dizocilpine-maleate and glutaric-acid

It has been shown that synergistic toxic effects of quinolinic acid (QUIN) and glutaric acid (GA), both in isolated nerve endings and in vivo conditions, suggest the contribution of these metabolites to neurodegeneration. However, this synergism still requires a detailed characterization of the mechanisms involved in cell damage during its occurrence. In this study, the effects of subtoxic concentrations of QUIN and/or GA were tested in neuronal cultures, co-cultures (neuronal cells + astrocytes), and mixed cultures (neuronal cells + astrocytes + microglia) from rat cortex and striatum. The exposure of different cortical and striatal cell cultures to QUIN + GA resulted in cell death and stimulated different markers of oxidative stress, including reactive oxygen species (ROS) formation; changes in the activity of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase; and depletion of endogenous antioxidants such as -SH groups and glutathione. The co-incubation of neuronal cultures with QUIN + GA plus the N-methyl-D-aspartate antagonist MK-801 prevented cell death but not ROS formation, whereas the antioxidant melatonin reduced both parameters. Our results demonstrated that QUIN and GA can create synergistic scenarios, inducing toxic effects on some parameters of cell viability via the stimulation of oxidative damage. Therefore, it is likely that oxidative stress may play a major causative role in the synergistic actions exerted by QUIN + GA in a variety of cell culture conditions involving the interaction of different neural types.

Topics: Animals; Antioxidants; Catalase; Cell Survival; Cerebral Cortex; Coculture Techniques; Dizocilpine Maleate; Female; Gliosis; Glutarates; Glutathione; Melatonin; Models, Biological; Neostriatum; Neurites; Neurons; Oxidative Stress; Quinolinic Acid; Rats, Wistar; Reactive Oxygen Species; Superoxide Dismutase

Monosialoganglioside (GM1) is a glycosphingolipid that protects against some neurological conditions, such as seizures and ischemia. Glutaric acidemia type I (GA-I) is an inherited disease characterized by striatal degeneration, seizures, and accumulation of glutaric acid (GA). In this study, we show that GA inhibits Na+,K+-ATPase activity and increases oxidative damage markers (total protein carbonylation and thiobarbituric acid-reactive substances-TBARS) production in striatal homogenates from rats in vitro and ex vivo. It is also shown that GM1 (50 mg/kg, i.p., twice) protects against GA-induced (4 micromol/striatum) seizures, protein carbonylation, TBARS increase, and inhibition of Na+,K+-ATPase activity ex vivo. Convulsive episodes induced by GA strongly correlated with Na+,K+-ATPase activity inhibition in the injected striatum but not with oxidative stress marker measures. Muscimol (46 pmol/striatum), but not MK-801 (3 nmol/striatum) and DNQX (8 nmol/striatum) prevented GA-induced convulsions, increase of TBARS and protein carbonylation and inhibition of Na+,K+-ATPase activity. The protection of GM1 and muscimol against GA-induced seizures strongly correlated with Na+,K+-ATPase activity maintenance ex vivo. In addition, GM1 (50-200 microM) protected against Na+,K+-ATPase inhibition induced by GA (6 mM) but not against oxidative damage in vitro. GM1 also decreased pentylenetetrazole (PTZ)-induced (1.8 micromol/striatum) seizures, Na+,K+-ATPase inhibition, and increase of TBARS and protein carbonyl in the striatum. These data suggest that Na+,K+-ATPase and GABA(A) receptor-mediated mechanisms may play important roles in GA-induced seizures and in their prevention by GM1.

Topics: Animals; Convulsants; Dizocilpine Maleate; Electroencephalography; Excitatory Amino Acid Antagonists; G(M1) Ganglioside; GABA Agonists; Glutarates; Injections, Intraventricular; Male; Muscimol; Neuroprotective Agents; Oxidative Stress; Pentylenetetrazole; Protein Carbonylation; Rats; Rats, Wistar; Receptors, GABA-A; Seizures; Sodium-Potassium-Exchanging ATPase; Thiobarbituric Acid Reactive Substances

Glutaryl-CoA dehydrogenase deficiency is a neurometabolic disorder with a specific age- and region-dependent neuropathology. Between 6 and 18 mo of age, unspecific illnesses trigger acute encephalopathic crises resulting in acute striatal and cortical necrosis. We hypothesized that acute brain damage in glutaryl-CoA dehydrogenase deficiency is caused by the main pathologic metabolites 3-hydroxyglutaric and glutaric acids through an excitotoxic sequence. Therefore, we investigated the effect of 3-hydroxyglutaric acid and glutaric acid on primary neuronal cultures from chick embryo telencephalons and mixed neuronal and glial cell cultures from neonatal rat hippocampi. Exposure to glutaric acid and 3-hydroxyglutaric acid decreased cell viability in a concentration- and time-dependent fashion. This neurotoxic effect could be totally prevented by preincubation with an N-methyl-D-aspartate receptor subunit 2B (NR2B)-specific antagonist, NR2B antibodies, and an unspecific N-methyl-D-aspartate receptor blocker and was partially blocked with an NR2A-specific antagonist but not with NR2A antibodies or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor and metabotropic glutamate receptor antagonists. Furthermore, metabolite toxicity increased in parallel with the increasing expression of the NR2B subunit on cultured neurons from second to sixth day in vitro. We conclude from these results that 3-hydroxyglutaric acid and glutaric acid act as false neurotransmitters, in particular through NR1/2B, and that the extent of induced neurotoxicity is dependent on the temporal and spatial expression of NR1/2B in the CNS during maturation. Beyond favorable implications for treatment and long-term prognosis, glutaryl-CoA dehydrogenase deficiency is the first neurologic disease in which specific neuropathology could be experimentally linked to ontogenetic expression of a particular neurotransmitter receptor subtype.

Topics: Animals; Antibodies; Brain Diseases, Metabolic, Inborn; Cells, Cultured; Chick Embryo; Dizocilpine Maleate; Glutarates; Glutaryl-CoA Dehydrogenase; Neurons; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Piperidines; Rats

The effect of intrastriatal administration of glutaric acid (GTR), a metabolite that accumulates in glutaric acidemia type I (GA-I), on the behavior of adult male rats was investigated. After cannula placing, rats received unilateral intrastriatal injections of GTR buffered to pH 7.4 with NaOH or NaCl. GTR induced rotational behavior toward the contralateral side of injection and clonic convulsions in a dose-dependent manner. Rotational behavior was prevented by intrastriatal preadministration of DNQX and muscimol, but not by the preadministration of MK-801. Convulsions were prevented by intrastriatal preinjection of muscimol. This study provides evidence for a participation of glutamatergic non-NMDA and GABAergic mechanisms in the GTR-induced behavioral alterations. These findings may be of value in understanding the physiopathology of the neurological dysfunction in glutaric acidemia.

Topics: Animals; Behavior, Animal; Convulsants; Corpus Striatum; Dizocilpine Maleate; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; GABA Agonists; gamma-Aminobutyric Acid; Glutamates; Glutarates; Injections; Male; Muscimol; Quinoxalines; Rats; Rats, Wistar; Seizures; Stereotyped Behavior