title: Molecular mechanisms contributing to dendritic spine alterations in the prefrontal cortex of subjects with schizophrenia.
abstract: Postmortem studies have revealed reduced densities of dendritic spines in the dorsal lateral prefrontal cortex (DLPFC) of subjects with schizophrenia. However, the molecular mechanisms that might contribute to these alterations are unknown. Recent studies of the intracellular signals that regulate spine dynamics have identified members of the RhoGTPase family (e.g., Cdc42, Rac1, RhoA) as critical regulators of spine structure. In addition, Duo and drebrin are spine-specific proteins that are critical for spine maintenance and spine formation, respectively. In order to determine whether the mRNA expression levels of Cdc42, Rac1, RhoA, Duo or drebrin are altered in schizophrenia, tissue sections containing DLPFC area 9 from 15 matched pairs of subjects with schizophrenia and control subjects were processed for in situ hybridization. Expression levels of these mRNAs were also correlated with DLPFC spine density in a subset of the same subjects. In order to assess the potential influence of antipsychotic medications on the expression of these mRNAs, similar studies were conducted in monkeys chronically exposed to haloperidol or olanzapine. The expression of each of these mRNAs was lower in the gray matter of the subjects with schizophrenia compared to the control subjects, although only the reductions in Cdc42 and Duo remained significant after corrections for multiple comparisons. In addition, spine density was strongly correlated with the expression levels of both Duo (r=0.73, P=0.007) and Cdc42 (r=0.71, P=0.009) mRNAs. In contrast, the expression levels of Cdc42 and Duo mRNAs were not altered in monkeys chronically exposed to antipsychotic medications. In conclusion, reduced expression of Cdc42 and Duo mRNAs may represent molecular mechanisms that contribute to the decreased density of dendritic spines in the DLPFC of subjects with schizophrenia.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Hill
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: D A
authors.initials: DA
authors.lastname: Lewis
mesh_terms: D000328:Adult; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D049229:Dendritic Spines / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D020662:Guanine Nucleotide Exchange Factors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000882:Haplorhini; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009479:Neuropeptides / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017397:Prefrontal Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012559:Schizophrenia / Q000188:drug therapy / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D014150:Antipsychotic Agents; D020662:Guanine Nucleotide Exchange Factors; D009479:Neuropeptides; D012333:RNA, Messenger; C053386:drebrins; C503866:KALRN protein, human; D017346:Protein Serine-Threonine Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein