Glutathione depletion in the liver and brain produced by 2-chloropropionic acid: relevance to cerebellar granule cell necrosis.
L- and D-2-chloropropionic acid (L-CPA and D-CPA) produce selective damage to granule cells of the rat cerebellum by a mechanism that is not currently understood. We have demonstrated that both L- and D-CPA produce a rapid, dose and time dependent depletion of liver non-protein sulphydryl (NP-SH) content, mainly glutathione (GSH), while in the cerebellum and forebrain, there is a slower, dose and time dependent decrease in NP-SH. Twenty-four hours after a single dose of 750 mg/kg L-CPA (a dose sufficient to produce cerebellar toxicity, but a time prior to the onset of cellular necrosis), the content of total GSH was depleted by 85% in the cerebellum and to a lesser degree in the forebrain, while no increase in oxidised glutathione was observed in either tissue. In vitro both L- and D-CPA caused a marked reduction in GSH concentration when incubated with hepatic cytosol but not hepatic microsomes or brain cytosol. The hepatic cytosolic depletion appeared to be due to a direct reaction catalysed by a theta class glutathione S-transferase. A GSH adduct of L-CPA was isolated by high pressure liquid chromatography and identified by mass spectrometry as 2-S-glutathionyl propanoic acid, confirming a direct substitution reaction. No GSH adducts were formed by cerebellar or forebrain cytosol, suggesting that the particular isoform of glutathione S-transferase catalysing the reaction may not be present in the brain. We suggest that the marked and sustained CPA-mediated GSH depletion in the granule cells of the cerebellum may render these cells more vulnerable to oxidative free radical damage.
Wyatt
I
I
Zeneca Central Toxicology Laboratory, Alderley Park, Cheshire, UK.
Gyte
A
A
Mainwaring
G
G
Widdowson
P S
PS
Lock
E A
EA
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism*; D002531:Cerebellum / Q000187:drug effects / Q000473:pathology*; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000473:pathology*; D005978:Glutathione / Q000187:drug effects* / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008297:Male; D009336:Necrosis; D011422:Propionates / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
D006843:Hydrocarbons, Chlorinated; D011422:Propionates; C021974:2-chloropropionic acid; D005978:Glutathione