Growth hormone expression and neuroprotective activity in a quail neural retina cell line

We have previously shown that growth hormone (GH) is produced within cells of the chick embryo retina where it appears to act as an autocrine/paracrine anti-apoptotic factor in the regulation of programmed cell death during retinal development. These investigations were carried out on cultured chick embryo retinal ganglion cells (RGCs) as well as on the chick embryo retina in ovo, using GH protein knock-down by immunoneutralization. We have now investigated the putative neuroprotective actions of GH using a quail embryo neural retina cell line (QNR/D) treated with GH siRNA to silence the local synthesis of GH. We now show that knock-down of GH by gene silencing in cells of this cultured embryonic neural retina cell line, using NR-cGH-1 siRNA, correlates with the increased appearance in the cultures of cells with apoptotic nuclear morphology. This result is consistent with our previous results using protein knock-down by immunoneutralization. We thus validate, using different technology and a different culture system, our contention that GH, produced locally by cells of the neural retina acts in an autocrine or paracrine manner to regulate cell survival in the retina.