The brain's supply and demand in obesity

Abstract

During psychosocial stress, the brain demands extra energy from the body to satisfy its increased needs. For that purpose it uses a mechanism referred to as “cerebral insulin suppression” (CIS). Specifically, activation of the stress system suppresses insulin secretion from pancreatic beta-cells, and in this way energy—particularly glucose—is allocated to the brain rather than the periphery. It is unknown, however, how the brain of obese humans organizes its supply and demand during psychosocial stress. To answer this question, we examined 20 obese and 20 normal weight men in two sessions (Trier Social Stress Test and non-stress control condition followed by either a rich buffet or a meager salad). Blood samples were continuously taken and subjects rated their vigilance and mood by standard questionnaires. First, we found a low reactive stress system in obesity. While obese subjects showed a marked hormonal response to the psychosocial challenge, the cortisol response to the subsequent meal was absent. Whereas the brains of normal weight subjects demanded for extra energy from the body by using CIS, CIS was not detectable in obese subjects. Our findings suggest that the absence of CIS in obese subjects is due to the absence of their meal-related cortisol peak. Second, normal weight men were high reactive during psychosocial stress in changing their vigilance, thereby increasing their cerebral energy need, whereas obese men were low reactive in this respect. Third, normal weight subjects preferred carbohydrates after stress to supply their brain, while obese men preferred fat and protein instead. We conclude that the brain of obese people organizes its need, supply, and demand in a low reactive manner.

Stress habituation, body shape and cardiovascular mortality

“…Epidemiological evidence demonstrates that individuals with low stress reactivity are at risk of gaining body mass over the next decades (Flaa et al, 2008;Phillips et al, 2012;Carroll et al, 2008). Experimental evidence shows that corpulent subjects react to a mental and psychosocial stress test in a low reactive manner (Jones et al, 2012;Kubera et al, 2012). When compared to lean subjects, the subjects with a high body mass displayed low cortisol reactivity to both an acute mental challenge and to a subsequent meal, displayed smaller changes in the vigilant state, less pronounced post-stress-neuroglycopenic states, less pronounced rises in serum ketone concentrations, and showed less 'cerebral insulin suppression' during a meal (Jones et al, 2012;Kubera et al, 2012Kubera et al, , 2014.…”

“…Now, that the conventional view advocating the null hypothesis has become increasingly unlikely, it seems promising to look at the 'obesity paradox' observations in the light of brain-pull mechanisms. Acute stress belongs to the conditions when the brain enters a hypervigilant state; the additional cerebral energy needs arising from this transition are covered by brain-pull mechanisms (Hitze et al, 2010;Madsen et al, 1995;Kubera et al, 2012). One of these mechanisms is called 'cerebral insulin suppression'.…”

“…Subjects who feel uncertain about their future wellbeing typically display interactions between ACC and amygdala (Sarinopoulos et al, 2010). The ACC-amygdala complex can activate two descending pathways: first, projections to the locus coeruleus norepinephrine (LC-NE) system, (thereby inducing a hypervigilant state (Valentino and Van Bockstaele, 2008;Reyes et al, 2011), which has been found associated with an increased cerebral energy need, Hitze et al, 2010;Kubera et al, 2012); and second, projections to the ventromedial hypothalamus and the paraventricular nucleus (thereby activating the SNS and HPA-axis, which in turn procure the brain with the extra energy needed) (Hitze et al, 2010;Kubera et al, 2012).…”

“…Experimental evidence shows that corpulent subjects react to a mental and psychosocial stress test in a low reactive manner (Jones et al, 2012;Kubera et al, 2012). When compared to lean subjects, the subjects with a high body mass displayed low cortisol reactivity to both an acute mental challenge and to a subsequent meal, displayed smaller changes in the vigilant state, less pronounced post-stress-neuroglycopenic states, less pronounced rises in serum ketone concentrations, and showed less 'cerebral insulin suppression' during a meal (Jones et al, 2012;Kubera et al, 2012Kubera et al, , 2014. Moreover, the corpulent subjects showed less anxiety, less uneasiness, less physical malaise and less sadness during the psychosocial challenge .…”

Efeito da redução de ninhada sobre as respostas autonômicas e metabólicas de ratos Wistar

“…O cérebro desempenha importante papel na homeostase energética 37 . O controle da ingestão de nutrientes e o equilíbrio homeostático dependem de sinais periféricos que atuam diretamente sobre SNC, desempenhando a região hipotalâmica um papel chave na integração de sinais periféricos e controle da homeostase energética 29 .…”