title: The insulin effect on cerebrocortical theta activity is associated with serum concentrations of saturated nonesterified Fatty acids.
abstract: BACKGROUND
  Insulin action in the brain contributes to adequate regulation of body weight, neuronal survival, and suppression of endogenous glucose production. We previously demonstrated by magnetoencephalography in lean humans that insulin stimulates activity in beta and theta frequency bands, whereas this effect was abolished in obese individuals.
  
  
  OBJECTIVE
  The present study aims to define metabolic signals associated with the suppression of the cerebrocortical response in obese humans.
  
  
  METHODS
  We determined insulin-mediated modulation of spontaneous cerebrocortical activity by magnetoencephalography during a hyperinsulinemic euglycemic clamp and related it to measures of ectopic fat deposition and mediators of peripheral insulin resistance. Visceral fat mass and intrahepatic lipid content were quantified by magnetic resonance imaging and spectroscopy. Multiple regression analysis was used to analyze associations of cerebrocortical insulin sensitivity and metabolic markers related to obesity.
  
  
  METHODS
  Forty-nine healthy, nondiabetic humans participated in the study.
  
  
  RESULTS
  In a multiple regression, insulin-mediated stimulation of theta activity was negatively correlated to body mass index, visceral fat mass, and intrahepatic lipid content. Although fasting saturated nonesterified fatty acids mediated the correlations of theta activity with abdominal and intrahepatic lipid stores, adipocytokines displayed no independent correlation with insulin-mediated cortical activity in the theta frequency band.
  
  
  CONCLUSIONS
  Thus, insulin action at the level of cerebrocortical activity in the brain is diminished in the presence of elevated levels of saturated nonesterified fatty acids.
authors.affiliation: Department of Internal Medicine IV, University Hospital, University of Tübingen, 72076 Tübingen, Germany. otto.tschritter@med.uni-tuebingen.de
authors.forename: Otto
authors.initials: O
authors.lastname: Tschritter
authors.forename: Hubert
authors.initials: H
authors.lastname: Preissl
authors.forename: Anita M
authors.initials: AM
authors.lastname: Hennige
authors.forename: Tina
authors.initials: T
authors.lastname: Sartorius
authors.forename: Yuko
authors.initials: Y
authors.lastname: Grichisch
authors.forename: Norbert
authors.initials: N
authors.lastname: Stefan
authors.forename: Martina
authors.initials: M
authors.lastname: Guthoff
authors.forename: Stephan
authors.initials: S
authors.lastname: Düsing
authors.forename: Jürgen
authors.initials: J
authors.lastname: Machann
authors.forename: Erwin
authors.initials: E
authors.lastname: Schleicher
authors.forename: Alexander
authors.initials: A
authors.lastname: Cegan
authors.forename: Niels
authors.initials: N
authors.lastname: Birbaumer
authors.forename: Andreas
authors.initials: A
authors.lastname: Fritsche
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Häring
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D008055:Lipids / Q000502:physiology; D015225:Magnetoencephalography; D008297:Male; D009765:Obesity / Q000097:blood / Q000503:physiopathology; D013826:Theta Rhythm / Q000187:drug effects*; D049629:Waist-Hip Ratio
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids