Partial Reversibility of Hypothalamic Dysfunction and Changes in Brain Activity After Body Mass Reduction in Obese Subjects

Abstract

OBJECTIVEInflammation and dysfunction of the hypothalamus are common features of experimental obesity. However, it is unknown whether obesity and massive loss of body mass can modify the immunologic status or the functional activity of the human brain. Therefore, the aim of this study was to determine the effect of body mass reduction on brain functionality.RESEARCH DESIGN AND METHODSIn humans, changes in hypothalamic activity after a meal or glucose intake can be detected by functional magnetic resonance imaging (fMRI). Distinct fMRI analytic methods have been developed to explore changes in the brain’s activity in several physiologic and pathologic conditions. We used two analytic methods of fMRI to explore the changes in the brain activity after body mass reduction.RESULTSObese patients present distinct functional activity patterns in selected brain regions compared with lean subjects. On massive loss of body mass, after bariatric surgery, increases in the cerebrospinal fluid (CSF) concentrations of interleukin (IL)-10 and IL-6 are accompanied by changes in fMRI patterns, particularly in the hypothalamus.CONCLUSIONSMassive reduction of body mass promotes a partial reversal of hypothalamic dysfunction and increases anti-inflammatory activity in the CSF.

Food preferences and underlying mechanisms after bariatric surgery

“…RYGB appears to be far superior in modulating brain activity. In fact, several fMRI studies carried out at least 6 months after RYGB, report a restoration in patterns of brain activation to food or glucose stimuli, similar to those observed in normal weight individuals (51,52) . It is worth noting that patients who are less successful at losing weight after RYGB have been shown to have a lower increase in activation of the areas involved in restraint and inhibition but no significant change in the limbic reward areas compared with their more successful weight loss counterparts (53) .…”

IMAGING IN ENDOCRINOLOGY: The use of functional MRI to study the endocrinology of appetite

“…In 2011, van de Sande-Lee et al (67) performed fMRI studies on eight lean control subjects and 13 obese patients before and after RYGB, through which an average 30% reduction in body weight had been achieved. Using a BOLD fMRI paradigm that investigated areas of the brain whose signal intensity and pattern co-varied, they reported a high level of functional connectivity between the hypothalamus and the orbitofrontal and somatosensory cortices that was absent in obese subjects but was re-established with post-operative weight loss.…”

MRI Techniques and New Animal Models for Imaging the Brain

“…It would be interesting to compare the impact of different neuropeptides or diets on brain activation that could be measured at different times of life, but this type of protocol would be difficult to standardize in humans. The effects of gastric bypass surgery on hypothalamic functional connectivity and on various indicators (inflammatory and metabolic) have been studied in obese human subjects (van de Sande-Lee et al 2011). Similar protocols could be designed in the pig, making it easier to select animals and to set up a sham-surgery control group, and could be used to study the long-term effects of surgery.…”