Abstract
Purpose::
To access the role for poly(ADP-ribose) polymerase activation in oxidative stress and apoptosis in diabetic retina and FFA-exposed retinal pericytes and endothelial cells. FFA are an important player in oxidative stress and apoptosis of vascular cells in diabetes.
Methods::
Control (C) and STZ-diabetic (D) rats were treated with/without the PARP inhibitors, 1,5-isoquinolinediol (ISO, 3 mgkg-1d-1 i.p.) or 10-(4-Methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]-anthracen-3-one (GPI 15427, 30 mgkg-1d-1), for 10 wks after 2 wks without treatment. The rate of apoptosis was assessed in flat-mounted retinas by TUNEL assay with immunoperoxidase staining. Primary bovine retinal pericytes and endothelial cells were cultured with/without 0.6 M palmitate, for 48 h. Apoptosis was assessed by TUNEL and caspase-3 assays, superoxide production by ethidium fluorescence, cell viability with Trypan blue, and nitrotyrosine (NT) and poly(ADP-ribose) (PAR) by immunocytochemistry.
Results::
The number of TUNEL-positive nuclei (Mean ± SEM) was increased ~4-fold in D (207 ± 33 vs 49 ± 4 in C, p < 0.01), and this increase was completely corrected in D+ISO and D+GPI 15427 (49 ± 15 and 43 ± 7, respectively, p < 0.01 vs D). Palmitate, at the 0.2-0.8 M concentrations, dose dependently increased superoxide production and reduced cell viability in cultured retinal cells. GPI 15427, 20 microM, prevented FFA-induced increase in the rate of apoptosis, and alleviated NT and PAR accumulation in both pericytes and endothelial cells.
Conclusions::
PARP inhibition counteracts oxidative stress and prevents apoptosis in diabetic retina and FFA-exposed retinal pericytes and endothelial cells.
Keywords: apoptosis/cell death • diabetic retinopathy • oxidation/oxidative or free radical damage