title: Insulin, Central Dopamine D2 Receptors, and Monetary Reward Discounting in Obesity.
abstract: Animal research finds that insulin regulates dopamine signaling and reward behavior, but similar research in humans is lacking. We investigated whether individual differences in body mass index, percent body fat, pancreatic β-cell function, and dopamine D2 receptor binding were related to reward discounting in obese and non-obese adult men and women. Obese (n = 27; body mass index>30) and non-obese (n = 20; body mass index<30) adults were assessed for percent body fat with dual-energy X-ray absorptiometry and for β-cell function using disposition index. Choice of larger, but delayed or less certain, monetary rewards relative to immediate, certain smaller monetary rewards was measured using delayed and probabilistic reward discounting tasks. Positron emission tomography using a non-displaceable D2-specific radioligand, [11C](N-methyl)benperidol quantified striatal D2 receptor binding. Groups differed in body mass index, percent body fat, and disposition index, but not in striatal D2 receptor specific binding or reward discounting. Higher percent body fat in non-obese women related to preference for a smaller, certain reward over a larger, less likely one (greater probabilistic discounting). Lower β-cell function in the total sample and lower insulin sensitivity in obese related to stronger preference for an immediate and smaller monetary reward over delayed receipt of a larger one (greater delay discounting). In obese adults, higher striatal D2 receptor binding related to greater delay discounting. Interestingly, striatal D2 receptor binding was not significantly related to body mass index, percent body fat, or β-cell function in either group. Our findings indicate that individual differences in percent body fat, β-cell function, and striatal D2 receptor binding may each contribute to altered reward discounting behavior in non-obese and obese individuals. These results raise interesting questions about whether and how striatal D2 receptor binding and metabolic factors, including β-cell function, interact to affect reward discounting in humans.
authors.affiliation: Psychiatry Department, Washington University in St. Louis, St. Louis, MO, United States of America; Radiology Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Eisenstein
authors.affiliation: Psychology Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Danuta M
authors.initials: DM
authors.lastname: Gredysa
authors.affiliation: Psychiatry Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Jo Ann
authors.initials: JA
authors.lastname: Antenor-Dorsey
authors.affiliation: Psychology Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Leonard
authors.initials: L
authors.lastname: Green
authors.affiliation: Pediatrics Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Arbeláez
authors.affiliation: Psychiatry Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Koller
authors.affiliation: Psychiatry Department, Washington University in St. Louis, St. Louis, MO, United States of America; Radiology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Neurology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Anatomy and Neurobiology Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Black
authors.affiliation: Radiology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Neurology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Anatomy and Neurobiology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Programs in Physical Therapy and Occupational Therapy, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Perlmutter
authors.affiliation: Radiology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Biochemistry and Molecular Biophysics Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Moerlein
authors.affiliation: Psychiatry Department, Washington University in St. Louis, St. Louis, MO, United States of America; Radiology Department, Washington University in St. Louis, St. Louis, MO, United States of America; Neurology Department, Washington University in St. Louis, St. Louis, MO, United States of America.
authors.forename: Tamara
authors.initials: T
authors.lastname: Hershey
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000818:Animals; D001667:Binding, Competitive; D015992:Body Mass Index; D002250:Carbon Radioisotopes; D003342:Corpus Striatum / Q000378:metabolism; D065786:Delay Discounting; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000378:metabolism; D016014:Linear Models; D008297:Male; D009765:Obesity / Q000175:diagnosis / Q000378:metabolism* / Q000523:psychology; D049268:Positron-Emission Tomography; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012201:Reward; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D007328:Insulin; D017448:Receptors, Dopamine D2