title: Forebrain-specific expression of monoamine oxidase A reduces neurotransmitter levels, restores the brain structure, and rescues aggressive behavior in monoamine oxidase A-deficient mice.
abstract: Previous studies have established that abrogation of monoamine oxidase (MAO) A expression leads to a neurochemical, morphological, and behavioral specific phenotype with increased levels of serotonin (5-HT), norepinephrine, and dopamine, loss of barrel field structure in mouse somatosensory cortex, and an association with increased aggression in adults. Forebrain-specific MAO A transgenic mice were generated from MAO A knock-out (KO) mice by using the promoter of calcium-dependent kinase IIalpha (CaMKIIalpha). The presence of human MAO A transgene and its expression were verified by PCR of genomic DNA and reverse transcription-PCR of mRNA and Western blot, respectively. Significant MAO A catalytic activity, autoradiographic labeling of 5-HT, and immunocytochemistry of MAO A were found in the frontal cortex, striatum, and hippocampus but not in the cerebellum of the forebrain transgenic mice. Also, compared with MAO A KO mice, lower levels of 5-HT, norepinephrine, and DA and higher levels of MAO A metabolite 5-hydroxyindoleacetic acid were found in the forebrain regions but not in the cerebellum of the transgenic mice. These results suggest that MAO A is specifically expressed in the forebrain regions of transgenic mice. This forebrain-specific differential expression resulted in abrogation of the aggressive phenotype. Furthermore, the disorganization of the somatosensory cortex barrel field structure associated with MAO A KO mice was restored and became morphologically similar to wild type. Thus, the lack of MAO A in the forebrain of MAO A KO mice may underlie their phenotypes.
authors.affiliation: Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Chen
authors.forename: Olivier
authors.initials: O
authors.lastname: Cases
authors.forename: Igor
authors.initials: I
authors.lastname: Rebrin
authors.forename: Weihua
authors.initials: W
authors.lastname: Wu
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Gallaher
authors.forename: Isabelle
authors.initials: I
authors.lastname: Seif
authors.forename: Jean Chen
authors.initials: JC
authors.lastname: Shih
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002384:Catalysis; D005838:Genotype; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008954:Models, Biological; D008995:Monoamine Oxidase / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010641:Phenotype; D016548:Prosencephalon / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018377:Neurotransmitter Agents; D012333:RNA, Messenger; D008995:Monoamine Oxidase