title: Release of retinal growth hormone in the chick embryo: local regulation?
abstract: The neural retina is an extrapituitary site of growth hormone (GH) production and an autocrine or paracrine site of retinal GH action. Retinal GH is released from retinal tissue and may be secreted into the vitreous. Ontogenetic changes in the abundance of retinal GH during embryogenesis indicate that the amount of GH released may be regulated. The presence of pituitary GH secretagogues (GH-releasing hormone, GHRH; thyrotropin-releasing hormone, TRH; and ghrelin) and pituitary GH inhibitors (somatostatin, SRIF and insulin-like growth factor, IGF-1) within the neural retina may indicate the involvement of these factors in retinal GH release. This possibility is supported by the finding that GHRH is colocalized with GH in chick retinal ganglion cells (RGCs) and in immortalized cells (QNRD) derived from quail neuroretinal cells and by the induction of GH mRNA in incubated QNRD cells. In summary, these results provide evidence for the autocrine or paracrine regulation of retinal GH release in the ganglion cells of the embryonic chick retina.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7. steve.harvey@ualberta.ca
authors.forename: Steve
authors.initials: S
authors.lastname: Harvey
authors.forename: Winnie
authors.initials: W
authors.lastname: Lin
authors.forename: Daniel
authors.initials: D
authors.lastname: Giterman
authors.forename: Nasra
authors.initials: N
authors.lastname: El-Abry
authors.forename: Wei
authors.initials: W
authors.lastname: Qiang
authors.forename: Esmond J
authors.initials: EJ
authors.lastname: Sanders
mesh_terms: D000818:Animals; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental; D054439:Ghrelin / Q000502:physiology; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013007:Growth Hormone-Releasing Hormone / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D017481:Receptors, Somatostatin / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology
chemical_list: D054439:Ghrelin; D017481:Receptors, Somatostatin; C101130:somatostatin receptor type 1; D013973:Thyrotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone