title: Compound 49b prevents diabetes-induced apoptosis through increased IGFBP-3 levels.
abstract: OBJECTIVE
  To determine whether Compound 49b, a novel PKA-activating drug, can prevent diabetic-like changes in the rat retina through increased insulin-like growth factor binding protein-3 (IGFBP-3) levels.
  
  
  METHODS
  For the cell culture studies, we used both human retinal endothelial cells (REC) and retinal Müller cells in either 5 mM (normal) or 25 mM (high) glucose. Cells were treated with 50 nM Compound 49b alone of following treatment with protein kinase A (PKA) siRNA or IGFBP-3 siRNA. Western blotting and ELISA analyses were done to verify PKA and IGFBP-3 knockdown, as well as to measure apoptotic markers. For animal studies, we used streptozotocin-treated rats after 2 and 8 months of diabetes. Some rats were treated topically with 1 mM Compound 49b. Analyses were done for retinal thickness, cell numbers in the ganglion cell layer, pericyte ghosts, and numbers of degenerate capillaries, as well as electroretinogram and heart morphology.
  
  
  RESULTS
  Compound 49b requires active PKA and IGFBP-3 to prevent apoptosis of REC. Compound 49b significantly reduced the numbers of degenerate capillaries and pericyte ghosts, while preventing the decreased retinal thickness and loss of cells in the ganglion cell layer. Compound 49b maintained a normal electroretinogram, with no changes in blood pressure, intraocular pressure, or heart morphological changes.
  
  
  CONCLUSIONS
  Topical Compound 49b is able to prevent diabetic-like changes in the rat retina, without producing systemic changes. Compound 49b is able to prevent REC apoptosis through increasing IGFBP-3 levels, which are reduced in response to hyperglycemia.
authors.affiliation: Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
authors.forename: Qiuhua
authors.initials: Q
authors.lastname: Zhang
authors.forename: Kimberly
authors.initials: K
authors.lastname: Guy
authors.forename: Jayaprakash
authors.initials: J
authors.lastname: Pagadala
authors.forename: Youde
authors.initials: Y
authors.lastname: Jiang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Walker
authors.forename: Luhong
authors.initials: L
authors.lastname: Liu
authors.forename: Carl
authors.initials: C
authors.lastname: Soderland
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Kern
authors.forename: Robert
authors.initials: R
authors.lastname: Ferry
authors.forename: Hui
authors.initials: H
authors.lastname: He
authors.forename: C Ryan
authors.initials: CR
authors.lastname: Yates
authors.forename: Duane D
authors.initials: DD
authors.lastname: Miller
authors.forename: Jena J
authors.initials: JJ
authors.lastname: Steinle
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000473:pathology / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D004596:Electroretinography; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D006352:Heart Ventricles / Q000473:pathology; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009883:Ophthalmic Solutions; D034741:RNA, Small Interfering; D051381:Rats; D012160:Retina / Q000378:metabolism / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000473:pathology; D012171:Retinal Vessels / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014822:Vitreous Body / Q000737:chemistry
chemical_list: D000318:Adrenergic beta-Agonists; D018972:Insulin-Like Growth Factor Binding Protein 3; D009883:Ophthalmic Solutions; D034741:RNA, Small Interfering; D017868:Cyclic AMP-Dependent Protein Kinases