Abstract
Purpose: :
Neuroprostanes (NeuroPs) are isoprostane-like compounds that are derived from non-enzymatic, free-radical catalyzed peroxidation of docosahexaenoic (22:6 n-3) acid and docosapentaenoic acid (DPA; 22:5 n-6). We have evidence that the synthetic, DPA-derived NP, BA-12high regulates excitatory neurotransmitter release in bovine retina, in vitro (Opere et al., IOVS 46: E-Abstract 3315, 2010). However, the signal transduction processes activated by BA-12high in mammalian retina remain unknown. The present study investigates whether BA-12high regulates cyclic AMP production in rat retinal pigmented epithelial cells (RPE-J).
Methods: :
RPE-J cells were exposed to DMEM medium containing cyclooxygenase inhibitor, flurbiprofen (3 µM) and the phosphodiesterase inhibitor isobutylmethylxanthine (2 mM) for 30 minutes prior to treatment with BA12-high or forskolin (positive control) for 20 minutes. After termination of the reaction, cells were lysed and then prepared for cyclic AMP assays using an Enzyme Immunoassay (EIA) kit. Cyclic AMP production was expressed as pmol/mg of protein.
Results: :
In the concentration range, 10-9M to 10-4M, BA-12high caused a concentration-dependent increase in cyclic AMP concentrations over basal levels. For instance, BA-12high (10-8M) stimulated cyclic AMP accumulation by 170.5% (n=6; p <.0.05). Furthermore, a maximal stimulatory response of 388.4% (n=6; p < 0.001) was achieved at 1 µM concentration of the NeuroP. The response elicited by forskolin (10 µM) in RPE-J cells was comparable to that of BA-12high (1 µM).
Conclusions: :
The synthetic DPA-derived NeuroP, BA-12high can increase cyclic AMP production in rat retinal pigmented epithelial cells. Furthermore, NeuroPs may play a regulatory role in signal transduction processes in mammalian retina.
Keywords: retina • signal transduction • oxidation/oxidative or free radical damage