Regulation of retinal morphology and posterior segment amino acids by 8-isoprostaglandin E2 in bovine eyes ex vivo

Abstract

There is evidence that isoprostanes (IsoPs) can regulate exogenously applied excitatory amino acid neurotransmitters in bovine retina in vitro. However, the regulation of retinal morphology and endogenous neurotransmitter levels by IsoPs is unknown. We examined the effects of intravitreally injected 8-iso-PGE(2) on retinal tissue integrity and viability and amino acid neurotransmitters in bovine eye organ culture ex vivo. Exposure of bovine eyeballs to simulated experimental conditions revealed no retinal apoptosis and necrosis in TUNEL and DAPI staining and hematoxylin and eosin staining assays, respectively, and no changes in basal levels of amino acids in retina and vitreous humor. Furthermore, intravitreal injection of 8-iso-PGE(2) into bovine eyeballs had no effect on retinal apoptosis and integrity. Interestingly, 8-iso-PGE(2) caused a concentration-dependent attenuation of retinal glutamate and its metabolite glutamine and glycine levels, while GABA was unaffected. 8-Iso-PGE(2) (1 and 100 microM) significantly (P < 0.001) attenuated glutamate levels by 33.9% and 48.0%, respectively. 8-Iso-PGE(2) (100 microM) inhibited (P < 0.01) retinal glutamine and glycine levels by 37.7% and 35.5%, respectively. The IsoP exhibited no effect on vitreous humor glutamine and glycine levels, while glutamate and GABA were not detected. Thus, 8-iso-PGE(2) can regulate retinal amino acids without inducing cell death in bovine retina ex vivo.