Nephrotoxicity induced by the R- and S-enantiomers of N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and their sulfate conjugates in male Fischer 344 rats

Abstract

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity characterized as polyuric renal failure and mediated via metabolites arising from oxidation of the succinimide ring. Recent findings have suggested that the stereochemical nature of NDPS metabolites may be an important factor in NDPS metabolite-induced nephrotoxicity. The purpose of the present study was to determine the role of stereochemistry in the in vivo nephrotoxicity induced by R-(+)- and S-(-)-N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (R- and S-NDHS) and the in vitro nephrotoxicity induced by their enantiomeric sulfate conjugates, R-(-)- and S-(+)-N-(3,5-dichlorophenyl)-2-hydroxysuccinimide-O-sulfate (R- and S-NSC). Male Fischer 344 rats (four rats/group) were administered intraperitoneally (i.p.) an enantiomer of NDHS (0.05, 0.1 or 0.2 mmol/kg) or vehicle, and renal function monitored for 48 h. R-NDHS (0.1 or 0.2 mmol/kg) had little effect on renal function. In contrast, S-NDHS (0.1 mmol/kg) induced marked nephrotoxicity. The nephrotoxic potential of R- and S-NSC (0.5, 0.75 or 1.0mM) was determined using freshly isolated rat renal cortical cells (IRCC, 3-4 x 10(6)cells/ml). Cytotoxicity was determined by measuring the release of lactate dehydrogenase (LDH) at the end of a 1h incubation period. The LDH release observed in these studies was similar between R- and S-NSC. These results indicate that stereochemistry is an important factor for NDPS metabolite nephrotoxicity and that the role of stereochemistry, at least for NSC, occurs at extra-renal sites.

Figure 1

Biotransformation pathway for NDPS.

Figure 2

Stereochemical configuration for R-(+)- and S-(-)-NDHS and R-(-)- and S-(+)-NSC.

Figure 3

The effect of R- or S-NDHS administration on urine volume. Rats (4 per group) were administered R-NDHS (A) or S-NDHS (B) or vehicle and urine volume monitored for 48 h. Values are means ± S.E. An * symbol indicates significantly different from the Day 0 value within a group, P < 0.05. A # symbol indicates significantly different from the control group value for that day’s measurement, P < 0.05.

Figure 4

The effect of R- or S-NDHS administration on urinary protein excretion. Urine was collected between 0900h and 1500h each day (Day 0, 1 and 2) for these measurements. Rats (4 per group) were administered R-NDHS (A) or S-NDHS (B) or vehicle. Values are means ± S.E. An * symbol indicates significantly different from the Day 0 value within a group, P < 0.05. A # symbol indicates significantly different from the control group value for that day’s measurement, P < 0.05.

Figure 5

The effect of R- or S-NDHS on kidney weight. Rats (4 per group) were administered an NDHS enantiomer (treated) or vehicle (control). Kidneys were obtained at 48 post-treatment. Values are means ± S.E. A # symbol indicates significantly different from the appropriate control group value, P < 0.05.

Figure 6

The effect of concentration on R- and S-NSC cytotoxicity in IRCC. IRCC used in these experiments were isolated from male Fischer 344 rats. Data are presented as the mean ± S.E. for four separate experiments. Experiments examining NSC concentration (treated) or vehicle (distilled water; control) effects were conducted using a 1 h exposure time. An * symbol indicates significantly different from the appropriate control group value, P< 0.05. A # symbol indicates significantly different from the opposite enantiomer group value for that concentration, P< 0.05.