title: Expression of NR1/NR2B N-methyl-D-aspartate receptors enhances heroin toxicity in HEK293 cells.
abstract: Repeated use of drugs of abuse, namely opiates, has been shown to affect glutamate-releasing neurons. Moreover, blockade of N-methyl-D-aspartate (NMDA) receptors (NMDAR) prevents cell death by apoptosis induced by morphine, a heroin metabolite. Thus, in this article we investigated the involvement of different NMDAR subunits in heroin cytotoxicity. Human embryonic kidney (HEK293) cells, which do not express native NMDAR, were transfected with NR1/NR2A or NR1/NR2B subunits. As a control, cells were transfected with NR1 alone, which does not form functional channels. Incubation with heroin for 24 h induced a dose-dependent decrease in cell viability both in NR1-transfected and nontransfected cells. The loss of membrane integrity induced by heroin was more evident in cells transfected with NR1/NR2B than in cells transfected with NR1 alone or NR1/NR2A. This decrease in cell viability was blocked by MK-801, a selective and noncompetitive antagonist of NMDAR. Nevertheless, no significant changes in intracellular adenosine 5'-triphosphate (ATP) were observed in cells treated with heroin. These data implicate NR2B-composed NMDAR as important mediators of heroin neurotoxicity.
authors.affiliation: Institute of Biochemistry, Faculty of Medicine and Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Domingues
authors.forename: Teresa
authors.initials: T
authors.lastname: Cunha Oliveira
authors.forename: Mário L N
authors.initials: ML
authors.lastname: Laço
authors.forename: Tice R A
authors.initials: TR
authors.lastname: Macedo
authors.forename: Catarina R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: A Cristina
authors.initials: AC
authors.lastname: Rego
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D002470:Cell Survival; D003932:Heroin / Q000633:toxicity*; D006801:Humans; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
chemical_list: C409466:NR1 NMDA receptor; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; D003932:Heroin