title: Use of Arc expression as a molecular marker of increased postsynaptic 5-HT function after SSRI/5-HT1A receptor antagonist co-administration.
abstract: An increase in central postsynaptic 5-hydroxytryptamine (5-HT) function activates expression of activity-related cytoskeletal protein (Arc). Here, Arc expression was used to test whether, in rats, co-administration of a 5-HT re-uptake inhibitor (paroxetine) and a 5-HT1A receptor antagonist (WAY 100635) increases postsynaptic 5-HT function. After pre-treatment with WAY 100635 (0.3 mg/kg s.c.), paroxetine (5 mg/kg s.c.) caused a threefold increase in 5-HT in prefrontal cortex microdialysates. In situ hybridization studies found that neither paroxetine (5 mg/kg s.c.) nor WAY 1000635 (0.3 mg/kg s.c.) altered Arc mRNA abundance in any region examined. In contrast, paroxetine (5 mg/kg s.c.) increased Arc mRNA after pre-treatment with WAY 100635 (0.3 mg/kg s.c.). This increase was apparent in cortical regions (frontal, parietal and cingulate) and caudate nucleus but was absent in hippocampus (CA1). Increases in Arc mRNA were accompanied by an increase in c-fos mRNA. The increase in Arc expression induced by paroxetine/WAY 100635 was abolished by the 5-HT synthesis inhibitor, p-chlorophenylalanine (300 mg/kg i.p., daily for two days). In conclusion, paroxetine and WAY 100635 injected in combination (but not alone) caused a region-specific, 5-HT-mediated increase in Arc expression. These data provide molecular evidence that co-administration of a 5-HT re-uptake inhibitor and 5-HT1A receptor antagonist increases 5-HT function at the postsynaptic level.
authors.affiliation: Department of Physiology and Pharmacology, University of Cantabria, Santander, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Castro
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Tordera
authors.forename: Zoe A
authors.initials: ZA
authors.lastname: Hughes
authors.forename: Qi
authors.initials: Q
authors.lastname: Pei
authors.forename: Trevor
authors.initials: T
authors.lastname: Sharp
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003598:Cytoskeletal Proteins / Q000235:genetics*; D004357:Drug Synergism; D005110:Extracellular Space / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D008297:Male; D017551:Microdialysis; D009419:Nerve Tissue Proteins / Q000235:genetics*; D017374:Paroxetine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000032:analysis / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013569:Synapses / Q000378:metabolism
chemical_list: D015415:Biomarkers; D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D017374:Paroxetine; D010879:Piperazines; D016760:Proto-Oncogene Proteins c-fos; D011725:Pyridines; D012333:RNA, Messenger; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors; C092069:activity regulated cytoskeletal-associated protein; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide