title: Dopamine receptor signaling in the medial orbital frontal cortex and the acquisition and expression of fructose-conditioned flavor preferences in rats.
abstract: Systemic dopamine (DA) D1 (SCH23390: SCH) and D2 (raclopride: RAC) antagonists blocked fructose-conditioned flavor preference (CFP) acquisition and expression. Fructose-CFP acquisition was eliminated by medial prefrontal cortex (mPFC) SCH and mPFC or amygdala (AMY) RAC. Fructose-CFP expression was reduced following SCH or RAC in AMY or nucleus accumbens (NAc). The present study examined fructose-CFP acquisition and expression following SCH and RAC in the medial orbital frontal cortex (MOFC), another ventral tegmental area DA target. For fructose-CFP acquisition, five groups of rats received vehicle, SCH (24 or 48 nmol) or RAC (24 or 48 nmol) in the MOFC 0.5h prior to 8 training sessions with one flavor (CS+/Fs) mixed in 8% fructose and 0.2% saccharin, and another flavor (CS-/s) mixed in 0.2% saccharin. In six 2-bottle choice tests in 0.2% saccharin, similar fructose-CFP preferences occurred in groups trained with vehicle (76-77%), SCH24 (69-78%), SCH48 (70-74%) and RAC48 (85-92%). RAC24-trained rats displayed significant CS+ preferences during the first (79%) and third (71%), but not second (58%) test pair. For fructose-CFP expression, rats similarly trained with CS+/Fs and CS- solutions received 2-bottle choice tests following MOFC injections of SCH or RAC (12-48 nmol). CS+ preference expression was significantly reduced by RAC (48 nmol: 58%), but not SCH relative to vehicle (78%). A control group receiving RAC in the dorsolateral prefrontal cortex displayed fructose-CFP expression similar to vehicle. These data demonstrate differential frontal cortical DA mediation of fructose-CFP with mPFC D1 and D2 signaling exclusively mediating acquisition, and MOFC D2 signaling primarily mediating expression.
authors.affiliation: Behavioral and Cognitive Neuroscience Cluster, Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, United States.
authors.forename: Danielle C
authors.initials: DC
authors.lastname: Malkusz
authors.affiliation: Department of Psychology, Queens College, City University of New York, New York, NY, United States.
authors.forename: Ira
authors.initials: I
authors.lastname: Yenko
authors.affiliation: Behavioral and Cognitive Neuroscience Cluster, Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, United States.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Rotella
authors.affiliation: Department of Psychology, Queens College, City University of New York, New York, NY, United States.
authors.forename: Theodore
authors.initials: T
authors.lastname: Banakos
authors.affiliation: Department of Psychology, Queens College, City University of New York, New York, NY, United States.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Olsson
authors.affiliation: Department of Psychology, Queens College, City University of New York, New York, NY, United States.
authors.forename: Trisha
authors.initials: T
authors.lastname: Dindyal
authors.affiliation: Department of Psychology, Queens College, City University of New York, New York, NY, United States.
authors.forename: Vishal
authors.initials: V
authors.lastname: Vig
authors.affiliation: Behavioral and Cognitive Neuroscience Cluster, Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, United States; Department of Psychology, Queens College, City University of New York, New York, NY, United States. Electronic address: richard.bodnar@qc.cuny.edu.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bodnar
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D015259:Dopamine Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005518:Food Preferences / Q000187:drug effects / Q000502:physiology*; D005632:Fructose / Q000008:administration & dosage; D008297:Male; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013549:Sweetening Agents / Q000008:administration & dosage
chemical_list: D015259:Dopamine Agents; D011954:Receptors, Dopamine; D013549:Sweetening Agents; D005632:Fructose
keywords: Flavor–flavor learning; Raclopride; SCH23390; Saccharin; Sweet taste