title: Acquisition of an appetitive behavior prevents development of stress-induced neurochemical modifications in rat nucleus accumbens.
abstract: In rats, exposure to chronic unavoidable stress produces a decrease in dopamine output in the nucleus accumbens shell that is accompanied by a decreased density of the dopamine transporter and an increased activity of the dopamine-D(1) receptor complex. These modifications have been hypothesized to be adaptive to decreased dopamine output in stressed rats. We investigated whether the learning of an appetitive behavior sustained by palatable food, which is associated with increased dopamine output in the nucleus accumbens shell as measured by microdialysis experiments, would affect the modifications induced by chronic stress exposure on dopamine transporter density and dopamine-D(1) receptor complex activity in the nucleus accumbens. Rats exposed to chronic unavoidable stress after acquisition of the appetitive behavior showed a higher dopamine extraneuronal release in the nucleus accumbens shell than that of stressed animals, and similar to that of control rats. Moreover, previous acquisition of the appetitive behavior prevented development of a stress-induced decrease in dopamine transporter density, measured by [(3)H]-WIN 35428 binding, a stress-induced increase in dopamine-D(1) receptor density, measured by binding of [(3)H]-SCH 23390, and SKF 38393-stimulated adenylyl cyclase activity in the nucleus accumbens. These results support the hypothesis that changes induced in pre- and postsynaptic dopaminergic transmission by chronic stress exposure are related to decreased dopamine output.
authors.affiliation: Department of Neuroscience, University of Siena, Siena, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Nanni
authors.forename: Simona
authors.initials: S
authors.lastname: Scheggi
authors.forename: Benedetta
authors.initials: B
authors.lastname: Leggio
authors.forename: Silvia
authors.initials: S
authors.lastname: Grappi
authors.forename: Flavio
authors.initials: F
authors.lastname: Masi
authors.forename: Riccardo
authors.initials: R
authors.lastname: Rauggi
authors.forename: Maria Graziella
authors.initials: MG
authors.lastname: De Montis
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000032:analysis; D000704:Analysis of Variance; D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal; D001552:Benzazepines / Q000493:pharmacokinetics; D001665:Binding Sites; D001923:Brain Chemistry; D002241:Carbohydrates / Q000494:pharmacology; D002452:Cell Count / Q000379:methods; D003042:Cocaine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D003216:Conditioning, Operant; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000493:pharmacokinetics; D004924:Escape Reaction; D008297:Male; D018782:Maze Learning; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000378:metabolism; D017551:Microdialysis; D009419:Nerve Tissue Proteins; D009714:Nucleus Accumbens / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000378:metabolism / Q000517:prevention & control; D013997:Time Factors; D014316:Tritium / Q000493:pharmacokinetics; D031669:Vanilla / Q000502:physiology
chemical_list: D001552:Benzazepines; D002241:Carbohydrates; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D014316:Tritium; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000262:Adenylyl Cyclases; D003042:Cocaine; D004298:Dopamine