title: Acute, short-term hyperinsulinemia increases olfactory threshold in healthy subjects.
abstract: OBJECTIVE
  Smell plays an important role in feeding behavior. We therefore tested whether insulin as a postprandial signal is involved in the regulation of olfactory function.
  
  
  METHODS
  We assessed olfactory thresholds in eight lean subjects (age: 34 ± 7 years, M/F: 5/3) before and during a 2-h hyperinsulinemic (1 mU kg(-1) min(-1)) euglycemic clamp and in eight lean fasted subjects (age: 36 ± 6 years, M/F: 5/3) without insulin infusion at the same time of the day. To define odor thresholds, standardized 'sniffing sticks' were used.
  
  
  RESULTS
  Odor thresholds decreased from 7.8 ± 1.2 to 6.2 ± 1.1 during euglycemic hyperinsulinemia (P=0.0173), representing an increase in odor threshold. In the control group, odor thresholds were 8.3 ± 1.6 and did not change after 120 min of fasting (8.9 ± 2.2, P=0.6).
  
  
  CONCLUSIONS
  Increased insulin levels lead to a reduced smelling capacity, potentially reducing the pleasantness of eating. Therefore, insulin action in the olfactory bulb may be involved in the process of satiation and may thus be of interest in the pathogenesis of obesity.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tübingen, Tübingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Ketterer
authors.forename: M
authors.initials: M
authors.lastname: Heni
authors.forename: C
authors.initials: C
authors.lastname: Thamer
authors.forename: S A
authors.initials: SA
authors.lastname: Herzberg-Schäfer
authors.forename: H-U
authors.initials: HU
authors.lastname: Häring
authors.forename: A
authors.initials: A
authors.lastname: Fritsche
mesh_terms: D000328:Adult; D004435:Eating / Q000502:physiology; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D008297:Male; D019518:Postprandial Period; D012528:Satiety Response; D012903:Smell / Q000502:physiology; D013997:Time Factors
chemical_list: D007328:Insulin