Neurovascular protective effect of FeTPPs in N-methyl-D-aspartate model: similarities to diabetes.
We have previously shown a causal role of peroxynitrite in mediating retinal ganglion cell (RGC) death in diabetic and neurotoxicity models. In the present study, the role of peroxynitrite in altering the antioxidant and antiapoptotic thioredoxin (Trx) system will be investigated as well as the subsequent effects on glial activation and capillary degeneration. Excitotoxicity of the retina was induced by intravitreal injection of N-methyl-d-aspartate (NMDA) in rats, which also received the peroxynitrite decomposition catalyst FeTPPs. RGC loss was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and GC count. Glial activation and nitrotyrosine were assessed by immunohistochemistry. Acellular capillaries and pericytes were counted in retinal trypsin digest. NMDA-induced peroxynitrite formation caused RGC loss, which was associated with enhanced expression of Trx and its endogenous inhibitor thioredoxin interacting protein. The results also showed enhanced thioredoxin interacting protein/Trx binding and disruption of the Trx/apoptosis signal-regulating kinase 1 "inhibitory complex," leading to release of apoptosis signal-regulating kinase 1 and activation of the apoptotic pathway, as evidenced by p38 MAPK and poly-ADP-ribose polymerase activation. Furthermore, NMDA caused glial activation and compromised retinal vasculature, as indicated by acellular-capillary formation and pericyte loss. Treatment with FeTPPs blocked these effects. In conclusion, NMDA-induced retinal neuro/vascular injury is mediated by peroxynitrite-altered Trx antioxidant defense, which in turn activates the apoptosis signal-regulating kinase-1 apoptotic pathway. In addition to acute RGC death, an NMDA model can be a useful tool to study glial activation and capillary degeneration in retinal neurodegenerative disorders, including diabetic retinopathy.
Al-Gayyar
Mohammed M H
MM
Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA 30912, USA.
Abdelsaid
Mohammed A
MA
Matragoon
Suraporn
S
Pillai
Bindu A
BA
El-Remessy
Azza B
AB
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002452:Cell Count; D003930:Diabetic Retinopathy / Q000209:etiology / Q000378:metabolism*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D058449:Intravitreal Injections; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology*; D016202:N-Methylaspartate / Q000494:pharmacology*; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism; D012171:Retinal Vessels / Q000187:drug effects* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
C466420:5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron(III) chloride; D008665:Metalloporphyrins; D030421:Peroxynitrous Acid; D016202:N-Methylaspartate; D048848:MAP Kinase Kinase Kinase 5