TY - JOUR
T1 - Suprachiasmatic nucleus neurons display endogenous resistance to excitotoxicity
AU - Bottum, Kathleen
AU - Poon, Emily
AU - Haley, Benjamin
AU - Karmarkar, Sumedha
AU - Tischkau, Shelley A.
N1 - Funding Information:
We gratefully acknowledge the expert technical assistance of Kelly Barry, Molly Comiskey, Caitlin Allen, Dr Richard Pamenter and Stacey Krager. Financial support was provided by the American Heart Association through a Fellow to Faculty Transition Award to KB (0375011N), and the University of Illinois Research Board through an award to SAT.
PY - 2010/2
Y1 - 2010/2
N2 - A comprehensive understanding of neuroprotective pathways is essential to progress in the battle against numerous neurodegenerative conditions. The hypothalamic suprachiasmatic nucleus (SCN) is endogenously resistant to glutamate (Glu) excitotoxicity in vivo. This study was designed to determine whether immortalized SCN neurons (SCN2.2 cells) retain this characteristic. We first established that SCN2.2 cells retained the ability to respond to Glu. SCN2.2 cells expressed N-methyl-D-aspartate (NMDA) receptor subtypes NR1 and NR2A/2B, suggesting the presence of functional receptors. mRNA for the NMDA receptor subunits NR2A and NR2B were higher in the SCN2.2 than in the control hypothalamic neurons (GT1-7). Specific NMDA receptor antagonists (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate and D-(-)-2-amino-5-phosphonovaleric acid blocked Glu-induced activation of gene expression. SCN2.2 cells were resistant to Glu excitotoxicity compared with GT1-7 neurons as assessed with a mitochondrial function assay, cell death by trypan blue exclusion and apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling. SCN2.2 resistance to Glu excitoxicity was retained in the presence of the broad spectrum Glu transport inhibitor, ⌊- transpyrrolidine-2,4 dicarboxylate, excluding glial Glu uptake as a major neuroprotective mechanism. Collectively, these observations demonstrate endogenous neuroprotection in SCN2.2 cells; this cell line is resistant to excitotoxicity under conditions that are toxic to other immortalized cell lines. Thus, the SCN2.2 cell line may provide insights into the molecular mechanisms that confer endogenous neuroprotection in the SCN.
AB - A comprehensive understanding of neuroprotective pathways is essential to progress in the battle against numerous neurodegenerative conditions. The hypothalamic suprachiasmatic nucleus (SCN) is endogenously resistant to glutamate (Glu) excitotoxicity in vivo. This study was designed to determine whether immortalized SCN neurons (SCN2.2 cells) retain this characteristic. We first established that SCN2.2 cells retained the ability to respond to Glu. SCN2.2 cells expressed N-methyl-D-aspartate (NMDA) receptor subtypes NR1 and NR2A/2B, suggesting the presence of functional receptors. mRNA for the NMDA receptor subunits NR2A and NR2B were higher in the SCN2.2 than in the control hypothalamic neurons (GT1-7). Specific NMDA receptor antagonists (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate and D-(-)-2-amino-5-phosphonovaleric acid blocked Glu-induced activation of gene expression. SCN2.2 cells were resistant to Glu excitotoxicity compared with GT1-7 neurons as assessed with a mitochondrial function assay, cell death by trypan blue exclusion and apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling. SCN2.2 resistance to Glu excitoxicity was retained in the presence of the broad spectrum Glu transport inhibitor, ⌊- transpyrrolidine-2,4 dicarboxylate, excluding glial Glu uptake as a major neuroprotective mechanism. Collectively, these observations demonstrate endogenous neuroprotection in SCN2.2 cells; this cell line is resistant to excitotoxicity under conditions that are toxic to other immortalized cell lines. Thus, the SCN2.2 cell line may provide insights into the molecular mechanisms that confer endogenous neuroprotection in the SCN.
KW - Apoptosis
KW - Excitotoxicity
KW - Glutamate
KW - NMDA receptor
KW - Neurotoxicity
KW - Suprachiasmatic nucleus
UR - http://www.scopus.com/inward/record.url?scp=77649109142&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77649109142&partnerID=8YFLogxK
U2 - 10.1258/ebm.2009.009244
DO - 10.1258/ebm.2009.009244
M3 - Article
C2 - 20404040
AN - SCOPUS:77649109142
SN - 1535-3702
VL - 235
SP - 237
EP - 246
JO - Experimental Biology and Medicine
JF - Experimental Biology and Medicine
IS - 2
ER -