INVOLVEMENT OF PLATELET-ACTIVATING-FACTOR (PAF) IN GLUTAMATE NEUROTOXICITY IN RAT NEURONAL CULTURES

To clarify the role of platelet-activating factor (PAF) in glutamate n eurotoxicity, in vitro experiments using primary neuronal cultures wer e performed. The anti-PAF immunoglobulin-G (aPAF-IgC) and the three PA F receptor antagonists (BN52021, CV6209, and E5880) were tested for th eir neuroprotective activity in primary neuronal cultures isolated fro m embryonic rat cerebral cortex. The cultured neurons were exposed to glutamate (1 mM) for 60 min. Twenty-four hours after this exposure, aP AF-IgG demonstrated evidence of protective effects against neuronal da mage in a dose-dependent manner. Protective effects also; were observe d in cultures treated with the three PAF antagonists (P < 0.05 at 1 mu g/ml aPAF-IgG, P < 0.01 at 100 mu M BN52O21, P < 0.05 at 10 nM CV6209 and P < 0.01 at 10 nM E5880). The Fura-2 assay was used to estimate w hether low dosages of exogenous PAF affect cultured neurons. The cultu red neurons were loaded with Fura-2/AM. After preincubation for 120 mi n, the Fura-2-loaded neurons were exposed to various concentrations of PAF for 60 min. By measuring the fluorescent intensity of the medium as representing the amount of Fura-2 released from damaged neurons, we detected an increased release of Fura-2, even at low doses of PAF (P < 0.01 at 10 nM PAF). We further studied PAF production by neurons in response to glutamate. The level of PAF measured in the medium exposed to glutamate was significantly higher than the level in the medium un exposed to glutamate (P < 0.05). Our results suggest an important role of PAF in glutamate neurotoxicity. (C) 1997 Elsevier Science B.V.