The Effects of Weight Loss Versus Weight Loss Maintenance on Sympathetic Nervous System Activity and Metabolic Syndrome Components

• Published in: The journal of clinical endocrinology and metabolism Vol. 96; no. 3; pp. E503 - E508
• Main Authors: Straznicky, Nora E, Grima, Mariee T, Eikelis, Nina, Nestel, Paul J, Dawood, Tye, Schlaich, Markus P, Chopra, Reena, Masuo, Kazuko, Esler, Murray D, Sari, Carolina I, Lambert, Gavin W, Lambert, Elisabeth A
• Format: Journal Article
• Language: English
• Published: United States Endocrine Society 01.03.2011; Copyright by The Endocrine Society
• Subjects: Anthropometry; Baroreceptors; Baroreflex - physiology; Body mass index; Body Weight - physiology; Calorimetry; Clinical trials; Diet, Reducing; Differentiation; Energy balance; Energy Intake; Exercise Therapy; Female; Heart; Heart - physiology; Humans; Hypocaloric diet; Kinetics; Life Style; Male; Metabolic disorders; Metabolic Syndrome - diet therapy; Metabolic Syndrome - physiopathology; Metabolic Syndrome - therapy; microneurography; Middle Aged; Muscle, Skeletal - blood supply; Muscle, Skeletal - innervation; Muscles; Norepinephrine; Norepinephrine - metabolism; Obesity; Oxidation; Physical Fitness; Physical training; Radioisotope Dilution Technique; Reflexes; Regional Blood Flow - physiology; sympathetic nerves; Sympathetic nervous system; Sympathetic Nervous System - physiopathology; Weight Loss - physiology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2010-2204

This study demonstrates divergent effects of successful weight loss maintenance on whole body norepinephrine spillover rate and muscle sympathetic nerve activity in obese metabolic syndrome subjects. Context: Sympathetic nervous system (SNS) overactivity participates in both the pathogenesis and adverse clinical complications of metabolic syndrome (MetS) obesity. Objective: We conducted a prospective lifestyle intervention trial to compare the effects of active weight loss and extended weight loss maintenance on SNS function and MetS components. Methods: Untreated subjects (14 males, four females; mean age, 53 ± 1 yr; body mass index, 30.9 ± 0.9 kg/m2) who fulfilled Adult Treatment Panel III criteria were randomized to 12-wk hypocaloric diet alone (n = 8) or together with aerobic exercise training (n = 10). This was followed by a 4-month weight maintenance period. Measurements of muscle sympathetic nerve activity (MSNA) by microneurography, whole-body norepinephrine kinetics, substrate oxidation by indirect calorimetry, baroreflex sensitivity, plasma renin activity (PRA), and MetS components were performed. Results: Body weight decreased by 9.3 ± 0.8% at wk 12 (P < 0.001), and this was maintained. During active weight loss, norepinephrine spillover rate decreased by 23 ± 16% (P = 0.004), MSNA by 25 ± 3 bursts per 100 heartbeats (P < 0.001), and PRA by 0.25 ± 0.09 ng/ml · h (P = 0.007), whereas baroreflex sensitivity increased by 5.2 ± 2.2 msec/mm Hg (P = 0.005). After weight maintenance, beneficial effects of weight loss on norepinephrine spillover rate were preserved, whereas PRA and MSNA rebounded (by 0.24 ± 0.11 ng/ml · h, P = 0.02; and 20 ± 5 bursts/100 heartbeats, P = 0.0003), and baroreflex sensitivity was attenuated. Conclusions: Divergent effects of successful weight loss maintenance on whole-body norepinephrine spillover rate and MSNA suggest organ-specific differentiation in SNS adaptation to weight loss under conditions of negative vs. stable energy balance.