Effect of glutathione depletion on the irreversible association of acrylonitrile with tissue macromolecules after oral administration to rats.
Binding of acrylonitrile and its reactive metabolites to tissue macromolecules, especially nucleic acids, may be responsible for its carcinogenicity in rats. Both acrylonitrile and its primary metabolite, 2-cyanoethylene oxide, also react with glutathione. To better understand the role of glutathione in the manifestation of acrylonitrile toxicity, the irreversible binding to tissue macromolecules was assessed in control and glutathione-depleted F-344 rats treated with a 4 mg/kg dose (po) of [2,3-14C]acrylonitrile. Glutathione was depleted in rat tissues by the administration of a combined intraperitoneal phorone/buthionine sulfoximine treatment (300 mg/kg and 2 mmol/kg, respectively) given 30 min prior to acrylonitrile administration. The amount of total radioactivity recovered from brain, stomach (target organs), liver, kidney, lung, and blood (nontarget organs) was similar between control and glutathione-depleted rats. However, stomach, lung, blood, and liver showed an increase in total radioactivity content after glutathione depletion by phorone/buthionine sulfoximine treatment. Glutathione depletion also caused an increase in acrylonitrile-derived non-dialysable radioactivity (MW greater than 3500 Da) in liver, lung, kidney, stomach, blood, and brain macromolecules between 6 and 24 hr after the dose. There was no organ-specific accumulation of radiolabel in RNA in control rats. However, an increase in the radiolabel associated with nucleic acids in the target organs but not in the nontarget organs was measured in glutathione-depleted rats. Urinary excretion of thiocyanate, a metabolite derived from the epoxide pathway, was also increased by 300% in glutathione-depleted rats. These results suggest that glutathione might play a role in the extent of 2-cyanoethylene oxide formation and in the distribution of the radiolabel among tissues.
Department of Biochemical Toxicology and Pathobiology, Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709.
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D000181:Acrylonitrile / Q000008:administration & dosage / Q000378:metabolism*; D000284:Administration, Oral; D000818:Animals; D005978:Glutathione / Q000378:metabolism*; D046911:Macromolecular Substances; D008297:Male; D009570:Nitriles / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D013861:Thiocyanates / Q000652:urine
D046911:Macromolecular Substances; D009570:Nitriles; D013861:Thiocyanates; D005978:Glutathione; D000181:Acrylonitrile; C031760:thiocyanate