NMDA receptors mediate anoxia/aglycemia-induced release of eicosanoids in immature rat hippocampal slices: utility of an in vitro "ischemic" superfusion model with temporary arrest of medium flow

• Published in: Folia neuropathologica Vol. 32; no. 3; pp. 155 - 159
• Main Authors: Salińska, E, Lazarewicz, J W
• Format: Journal Article
• Language: English
• Published: Poland 1994
• Subjects: 6-Ketoprostaglandin F1 alpha - analysis; 6-Ketoprostaglandin F1 alpha - metabolism; 6-Ketoprostaglandin F1 alpha - secretion; Animals; Arachidonic Acid - secretion; Brain Ischemia - etiology; Calcium - pharmacology; Culture Techniques; Dizocilpine Maleate - pharmacology; Eicosanoids - analysis; Eicosanoids - metabolism; Eicosanoids - secretion; Hippocampus - chemistry; Hypoxia - complications; N-Methylaspartate - antagonists & inhibitors; Quinacrine - pharmacology; Radioimmunoassay; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate - drug effects; Thromboxane B2 - analysis; Thromboxane B2 - metabolism; Thromboxane B2 - secretion
• ISSN: 1641-4640

Hippocampal slices of rats at postnatal day 7 were submitted to superfusion with Ca(2+)- and Mg(2+)-free, bicarbonate buffered ion balanced medium, and perfusate concentrations of eicosanoids: thromboxane B2 and 6-keto prostaglandin F1 alpha were determined by the radioimmunoassay. It was noted that the permanent presence of Ca2+ increased the basal eicosanoid level, and in these conditions modulation of eicosanoid production was lost, whereas temporary, a 20 min application of 1.3 mM Ca2+ did not influence significantly eicosanoid release. A 20 min application of the anoxic/aglycemic medium containing calcium did not change the content of eicosanoids in superfusates. A significant stimulation of the thromboxane B2 and 6-keto prostaglandin F1 alpha release was noted provided the application of the experimental medium was accompanied by a 10 min arrest of superfusion. This effect was inhibited by MK-801 and quinacrine, suggesting an involvement of NMDA receptors and phospholipase A2. We propose that a model of anoxic/aglycemic superfusion with a stop flow period allows retention of endogenous glutamate in the extracellular fluid, resembling a similar effect during in vivo ischemia, whereas during a continuous superfusion glutamate is immediately washed out. Consequently, an application of the anoxic/aglycemic medium accompanied by a temporary arrest of superfusion represents more adequate in vitro model of ischemia than a constant superfusion with this medium. In these conditions NMDA receptors mediate eicosanoid release.