title: Localization of organic cation transporter 2 (OCT2) in monoaminergic and cholinergic axon terminals of the mouse brain.
abstract: Organic cation transporters (OCTs) are low-affinity, high-capacity carriers that mediate sodium-independent transport for biogenic cations, including catecholamine, serotonin, histamine, and choline/acetylcholine. Among them, OCT2 is expressed in neurons of the central nervous system. Although previous studies show OCT2 expression in several populations of cholinergic and monoaminergic neurons, the regional distribution of OCT2 in the brain remains largely unknown. Here we performed immunohistochemical analyses to reveal the distribution of OCT2 throughout the mouse forebrain. OCT2 immunoreactivity was widely distributed, with substantial regional specificity in cortical and subcortical structures including the hippocampus, striatum, and some subdivisions of the amygdala and extended amygdala. Interestingly, OCT2 appeared as punctate, bouton-like labeling in cholinergic, dopaminergic, and serotonergic axon terminals that were co-labeled with presynaptic neurochemical markers. We also co-labeled OCT2 and an anterograde tract-tracer injected into the locus coeruleus, demonstrating that OCT2 was localized to presumptive noradrenergic terminals in the forebrain. Together, our results demonstrated that the polyspecific cation transporter OCT2 is distributed in cholinergic and monoaminergic terminals in various forebrain regions, suggesting that OCT2 could play a role in regulating presynaptic reuptake and recycling of choline and monoamines.
authors.affiliation: Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama, Japan.
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Molecular and Cellular Anatomy, Faculty of Health Promotional Sciences, Tokoha University, Hamamatsu, Shizuoka, Japan; Department of Health Science, Ishikawa Prefectural Nursing University, Ishikawa, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakata
authors.affiliation: Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama, Japan. Electronic address: yasushi@ndmc.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D059329:Cholinergic Neurons / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000378:metabolism*; D005260:Female; D008125:Locus Coeruleus / Q000378:metabolism; D008297:Male; D008813:Mice, Inbred ICR; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D000075102:Organic Cation Transporter 2; D017729:Presynaptic Terminals / Q000378:metabolism*; D016548:Prosencephalon / Q000378:metabolism; D059326:Serotonergic Neurons / Q000378:metabolism*
chemical_list: D027701:Organic Cation Transport Proteins; D000075102:Organic Cation Transporter 2; C491012:Slc22a2 protein, mouse
keywords: Acetylcholine; Monoamine; Neurotransmitter reuptake; Neurotransmitter transporter; Organic cation transporter