Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures

Using organotypic slice cultures of hippocampus and cortex-striatum from ne wborn to 7 day old rats, we are currently studying the excitotoxic effects of kainic acid (KA), AMPA and NMDA and the neuroprotective effects of gluta mate receptor blockers, like NBQX. For detection and quantitation of the in duced neurodegeneration, we have developed standardized protocols, includin g - a) densitometric measurements of the cellular uptake of propidium iodid e (PI), - b) histological staining by Flouro-Jade, - c) lactate dehydrogena se (LDH) release to the culture medium, - d) immunostaining for microtubuli n-associated protein 2, and - e) general and specific neuronal and glial ce ll stains. The results show good correlation between the different markers, and are in accordance with results obtained in vivo. Examples presented in this review will focus ori the use of PI uptake to monitor the excitotoxic effects of - a) KA and AMPA land NMDA) in hippocampal slice cultures, and - b) KA and AMPA in corticostriatal slice cocultures, with demonstration of differentiated neuroprotective effects of NBQX in relation to cortex and s triatum and KA and AMPA. A second set of studies include modulation of hipp ocampal KA-induced excitotoxicity and KA-glutamate receptor subunit mRNA ex pression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardiz ed procedures for quantitation of cell damage and receptor subunit changes is of great potential use for studies of excitotoxic, glutamate receptor-in duced neuronal cell death, receptor modulation and related neuroprotection.