title: Neuroprotective effects of curcumin on endothelin-1 mediated cell death in hippocampal neurons.
abstract: OBJECTIVE
  Alzheimer's disease is a progressive neurodegenerative disease characterized by loss of hippocampal neurons leading to memory deficits and cognitive decline. Studies suggest that levels of the vasoactive peptide endothelin-1 (ET-1) are increased in the brain tissue of Alzheimer's patients. Curcumin, the main ingredient of the spice turmeric, has been shown to have anti-inflammatory, anti-cancer, and neuroprotective effects. However, the mechanisms underlying some of these beneficial effects are not completely understood. The objective of this study was to determine if curcumin could protect hippocampal neurons from ET-1 mediated cell death and examine the involvement of c-Jun in this pathway.
  
  
  METHODS
  Primary hippocampal neurons from rat pups were isolated using a previously published protocol. Viability of the cells was measured by the live/dead assay. Immunoblot and immunohistochemical analyses were performed to analyze c-Jun levels in hippocampal neurons treated with either ET-1 or a combination of ET-1 and curcumin. Apoptotic changes were evaluated by immunoblot detection of cleaved caspase-3, cleaved fodrin, and a caspase 3/7 activation assay.
  
  
  RESULTS
  ET-1 treatment produced a 2-fold increase in the levels of c-Jun as determined by an immunoblot analysis in hippocampal neurons. Co-treatment with curcumin significantly attenuated the ET-1 mediated increase in c-Jun levels. ET-1 caused increased neuronal cell death of hippocampal neurons indicated by elevation of cleaved caspase-3, cleaved fodrin and an increased activity of caspases 3 and 7 which was attenuated by co-treatment with curcumin. Blockade of JNK, an upstream effector of c-Jun by specific inhibitor SP600125 did not fully protect from ET-1 mediated activation of pro-apoptotic enzymes in primary hippocampal cells.
  
  
  CONCLUSIONS
  Our data suggests that one mechanism by which curcumin protects against ET-1-mediated cell death is through blocking an increase in c-Jun levels. Other possible mechanisms include decreasing pro-apoptotic signaling activated by ET-1 in primary hippocampal neurons.
authors.affiliation: a University of North Texas Health Science Center, North Texas Eye Research Institute , 3500 Camp Bowie Boulevard, Fort Worth , TX 76107 , USA.
authors.forename: Dorota L
authors.initials: DL
authors.lastname: Stankowska
authors.affiliation: b University of Texas at Dallas , 800 West Campbell Road, Richardson , TX 75080 , USA.
authors.forename: Vignesh R
authors.initials: VR
authors.lastname: Krishnamoorthy
authors.affiliation: c Department of Pharmaceutical Sciences , College of Pharmacy , 3500 Camp Bowie Boulevard, Fort Worth , TX 76107 , USA.
authors.forename: Dorette Z
authors.initials: DZ
authors.lastname: Ellis
authors.affiliation: a University of North Texas Health Science Center, North Texas Eye Research Institute , 3500 Camp Bowie Boulevard, Fort Worth , TX 76107 , USA.
authors.forename: Raghu R
authors.initials: RR
authors.lastname: Krishnamoorthy
mesh_terms: D000544:Alzheimer Disease; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000032:analysis; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D003474:Curcumin / Q000494:pharmacology*; D019332:Endothelin-1 / Q000494:pharmacology*; D006624:Hippocampus / Q000737:chemistry / Q000166:cytology*; D008840:Microfilament Proteins / Q000032:analysis; D009474:Neurons / Q000737:chemistry / Q000187:drug effects*; D018696:Neuroprotective Agents; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013049:Spectrin
chemical_list: D002352:Carrier Proteins; D053148:Caspase 3; D053179:Caspase 7; D003474:Curcumin; D019332:Endothelin-1; D008840:Microfilament Proteins; D018696:Neuroprotective Agents; D016755:Proto-Oncogene Proteins c-jun; D013049:Spectrin
keywords: Alzheimer's disease; Curcumin; Endothelin; Neuroprotection; Primary hippocampal neurons