The role of insulin sensitivity and intranasally applied insulin on olfactory perception

• Published in: Scientific reports Vol. 9; no. 1; p. 7222
• Main Authors: Edwin Thanarajah, Sharmili, Hoffstall, Vera, Rigoux, Lionel, Hanssen, Ruth, Brüning, Jens C., Tittgemeyer, Marc
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.05.2019; Nature Publishing Group
• Subjects: 631/443/376; 692/163/2743; Administration, Intranasal; Adult; Blood Glucose - analysis; Body weight; Chemosensory perception; Cross-Over Studies; Energy balance; Food selection; Homeostasis; Humanities and Social Sciences; Humans; Insulin; Insulin - administration & dosage; Insulin - blood; Insulin - pharmacology; Insulin Resistance; Intranasal administration; Male; multidisciplinary; Nutritional status; Odor thresholds; Odors; Olfactory discrimination; Olfactory discrimination learning; Olfactory neurons; Olfactory perception; Olfactory Perception - drug effects; Olfactory Perception - physiology; Olfactory thresholds; Overweight; Perception; Placebo Effect; Science; Science (multidisciplinary); Single-Blind Method; Smell; Young Adult
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-43693-7

Olfactory perception determines food selection behavior depending on energy homeostasis and nutritional status. The mechanisms, however, by which metabolic signals in turn regulate olfactory perception remain largely unclear. Given the evidence for direct insulin action on olfactory neurons, we tested olfactory performance (olfactory threshold, olfactory discrimination) in 36 subjects of normal- and overweight after administration of three different insulin doses (40 I.U., 100 I.U., 160 I.U.) or corresponding placebo volume in a within-subject design. Poor peripheral insulin sensitivity as quantified by HOMA-IR in baseline condition and increases in systemic insulin levels reactive to intranasal administration predicted poor olfactory performance. In contrast, intranasal insulin enhanced odor perception with a dose-dependent improvement of olfactory threshold. These findings indicate a new diametric impact of insulin on olfactory perception depending on peripheral or central availability.