Journal Article

Effects of weight loss and exercise on insulin resistance, and intramyocellular triacylglycerol, diacylglycerol and ceramide

Stefanovic-Racic, M., Toledo, F. G. S., Goodpaster, B. H., Rossi, A., Coen, P., Dubé, J. J., Amati, F.

2011

Overview

Aims/hypothesis Intramyocellular lipids, including diacylglycerol (DAG) and ceramides, have been linked to insulin resistance. This randomised repeated-measures study examined the effects of diet-induced weight loss (DIWL) and aerobic exercise (EX) on insulin sensitivity and intramyocellular triacylglycerol (IMTG), DAG and ceramide. Methods Sixteen overweight to obese adults (BMI 30.6 ± 0.8; 67.2 ± 4.0 years of age) with either impaired fasting glucose, or impaired glucose tolerance completed one of two lifestyle interventions: DIWL ( n  = 8) or EX ( n  = 8). Insulin sensitivity was determined using hyperinsulinaemic–euglycaemic clamps. Intramyocellular lipids were measured in muscle biopsies using histochemistry and tandem mass spectrometry. Results Insulin sensitivity was improved with DIWL (20.6 ± 4.7%) and EX (19.2 ± 12.9%). Body weight and body fat were decreased by both interventions, with greater decreases in DIWL compared with EX. Muscle glycogen, IMTG content and oxidative capacity were all significantly ( p  < 0.05) decreased with DIWL and increased with EX. There were decreases in DAG with DIWL (−12.4 ± 14.6%) and EX (−40.9 ± 12.0%). Ceramide decreased with EX (−33.7 ± 11.2%), but not with DIWL. Dihydroceramide was decreased with both interventions. Sphingosine was decreased only with EX. Changes in total DAG, total ceramides and other sphingolipids did not correlate with changes in glucose disposal. Stearoyl-coenzyme A desaturase 1 (SCD1) content was decreased with DIWL (−19.5 ± 8.5%, p  < 0.05), but increased with EX (19.6 ± 7.4%, p  < 0.05). Diacylglycerol acyltransferase 1 (DGAT1) was unchanged with the interventions. Conclusions/interpretation Diet-induced weight loss and exercise training both improved insulin resistance and decreased DAG, while only exercise decreased ceramides, despite the interventions having different effects on IMTG. These alterations may be mediated through differential changes in skeletal muscle capacity for oxidation and triacylglycerol synthesis. Trial registration: ClinicalTrials.gov NCT00766298 Funding: ADA Clinical Research Award (B. H. Goodpaster), NIH R01 AG20128 (B. H. Goodpaster), Obesity and Nutrition Research (1P30DK46204) and Clinical and Translational Research Centers (UL1 RR024153)

• Publisher: Springer-Verlag,Springer,Springer Nature B.V
• Subject: Aerobics / Aged / Biological and medical sciences / Body Composition / Ceramides - metabolism / Diabetes. Impaired glucose tolerance / Diet, Reducing / Diglycerides - metabolism / Endocrine pancreas. Apud cells (diseases) / Endocrinopathies / Etiopathogenesis. Screening. Investigations. Target tissue resistance / Exercise - physiology / Female / Fundamental and applied biological sciences. Psychology / Hormones / Human Physiology / Humans / Insulin resistance / Insulin Resistance - physiology / Internal Medicine / Kinases / Lipids / Male / Medical sciences / Medicine / Medicine & Public Health / Metabolic Diseases / Middle Aged / Muscle, Skeletal - metabolism / Nutrition research / Obesity / Objectives / Resistance exercise / Striated muscle. Tendons / Triglycerides - metabolism / Vertebrates: osteoarticular system, musculoskeletal system / Weight control / Weight Loss - physiology