[Effect of astrgaloside IV on the long-term consequences of renal ischemia-reperfusion injury in rat].

OBJECTIVE: To observe the effect of astrgaloside IV (Astr) on the long-term consequences of renal ischemia-reperfusion injury (IRI) in rat.

METHODS: Fifty-four male Sprague-Dawley rats were randomized into 3 equal groups: IRI group, Astr group, and sham operation group. All rats underwent right nephrectomy and isolation of the left renal artery. The left renal arteries of the IRI group and Astr group were gripped by vascular clamp for 60 minutes and that of the sham operation group was only isolated without gripping. Two milliliters of Astr solution (0.1 g/L) was perfused into the stomach of the rats in the Astr group three days before and after the operation respectively. The rats in the IRI and sham operation groups were perfused with normal saline of the same volume. Four, twelve, and twenty-four weeks after the operation 24-hour urine specimens of the rats were collected to detect the urine protein. At each time point 6 rats from each group were anesthetized and blood was collected from the abdominal aorta to measure the level of serum creatinine (Cr), their left kidneys were taken out to undergo pathological examination and extraction of mRNA. Histochemistry was used to detect the expression of tumor growth factor (TGF)-beta1 protein in the renal tissues. RT-PCR was used to detect the expression of TGF-beta1 mRNA. Collagen staining and immunohistochemistry were used to measure the proportion of collagen positive material to the total area.

RESULTS: The level of urine protein was increased progressively, those 12 and 24 weeks after the operation in the IRI group were significantly higher than those in the Astr and sham operation groups (all P < 0.05). The serum Cr 4 weeks after the operation was 36 micromol/L +/- 4 micromol/L, significantly higher than those in the Astr and sham operation groups (31 micromol/L +/- 8 micromol/L and 31 micromol/L +/- 5 micromol/L), and the serum Cr levels 4 weeks 12 and 24 weeks after the operation in the IRI group remained significantly higher than those in the Astr and sham operation groups (all P < 0.05). Collagen staining showed that the glomerular basement membrane, tunica adventitia vasorum, and adventitia of renal tubule were remarkably redder in the IRI than in the Astr and sham operation groups. The expression of TGF-beta1 protein was progressively increased since 12 weeks after the operation in the IRI group, significantly stronger in the Astr and sham operation groups. The expression of TGF-beta1 mRNA was progressively increased since 12 weeks after the operation in the IRI and Astr groups, significantly stronger than that in the sham operation group (P < 0.05). However, the expression of TGF-beta1 mRNA 24 weeks after the operation was significantly stronger in the IRI group than in the Astr group (P < 0.05).

CONCLUSION: After renal IRI the probability of development of renal fibrosis increases. Astrgaloside IV markedly ameliorates renal injury by downregulating the TGF-beta1 expression.