Regulation of adult olfactory neurogenesis by insulin-like growth factor-I.
Insulin-like growth factor-I (IGF-I) has multiple effects within the developing nervous system but its role in neurogenesis in the adult nervous system is less clear. The adult olfactory mucosa is a site of continuing neurogenesis that expresses IGF-I, its receptor and its binding proteins. The aim of the present study was to investigate the roles of IGF-I in regulating proliferation and differentiation in the olfactory mucosa. The action of IGF-I was assayed in serum-free culture combined with bromodeoxyuridine-labelling of proliferating cells and immunochemistry for specific cell types. IGF-I and its receptor were expressed by globose basal cells (the neuronal precursor) and by olfactory neurons. IGF-I reduced the numbers of proliferating neuronal precursors, induced their differentiation into neurons and promoted morphological differentiation of neurons. The evidence suggests that IGF-I is an autocrine and/or paracrine signal that induces neuronal precursors to differentiate into olfactory sensory neurons. These effects appear to be similar to the cellular effects of IGF-I in the developing nervous system.
McCurdy
Richard D
RD
Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, QLD 4111, Australia.
Féron
François
F
McGrath
John J
JJ
Mackay-Sim
Alan
A
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015152:Blotting, Northern; D001973:Bromodeoxyuridine / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000502:physiology; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009831:Olfactory Mucosa / Q000187:drug effects* / Q000502:physiology; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013002:Somatomedins / Q000276:immunology / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism
D000906:Antibodies; D012333:RNA, Messenger; D013002:Somatomedins; D014404:Tubulin; D001973:Bromodeoxyuridine