title: Age-dependent neurotransmitter plasticity of ciliary ganglion neurons.
abstract: We have examined neurotransmitter plasticity in postmitotic cholinergic neurons isolated from 6.5- to 11-day-old embryonic quail ciliary ganglia. Purified neurons were labeled with DiI, transplanted into the trunk of young chick embryos, and assayed for catecholamine content and [3H]thymidine uptake 4 to 5 days later. For ciliary neurons derived from 6.5- to 8-day-old embryos, as many as 25% (average of 9% overall) expressed catecholamines in the host sympathetic ganglia, migratory stream, aortic plexuses, and adrenal medulla. In contrast, neurons from >8-day-old ganglia did not acquire or produce detectable catecholamines, indicating a limited time period over which phenotypic conversion can occur in vivo. As a control, ciliary neurons were also injected into the head mesenchyme of young embryos; no catecholamine expression was observed. Interestingly, after transplantation some DiI-labeled postmitotic ciliary neurons took up [3H]thymidine with or without phenotypic change. These results suggest that phenotypic plasticity in ciliary neurons is age-dependent, is location-dependent, and may involve resumption of DNA replication, a characteristic feature of some differentiating adrenergic sympathetic neurons. Apoptosis of a few proliferating transplanted cells may be induced independently or in association with transmitter change.
authors.affiliation: Division of Biology 139-74, California Institute of Technology, Pasadena, California, 91125, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Sechrist
authors.forename: J
authors.initials: J
authors.lastname: Wolf
authors.forename: M
authors.initials: M
authors.lastname: Bronner-Fraser
mesh_terms: D000313:Adrenal Medulla; D000818:Animals; D002232:Carbocyanines; D002395:Catecholamines / Q000378:metabolism; D002455:Cell Division; D002642:Chick Embryo; D004625:Embryo, Nonmammalian / Q000502:physiology*; D016332:Fetal Tissue Transplantation / Q000502:physiology; D005456:Fluorescent Dyes; D005726:Ganglia, Parasympathetic / Q000196:embryology / Q000502:physiology*; D005728:Ganglia, Sympathetic / Q000196:embryology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology* / Q000637:transplantation*; D011784:Quail; D013997:Time Factors
chemical_list: D002232:Carbocyanines; D002395:Catecholamines; D005456:Fluorescent Dyes; C097511:didodecylindocarbocyanine