Contribution of Reactive Oxygen Species to 3-Hydroxyglutarate Neurotoxicity in Primary Neuronal Cultures from Chick Embryo Telencephalons

Abstract

Glutaryl-CoA dehydrogenase deficiency is an autosomal recessively inherited neurometabolic disorder with a distinct neuropathology characterized by acute encephalopathic crises during a vulnerable period of brain development. 3-Hydroxyglutarate (3-OH-GA), which accumulates in affected patients, has been identified as an endogenous neurotoxin mediating excitotoxicity via N-methyl-D-aspartate receptors. As increased generation of reactive oxygen species (ROS) and nitric oxide (NO) plays an important role in excitotoxic neuronal damage, we investigated whether ROS and NO contribute to 3-OH-GA neurotoxicity. 3-OH-GA increased mitochondrial ROS generation in primary neuronal cultures from chick embryo telencephalons, which could be prevented by MK-801, confirming the central role of N-methyl-D-aspartate receptor stimulation in 3-OH-GA toxicity. ROS increase was reduced by alpha-tocopherol and--less effectively-by melatonin. alpha-Tocopherol revealed a wider time frame for neuroprotection than melatonin. Creatine also reduced neuronal damage and ROS formation but only if it was administered >or=6 h before 3-OH-GA. NO production revealed only a slight increase after 3-OH-GA incubation. NO synthase inhibitor N(omega)-nitro-L-arginine prevented NO increase but did not protect neurons against 3-OH-GA. The NO donor S-nitroso-N-acetylpenicillamine revealed no effect on 3-OH-GA toxicity at low concentrations (0.5-5 microM), whereas it potentiated neuronal damage at high concentrations (50-500 microM), suggesting that weak endogenous NO production elicited by 3-OH-GA did not affect neuronal viability. We conclude from our results that ROS generation contributes to 3-OH-GA neurotoxicity in vitro and that radical scavenging and stabilization of brain energy metabolism by creatine are hopeful new strategies in glutaryl-CoA dehydrogenase deficiency.

Glutaric Acid and Its Metabolites Cause Apoptosis in Immature Oligodendrocytes: A Novel Mechanism of White Matter Degeneration in Glutaryl-CoA Dehydrogenase Deficiency

“…Little is known about cerebrospinal fluid and brain tissue concentrations of GA and its metabolites in GDD patients (1), and there is a complete lack of fetal data. Whereas in most experimental settings described in this article, oligodendrocyte apoptosis was observed with concentrations as little as 0.1 mM, neuronal apoptosis was elicited experimentally using higher concentrations, up to 50 mM (2)(3)(4)17,21,30). Moreover, although experiments have been performed with GA, 3-OH-GA, or GC, all three substances are present within in vivo situations.…”

Mitochondrial Creatine Kinase Activity Prevents Reactive Oxygen Species Generation

“…In cultured rat neurons, as well as in astrocytes, Cr protected against glutamate, ␤-amyloid, and 3-nitropropionic acid toxicity (18,19,69). Furthermore, reduced neuronal damage and ROS formation were observed when cultures were administered with Cr at least 6 h before 3-hydroxyglutarate treatment (53). In isolated mitochondria, the inhibition of the MPT by CK substrates seems to be an important blocker of both necrotic and apoptotic cell death (42,52).…”

“…Several lines of evidence have shown that Cr supplementation prevented induction of mitochondrial permeability transition and ROS formation (52,53). As an attempt to gain insight into other mechanisms involved in ADP recycling in mitochondria, in subsequent experiments we investigated whether mt-CK activation by Cr would also affect physiological functions of RBM.…”

Oxidative Stress and Neurodegenerative Disorders

“…These include Zinc chloride, N-acetyl-L-cysteine, 1,10-phenanthroline and pyrrolidine [164][165][166]. In addition, natural products such as vitamin C, vitamine E, melatonin, etc have also been utilized for blockage of ROS-mediated neurotoxicity [167][168][169].…”