Regulation of extracellular serotonin levels and brain-derived neurotrophic factor in rats with high and low exploratory activity.
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.
Mällo
Tanel
T
Department of Psychology, Centre of Behavioural and Health Sciences, University of Tartu, Tiigi 78, 50410 Tartu, Estonia.
Kõiv
Kadri
K
Koppel
Indrek
I
Raudkivi
Karita
K
Uustare
Ain
A
Rinken
Ago
A
Timmusk
Tõnis
T
Harro
Jaanus
J
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
D019208:Brain-Derived Neurotrophic Factor; D015283:Citalopram; D012333:RNA, Messenger; D012701:Serotonin; D018490:Serotonin Agents; D017367:Selective Serotonin Reuptake Inhibitors; D010133:p-Chloroamphetamine