Induction of cell proliferation in avian inner ear sensory epithelia by insulin-like growth factor-I and insulin.
Postembryonic production of inner-ear hair cells occurs both normally and after insult in lower vertebrates and avians. To determine how this proliferation is controlled, several growth factors were tested for effects on progenitor-cell division in cultured avian vestibular sensory epithelium. Mitogenic effects of bombesin, epidermal growth factor, insulin-like growth factor-I (IGF-I), insulin, and transforming growth factor-alpha were assayed in organo-typic cultures of utricles from the mature, undamaged (normal) chicken inner ear. Tritiated thymidine and autoradiographic techniques and 5-bromo-2'-deoxyuridine (BrdU) immunocytochemistry were used to identify cells synthesizing DNA. IGF-I stimulated DNA synthesis in the vestibular sensory receptor epithelium in a dose-dependent manner. DNA synthesis was also stimulated by insulin. These results suggest that stimulation of the IGF-I receptors by IGF-I or insulin binding stimulates cell proliferation in the mature avian vestibular sensory epithelium.
Oesterle
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Department of Otolaryngology-HNS, University of Washington, Seattle 98195, USA. Oesterle@otomail.u.washington.edu
Tsue
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Rubel
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D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D002645:Chickens; D007758:Ear, Inner / Q000187:drug effects*; D004848:Epithelium / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D011984:Sensory Receptor Cells / Q000187:drug effects*
D007328:Insulin; D007334:Insulin-Like Growth Factor I