The role of enzymes and receptors of the prostanoid pathway in the inhibitory effect of 8-isoprostaglandin E 2 (8-isoPGE 2) on endogenous amino acid neurotransmitter levels was examined, ex vivo. Freshly isolated bovine eyeballs were injected intravitreally with IsoPs, incubated in Krebs buffer for 30 min and retina prepared for HPLC-ECD detection of amino acids. 8-isoPGE 2 attenuated retinal glutamate and its metabolite, glutamine and glycine in a concentration-dependent manner. The non-selective cyclooxygenase (COX)-inhibitor, flurbiprofen, COX-2 selective inhibitor, NS-398 and thromboxane (Tx) synthase inhibitor, furegrelate had no effect on both basal amino acid levels and the inhibitory effects of 8-isoPGE 2 (1-100 μM) on the retinal amino acids. Whereas the TP-receptor antagonist SQ-29548(10 μM) exhibited no effect, SC-19220(EP 1; 30 μM), AH-6809(EP 1-3; 30 μM) and AH-23848(EP 4; 30 μM) reversed the inhibitory effects of 8-isoPGE 2 (0.01-100 μM) on glutamate, glutamine and glycine levels. We conclude that prostanoid EP-receptors regulate the inhibitory effect of 8-isoPGE 2 on basal levels of endogenous amino acids in bovine retina, ex vivo.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience