Brown adipose tissue activation as measured by infrared thermography by mild anticipatory psychological stress in lean healthy females

Abstract

New Findings r What is the central question of this study?Does psychological stress, which is known to promote cortisol secretion, simultaneously activate brown adipose tissue function in healthy adult females? r What is the main finding and its importance?One explanation for the pronounced differences in brown adipose tissue function between individuals lies in their responsiveness to psychological stress and, as such, should be taken into account when examining its in vivo stimulation.Brown adipose tissue (BAT) has been implicated in the pathogenesis of obesity, type 2 diabetes and the metabolic syndrome and is a potential therapeutic target. Brown adipose tissue can have a significant impact on energy balance and glucose homeostasis through the action of uncoupling protein 1, dissipating chemical energy as heat following neuroendocrine stimulation. We hypothesized that psychological stress, which is known to promote cortisol secretion, would simultaneously activate BAT at thermoneutrality. Brown adipose tissue activity was measured using infrared thermography to determine changes in the temperature of the skin overlying supraclavicular BAT (T SCR ). A mild psychological stress was induced in five healthy, lean, female, Caucasian volunteers using a short mental arithmetic (MA) test. The T SCR was compared with a repeated assessment, in which the MA test was replaced with a period of relaxation. Although MA did not elicit an acute stress response, anticipation of MA testing led to an increase in salivary cortisol, indicative of an anticipatory stress response, that was associated with a trend towards higher absolute and relative T SCR . A positive correlation between T SCR and cortisol was found during the anticipatory phase, a relationship that was enhanced by increased cortisol linked to MA. Our findings suggest that subtle changes in the level of psychological stress can stimulate BAT, findings that may account for the high variability and inconsistency in reported BAT prevalence and activity measured by other modalities. Consistent assessment of this uniquely metabolic tissue is fundamental to the discovery of potential therapeutic strategies against metabolic disease.

The Dichotomous Effect of Chronic Stress on Obesity

“…Mild mental arithmetic challenge elicits acute BAT activation in healthy lean humans [97], supporting the hypothesis that subjects manifesting detectable BAT at thermoneutrality could be characterized by increased sensitivity to stress experienced during the PET or MRI scans. Furthermore, it is well established that cold acutely activates and chronically recruits the BAT in humans [76,77].…”

“…It is important to note that DMH is also a crucial node regulating stress-induced cardiovascular and neuroendocrine functions [71]. Importantly, the thermogenic efficacy of stress has recently been replicated in humans where an acute psychological challenge in thermoneutral conditions has been associated to increased supraclavicular BAT temperature [82]. Altogether, these evidences constitute a strong case for the inclusion of psycho-emotional stress as a naturalistic stimulus for BAT function, together with cold and diet induced thermogenesis in rodent models and humans.…”

The Placenta, Maternal Diet and Adipose Tissue Development in the Newborn

“…The anatomical location is likely to be highly significant with respect to its functional role, given that brown fat has the capacity to ensure that the temperature of blood supplying the brain is maintained. This role will therefore not only be critical at birth but throughout the life cycle and could explain why acute stress, and the accompanying rise in cortisol stimulates heat production in supraclavicular brown fat [21] . In contrast, in rodents, at least, glucocorticoids inhibit brown fat function within the interscapular depot [22] .…”

The color of fat and its central role in the development and progression of metabolic diseases

“…An even more extreme cold exposure (10°C for 2 h a day, 5 days/week for 4 weeks) increased BAT volume by 45% and fractional glucose uptake [90]. Increased stress has recently been associated with activation of supraclavicular brown fat [91]. Stress is associated with increased secretion of cortisol and catecholamines and the two hormones are released also during the stress induced by exposure to low temperatures.…”