The effects of dietary weight loss on indices of norepinephrine turnover: Modulatory influence of hyperinsulinemia

Objectives This study was conducted to examine 1) the effects of dietary weight loss on indices of norepinephrine (NE) turnover and 2) whether baseline hyperinsulinemia modulates sympathetic neural adaptations. Methods Obese individuals aged 56 ± 1 year, BMI 32.5 ± 0.4 kg/m2, with metabolic syndrome, underwent a 12‐week hypocaloric diet (HCD, n = 39) or no treatment (n = 26). Neurochemical measurements comprised arterial dihydroxyphenylalanine (DOPA), 3,4‐dihydroxyphenylglycol (DHPG), and NE concentrations, the steady‐state ratio of [3H]‐DHPG to [3H]‐NE, as an index of neuronal uptake, and calculated whole‐body plasma NE clearance and spillover rates. Results Body weight decreased by −7.4 ± 0.5% in HCD group (P < 0.001) and was accompanied by reductions in DOPA, NE, and DHPG averaging −14 ± 5% (P = 0.001), −23 ± 4% (P