title: Sigma receptor ligand, (+)-pentazocine, suppresses inflammatory responses of retinal microglia.
abstract: OBJECTIVE
  To evaluate the effects of the σ 1 receptor (σR1) agonist, (+)-pentazocine, on lipopolysaccharide (LPS)-induced inflammatory changes in retinal microglia cells.
  
  
  METHODS
  Retinal microglia cells were isolated from Sprague-Dawley rat pups. Cells were treated with LPS with or without (+)-pentazocine and with or without the σR1 antagonist BD1063. Morphologic changes were assayed. Cell viability was assessed by using MTT assay. Supernatant levels of tumor necrosis factor α (TNF-α), interleukin 10, (IL-10), monocyte chemoattractant protein-1 (MCP-1), and nitric oxide (NO) were determined. Reactive oxygen species (ROS) formation was assayed, and levels of mitogen-activated protein kinases (MAPKs) were analyzed by using Western blot.
  
  
  RESULTS
  The σR1 protein was expressed in retinal microglia. Incubation with LPS and/or (+)-pentazocine did not alter cell viability or σR1 protein levels. Incubation with LPS for 24 hours induced a marked change in microglial morphology and a significant increase in secreted levels of TNF-α, IL-10, MCP-1, and NO. Pretreatment with (+)-pentazocine inhibited the LPS-induced morphologic changes. Release of TNF-α, IL-10, MCP-1, and NO was reduced with (+)-pentazocine. Intracellular ROS formation was suppressed with (+)-pentazocine. Phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) was reduced in the presence of (+)-pentazocine. The σR1 antagonist BD1063 blocked the (+)-pentazocine-mediated inhibition of LPS-induced morphologic changes. In addition, BD1063 treatment blocked (+)-pentazocine-mediated suppression of LPS-induced TNF-α, IL-10, MCP-1, NO, and intracellular ROS release.
  
  
  CONCLUSIONS
  Treatment with (+)-pentazocine suppressed inflammatory responses of retinal microglia and inhibited LPS-induced activation of ERK/JNK MAPK. In neurodegenerative disease, (+)-pentazocine may exert neuroprotective effects through manipulation of microglia.
authors.affiliation: James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Yonju
authors.initials: Y
authors.lastname: Ha
authors.affiliation: James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States Department of Ophthalmology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Gregory I
authors.initials: GI
authors.lastname: Liou
authors.affiliation: Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Graydon B
authors.initials: GB
authors.lastname: Gonsalvez
authors.affiliation: James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Sylvia B
authors.initials: SB
authors.lastname: Smith
authors.affiliation: James and Jean Culver Vision Discovery Institute, Georgia Regents University, Augusta, Georgia, United States.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Bollinger
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009900:Optic Nerve / Q000378:metabolism / Q000473:pathology; D010423:Pentazocine / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D017480:Receptors, sigma / Q000096:biosynthesis* / Q000187:drug effects; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology*; D012173:Retinitis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000097605:Sigma-1 Receptor
chemical_list: D016207:Cytokines; D020928:Mitogen-Activated Protein Kinases; D010423:Pentazocine; D010879:Piperazines; D017382:Reactive Oxygen Species; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C093337:1-(2-(3,4-dichlorophenyl)ethyl)-4-methylpiperazine
keywords: microglia; neuron–glia interactions; optic nerve; sigma receptor