[Mechanism of nephrotoxicity of rhubarb in rats].

ABSTRACT

The aim of this study was to investigate the renal toxicity of rhubarb and its mechanism. The SD rats were randomly divided into three groups normal group and two rhubarb extract groups (16, 2 g·kg⁻¹). According to the dose conversion method between human and animal, rhubarb 16 g·kg⁻¹ and 2 g·kg⁻¹ were equivalent to 10 times and 1.25 times of human clinical dose respectively. Rhubarb extract was administered by a gastric gavage to rats once daily for 30 days. Serum urea nitrogen （BUN）, creatinine （CRE） and urine KIM-1, NGAL and renal morphology were analyzed. The expressions of OAT1, OAT3 and clusterin mRNA in kidney were measured. The results showed that the low dose of rhubarb had no obvious renal toxicity. The high dose group showed mild and moderate renal injury and a down-regulation of clusterin mRNA expression in the kidney tissue. The renal toxicity in male animals was heavier than that in female animals. There was no significant change in blood BUN and CRE in the high dose group. But urine NGAL level of the high dose group increased by 51.53% compared with normal group, of which male animals increased more significantly (P<0.05, compared with the normal group). The expressions of renal OAT1 and OAT3 mRNA in the low dose group were obviously higher than that in the normal group. The results indicated that the high dose of rhubarb could cause the renal toxicity. The dosage should be controlled reasonably in the clinical use. OAT1 and OAT3 mRNA related to anionic transport in kidney tissue played a compensatory protective role in rhubarb-induced renal injury. But the compensatory effect is relatively weak at the high dose level. In addition, routine renal function indicators BUN and CRE had limitation for monitoring the kidney toxicity of rhubarb. It is suggested that urine NGAL detection might be helpful for monitoring the renal toxicity of rhubarb.