title: Functional aspects of dopamine metabolism in the putative prefrontal cortex analogue and striatum of pigeons (Columba livia).
abstract: Dopamine (DA) in mammalian associative structures, such as the prefrontal cortex (PFC), plays a prominent role in learning and memory processes, and its homeostasis differs from that of DA in the striatum, a sensorimotor region. The neostriatum caudolaterale (NCL) of birds resembles the mammalian PFC according to connectional, electrophysiological, and behavioral data. In the present study, DA regulation in the associative NCL and the striatal lobus parolfactorius (LPO) of pigeons was compared to uncover possible differences corresponding to those between mammalian PFC and striatum. Extracellular levels of DA and its metabolites (homovanillic acid [HVA], dihydroxyphenylacetic acid [DOPAC]) and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) were investigated by in vivo microdialysis of urethane-anesthetized pigeons under basal conditions and after systemic administration of D-amphetamine. DA was reliably determined only in LPO dialysates, and DA metabolite levels were significantly higher in LPO than in NCL. The HVA/DOPAC ratio, indicating extracellular lifetime of DA, was more than twice as high in NCL than in LPO dialysates. After amphetamine, DA increased in LPO while still being undetectable in NCL, and DA metabolites decreased in both regions. 5-HIAA slightly decreased in NCL dialysates. Amphetamine effects were delayed in NCL compared with the striatum. In conclusion, effects of amphetamine on the pigeon's ascending monoamine systems resemble those found in mammals, suggesting similar regulatory properties. The neurochemical differences between NCL and LPO parallel those between associative regions, such as PFC and dorsal striatum in mammals. They may reflect weaker regulation of extracellular DA, favoring DAergic volume transmission, in associative than striatal forebrain regions.
authors.affiliation: Biopsychologie, Fakultät für Psychologie, Ruhr-Universität Bochum, 44780 Bochum, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Bast
authors.forename: Bettina
authors.initials: B
authors.lastname: Diekamp
authors.forename: Christiane
authors.initials: C
authors.lastname: Thiel
authors.forename: Rainer K W
authors.initials: RK
authors.lastname: Schwarting
authors.forename: Onur
authors.initials: O
authors.lastname: Güntürkün
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D010856:Columbidae / Q000033:anatomy & histology* / Q000378:metabolism; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D006719:Homovanillic Acid / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism; D008636:Mesencephalon / Q000166:cytology / Q000378:metabolism*; D017551:Microdialysis; D009419:Nerve Tissue Proteins; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000166:cytology / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D012701:Serotonin / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D000661:Amphetamine; D004298:Dopamine; D006719:Homovanillic Acid