title: Regulation of extracellular serotonin levels and brain-derived neurotrophic factor in rats with high and low exploratory activity.
abstract: Serotonin (5-HT) system has a significant role in anxiety- and depression-related states and may be influenced by brain-derived neurotrophic factor (BDNF). This study examined extracellular 5-HT levels and expression of BDNF in rats with persistently low or high levels of exploratory activity (LE and HE, respectively). Baseline extracellular levels of 5-HT as assessed by in vivo microdialysis in conscious animals were similar in both groups in medial prefrontal cortex (PFC) and dentate gyrus (DG). No differences were found in parachloroamphetamine-induced 5-HT release in either region. However, LE animals had significantly higher levels of 5-HT transporter (5-HTT) binding in PFC and a larger increase in extracellular 5-HT levels after administration of citalopram (1 microM) into this area by retrograde dialysis. No difference in 5-HTT levels was found in hippocampus, while perfusion with citalopram was accompanied by a greater increase in extracellular 5-HT in the HE group in this brain region. LE-rats had higher levels of BDNF mRNA in the PFC but not hippocampus. In contrast, levels of nerve growth factor mRNA were similar in these brain regions of LE- and HE-rats. The differential regulation of 5-HT-ergic system in LE- and HE-rats in PFC and hippocampus may form the basis for their distinct anxiety-related behaviours.
authors.affiliation: Department of Psychology, Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410 Tartu, Estonia.
authors.forename: Tanel
authors.initials: T
authors.lastname: Mällo
authors.forename: Kadri
authors.initials: K
authors.lastname: Kõiv
authors.forename: Indrek
authors.initials: I
authors.lastname: Koppel
authors.forename: Karita
authors.initials: K
authors.lastname: Raudkivi
authors.forename: Ain
authors.initials: A
authors.lastname: Uustare
authors.forename: Ago
authors.initials: A
authors.lastname: Rinken
authors.forename: Tõnis
authors.initials: T
authors.lastname: Timmusk
authors.forename: Jaanus
authors.initials: J
authors.lastname: Harro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D015283:Citalopram / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology*; D045604:Extracellular Fluid / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D018490:Serotonin Agents / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D010133:p-Chloroamphetamine / Q000494:pharmacology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D015283:Citalopram; D012333:RNA, Messenger; D012701:Serotonin; D018490:Serotonin Agents; D017367:Selective Serotonin Reuptake Inhibitors; D010133:p-Chloroamphetamine