title: Stimulation of Dopamine D3 Receptor Attenuates Renal Ischemia-Reperfusion Injury via Increased Linkage With Gα12.
abstract: BACKGROUND
  Renal ischemia-reperfusion (I/R) injury causes renal tubular necrosis, apoptosis, and inflammation leading to acute renal dysfunction. Recent studies have revealed that deletion of Gα12 mitigates the renal damage due to I/R injury. Our previous study showed that activation of dopamine D3 receptor (D3R) increased its linkage with Gα12, and hampered Gα12-mediated stimulation of renal sodium transport. In the present study, we used an in-vivo rat model and an in vitro study of the renal epithelial cell line (NRK52E) to investigate whether or not an increased linkage between D3R and Gα12 contributes to the protective effect of D3R on renal I/R injury.
  
  
  METHODS
  For in vivo studies, I/R injury was induced in a rat renal unilateral clamping model. For in vitro studies, hypoxia/reoxygenation and cold storage/rewarming injuries were performed in NRK52E cells. PD128907, a D3R agonist, or vehicle, was administered 15 minutes before clamping (or hypoxia) in both the in vivo or in vitro studies.
  
  
  RESULTS
  In the rat renal unilateral clamping model, pretreatment with PD128907 (0.2 mg/kg, intravenous) protected against renal I/R injury and increased survival rate during a long-term follow-up after 7 days. A decrease in the generation of reactive oxygen species, apoptosis, and inflammation may be involved in the D3R-mediated protection because pretreatment with PD128907 increased renal glutathione and superoxide dismutase levels and decreased malondialdehyde levels in the I/R group. The increase in cytokines (TNF-α, IL-1β, and IL-10) and myeloperoxidase in I/R injured kidney was also prevented with a simultaneous decrease in the apoptosis of the epithelial cells and expression of apoptosis biomarkers in kidney harvested 1 day after I/R injury. The increase in the coimmunoprecipitation between D3R and Gα12 with D3R stimulation paralleled the observed renal protection from I/R injury. Moreover, in vitro studies showed that transient overexpression of Gα12 in the NRK52E cells attenuated the protective effect of PD128907 on hypoxia/reoxygenation injury. The protective effect of PD128907 might be of significance to renal transplantation because cold storage/rewarming induced injury increased lactate dehydrogenase release and decreased cell viability in NRK52E cells. Conversely, in the presence of PD128907, the increased lactate dehydrogenase release and decreased cell viability were reversed.
  
  
  CONCLUSIONS
  These results suggest that activation of D3R, by decreasing Gα12-induced renal damage, may exert a protective effect from I/R injury.
authors.affiliation: 1 Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, P.R. China. 2 Department of Anesthesiology, Daping Hospital, The Third Military Medical University, Chongqing, P.R. China. 3 Chongqing Institute of Cardiology, Chongqing, P.R. China. 4 Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD. 5 Department of Physiology, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Weiwei
authors.initials: W
authors.lastname: Guan
authors.forename: Yu
authors.initials: Y
authors.lastname: Han
authors.forename: Hongmei
authors.initials: H
authors.lastname: Ren
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tang
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Yukai
authors.initials: Y
authors.lastname: Liu
authors.forename: Jinjuan
authors.initials: J
authors.lastname: Fu
authors.forename: Duofen
authors.initials: D
authors.lastname: He
authors.forename: Laureano D
authors.initials: LD
authors.lastname: Asico
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Jose
authors.forename: Lin
authors.initials: L
authors.lastname: Zhou
authors.forename: Liyong
authors.initials: L
authors.lastname: Chen
authors.forename: Chunyu
authors.initials: C
authors.lastname: Zeng
mesh_terms: D058186:Acute Kidney Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001578:Benzopyrans / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection; D004195:Disease Models, Animal; D018491:Dopamine Agonists / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D007668:Kidney / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D010078:Oxazines / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D017208:Rats, Wistar; D050637:Receptors, Dopamine D3 / Q000819:agonists* / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D015398:Signal Transduction / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D001578:Benzopyrans; D018491:Dopamine Agonists; C493595:Drd3 protein, rat; D018836:Inflammation Mediators; D010078:Oxazines; D050637:Receptors, Dopamine D3; C062458:3,4,4a,10b-tetrahydro-4-propyl-2H,5H-(1)benzopyrano(4,3-b)-1,4-oxazin-9-ol; D008315:Malondialdehyde; D013482:Superoxide Dismutase; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D005978:Glutathione