The Effect of Hypoxia on G Protein Coupled (Opioid) Receptor Gene Expression in Cortical B50 Neurons in Culture

Abstract

Hypoxia adversely affects cells and tissues, and neuronal cells in particular have been shown to be more susceptible to the injurious effects of hypoxia in which they may begin to die when oxygen supply is reduced or completely eliminated. Opioid receptor agonists have been shown to elicit several central nervous system effects, mediated via G protein-coupled receptors. The aim of this study was to study the effect of hypoxia on G protein coupled receptor gene expression using mu opioid receptor as a case study in cortical neuronal B50 cell lines in culture. The B50 cells were cultured in normoxia (21% O2; 5% CO2) and hypoxia (5% O2; 5% CO2), and were treated with opioid agonists to determine their effects on hypoxia-induced changes. Three opioid agonists {DAMGO(_), DSLET(*) and ICI--199,441(6)}, were administered to the cells as treatment for 48 hours after 48 hours of initial culture for a total of 96 hours of culture in hypoxic conditions at concentrations of 10, 50 and 100 :M. The levels of G-protein coupled receptor (mu opioid) mRNAs were assessed using RT-PCR. The results showed that hypoxia induced morphological changes in B50 cells in hypoxia while the mu opioid RT-PCR mRNA levels showed no appreciable changes in normal, hypoxic and treated cells. The results show that B50 neuronal cells are susceptible to damage and injurious effects of hypoxia, as are most brain cells and the opioid agonist treatments showed there were no changes in the level of mu opioid receptor gene expression due to hypoxia or agonist treatment in neuronal B50 cells in culture.