Effects of Morbid Obesity and Bariatric Surgery on Brain Inflammation, and Activation of Central Reward System

Background: The investigators have found that obesity and insulin resistance result in significantly increased brain insulin-stimulated glucose uptake, whereas in every other tissue glucose uptake is lower in the obese compared to lean individuals. One possible explanation to this could be central inflammation and activation of brain glial cells, which has been shown to occur in animal models of obesity. Aims: The objective of this study is to investigate whether there is brain inflammation in human obesity, and whether weight loss following bariatric surgery decreases brain inflammation. Methods: A total of 60 morbidly obese subjects, assigned for Roux-en-Y gastric bypass or for sleeve gastrectomy according to routine treatment protocols will be recruited for this study. A control group of 30 healthy subjects will also be recruited. The following studies will be performed to patients and healthy subjects: 1) structural MRI and MRS, 2) functional MRI, 3) PET imaging of cerebral inflammation and astrocyte activation using \[11C\]-PK11195, 4) measurement of whole-body and tissue insulin sensitivity by combining hyperinsulinemic, euglycemic clamp with \[18F\]-FDG-PET, 5) neuropsychological testing. The study procedures will be repeated for the morbidly obese 6 months postoperatively.