Protection from 1-cyano-3,4-epithiobutane nephrotoxicity by aminooxyacetic acid and effect on xenobiotic-metabolizing enzymes in male Fischer 344 rats.

1-Cyano-3,4-epithiobutane (CEB), a naturally occurring nitrile derived from cruciferous plants, causes nephrotoxicity and increased renal glutathione (GSH) concentration in male F-344 rats. This CEB-induced nephrotoxicity is dependent on GSH conjugation and bioactivation. The objectives of the present study were to investigate the effect of CEB on several xenobiotic-metabolizing enzymes and to evaluate the effect of modulators of GSH transport and metabolism on CEB-induced nephrotoxicity and GSH concentration. Animals received 125 mg kg-1 CEB alone or following pretreatment with one of three selective inhibitors of GSH metabolism: acivicin, probenecid or aminooxyacetic acid. There were no significant alterations in epoxide hydrolase (EH), P-450, ethoxyresorufin O-deethylase (EROD) or pentoxyresorufin O-depentylase (PROD) enzyme activity, but renal glutamyl cysteine synthetase (GCS) activity was decreased at 12 and 24 h, as was renal glutathione S-transferase 4 h after CEB administration. Renal ECOD activity was also diminished at 24 h and at 12 and 24 h in liver. Aminooxyacetic acid (AOAA) abrogated the nephrotoxicity, the renal GSH-enhancing effect, and decreased GCS of CEB alone. These findings provide further evidence for the importance of GSH conjugation as a significant pathway in CEB metabolism and the role of a reactive thiol in nephrotoxicity and altered renal GSH.