title: Evidence for an important role of IGF-I and IGF-II for the early development of chick sympathetic neurons.
abstract: The ability of immature neurons from chick lumbosacral sympathetic ganglia to proliferate in vitro was used to identify factors that affect neurogenesis. Under serum-free culture conditions, insulin-like growth factor I (IGF-I), IGF-II, or insulin caused an increase in the proportion of cells that incorporated [3H]thymidine. In addition, IGFs also stimulated neurite outgrowth from these immature sympathetic neurons. IGF-I and IGF-II mRNA was found to be expressed in E7 sympathetic ganglia during the period of neurogenesis. IGF-I was detectable in fibroblasts, whereas IGF-II mRNA was expressed by neurons, glia, and fibroblasts. Elimination of endogenous IGFs by neutralizing antibodies resulted in a reduction of neuron proliferation and neuron number, whereas elevation of IGF levels by treatment with IGF-I increased sympathetic neuron proliferation in vivo. These findings suggest an important role of IGFs for the development of sympathetic neurons and imply a general role of IGFs in the control of neurogenesis and neurite outgrowth.
authors.affiliation: Max-Planck-Institut für Hirnforschung, Abt. Neurochemie, Frankfurt/M., Germany.
authors.forename: K
authors.initials: K
authors.lastname: Zackenfels
authors.forename: R W
authors.initials: RW
authors.lastname: Oppenheim
authors.forename: H
authors.initials: H
authors.lastname: Rohrer
mesh_terms: D000818:Animals; D001483:Base Sequence; D002452:Cell Count; D002455:Cell Division; D002478:Cells, Cultured; D002642:Chick Embryo; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016501:Neurites / Q000502:physiology; D009474:Neurons / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology / Q000196:embryology*
chemical_list: D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II