The proteoglycan decorin does not influence adiposity, glucose tolerance, or aerobic exercise capacity in mice

Physical activity is associated with improvements in insulin sensitivity and muscle function. The proteoglycan decorin is increased in skeletal muscle and plasma in response to exercise, but the biological implications are unknown. We investigated the effects of decorin deficiency on obesity, glucose tolerance, and exercise adaptation in C57BL/6J mice. Decorin deficiency did not influence adiposity, insulin- and glucose- tolerance, or energy metabolism in obese, high fat diet fed mice (Dcn^-/- vs. Dcn^+/+). Decorin is abundant in the skeletal muscle extracellular matrix, thus we further compared the skeletal muscle of Dcn^-/- and Dcn^+/+ littermates. There were no effects on muscle morphology or the expression of metabolic markers. Dcn^-/- mice had normal exercise capacity measured as running distance on a treadmill. To study the effects of long-term exercise, mice were housed with access to running wheels. Overall, there were no major differences in voluntary wheel running or skeletal muscle metabolic markers, but Dcn^-/- mice had a tendency for reduced running wheel activity compared to Dcn^+/+ mice. This was accompanied by a smaller exercise effect on metabolic markers in muscle Dcn^-/- mice. Our findings indicate that decorin does not have a major impact on glucose tolerance, metabolic adaptation, or aerobic exercise performance.