title: Intranasal insulin modulates intrinsic reward and prefrontal circuitry of the human brain in lean women.
abstract: OBJECTIVE
  There is accumulating evidence that food consumption is controlled by a wide range of brain circuits outside of the homeostatic system. Activation in these brain circuits may override the homeostatic system and also contribute to the enormous increase of obesity. However, little is known about the influence of hormonal signals on the brain's non-homeostatic system. Thus, selective insulin action in the brain was investigated by using intranasal application.
  
  
  METHODS
  We performed 'resting-state' functional magnetic resonance imaging in 17 healthy lean female subjects to assess intrinsic brain activity by fractional amplitude of low-frequency fluctuations (fALFF) before, 30 and 90 min after application of intranasal insulin.
  
  
  RESULTS
  Here, we showed that insulin modulates intrinsic brain activity in the hypothalamus and orbitofrontal cortex. Furthermore, we could show that the prefrontal and anterior cingulate cortex response to insulin is associated with body mass index.
  
  
  CONCLUSIONS
  This demonstrates that hormonal signals as insulin may reduce food intake by modifying the reward and prefrontal circuitry of the human brain, thereby potentially decreasing the rewarding properties of food. Due to the alarming increase in obesity worldwide, it is of great importance to identify neural mechanisms of interaction between the homeostatic and non-homeostatic system to generate new targets for obesity therapy.
authors.affiliation: MEG Center, University of Tübingen, Tübingen, Germany. stephanie.kullmann@med.uni-tuebingen.de
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kullmann
authors.forename: Sabine
authors.initials: S
authors.lastname: Frank
authors.forename: Martin
authors.initials: M
authors.lastname: Heni
authors.forename: Caroline
authors.initials: C
authors.lastname: Ketterer
authors.forename: Ralf
authors.initials: R
authors.lastname: Veit
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Häring
authors.forename: Andreas
authors.initials: A
authors.lastname: Fritsche
authors.forename: Hubert
authors.initials: H
authors.lastname: Preissl
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D015992:Body Mass Index; D001921:Brain / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D010919:Placebos; D017397:Prefrontal Cortex / Q000187:drug effects* / Q000502:physiology; D012201:Reward; D013851:Thinness / Q000503:physiopathology* / Q000523:psychology; D055815:Young Adult
chemical_list: D007328:Insulin; D010919:Placebos