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@#Free fatty acid receptors(FFARs)are a series of orphan G protein-coupled receptors(GPCRs)activated by free fatty acids(FFAs)and their derivatives. As transmembrane receptors,GPCRs are involved in the occurrence and development of many diseases and provide a wide range of therapeutic targets for these diseases. FFARs combined with FFAs are mainly involved in the secretion of endocrine hormones such as insulin,adipocyte differentiation,inflammatory response,autoimmune response and other processes,which was a potential therapeutic target for energy metabolism disorders and immune diseases. However,recent studies have shown that FFAs and its receptor FFARs are widely involved in neuroinflammation and neuroimmunity directly or through the brain-intestinal axis,and are expected to be a therapeutic target for multiple sclerosis,Alzheimer′s disease(AD),Parkinson′s disease(PD),depression and other diseases. This paper reviews the research progress of the role of FFARs in nervous system diseases.
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ABSTRACT Deleterious effects of free fatty acids, FFAs, on insulin sensitivity are observed in vivo studies in humans. Mechanisms include impaired insulin signaling, oxidative stress, inflammation, and mitochondrial dysfunction, but the effects on insulin secretion are less well known. Our aim was to review the relationship of increased FFAs with insulin resistance, secretion and mainly with the incretin effect in humans. Narrative review. Increased endogenous or administered FFAs induce insulin resistance. FFAs effects on insulin secretion are debatable; inhibition and stimulation have been reported, depending on the type and duration of lipids exposition and the study subjects. Chronically elevated FFAs seem to decrease insulin biosynthesis, glucose-stimulated insulin secretion and β-cell glucose sensitivity. Lipids infusion decreases the response to incretins with unchanged incretin levels in volunteers with normal glucose tolerance. In contrast, FFAs reduction by acipimox did not restore the incretin effect in type-2 diabetes, probably due to the dysfunctional β-cell. Possible mechanisms of FFAs excess on incretin effect include reduction of the expression and levels of GLP-1 (glucagon like peptide-1) receptor, reduction of connexin-36 expression thus the coordinated secretory activity in response to GLP-1, and GIP (glucose-dependent insulinotropic polypeptide) receptors downregulation in islets cells. Increased circulating FFAs impair insulin sensitivity. Effects on insulin secretion are complex and controversial. Deleterious effects on the incretin-induced potentiation of insulin secretion were reported. More investigation is needed to better understand the extent and mechanisms of β-cell impairment and insulin resistance induced by increased FFAs and how to prevent them.
Subject(s)
Humans , Insulin Resistance , Diabetes Mellitus, Type 2 , Diabetes Mellitus, Type 2/drug therapy , Blood Glucose , Gastric Inhibitory Polypeptide/metabolism , Incretins , Fatty Acids, Nonesterified , Insulin Secretion , Insulin/metabolismABSTRACT
Objective To investigate the effect of rh-resistin on lipid metabolism in HepG2 cells and to elucidate its relation to AMPK pathway. Methods We treated the HepG2 cells with 50 ng/ml rh-resistin and 0.5 mmol/L palmitic acid,used siRNA technique to inhibite α2 subunite expression of AMPK in HepG2 cells and quantitative RT-PCR to detect ACC1,ACC2,and HL mRNA expression levels of related lipid metabolism genes. The P-AMPK-Thr172 of AMPK and P-ACC-Ser79 of ACC were determined by Western blotting. The Lipid accumu-lation in cells was determined by images of Laser Scanning Confocal Microscope after Nile red staining. Results Rh-resistin decreased the AMPKα2,HL mRNA expressions and the phosphorylation level of AMPK and ACC in both basal and insulin-stimulated conditions (P 0.05),while it increased ACC2 mRNA expressions and cytoplasmic lipid droplets in the same conditions (P <0.05). Conclusion Rh-resistin may affect lipid metabolism via AMPK pathway with increase of fatty acid synthe-sis and inhibition of triglyceride catabolism,which leading to lipid accumulation in HepG2 cells.
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0.05).Conclusions:1.The acute rise in FFAs level for a short term can inhibit ACTH and cortisol secretion in healthy male adults,but with prolonged FFA elevation this inhibition last less than 24 hours.2.The acute FFAs rise has no influence on ACTH or cortisol circadian rhythm.
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Objective To investigate the changes of WBC count and free fatty acids (FFAs) level in diabetic patients with angiopathy, and explore the role of WBC and FFAs in the pathogenesis of diabetic angiopathy. Methods The number of WBC and the concentration of FFAs were determined in 22 diabetic patients without angiopathy, 38 diabetic patients with angiopathy and 20 healthy subjects. Results Both WBC count and FFAs concentration in the diabetic patients were obviously higher than those in healthy subjects (P