Postlesional transcriptional regulation of metabotropic glutamate receptors: implications for plasticity and excitotoxicity

Abstract.

Metabotropic glutamate receptors (mGluRs) seem to be involved both in neuronal excitotoxicity evoked by pathological conditions such as ischemia, and in processes associated with neuronal plasticity and regulation of synaptic strength. Using semiquantitative reverse transcription-polymerase chain reaction, we measured the messenger RNA levels of mGluR2–5, 24 h and 7 days after experimentally induced focal cortical infarcts in rat motor cortex. The mRNA level of mGluR3 was strikingly decreased ipsilaterally after 24 h. On day 7, the expression of mGluR2 was down-regulated both ipsi- and contralaterally. Other receptors of this family showed either a slight or no regulation at both time points. The early changes in the expression pattern of mGluRs might be primarily linked to excitotoxicity processes which occur immediately after an ischemic lesion in cortex, whereas the delayed changes might represent one chain link in the cascade of compensatory mechanisms contributing to functional amelioration.