No abstract

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

explored and provide evidence supporting this concept. This includes inactivation of hormone sensitive lipase (HSL) ( 5, 6 ) and A 1 -adenosine receptor agonists ( 7 ). In addition, several other G protein-coupled receptors (GPRs) are involved in controlling adipocyte FFA release, including GPR43, GPR81, and GPR109A ( 8-10 ).The GPR109A agonist nicotinic acid (NiAc) has been used clinically ever since its antidyslipidemic effects (HDL elevation and reductions of total cholesterol, LDL-cholesterol, and TG) were discovered more than 50 years ago ( 11-15 ). Although NiAc potently lowers FFA acutely, large-scale clinical studies, with repeated oral NiAc administration, often report increased levels of fasting glycemia ( 16-19 ). NiAc has not been optimized to achieve durable and therapeutically meaningful FFA lowering. By this, we specifi cally mean reducing around-the-clock FFA area under the curve (AUC). In theory, this might be achieved by sustained NiAc exposure; however, the FFA-lowering effect seen initially appears to be lost over time despite maintained NiAc exposure (tolerance development) ( 20 ). Time-dependent loss of both FFA lowering and glucose control improvement also occur in patients with type 2 diabetes, treated with the NiAc analog acipimox ( 21,22 ). To avoid tolerance development, drug holidays are needed. However, at the end of each NiAc exposure period, there is the risk of FFA rebound (here referring to the situation where FFA overshoots pretreatment levels in connection with NiAc decline) due to the short NiAc plasma half-life ( 23 ). FFA rebound is associated with impaired glucose control ( 24, 25 ). The question of whether there might be an optimal balance between periods of continuous exposure (which would minimize rebound) and drug holidays (which would minimize tolerance) in order to achieve maximal FFA lowering has not been addressed. Lipid overload in nonadipose tissues has been linked to the pathogenesis of insulin resistance and atherogenesis ( 1-4 ). A potential means for reversing peripheral lipid overload is to restrict the release of FFAs from adipose tissues. A number of independent mechanisms have been N.D. Oakes, P. Thalén, and A. Kjellstedt Abbreviations: ATGL, adipocyte triglyceride lipase; AUC, area under the curve; ER, extended release; GIR, glucose infusion rate; GPR, G protein-coupled receptor; HOMA-IR, homeostasis model assessment for insulin resistance; HSL, hormone sensitive lipase; NiAc, nicotinic acid; PDE-3B, phosphodiesterase-3B .