Gangliosides prevent glutamate and kainate neurotoxicity in primary neuronal cultures of neonatal rat cerebellum and cortex.

Abstract

Using a sensitive histofluorescence staining method that allows for a quantitation of neuronal death, we compared the protective effects of gangliosides (a group of naturally occurring glycosphingolipids), phencyclidine (PCP), and MK-801 (dibenzocyclohepteneimine) on glutamate-and kainate-induced neuronal death in primary cultures of cortical and cerebellar neurons prepared from neonatal rats. PCP and MK-801 block neurotoxicity induced by glutamate doses 50 times higher than the LD50 (LD50 in Mg2+ free medium, 10 ,uM) but only partially block the kainate neurotoxicity (LD50 in presence of Mg2+, 100 ,uM). In contrast, pretreatment with gangliosides (GT1b > GD1b > GM1) results in complete and insurmountable protection against the neurotoxicity elicited by glutamate or kainate. In primary cultures of cerebellar granule cells gangliosides, unlike PCP and MK-801, fail to block glutamate-gated cationic currents and the glutamate-evoked increase of (i) inositol phospholipid hydrolysis, (ii) c-fos mRNA content, and (iii) nuclear accumulation of c-fos protein. Protection of glutamate neurotoxicity by gangliosides does not require their presence in the incubation medium; however, it is proportional to the amount of glycosphingolipid accumulated in the neuronal membranes. The ganglioside concentration (30-60 ,uM) that blocks glutamate-elicited neuronal death also prevents glutamate-and kainate-induced protein kinase C translocation from cytosol to neuronal membranes.High-affinity glutamate binding sites that recognize Nmethyl-D-aspartate (NMDA) are located on a specific excitatory amino acid receptorial domain that operates ionotropic (1)(2)(3)(4) and/or metabolotropic (4-10) signal transduction. These glutamate receptorial domains, in addition to the recognition site for the putative excitatory neurotransmitter, include two kinds of noncompetitive inhibitory sites regulated by Mg2 + and by an unknown natural ligand acting on a site that recognizes phencyclidine (PCP) (1,4,(11)(12)(13). Moreover, positive and/or negative allosteric centers modulate NMDA-sensitive glutamate recognition sites (13)(14)(15); these are believed to have glycine (13,14) or kynurenate (15) as putative endogenous modulators, respectively. These NMDAsensitive recognition sites operate cationic channels (1, 4), stimulate inositol phospholipid hydrolysis (4-6), or release arachidonic acid (7) and cause a Ca2 -dependent accumulation of cGMP (4,8). Transduction mechanisms operated by activation of NMDA-sensitive glutamate recognition sites elicit a sequelae ofevents, including an increase in c-fos protooncogene mRNA content (9) and the nuclear accumulation of c-fos protein, which in turn promotes the coordinated expression of selected mRNAs encoding proteins (16) (19,(23)(24)(25), a possible therapeutic application of these drugs to limit secondary neurotoxicity occurring in brain regions surrounding ischemic areas has been proposed (19,24,25). Gangliosides and sphingosine applied to primary cultures of neonatal rat cerebellar granule cells pre...

Neuroprotection by Peptide Growth Factors against Anoxia and Nitric Oxide Toxicity Requires Modulation of Protein Kinase C

“…Inhibition of PKC activity is protective during several models of ischemic injury, including anoxia (Maiese et al, 1993b), NO exposure (Maiese et al, 1993b,c), glutamate toxicity (Favaron et al, 1988), and animal models of global ischemia (Hara et al, 1990). In contrast to these studies, the down regulation of PKC activity with PMA (1 f..L M) and the combined application of either bFGF or EGF reduced the protective effects of the growth factors during anoxia and NO exposure.…”

“…15, No. 3, 1995 against glutamate tOXICIty (Favaron et al, 1988), anoxia (Maiese et al, 1993b), and NO (Maiese et al, 1993b,c).…”

“…In vitro experiments have linked PKC with both excitatory amino acid and NO toxicity. Inhibition of PKC activity has been shown to reduce neuronal death during peri ods of glutamate and kainate toxicity (Favaron et al, 1988). In addition, we have recently demon strated that inhibition of PKC activity is protective against both anoxia and NO exposure in primary hippocampal neuronal cultures (Maiese et al, 1993b,c).…”

GM1 induces p38 and microtubule dependent ramification of rat primary microglia in vitro

“…1B) and LPS-and IFN-γ-treated microglia (data not shown). Furthermore, several studies indicated that gangliosides increase the rates of neuritogenesis both in vivo and in vitro (Ferrari et al, 1983;Mendez-Otero and Santiago, 2003;Roisen et al, 1984) and possess a neuroprotective action (Favaron et al, 1988;Geisler et al, 1991;Karpiak et al, 1990;Manev et al, 1990;Seren et al, 1990). These effects have partly been explained by the fact that GM1 induces a rapid and significant increase in the amount of NT-3, which was observed in fibroblast cells and cerebellar granule cells (Rabin et al, 2002).…”

7-Chloro-3-methyl-3,4-dihydro-2 H -1,2,4-benzothiadiazine S , S -dioxide: A partial modulator of AMPA receptor desensitization devoid of neurotoxicity

“…Dissociated neurons enriched in granule cells (about 95%) were prepared from cerebella of 8-day-old Sprague-Dawley rats and cultured for 8-9 days in medium containing 25 mM K ϩ as described (18).…”