Studies on the effects ofl(αS,5S)-α-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125) on 4-aminophenol-induced nephrotoxicity in the Fischer 344 rat

4-Aminophenol (para-aminophenol; PAP) causes selective necrosis to the S3 segment of the proximal tubule in experimental animals. The mechanism of PAP nephrotoxicity has not been fully elucidated, although it has been suggested to involve glutathione (GSH)-dependentS-conjugation followed by processing by the enzyme γ-glutamyl transpeptidase (γGT) to the corresponding cysteineS-conjugate. This proposed toxicity mechanism was probed further by administering L-(αS,5S)-α-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125), a potent γGT inhibitor, to Fischer 344 (F344) rats before treatment with PAP (100 mg/kg). AT-125 pretreatment did not appear to protect against PAP-induced nephrotoxicity as assessed by renal histopathology, clinical chemistry and proton nuclear magnetic resonance (1H NMR) spectroscopy of urine. These data suggest that renal γGT activity is not a prerequisite for PAP nephrotoxicity and that the generation of a cysteineS-conjugate is not a unique requirement for the induction of PAP nephrotoxicity.