title: Growth hormone promotes the survival of retinal cells in vivo.
abstract: Growth hormone (GH) is synthesized and present in the developing chick retina, where it may have local actions in retinal cell differentiation similar to those of conventional growth factors. We have previously shown that retinal GH has neuroprotective effects in retinal ganglion cells. In this paper, we extend our earlier functional studies by examining the in vivo effects of a GH siRNA (NR-cGH-1) after microinjection into the eye cup of the developing chick embryo in ovo. We show that intra-vitreous cGH siRNA lowers both GH mRNA and insulin-like growth factor-1 (IGF-1) mRNA levels in the retina in vivo, and concomitantly elevates the numbers of apoptotic cells in the retina. These effects are apparent 6h after treatment, and persist for at least 24h. The apoptotic cells induced by GH withdrawal were primarily located close to the optic fissure of the developing eye, and were distributed in clusters, suggesting that there are sub-populations of retinal cells that are particularly susceptible to apoptotic stimuli. These results support our view that a GH/IGF-1 axis in retinal cells regulates retinal cell survival in vivo.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alta., Canada.
authors.forename: Esmond J
authors.initials: EJ
authors.lastname: Sanders
authors.forename: Wan-Ying
authors.initials: WY
authors.lastname: Lin
authors.forename: Eve
authors.initials: E
authors.lastname: Parker
authors.forename: Steve
authors.initials: S
authors.lastname: Harvey
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D013006:Growth Hormone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D058449:Intravitreal Injections; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011784:Quail / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000494:pharmacology; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone