Sublethal hypoxia up-regulates corticotropin releasing factor receptor type 1 in fetal hippocampal neurons

We analysed the influence of oxygen-glucose deprivation (OGD) on the expression of corticotropin releasing factor (CRF) receptors (CRF-R1 and CRF-R2) in fetal hippocampal neurons in vitro. A 2 h exposure of neurons to OGD resulted in death of 18+/-2.8% cells at 24 h following exposure, which was considered sublethal hypoxia. Expression of both receptors was quantitated by competitive reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Levels of mRNA for CRF-R1 were increased 3.2-fold compared to control neurons, while CRF-R2 mRNA levels remained unchanged. The increase of CRF-R1 mRNA levels was observed at 6 h and peaked at 24 h. CRF-R1 protein levels were also increased by 2.4-fold and 1.7-fold at 24 h and 48 h, respectively. These data suggest that the effects of CRF on neuronal survival are mediated in part through the induction and expression of CRF-R1 following a hypoxic/ischemic insult.