McMahon T F, Stefanski S A, Wilson R E, Blair P C, Clark A M, Birnbaum L S
Experimental Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Toxicology. 1991 Mar 11;66(3):297-311. doi: 10.1016/0300-483x(91)90201-b.
Experimental evidence suggests that the oxidative metabolites 2,3- and 2,5-dihydroxybenzoic acid (DIOH) may be responsible for the nephrotoxicity of salicylic acid (SAL). In the present study, enzymuria in conjunction with glucose (GLU) and protein (PRO) excretion were used as endpoints to compare the relative nephrotoxicity of SAL with 2,3- and 2,5-DIOH. In addition, the effect of age on enzymuria and GLU and PRO excretion following treatment with SAL or 2,3- and 2,5-DIOH was investigated because the elderly are at greater risk for SAL-induced nephrotoxicity. Three and 12-month male Fischer 344 rats were administered either no treatment, vehicle, SAL, 2,3-DIOH, or 2,5-DIOH at 500 mg/kg p.o. in 5 ml/kg corn oil/DMSO (5:1). Effects of these treatments on functional integrity of renal tissue was assessed from 0--72 h after dosing by measurement of urinary creatinine, GLU, and PRO, as well as excretion of proximal and distal tubular renal enzymes. Enzymes measured as indicators of proximal tubular damage were N-acetyl-beta-glucosaminidase (NAG), gamma glutamyltransferase (GGT), alanine aminotransferase (ALT), and alkaline phosphatase (AP), while urinary lactate dehydrogenase (LD) and aspartate aminotransferase (AST) were measured as indicators of distal tubular damage. In comparison to 3-month vehicle-treated rats, 2,3- and 2,5-DIOH caused a significant increase between 0-8 h in excretion of urinary GLU and activities of AST, NAG, and LD, with peak effects occurring between 4-8 h. Toxic effects of either metabolite were not evident beyond 24 h, and toxicity of 2,5-DIOH was significantly greater in comparison to 2,3-DIOH. SAL treatment resulted in similar effects on enzymuria as well as GLU and PRO excretion, but peak effects did not occur until 16-24 h, and often persisted until 72 h after dosing. Maximal enzymuria in response to SAL treatment was significantly greater in 12- vs. 3-month rats for AST, NAG, and LD. In response to 2,3-DIOH treatment, the maximal response was significantly greater in 12- vs. 3-month rats for LD and AST, and for NAG in response to 2,5-DIOH treatment. The results of this study suggest that both 2,3- and 2,5-DIOH are nephrotoxic metabolites of SAL, but implicate 2,5-DIOH as the more potent nephrotoxic metabolite. The relative lack of an age effect for 2,3- and 2,5-DIOH vs. SAL supports the hypothesis [2] that age-related differences in biotransformation of SAL, and not increased tissue sensitivity to 2,3- or 2,5-DIOH, contribute to the age-related increase in susceptibility to SAL-induced nephrotoxicity.
实验证据表明，氧化代谢产物2,3 - 二羟基苯甲酸和2,5 - 二羟基苯甲酸（DIOH）可能是水杨酸（SAL）肾毒性的原因。在本研究中，将酶尿症与葡萄糖（GLU）和蛋白质（PRO）排泄相结合作为终点指标，以比较SAL与2,3 - DIOH和2,5 - DIOH的相对肾毒性。此外，还研究了年龄对SAL或2,3 - DIOH和2,5 - DIOH治疗后酶尿症以及GLU和PRO排泄的影响，因为老年人发生SAL诱导的肾毒性风险更高。将3个月和12个月大的雄性Fischer 344大鼠分为未治疗组、赋形剂组、SAL组、2,3 - DIOH组或2,5 - DIOH组，以500 mg/kg的剂量经口给予5 ml/kg玉米油/二甲基亚砜（5:1）。给药后0至72小时，通过测量尿肌酐、GLU和PRO以及近端和远端肾小管肾酶的排泄，评估这些处理对肾组织功能完整性的影响。作为近端肾小管损伤指标测量的酶有N - 乙酰 - β - 氨基葡萄糖苷酶（NAG）、γ - 谷氨酰转移酶（GGT）、丙氨酸氨基转移酶（ALT）和碱性磷酸酶（AP），而尿乳酸脱氢酶（LD）和天冬氨酸氨基转移酶（AST）作为远端肾小管损伤指标进行测量。与3个月大的赋形剂处理大鼠相比，2,3 - DIOH和2, C5 - DIOH在给药后0至8小时导致尿GLU排泄以及AST、NAG和LD活性显著增加，峰值效应出现在4至8小时之间。两种代谢产物在24小时后均未出现明显的毒性作用，且2,5 - DIOH的毒性显著高于2,3 - DIOH。SAL处理对酶尿症以及GLU和PRO排泄产生类似影响，但峰值效应直到16至24小时才出现，且常常持续到给药后72小时。在12个月大的大鼠与3个月大的大鼠相比，SAL处理引起的最大酶尿症中，AST、NAG和LD显著更高。在2,3 - DIOH处理后，12个月大的大鼠与3个月大的大鼠相比，LD和AST的最大反应显著更高，在2,5 - DIOH处理后，NAG的最大反应显著更高。本研究结果表明，2,3 - DIOH和2,5 - DIOH都是SAL的肾毒性代谢产物，但表明2,5 - DIOH是更具肾毒性的代谢产物。与SAL相比，2,3 - DIOH和2,5 - DIOH相对缺乏年龄效应，这支持了以下假设[2]：SAL生物转化中与年龄相关的差异，而非组织对2,3 - DIOH或2,5 - DIOH敏感性增加，导致了对SAL诱导的肾毒性易感性的年龄相关增加。
