title: Ephrin-A5 regulates the formation of the ascending midbrain dopaminergic pathways.
abstract: Dopaminergic neurons from the substantia nigra and the ventral tegmental area of the midbrain project to the caudate/putamen and nucleus accumbens, respectively, establishing the mesostriatal and the mesolimbic pathways. However, the mechanisms underlying the development of these pathways are not well understood. In the current study, the EphA5 receptor and its corresponding ligand, ephrin-A5, were shown to regulate dopaminergic axon outgrowth and influence the formation of the midbrain dopaminergic pathways. Using a strain of mutant mice in which the EphA5 cytoplasmic domain was replaced with beta-galactosidase, EphA5 protein expression was detected in both the ventral tegmental area and the substantia nigra of the midbrain. Ephrin-A5 was found in both the dorsolateral and the ventromedial regions of the striatum, suggesting a role in mediating dopaminergic axon-target interactions. In the presence of ephrin-A5, dopaminergic neurons extended longer neurites in in vitro coculture assays. Furthermore, in mice lacking ephrin-A5, retrograde tracing studies revealed that fewer neurons sent axons to the striatum. These observations indicate that the interactions between ephrin-A ligands and EphA receptors promote growth and targeting of the midbrain dopaminergic axons to the striatum.
authors.affiliation: Department of Chemical Biology, Ernest P. Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Cooper
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Renping
authors.initials: R
authors.lastname: Zhou
mesh_terms: D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000502:physiology*; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D036386:Ephrin-A5 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008636:Mesencephalon / Q000033:anatomy & histology* / Q000196:embryology; D051379:Mice; D008817:Mice, Mutant Strains; D041681:NIH 3T3 Cells; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D054801:Phosphoinositide Phospholipase C / Q000494:pharmacology; D051381:Rats; D036123:Receptor, EphA5 / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D036386:Ephrin-A5; D036123:Receptor, EphA5; D054801:Phosphoinositide Phospholipase C; D001616:beta-Galactosidase; D004298:Dopamine