13. Hypothalamic Gliosis Is Associated with Obesity and Insulin Resistance in Humans (158-OR)

In rodents, high-fat diet induces obesity and a ‘reactive gliosis’ (expansion of microglia and astrocyte populations) in the mediobasal hypothalamus (MBH). To investigate the relevance of such findings to human obesity and insulin resistance, we utilized quantitative magnetic resonance imaging (MRI) to detect MBH gliosis in humans in vivo and in a separate study of postmortem brain tissue. Study 1 included sixty-eight participants (32 normal weight, never obese and 36 obese). Each had a fasting blood draw and multi-echo MRI sequence to measure T2 relaxation time in the MBH and in two reference regions (amygdala and putamen). Using a nested case-control design, we compared 22 cases within the highest tertile of left MBH T2 relaxation time (i.e., strongest radiologic evidence for gliosis) with the 23 controls in the bottom tertile.