorders [11].…”