title: Adipose triglyceride lipase-null mice are resistant to high-fat diet-induced insulin resistance despite reduced energy expenditure and ectopic lipid accumulation.
abstract: Adipose triglyceride lipase (ATGL) null (-/-) mice store vast amounts of triacylglycerol in key glucoregulatory tissues yet exhibit enhanced insulin sensitivity and glucose tolerance. The mechanisms underpinning these divergent observations are unknown but may relate to the reduced availability of circulating fatty acids. The aim of this study was to determine whether the enhancements in insulin stimulated glucose metabolism in ATGL-/- mice persist when challenged with a high-fat diet. ATGL-/- mice fed a low-fat diet exhibit improved whole-body insulin sensitivity and glucose tolerance compared with wild-type mice. Wild-type mice became hyperlipidemic and insulin-resistant when challenged with a high-fat diet (HFD, 60% fat) for 4 wk. ATGL-/- mice fed a HFD had elevated circulating fatty acids but had reduced fasting glycemia compared to pre-high-fat diet levels and were refractory to glucose intolerance and insulin resistance. This protection from high-fat diet-induced metabolic perturbations was associated with a preference for fatty acid utilization but reduced energy expenditure and no change in markers of mitochondrial capacity or density. The protection from high-fat diet-induced insulin resistance in ATGL-/- mice was due to increased cardiac and liver insulin-stimulated glucose clearance despite increased lipid content in these tissues. Additionally, there was no difference in skeletal muscle insulin-stimulated glucose disposal, but there was a reduction observed in brown adipose tissue. Overall, these results show that ATGL-/- mice are protected from HFD-induced insulin resistance and reveal a tissue specific disparity between lipid accumulation and insulin sensitivity.
authors.affiliation: Monash University, Department of Physiology, Wellington Road, Clayton Victoria, 3800, Australia. andrew.hoy@monash.edu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hoy
authors.forename: Clinton R
authors.initials: CR
authors.lastname: Bruce
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Turpin
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Morris
authors.forename: Mark A
authors.initials: MA
authors.lastname: Febbraio
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Watt
mesh_terms: D000818:Animals; D001786:Blood Glucose; D050260:Carbohydrate Metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics* / Q000378:metabolism; D002940:Circadian Rhythm; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D004734:Energy Metabolism / Q000502:physiology*; D044882:Glucose Metabolism Disorders / Q000378:metabolism; D007333:Insulin Resistance; D008049:Lipase; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010084:Oxidation-Reduction; D017440:Photoperiod; D000217:Acyltransferases
chemical_list: D001786:Blood Glucose; D002265:Carboxylic Ester Hydrolases; D004041:Dietary Fats; D008049:Lipase; C494445:PNPLA2 protein, mouse; D000217:Acyltransferases