Paraoxonase Responses to Exercise and Niacin Therapy in Men with Metabolic Syndrome

Abstract

Our purpose was to characterize changes in paraoxonase 1 (PON1) activity and concentration after single aerobic exercise sessions conducted before and after 6-weeks of niacin therapy in men with metabolic syndrome (MetS). Twelve men (44 + 7 yrs; BMI = 34.5 + 3.4 kg•m2; % fat = 35 + 5; O2max = 27.5 + 6.6 mL.min-1.kg-1; waist circumference = 108.8 + 8.2 cm; HDL-C = 39 + 8 and triglycerides = 287 + 96 mg∙dL-1; HOMA score = 4.4 + 2.0) expended 500 kcals by treadmill walking at 65% of O2max before and after a 6-week regimen of prescription niacin. Niacin doses were titrated by 500 mg∙wk-1 from 500 to 1500 mg∙dy-1 and maintained at 1500 mg∙dy-1 for the last 4 weeks. Fasting blood samples were collected before and 24 hours after each exercise session and analyzed for PON1 activity, PON1 concentration, myeloperoxidase (MPO), apolipoprotein A1 (Apo-A1), and oxidized LDL (oLDL) concentrations and NMR analyses of lipoprotein characteristics. PON1 activity, PON1 concentration, MPO and oLDL were unaltered following the independent effects of acute exercise and six-weeks of niacin therapy. HDL particle size decreased by 3% (from 8.6 + 0.1 to 8.5 + 0.1 nm) following acute exercise (p = 0.040*). Small LDL particle numbers were reduced by 16% (from 1480.0 + 111.2 to 1244.6 + 128.8 nmol∙L-1) following six weeks of niacin therapy (p = 0.057). PON1 activity increased 6.1% (from 115.9 + 24.0 to 122.9 + 19.8 kU∙L-1; p = 0.037*) and PON1 concentrations increased 11.3% (from 109.5 + 24.3 to 121.9 + 19.8 ug∙mL-1; p = 0.015*) with the combination of exercise and niacin. The combination of acute exercise and niacin therapy in men with MetS includes a modest increase in PON1 activity and PON1 concentration without observed changes in oLDL, MPO, or clinically-recognized measures of lipoprotein characteristics.