Effects of visceral adiposity on glycerol pathways in gluconeogenesis

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• 作者：Ian J. Neeland^a ; ^{ian.neeland@utsouthwestern.edu} ; Connor Hughes^a ; Colby R. Ayers^b ; Craig R. Malloy^c ; Eunsook S. Jin^d
• 关键词：DHS ; Dallas Heart Study ; DXA ; dual x-ray absorptiometry ; MAG ; monoacetone glucose ; MRI ; magnetic resonance imaging ; NMR ; nuclear magnetic resonance ; PPP ; pentose phosphate pathway ; TCA ; tricarboxylic acid ; TPI ; triose phosphate isomerase ; VAT ; visceral adipose tissue
• 刊名：Metabolism
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：67
• 期：Complete
• 页码：80-89
• 全文大小：763 K
• 卷排序：67

文摘

To determine the feasibility of using oral 13C labeled glycerol to assess effects of visceral adiposity on gluconeogenic pathways in obese humans.Research Design and MethodsObese (BMI ≥ 30 kg/m2) participants without type 2 diabetes underwent visceral adipose tissue (VAT) assessment and stratification by median VAT into high VAT-fasting (n = 3), low VAT-fasting (n = 4), and high VAT-refed (n = 2) groups. Participants ingested [U-13C3] glycerol and blood samples were subsequently analyzed at multiple time points over 3 h by NMR spectroscopy. The fractions of plasma glucose (enrichment) derived from [U-13C3] glycerol via hepatic gluconeogenesis, pentose phosphate pathway (PPP), and tricarboxylic acid (TCA) cycle were assessed using 13C NMR analysis of glucose. Mixed linear models were used to compare 13C enrichment in glucose between groups.ResultsMean age, BMI, and baseline glucose were 49 years, 40.1 kg/m2, and 98 mg/dl, respectively. Up to 20% of glycerol was metabolized in the TCA cycle prior to gluconeogenesis and PPP activity was minor (< 1% of total glucose) in all participants. There was a 21% decrease in 13C enrichment in plasma glucose in the high VAT-fasting compared with low VAT-fasting group (p = 0.03), suggesting dilution by endogenous glycerol. High VAT-refed participants had 37% less 13C enrichment in glucose compared with high VAT-fasting (p = 0.02). There was a trend toward lower [1,2-13C2] (via PPP) and [5,6-13C2]/[4,5,6-13C3] (via TCA cycle) glucose in high VAT versus low VAT groups.ConclusionsWe applied a simple method to detect gluconeogenesis from glycerol in obese humans. Our findings provide preliminary evidence that excess visceral fat disrupts multiple pathways in hepatic gluconeogenesis from glycerol.