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Horm Metab Res. 2014 Jun;46(6):390-6. doi: 10.1055/s-0034-1372600. Epub 2014 May 7.

Nicotinic acid effects on insulin sensitivity and hepatic lipid metabolism: an in vivo to in vitro study.

Author information

1
Research Centre in Human Nutrition Rhône-Alpes and CENS (Centre of -European Nutrition Safety and Health), Hospices Civils de Lyon, Pierre Bénite, France.
2
INSERM U1060, CarMeN Laboratory, Lyon 1 University, INRA 1235, Oullins, France.
3
INSERM U915 and Nantes Research Centre in Human Nutrition, 44000, Nantes, France.
4
Research Centre in Human Nutrition Rhône-Alpes, Centre Hospitalier -Universitaire Grenoble, Grenoble, France.
5
GlaxoSmithKline, Les Ulis, France.

Abstract

Our aim was to characterize the effects and the underlying mechanisms of the lipid-regulating agent Niaspan(®) on both insulin action and triglyceride decrease in 20 nondiabetic, dyslipidemic men with metabolic syndrome receiving Niaspan(®) (2 g/day) or placebo for 8 weeks in a randomized, cross-over study. The effects on plasma lipid profile were characterized at the beginning and the end of each treatment period; insulin sensitivity was assessed using the 2-step euglycemic hyperinsulinemic clamp and VLDL-triglyceride turnover by measuring plasma glycerol enrichment, both at the end of each treatment period. The mechanism of action of nicotinic acid was studied in HuH7 and mouse primary hepatocytes. Lipid profile was improved after Niaspan(®) treatment with a significant-28% decrease in triglyceride levels, a+17% increase in HDL-C concentration and unchanged levels of fasting nonesterified fatty acid. VLDL-tri-glyceride production rate was markedly reduced after Niaspan(®) (-68%). However, the treatment induced hepatic insulin resistance, as assessed by reduced inhibition of endogenous glucose production by insulin (0.7±0.4 vs. 1.0±0.5 mg/kg · min, p<0.05) and decrease in fasting hepatic insulin sensitivity index (4.8±1.8 vs. 3.2±1.6, p<0.05) in the Niaspan(®) condition. Nicotinic acid also reduced insulin action in HuH7 and primary hepatocytes, independently of the activation of hepatic PKCε. This effect was associated with an increase in diacylglycerol and a decrease in tri-glyceride contents that occurred in the absence of modification of DGAT2 expression and activity. Eight weeks of Niaspan(®) treatment in dyslipidemic patients with metabolic syndrome induce hepatic insulin resistance. The mechanism could involve an accumulation of diacylglycerol and an alteration of insulin signaling in hepatocytes.

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PMID:
24806747
DOI:
10.1055/s-0034-1372600
[Indexed for MEDLINE]
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