Glutathione peroxidase 1 and glutathione are required to protect mouse astrocytes from iron‐mediated hydrogen peroxide toxicity

Abstract

The enzyme glutathione peroxidase 1 (GPx1) is involved in the cellular detoxification of peroxides. To test for the consequences of GPx deficiency in astrocytes, astrocyte-rich primary cultures from wild-type and GPx1-deficient [GPx1(-/-)] mice were exposed to H(2)O(2). In GPx1(-/-) astrocytes, the clearance rate of H(2)O(2) was slower than in wild-type cells. In contrast to GPx1-deficient astrocytes, wild-type cells exhibited, within 2 min of H(2)O(2) application, a rapid and transient accumulation of cellular glutathione disulfide that amounted to 60% of total glutathione. The peroxide treatment did not affect the viability of wild-type astrocytes, whereas 45% of the GPx1(-/-) cells died within 8 hr. However, the viability of both types of astrocytes was strongly compromised by lowering cellular glutathione content before peroxide application. In contrast, inactivation of catalase caused substantial cell death only in GPx1(-/-) cells but not in wild-type astrocytes. The cell death observed was prevented by the iron chelators deferoxamine, 1,10-phenathroline, or 2,2'-dipyridyl, whereas preincubation with ferric ammonium citrate increased the toxicity of peroxide treatments. These results demonstrate that GPx1 contributes to the rapid clearance of H(2)O(2) by mouse astrocytes and that both GPx1 and a high concentration of glutathione are required to protect these cells from iron-dependent peroxide damage.

Iron in Chronic Brain Disorders: Imaging and Neurotherapeutic Implications

“…This reaction removes the likelihood of a reaction between the peroxides and iron that creates reactive radical species. 65 Glutathione has been shown to protect murine astrocyte cultures from iron-induced neurotoxicity. This reaction is catalyzed by the enzyme glutathione peroxidase and is accomplished by the clearance of hydrogen peroxide.…”

“…This reaction is catalyzed by the enzyme glutathione peroxidase and is accomplished by the clearance of hydrogen peroxide. 65 Experimental work has also demonstrated cells that are able to survive iron-induced toxicity do so by increasing the intracellular level of glutathione. 66 A form of vitamin E (i.e., alpha tocopherol) also plays a role as an antioxidant in limiting lipid peroxidation by donating a proton to reactive oxygen species, thus making them more stable and less reactive.…”

Effect of Paraquat and Amyloid-β-Peptide on the Metabolism in Primary Astrocytes Studied by 1H-NMR

“…Astrocytes are metabolically coupled to neurons [25,26] and contributes importantly in the protection of neurons against reactive oxygen species e.g H 2 O 2 [27,28]. Oxidative stress is known to affect metabolic pathways of astrocytes that are important for the delivery of metabolites to neurons.…”

“…The following chemicals were from SigmaAldrich: L-Glutamine, Gentamycin, Paraquat, Amyloid peptide , Amyloid peptide (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), dibutyl-cyclic AMP (dBcAMP), MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) and D 2 O. D-(+)-Glucose, NaHCO 3 and N,N-dimethylformamide were purchased from Merck. SDS was from Bio-Rad Laboratories Inc., Fetal calf serum (FCS) from Harlan Sera-Lab Ltd., Crawleydown, UK, micro-carriers Cellon (90-125 m) from Solo Hill Engineering Inc., USA.…”

“…The two major alloforms of A in the brain, A (1-42) and A and the synthetic and truncated form, A (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) have all been demonstrated to be neurotoxic to a wide variety of cells [9][10][11] through a freeradical-dependent oxidative stress mechanism leading to the generation of hydrogen peroxide (H 2 O 2 ) [12,13], which is the most abundant peroxide generated in the brain [14].…”