[Effects of ammonium pyrrolidine dithiocarbamate (PDTC) on osteopontin expression and autophagy in tubular cells in streptozotocin-induced diabetic nephropathy rat].

Objective: To investigate the effects of ammonium pyrrolidine dithiocarbamate (PDTC) on tubulointerstitial inflammatory molecules and autophagy in diabetic nephropathy (DN) rats. Methods: Twenty-four male Sprague-Dawley rats were assigned to DN group ( n =6) and DN+ PDTC group ( n =6, PDTC, ip, 100 mg·kg-1 ·d-1 ), all received streptozotocin (STZ) 60 mg/kg intraperitoneally, and the other 12 rats were randomly divided into control group ( n =6) and PDTC group ( n =6). At the end of 12 weeks, after serum creatine (Scr) and 24-hour urinary protein were determined, rats were sacrificed to determined the renal pathological damages and the changes of nuclear factor (NF)-κB p65, p62, osteopontin (OPN), microtubule associated protein 1 light chain 3 (LC3)-Ⅱ/LC3-Ⅰ, nuclear p-NF-κB p65 by immunohistological stainning and Western blot, and ultrastructural changes of autophagic process was observed by electron microscopy (EM). Results: Scr was similar among the four groups ( P >0.05). The levels of urinary protein in DN group and DN + PDTC group were significantly higher than the other two groups (all P <0.01), but the level of urinary protein in DN + PDTC group was lower than that of DN group ( P <0.05). DN + PDTC group had less tubulointerstitial damage compared with DN group ( P <0.05). Among the four groups, expressions of p62, p65, OPN of tubulointerstitial area in DN group were significantly higher than that of the other groups (all P <0.05), and Western blot showed that DN+ PDTC group had less expressions of NF-κB p65, nuclear p-p65, OPN and more expresssion of LC3-Ⅱ/LC3-Ⅰ compared with DN group (all P <0.05), which were consistent with the decreased autophagic vacuoles and increased mitochondria dysfunction revealed by EM. Correlation analysis showed that renal LC3-Ⅱ/LC3-Ⅰ was negatively correlated the expressions of nuclear p-p65 and OPN ( r =-0.45, P =0.02; r =-0.50, P =0.01), and p62 was positively correlated the expressions of nuclear p-p65 and OPN ( r =0.33, P =0.01; r =0.41, P =0.01). Conclusion: Tubular NF-κB activation is closely related to autophagy dysfunction in DN rats, and PDTC may enhance autophagy activity in tubule cells by blocking NF-κB activity.