Protective effect of N-acyl amino acids (NAAs) on cephaloridine (CER) nephrotoxicity in rabbits

Protective effect of morin on the imipenem-induced nephrotoxicity in rabbits

The present study investigated the protective effect of morin, a natural flavonoid, on the imipenem-induced nephrotoxicity in rabbits. Nephrotoxicity of imipenem was examined after the intravenous administrations of imipenem (200 mg/kg) to rabbits in the presence and the absence of morin (12, 25, 50 mg/kg, p.o.). Cytotoxicity of imipenem was also examined in the presence and the absence of morin (100 microM) by using MDCK cells overexpressing human organic anion transporter 1 and 3 (MDCK/hOAT1 or MDCK/hOAT3). Intravenous dosing of imipenem alone induced severe proximal tubular necrosis in rabbits, however, the concurrent use of morin (25 or 50 mg/kg, p.o.) significantly suppressed the histopathological damage in the kidney induced by imipenem. While imipenem was not cytotoxic in MDCK/hOAT1 cells over the tested concentrations up to 10 mM, it showed significant cellular toxicity with CC(50) of 0.77 mM in MDCK/hOAT3 cells, implying that OAT3 may involve more actively in the imipenem-induced nephrotoxicity. In addition, the cellular toxicity of imipenem decreased by approximately 20 folds in the presence of morin in MDCK/hOAT3 cells. In conclusion, the present study suggests that morin might be beneficial to reduce the nephrotoxicity of imipenem, at least in part, via the inhibition of OAT3-mediated renal excretion of imipenem.

Evaluation of a Short-term Rat Proximal Tubule Incubation System for the Detection of Nephrotoxicants

Many nephrotoxic agents act primarily on proximal tubule cells. Accordingly, the optimal conditions for isolating rat proximal tubule fragments by a collagenase digestion technique and their short-term maintenance have been defined, and the viability of the preparation and its sensitivity to toxicants have been determined. Tubular fragment viability was maintained in incubation for up to 6 hours, as assessed by measuring lactate dehydrogenase leakage, levels of intracellular glutathione, and ATP content. In addition, tubular transport function was maintained, as determined by measuring the uptake of p-aminohippuric acid and α-methylglucose, which could be blocked by the selective inhibitors, probenecid and phloridzin, respectively. In this study, the toxicities of allyl alcohol, cephalosporins and cisplatin to proximal tubular fragments were investigated. Allyl alcohol toxicity was greater in tubular fragments isolated from female rats than in those from male rats. Cephaloridine was toxic, while cephalexin and cephalothin were not. These features were consistent with the known in vivo responses to these agents. Toxicity was evident after exposure to cisplatin, with an early reduction in tubular transport being noted. The results highlight the potential of the system described for the isolation and incubation of rat proximal tubule fragments to study xenobiotic-mediated nephrotoxicity. This system could be of benefit in the high-throughput toxicity screening of novel therapeutic agents.

Betamipron reduces cisplatin nephrotoxicity in rodents without modifying its antileukemic activity in mice

Protective effects of betamipron (BP, N-benzoyl-beta-alanine), one of a series of N-acyl amino acids, on cisplatin-induced nephrotoxicity were examined. Since the damage observed in the kidney is localized to the proximal tubule cells, we investigated the influence of BP on urinary enzymes and excreta. Male Wistar rats and ddY mice were injected i.p. with 6 mg/kg and 16 mg/kg, respectively, of cisplatin combined with an i.p. 250 mg/kg BP dose. The toxicity of cisplatin as indicated by body weight gain, blood urea nitrogen, and serum creatinine levels was significantly (p < 0.05) suppressed by administration of BP after cisplatin treatment. The increase in urinary N-acetyl-beta-D-glucosaminidase activity, increase and subsequent decrease in gamma-glutamyl transferase activities, and increase in beta 2-microglobulin level observed after treatment with cisplatin were suppressed by administration of BP after cisplatin treatment. The combination of cisplatin and BP had no apparent effect on the efficacy of cisplatin against P388 leukemic cells in mice.

Protective effect of N-benzoyl-beta-alanine against cisplatin nephrotoxicity in rats

Prophylactic effects of N-benzoyl-beta-alanine (betamipron, BP), one of a series of N-acyl amino acids, were examined against cisplatin-induced nephrotoxicity. Male Wistar rats were injected i.p. with 6 mg/kg of cisplatin combined with an i.p. BP dose given at various times and various doses. Rats were sacrificed 5 days after cisplatin injection to weigh the kidney and liver, and to determine blood urea nitrogen (BUN) and serum creatinine (serum Cr) levels. Preliminary results suggest that treatment with BP is an effective means of protection against cisplatin-induced nephrotoxicity. Combination with BP reduced the weight loss following treatment with cisplatin. The ratios of the kidney and liver weights to the body weight in the animals treated with cisplatin followed later with BP are significantly different (p < 0.05) from those in the animals that received only cisplatin. The BUN and serum Cr levels in the animals treated with cisplatin followed from -1 to 4 hr, and from -4 to 4 hr later with 250 mg/kg BP dose and followed 1 hr later with from 250 to 1000 mg/kg, and from 250 to 2000 mg/kg BP doses differed significantly (p < 0.05) from those in the animals that received only cisplatin. Histological analysis of the kidneys confirmed the protective effect of BP.

Preventive effect of betamipron on nephrotoxicity and uptake of carbapenems in rabbit renal cortex

The preventive effect of betamipron (N-benzoyl-3-propionic acid: BP) on the renal uptake and nephrotoxicity of carbapenems (panipenem and imipenem) was studied in rabbits. Panipenem, a new carbapenem antibiotic, induced nephrotoxicity at a dose of 200 mg/kg, i.v., but this was less severe than that caused by a single dose of imipenem or cephaloridine. Along with the significant reduction of nephrotoxicity, the uptake of these carbapenems in the renal cortex was remarkably inhibited by simultaneous treatment with BP (200 mg/kg, i.v.). These results suggest that BP reduces the nephrotoxicity of carbapenems through inhibiting the active transport of carbapenems in the renal cortex. Because of the low toxicity of BP (LD50 in the rat, more than 3,000 mg/kg, i.v.), it was concluded that BP might be a good candidate for reducing the nephrotoxicity induced by panipenem or imipenem.