RGD Reference Report - Early exposure of cultured hippocampal neurons to excitatory amino acids protects from later excitotoxicity. - Rat Genome Database

RGD Reference Report - Early exposure of cultured hippocampal neurons to excitatory amino acids protects from later excitotoxicity. - Rat Genome Database

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Early exposure of cultured hippocampal neurons to excitatory amino acids protects from later excitotoxicity.
Authors:	Friedman, LK Segal, M
Citation:	Friedman LK and Segal M, Int J Dev Neurosci. 2010 Apr;28(2):195-205. Epub 2009 Nov 11.
RGD ID:	4107720
Pubmed:	PMID:19913087 (View Abstract at PubMed)
DOI:	DOI:10.1016/j.ijdevneu.2009.11.002 (Journal Full-text)
Status epilepticus occurring in early postnatal development protects CA1 hippocampal neurons, the region most sensitive to seizure-induced injury in the developing brain. Here, we developed a "two hit" model in dissociated cultures of the rat hippocampus to test whether pre-exposure of immature neurons to high concentrations of glutamate, N-methyl-D-aspartic acid (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) during a relatively resistant period prevents neurons from dying following a second exposure to the same chemicals after neurons mature and become highly vulnerable to excitatory amino acids (EAAs). Cultures were exposed to varied doses of glutamate, NMDA, or AMPA for 48 h at 5 DIV and again at 14 DIV for 5, 15, or 30 min. NeuN immunohistochemistry showed early exposure to glutamate (500 microM) killed approximately half of the neurons (52+/-8.6%) compared to the marked depletion that occurs after one exposure at 14 DIV (98+/-0.79%). When cultures were first challenged with moderate doses of glutamate (200 microM) followed by the high dose 7 days later, a significant population of neurons was spared (35.3+/-1.2%). Similarly, pre-exposure to maximal doses of NMDA (100 microM) increased the proportion of surviving cells following the second challenge. In contrast, AMPA (100 microM) was equally toxic after early or late applications and did not protect from the second exposure. GluR1 subunit expression was markedly decreased at 48 h after one or two exposures to 200 microM glutamate (by 44.57+/-3.6%, 45.07+/-3.69%) whereas GluR2 subunit expression was reduced by a lesser amount (25.7 57+/-3.8%). Confocal microscopy showed that one or two exposures to NMDA caused GluR2 protein to downregulate even further whereas parvalbumin (PV) was dramatically increased in the same neurons by over four-fold. On the other hand, calbindin (CB) immunoreactivity was nearly absent after the first exposure to 500 microM glutamate. These data indicate that early, transient exposure to certain EAAs at high doses can induce long-lasting neuroprotection. Alterations in the GluR1/GluR2 ratio as well as differential expression of specific calcium binding proteins may contribute to this neuroprotection.

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Term	Qualifier	Evidence	With	Reference	Notes	Source	Original Reference(s)
cellular response to amino acid stimulus		IEP		4107720	glutamate	RGD

Objects Annotated

Genes (Rattus norvegicus)

Gria1 (glutamate ionotropic receptor AMPA type subunit 1)

Additional Information