[Experimental study on early sensitive indexes of acute kidney injury in rats poisoned by diquat].

Objective: To establish the model of acute kidney injury (AKI), search for more sensitive and reliable biomarkers. Methods: In April 2018, 100 male Wister rats aged 6 to 8 weeks were selected and randomly divided into experimental group (n=90) and control group (n=10). The experimental group was given Diachalefin (140 mg/kg body weight) by intragastric administration, while the control group was given saline intragastric administration. Ten rats in the experimental group were killed 0.5 h, 2 h, 6 h, 24 h, 3 d, 7 d, 14 d, 21 d and 28 d after intragastric administration, respectively. Serum creatinine (Cr), urea nitrogen (BUN) and uric acid (UA) were detected by automatic biochemical analyzer with 5 ml of blood from inferior vena cava puncture. Serum neutrophil gelatinase-associated lipid carrier protein (NGAL), kidney damage molecule-1 (KIM-1) and transforming growth factor-β1 (TGF-β1) levels were determined by enzyme-linked immunosorbent assay (ELISA). The data between groups were compared using two independent sample t tests. Results: The renal tissue structure of rats in the control group was not significantly abnormal, while the renal tissue cell damage of rats in the experimental group was obvious, which gradually increased with the extension of time in the early stage, and gradually recovered in the later stage. UA in experimental group reached its peak at 24 h after exposure and was still higher than that in control group at 14 d (P<0.05), Cr reached its peak at 7 d, and then gradually decreased, and there was no statistical significance between experimental group and control group at 28 d (P>0.05). BUN increased at 6 h after exposure and reached the highest value at 7~14 d (P<0.05). Blood NGAL increased at 0.5 h after exposure, reached its peak at 24 h, continued to increase at 3, 7 and 14 days (P<0.05), and began to decrease at 21 days. KIM-1 began to increase at 0.5 h, continued to peak at 24 h, 3 and 7 d after exposure, and began to decrease at 14 d, but it was still higher than that in control group (P<0.05). There was no significant difference in TGF-β1 at each time point (P>0.05). Western blot assay results: Compared with control group, there was no significant difference in the expression level of TGF-β1 in kidney tissue of experimental group (P>0.05). NGAL increased gradually from 2 h and was higher at 7 and 14 d, with statistical significance (P<0.05). KIM-1 increased at 2 h, decreased at 6 and 24 h, and increased again at 3 and 7 d. Conclusion: NGAL and KIM-1 can be used as early diagnostic biomarkers for diquat-induced acute kidney injury.