Traditional reactive carbonyl scavengers do not prevent the carbonylation of brain proteins induced by acute glutathione depletion

Abstract

This study investigated the effect of reactive carbonyl species (RCS)-trapping agents on the formation of protein carbonyls during depletion of brain glutathione (GSH). To this end, rat brain slices were incubated with the GSH-depletor diethyl maleate in the absence or presence of chemically different RCS scavengers (hydralazine, methoxylamine, aminoguanidine, pyridoxamine, carnosine, taurine and z-histidine hydrazide). Despite their strong reactivity towards the most common RCS, none of the scavengers tested, with the exception of hydralazine, prevented protein carbonylation. These findings suggest that the majority of protein-associated carbonyl groups in this oxidative stress paradigm do not derive from stable lipid peroxidation products like malondialdehyde (MDA), acrolein and 4-hydroxynonenal (4-HNE). This conclusion was confirmed by the observation that the amount of MDA-, acrolein- and 4-HNE-protein adducts does not increase upon GSH depletion. Additional studies revealed that the efficacy of hydralazine at preventing carbonylation was due to its ability to reduce oxidative stress, most likely by inhibiting mitochondrial production of superoxide and/or by scavenging lipid free radicals.

Keywords::

• Carbonyl scavengers
• glutathione depletion
• hydralazine
• oxidative stress
• protein carbonylation
• reactive oxygen species

Acknowledgements

The authors thank Ms. Savanna Reyes for her technical help in some experiments.

Declaration of interest: This work was supported by PHHS grant NS057755 from the National Institutes of Health. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This paper was first published online on Early Online on 10 December 2009.