Reduced sympathetic nervous activity. A potential mechanism predisposing to body weight gain.

Abstract

The sympathetic nervous system is recognized to play a role in the etiology of animal and possibly human obesity through its impact on energy expenditure and/or food intake. We, therefore, measured fasting muscle sympathetic nerve activity (MSNA) in the peroneal nerve and its relationship with energy expenditure and body composition in 25 relatively lean Pima Indian males (means±SD; 26±6 yr, 82±19 kg, 28±10% body fat) and 19 Caucasian males (29±5 yr, 81±13 kg, 24±9% body fat). 24-h energy expenditure, sleeping metabolic rate, and resting metabolic rate were measured in a respiratory chamber, whereas body composition was estimated by hydrodensitometry.Pima Indians had lower MSNA than Caucasians (23±6 vs 33±10 bursts/min, P = 0.0007). MSNA was significantly related to percent body fat in Caucasians (r = 0.55, P = 0.01) but not in Pimas. MSNA also correlated with energy expenditure adjusted for fat-free mass, fat mass, and age in Caucasians (r = 0.51, P = 0.03; r = 0.54, P = 0.02; and r = 0.53, P = 0.02 for adjusted 24-h energy expenditure, sleeping metabolic rate, and resting metabolic rate, respectively) but not in Pima Indians.In conclusion, the activity of the sympathetic nervous system is a determinant of energy expenditure in Caucasians. Individuals with low resting MSNA may be at risk for body weight gain resulting from a lower metabolic rate. A low resting MSNA and the lack of impact of MSNA on metabolic rate might play a role in the etiology of obesity in Pima Indians. (J.

Metabolic and physiological effects of ingesting extracts of bitter orange, green tea and guarana at rest and during treadmill walking in overweight males

“…5 The b3-receptor seems to be the most abundant beta subtype in human brown adipocytes and is thought to play a key role in the lipolytic and thermogenic effects of adrenergic agents, 2,33 without exerting an effect on those receptors responsible for cardiovascular control. 2 These effects might be consistent with the results of study 1 in terms of the observed increase in plasma NEFA minus any significant changes in heart rate or blood pressure. However, the increase in plasma NEFA (observed in study 1 but not in study 2) could equally be the result of a reduced fat oxidation, as mentioned previously.…”

“…Spraul et al 2 identified a role for reduced sympathetic nervous system activity in bodyweight gain, which increases susceptibility to obesity. Recent data has suggested that obese individuals exhibit significantly lower sympathetic nervous system activity in response to various physiological challenges, such as food intake 3 and capsaicin intake.…”

Sympathetic nervous system behavior in human obesity

“…The results of numerous studies indicate that obese humans demonstrate ∼50-100% higher levels of MSNA compared with their non-obese peers (Spraul et al, 1993, Scherrer et al, 1994, Spraul et al, 1994, Gudbjornsdottir et al, 1996, Grassi et al, 2000, Weyer et al, 2000, Alvarez et al, 2002. In contrast, Hugget et al (Huggett et al, 2005) reported that MSNA was not elevated in overweight individuals.…”

Effects of a Stimulant-Free Dietary Supplement on Body Weight and Fat Loss in Obese Adults: A Six-Week Exploratory Study

“…[20][21][22] However, their use is controversial due to their ability to cause undesired effects, including tremors, insomnia, nervousness, dry mouth, palpitations, tachycardia, hypertension, and mood-altering effects. 20,21,[23][24][25] Other nutraceuticals, such as green tea and certain fibers, have shown moderate success in reducing body weight, 26,27 whereas several other compounds (eg, hydroxycitric acid) have demonstrated little or no effect. 28 Therefore, a tolerable and effective nutraceutical that can increase energy expenditure and/or decrease caloric intake is desirable for weight reduction.…”