Norepinephrine Spillover from Human Adipose Tissue before and after a 72-Hour Fast

Abstract

Adipose tissue lipolysis is at least in part stimulated by the sympathetic nervous system (SNS). Although there is a generalized decrease in SNS activity with fasting, the rate of lipolysis during fasting increases. The aim of this study was to determine whether there is an association between activation of sympathetic nerves innervating adipose tissue and the increase in lipolysis seen during fasting in humans. We used the isotope dilution technique to measure regional norepinephrine spillover from abdominal sc adipose tissue from seven healthy subjects before and after a 72-h fast. Our results showed a significant increase in adipose tissue spillover of norepinephrine (mean +/- SEM, 0.40 +/- 0.09 vs. 1.08 +/- 0.18 pmol.100 g(-1).min(-1), P < 0.05) and arterial norepinephrine concentrations (0.92 +/- 0.10 vs. 1.23 +/- 0.08 nmol.liter(-1), P < 0.05) after the fast with no significant change in total body norepinephrine spillover, forearm norepinephrine spillover, epinephrine concentrations, or energy expenditure. We show for the first time, in humans, a selective regional increase in adipose tissue norepinephrine spillover in response to a 72-h fast and suggest that the SNS may play a greater role in the regulation of lipid metabolism during fasting than previously thought.

The effects of dietary weight loss with or without exercise training on liver enzymes in obese metabolic syndrome subjects

“…Of interest, NEFA concentration did not change during the 12‐week active intervention in our study, but decreased significantly during WM. This may reflect that during active WL, when subjects are in negative energy balance, there may be a selective regional increase in adipose tissue noradrenaline spillover, promoting lipolysis and mobilization of energy stores [29]. It is tempting to speculate that the transient worsening of liver enzymes reported following very low calorie diets [30,31], may be attributed to these neuroadrenergic adaptive mechanisms.…”

White Adipose Tissue: Getting Nervous

“…Patel et al . (18) showed increased norepinephrine spillover in abdominal subcutaneous WAT in healthy subjects after a 72‐h fast, also pointing to a role for an increased sympathetic tone in lipid metabolism during fasting.…”

Sympathoneural and Adrenomedullary Responses to Mental Stress

“…It is very difficult to evaluate catecholamine reactivity to mental stress in a manner that (1) is independent of physical activity, which would be expected to increase sympathetic noradrenergic outflows and plasma NE levels differentially with respect to sympathetic adrenergic outflows and plasma EPI levels [133, 134]; (2) involves real-life distress, as opposed to laboratory challenges that are not particularly distressing [104]; (3) includes baseline measures prior to the stress [40]; and (4) takes into account factors such as systemic hemodynamics [135], posture [136], room temperature [137], meal ingestion [138, 139], the state of glycemia [140, 141], which differentially affects sympathetic adrenergic outflow, and medications [142, 143]. With these limitations in mind, the following discussion highlights particular areas in which catecholamine reactivity to mental stress may play a role in the pathogenesis of a variety of disorders.…”