Microarray analysis of rat hippocampus exposed to excitotoxicity: Reversal Na⁺/Ca²⁺ exchanger NCX3 is overexpressed in glial cells

Abstract

Multiple factors are involved in the glutamate-induced excitotoxicity phenomenon, such as overload of ionotropic and metabotropic receptors, excess Ca(2+) influx, nitric oxide synthase activation, oxidative damage due to increase in free radicals, and release of endogenous polyamine, among others. In order to attempt a more integrated approach to address this issue, we established, by microarray analysis, the hippocampus gene expression profiles under glutamate-induced excitotoxicity conditions. Increased gene expression is mainly related to excitotoxicity (CaMKII, glypican 2, GFAP, NCX3, IL-2, and Gmeb2) or with cell damage response (dynactin and Ecel1). Several genes that augmented their expression are related to glutamatergic system modulation, in particular with NMDA receptor modulation and calcium homeostasis (IL-2, CaMKII, acrosin, Gmeb2, hAChE, Slc83a, and SP1 factor). Conversely, among genes that diminished their expression, we found the Syngap 1, which is downregulated by CaMKII, and the MHC II, which is downregulated by glutamate. Changes observed in gene expression induced by monosodium glutamate (MSG) neonatal treatment in the hippocampus are consistent with the activation of the mechanisms that modulate NMDA receptor function as well as with the implementation of plastic response to cell damage and intracellular calcium homeostasis. Regarding this aspect, we report here that NCX3/Slc8a3, a Na(+)/Ca(2+) membrane exchanger, is highly expressed in astrocytes, both in vitro and in vivo, in response to glutamate-induced excitotoxicity. Hence, the results of this analysis present a broad view of the expression profile elicited by MSG neonatal treatment, and lead us to suggest the possible molecular pathways of action and reaction involved under this experimental model of excitotoxicity.

Alliin, a Garlic (Allium sativum) Compound, Prevents LPS-Induced Inflammation in 3T3-L1 Adipocytes

“…For the hybridization experiments, the RNA utilized was from cells collected from cultures. For cDNA synthesis, 10  μ g of total RNA was used as the template, incorporating dUTP-Cy3 or dUTP-Cy5, and equal quantities of labeled cDNA were hybridized to the 22,000 oligo mouse arrays, as described previously [28, 29]. …”

“…All images were captured as described previously [28, 29]. In all cases, the fluorescence signal was from seven to ten times more intensive than the background signal, and the background evaluation was always evaluated immediately beside the labeled spot.…”

“…The goal of GenArise is to identify genes that are good candidates for differential expression by calculating an intensity-dependent z -score, successfully used and recently reported [28, 29]. Applying these criteria, the elements with a z -score of >2 standard deviations (SD) are genes likely to be differentially expressed.…”

KB-R7943 reduces 4-aminopyridine-induced epileptiform activity in adult rats after neuronal damage induced by neonatal monosodium glutamate treatment

“…In a previous work, increases in the expression level of mRNA and protein of NCX3 were already observed at PD8 in the Hp after MSG treatment [19]. Here, NCX3 protein expression was augmented by MSG treatment in both the Hp and EC at PD60, which suggests that the upregulation of NCX3 expression could be a long-term effect of the treatment and also that this outcome may be present in other cerebral regions; however, these hypotheses should be tested yet.…”

“…Neonate animals are more susceptible to MSG toxic effects, and repeated systemic administration of MSG at neonatal age produces neuronal death in the short term [9, 10] and several degenerative changes in the long term [11–14]. The expression levels and functionality of numerous enzymes [15, 16], receptors [9, 10, 17, 18] and transporters [14, 19] are modified by neonatal MSG treatment. Recently, a significant increase in the expression level of mRNA encoding the sodium/calcium (Na + /Ca 2+ ) exchanger type 3 (NCX3) was reported in the hippocampus (Hp) twenty hours after cessation of treatment [19], but it is unknown if neonatal MSG treatment has any long-term effects on this exchanger.…”