Autonomic nervous system activity in diabetic and healthy obese female subjects and the effect of distinct weight loss strategies

Abstract

Objective: Obesity and type 2 diabetes mellitus (T2DM) are reported to be associated with relative overactivity of the sympathetic nervous system (SNS), which is reversible by weight loss. However, direct effects of weight loss by calorie restriction vs Roux-en-Y gastric bypass (RYGB) on SNS overactivity were not studied in parallel. This study compared the effects of RYGB vs restrictive weight loss in obese patients with normal glucose tolerance (NGT) and with T2DM on SNS function as measured by heart rate variability (HRV). Design and methods: Lean (nZ12), obese NGT (nZ27) and T2DM (nZ27) subjects were included in this study. Weight reduction in NGT subjects was achieved by gastric banding (GB) or RYGB and in T2DM subjects by RYGB or high-protein very-low-calorie diet (VLCD). HRV analysis was performed and blood samples were taken at baseline, 3 weeks and 3 months after intervention. Results: At baseline, T2DM subjects showed SNS overactivity and NGT subjects showed similar, but non-significant, findings when compared with lean controls. Weight loss after 3 weeks was comparable in all treatment groups, whereas after 3 months, weight loss was most in VLCD and RYGB subjects. RYGB and VLCD treatment reduced SNS activity within 3 weeks in T2DM patients. After 3 months, restoration to normal autonomic nervous system activity was evident for all groups, except for the NGT-GB group. Conclusion: We can conclude that SNS overactivity is more pronounced in obese T2DM subjects when compared with NGT subjects. Reduction of SNS overactivity coincides with weight loss with the timecourse of reduction dependent on the type of intervention. Surgery or caloric restriction may transiently induce SNS overactivity but do not prevent a direct restoration of sympathovagal balance.

Effect of Low-Energy Diets Differing in Fiber, Red Meat, and Coffee Intake on Cardiac Autonomic Function in Obese Individuals With Type 2 Diabetes

“…Weight loss induced by caloric restriction appears to exert favorable effects on ANS activity via enhancing vagal activity and/or reducing sympathetic modulation in overweight or obese otherwise healthy individuals (7)(8)(9)(10)(11)(12). However, the results across studies are inconsistent, and the mechanisms implicated in these effects are unclear.…”

Long-Term Sympathoinhibitory Effects of Surgically Induced Weight Loss in Severe Obese Patients

“…[5][6][7] In this context, however, little attention has to date been given to whether bariatric surgery is also associated with the improvement of another adverse phenomenon of obesity (ie, sympathetic activation). 8,9 The only information available comes from 3 studies that assessed sympathetic tone by making use of spectral analysis of heart rate signal or 24-hour norepinephrine urinary excretion [10][11][12] (ie, approaches that display major intrinsic limitations not allowing to provide any direct insight on the effects of the intervention on central sympathetic outflow, as the microneurographic technique only allows to achieve 13 .) The issue has pathophysiological and clinical relevance because sympathetic activation has been shown to be an adverse prognostic factor in several clinical conditions.…”

Roles of impaired intracellular calcium cycling in arrhythmogenicity of diabetic mouse model

“…Chronic overactivity of sympathetic nervous system is very common in diabetic patients and may contribute to increased p‐PLB level without increased protein level of PKA . The activated PKA further enhance phosphorylation of CaMKII.…”