Nephrotoxicity induced by N-(3,5-dichlorophenyl)-3-hydroxysuccinamic acid in male and female Fischer 344 rats.

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is a more potent nephrotoxicant in female rats than in males. Similarly, nephrotoxicant NDPS metabolites studied to date in male and female rats have also demonstrated gender differences, being twice as potent as nephrotoxicants in females as in males. The purpose of this study was to examine the nephrotoxic potential of N-(3,5-dichlorophenyl)-3-hydroxysuccinimide (3-NDHSA) in male and female Fisher 344 rats to determine if gender differences in nephrotoxic potential also exist for this metabolite. Rats (four per group) were administered a single intraperitoneal (i.p.) injection of 3-NDHSA (0.1, 0.2 or 0.4 mmol kg(-1)) or vehicle, and renal function was monitored at 24 and 48 h. 3-NDHSA 0.1 mmol kg(-1) did not induce nephrotoxicity in male or female rats. In male rats, 3-NDHSA 0.2 mmol kg(-1) induced mild nephrotoxicity seen as diuresis and transient, mild proteinuria. However, 3-NDHSA 0.4 mmol kg(-1) induced marked nephrotoxicity. In female rats, 3-NDHSA 0.2 mmol kg(-1) induced mild nephrotoxicity, as evidenced by transient diuresis and proteinuria. As in males, 3-NDHSA 0.4 mmol kg(-1) induced marked nephrotoxicity. These results indicate that, unlike NDPS and other nephrotoxic NDPS metabolites, 3-NDHSA does not exhibit gender differences in nephrotoxic potential. In addition, in comparison with NDPS and other nephrotoxic NDPS metabolites, 3-NDHSA is a less potent nephrotoxicant that NDHS or 2-NDHSA and similar to NDPS in nephrotoxic potential in male rats.

Mechanistic aspects of 4-amino-2,6-dichlorophenol-induced in vitro nephrotoxicity.

4-Amino-2,6-dichlorophenol (ADCP) is a potent acute nephrotoxicant in vivo inducing prominent renal corticomedullary necrosis. In vitro, ADCP exposure increases lactate dehydrogenase (LDH) release from rat renal cortical slices at 0.05 mM or greater. The purpose of this study was to examine the ability of antioxidants, cytochrome P450 (CYP) and flavin adenine dinucleotide monooxygenase (FMO) activity modulators, indomethacin, glutathione and inhibitors of glutathione conjugate metabolism to attenuate ADCP cytotoxicity in vitro. Renal cortical slices prepared from untreated male Fischer 344 rats (N=4/group) were preincubated at 37 degrees C under a 100% oxygen atmosphere with an inhibitor or vehicle for 5-30 min. ADCP (0.05-0.5mM) or vehicle was added and incubations continued for 120 min. At the end of the incubation period, LDH release was measured as an index of nephrotoxicity. ADCP cytotoxicity was partially attenuated by ascorbate (1.0 or 2.0mM), but not by N,N'-diphenyl-p-phenylenediamine (DPPD), alpha-tocopherol or deferoxamine. Inhibitors of CYP (metyrapone, piperonyl butoxide and isoniazid) and FMO activity modulators (methimazole, N-octylamine) had no effect on ADCP cytotoxicity. Indomethacin or glutathione 1.0mM completely and partially blocked ADCP 0.1 and 0.5mM cytotoxicity, respectively. N-acetylcysteine, AOAA (an inhibitor of cysteine conjugate beta-lyase) and probenecid (an organic anion transport inhibitor), but not AT-125 (an inhibitor of gamma-glutamyl transferase), partially attenuated ADCP 0.1mM cytotoxicity. Overall, these results suggest that reactive metabolites may be produced from ADCP primarily via a co-oxidation-mediated mechanism. The difference in the ability of ascorbate and glutathione to attenuate ADCP-induced cytotoxicity in vitro in kidney cells could indicate that alkylation via the reactive benzoquinoneimine metabolite might be responsible for cytotoxicity rather than a free radical-mediated mechanism.