OBJECTIVETo investigate the effects of glycyrrihizic acid (GA) and prednisone on renal injury in chronic aristolochic acid nephropathy (AAN) rat model.

METHODSNinety-eight male Wistar rats of SPF grade were randomly divided into 4 groups, the normal control group (n = 20), the GA group, the model group, and the prednisone group, 26 rats in each group. Rats in the latter 3 groups were made into AAN model by administration of aristolochic acid (AA, contained in extract of Caulis Aristolochiae Manshuriensis) 20 mg/(kg x d) by gastric gavage, and equal volume of drinking water was given to rats in the control group. Medication was started 2 h later, the GA group was treated with GA 25 mg/(kg x d), the prednisone group with prednisone 3.15 mg/(kg x d), and to the other two groups equal volume of drinking water was given. Body weight was measured weekly, renal function related indices and morphology of the renal tissue were examined at the 4th, 8th and 12th weekend.

RESULTSAlong with the feeding time, body weight in the control group increased steadily, while that in the treated groups increased slowly. The ratio of serum creatinine/body weight increased markedly in the model group, while it significantly lowered in the treated groups. Morphological examination showed that the structural injury in the treated groups was milder than that in the model group, and its degree of fibrosis was milder also (15% - 20% vs 30%). Electronmicroscopy showed that AA induced, injury degeneration and necrosis of renal tubular epithelial cells, and markedly injured the cell organs, such as mitochondria, and induced nuclear variation, while in the treated groups, it was mainly limited in renal tubule, with normal cell organs, few nucleolus variation and less interstitial collagen fibers.

CONCLUSIONGA and prednisone could reduce the serum creatinine level, improve renal function, relieve the renal morphological changes, and decrease the inter stitial fibrosis, showing a definite preventing effect on chronic AAN in rats.