title: Synergistic interaction of effective parts in Rehmanniae Radix and Cornus officinalis ameliorates renal injury in C57BL/KsJ-db/db diabetic mice: Involvement of suppression of AGEs/RAGE/SphK1 signaling pathway.
abstract: BACKGROUND
  Rehmanniae Radix (RR) and Cornus officinalis (CO) are two traditional Chinese medicines widely used in China for treating diabetes mellitus and its complications, such as diabetic nephropathy. Iridoid glycoside of Cornus officinalis (IGCO), triterpenoid acid of Cornus officinalis (TACO) and iridoid glycoside of Rehmanniae Radix (IGRR) formed an innovative formula named combinatorial bioactive parts (CBP). The aims of the present study were to investigate the renoprotective effects of CBP on DN through the inhibition of AGEs/RAGE/SphK1 signaling pathway activation, and identify the advantage of CBP compared with IGCO, TACO, IGRR.
  
  
  METHODS
  The db/db diabetic renal injury model was used to examine the renoprotective effects of CBP, IGCO, TACO and IGRR. For mechanistic studies, diabetic symptoms, renal functions, and pathohistology of pancreas and kidney were evaluated. AGEs/RAGE/SphK1 pathway were determined.
  
  
  RESULTS
  CBP, IGCO, TACO and IGRR inhibited the decrease in serum insulin levels and the increases in urine volume, food consumption, water intake, TC, TG, glycated serum protein, fasting blood glucose levels, 24h urine protein levels, and serum levels of urea nitrogen and creatinine. It also prevented ECM accumulation and improved the histology of pancreas and kidney, and alleviated the structural alterations in mesangial cells and podocytes in renal cortex. Moreover, CBP, IGCO, TACO and IGRR down-regulated the elevated staining, protein levels of RAGE, SphK1, TGF-β and NF-κB. Among the treatment groups, CBP produced the strongest effects.
  
  
  CONCLUSIONS
  These findings suggest that the inhibitory effect of CBP, IGCO, TACO and IGRR on the activation of AGEs/RAGE/SphK1 signaling pathway in db/db diabetic mice kidney is a novel mechanism by which CBP, IGCO, TACO and IGRR exerts renoprotective effects on DN. Among all the groups, CBP produced the strongest effect while IGCO, TACO and IGRR produced weaker effects.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Lv
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Guoying
authors.initials: G
authors.lastname: Dai
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Gaohong
authors.initials: G
authors.lastname: Lv
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Yunhao
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Shen
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China; Jiang Su key Laboratory for Efficacy and Safety Evaluation of Chinese Medicine, Nanjing, Jiangsu 210023, China. Electronic address: hqxu309@aliyun.com.
authors.forename: Huiqin
authors.initials: H
authors.lastname: Xu
mesh_terms: D000818:Animals; D029768:Cornus / Q000737:chemistry*; D003920:Diabetes Mellitus; D003928:Diabetic Nephropathies / Q000188:drug therapy*; D004357:Drug Synergism; D017127:Glycation End Products, Advanced / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D000067759:Receptor for Advanced Glycation End Products / Q000235:genetics / Q000378:metabolism*; D032267:Rehmannia / Q000737:chemistry*; D000099157:Sphingosine Kinase
chemical_list: D017127:Glycation End Products, Advanced; D016328:NF-kappa B; D017853:Phosphotransferases (Alcohol Group Acceptor); D010936:Plant Extracts; D000067759:Receptor for Advanced Glycation End Products; D000099157:Sphingosine Kinase; C000593873:Ager protein, mouse
keywords: AGEs/RAGE/SphK1 signaling pathway; Cornus officinalis; Diabetic nephropathy; Iridoid glycoside; Rehmanniae Radix; Triterpenoid acid