Poly(ADP-ribose)polymerase inhibition counteracts cataract formation and early retinal changes in streptozotocin-diabetic rats.
OBJECTIVE
This study evaluated the role for poly(ADP-ribose) polymerase (PARP) in diabetes-induced cataractogenesis and early retinal changes.


METHODS
Control and streptozotocin (STZ)-diabetic rats were treated with or without the PARP inhibitors 1,5-isoquinolinediol (ISO; 3 mg kg(-1) d(-1) intraperitoneally) and 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]anthracen-3-1 (GPI-15427, 30 mg kg(-1) d(-1) orally) for 10 weeks after the first 2 weeks without treatment. Lens clarity was evaluated by indirect ophthalmoscopy and slit lamp examination, and retinal changes were evaluated by immunohistochemistry and Western blot analysis. In in vitro studies, cultured human lens epithelial cells and bovine retinal pericytes and endothelial cells were exposed to high glucose or palmitate.


RESULTS
PARP is expressed in lens, and poly(ADP-ribosyl)ated proteins are primarily localized in the 38- to 87-kDa range of the protein spectrum, with several minor bands at 17 to 38 kDa. The 38- to 87-kDa and the 17- to 38-kDa poly(ADP-ribosyl)ated protein expression increased by 74% and 275%, respectively, after 4 weeks of diabetes and by approximately 65% early after exposure of lens epithelial cells to 30 mM glucose. Both PARP inhibitors delayed, but did not prevent, the formation of diabetic cataract. The number of TUNEL-positive nuclei in flatmounted retinas increased approximately 4-fold in STZ diabetic rats, and this increase was prevented by ISO and GPI-15427. Both PARP inhibitors reduced diabetes-induced retinal oxidative-nitrosative and endoplasmic reticulum stress and glial activation. GPI-15427 (20 microM) prevented oxidative-nitrosative stress and cell death in palmitate-exposed pericytes and endothelial cells.


CONCLUSIONS
PARP activation is implicated in the formation of diabetic cataract and in early retinal changes. These findings provide a rationale for the development of PARP inhibitors for the prevention of diabetic ocular complications.
Drel
Viktor R
VR
Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808, USA.
Xu
Weizheng
W
Zhang
Jie
J
Kador
Peter F
PF
Ali
Tayyeba K
TK
Shin
Jeho
J
Julius
Ulrich
U
Slusher
Barbara
B
El-Remessy
Azza B
AB
Obrosova
Irina G
IG
D000818:Animals; D015153:Blotting, Western; D002386:Cataract / Q000378:metabolism / Q000517:prevention & control*; D002417:Cattle; D018929:Cell Culture Techniques; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism / Q000517:prevention & control*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007546:Isoquinolines; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D009930:Organic Chemicals / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D020286:Pericytes / Q000187:drug effects / Q000378:metabolism; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects / Q000378:metabolism
D004791:Enzyme Inhibitors; D007546:Isoquinolines; D009930:Organic Chemicals; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011804:Quinolines; C095653:1,5-dihydroxyisoquinoline; C502278:GPI 15427; D011065:Poly(ADP-ribose) Polymerases