Changes in mRNA levels for group I metabotropic glutamate receptors following in utero hypoxia-ischemia.

The expression of group I metabotropic glutamate receptors (mGluR1 and mGluR5) and inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) mRNA was studied by in situ hybridization in the developing rat hippocampus after in utero hypoxia-ischemia. In utero hypoxia-ischemia was induced by clamping the uterine blood vessels of near-term fetuses for 10 min. Fetuses were delivered surgically, resuscitated and raised by foster mothers until postnatal day 7 and 14. Results indicated a temporal delay in the expression of mGluR1 mRNA in the dentate gyrus of the ischemic animals. The mGluR1 mRNA level was significantly lower in the ischemic animals at postnatal day 7, but reached a similar level as that of controls at postnatal day 14. In utero hypoxia-ischemia did not change the temporal-spatial expression pattern of either mGluR5 or IP3R1 mRNA in the hippocampus. Between postnatal day 7 and 14, mGluR5 mRNA showed a high and relatively constant expression, whereas IP3R1 mRNA levels were increased in all regions examined. The differences in the expressions of group I mGluRs indicate that these receptors may have different functions during hippocampal development and may play different roles in excitotoxicity.