8-isoprostaglandin-e2 and Necrosis

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.

Topics: Amino Acids; Animals; Apoptosis; Cattle; Dinoprostone; Dose-Response Relationship, Drug; gamma-Aminobutyric Acid; Glutamine; Glycine; Isoprostanes; Necrosis; Neurotransmitter Agents; Organ Culture Techniques; Retina

Free radical-induced peroxidation is an important factor in the genesis of hypoxic-ischemic encephalopathy, including that of the preterm infant. Isoprostanes are major peroxidation products. Since microvascular dysfunction seems to contribute to ischemic encephalopathies, we studied the cytotoxicity of 8-iso-prostaglandin F2alpha (PGF2alpha) on cerebral microvascular cells.. Microvascular endothelial, astroglial, and smooth muscle cells from newborn brain were cultured. The cytotoxicity of 8-iso-PGF2alpha on these cells was determined by MTT assays and lactate dehydrogenase (LDH) release, propidium iodide incorporation, and DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling [TUNEL]). In addition, effects of intraventricular injections of 8-iso-PGF2alpha and possible involvement of thromboxane in 8-iso-PGF2alpha-induced cytotoxicity were determined.. 8-Iso-PGF2alpha induced time- and concentration-dependent endothelial cell death (EC50=0.1 nmol/L) but exerted little effect on smooth muscle and astroglial cells; endothelial cell death seemed mostly of oncotic nature (propidium iodide incorporation and LDH release). Cell death was associated with increased endothelial thromboxane A2 (TXA2) formation and was prevented by TXA2 synthase inhibitors (CGS12970 and U63557A); TXA2 mimetics U46619 and I-BOP also caused endothelial cell death. Intraventricular injection of 8-iso-PGF2alpha induced periventricular damage, which was attenuated by CGS12970 pretreatment.. These data disclose a novel action of 8-iso-PGF2alpha involving TXA2 in oxidant stress-induced cerebral microvascular injury and brain damage.

Topics: Animals; Astrocytes; Brain; Brain Ischemia; Cell Death; Cell Survival; Cells, Cultured; Dinoprost; Dinoprostone; DNA Fragmentation; Dose-Response Relationship, Drug; Endothelium, Vascular; Enzyme Inhibitors; F2-Isoprostanes; In Vitro Techniques; Injections, Intraventricular; Isoprostanes; L-Lactate Dehydrogenase; Microcirculation; Muscle, Smooth, Vascular; Necrosis; Rats; Rats, Sprague-Dawley; Swine; Thromboxane A2; Thromboxane-A Synthase