METABOTROPIC GLUTAMATE-RECEPTOR MESSENGER-RNA EXPRESSION IN RAT SPINAL-CORD

It has recently become clear that, analogous to the situation observed in the brain, glutamatergic neurotransmission in the spinal cord reli es upon the activation of ionotropic and metabotropic glutamate recept ors (mGluRs). Although electrophysiological studies have emphasized th e relevance of mGluR activation in the modulation of spinal neuron res ponses to glutamate, a detailed study of the molecular forms of recept ors belonging to the mGluR family in the spinal cord is still lacking. Using a reverse transcriptase-polymerase chain reaction technique wit h primers specifically recognizing each cloned mGluR subtype, we found that rat adult spinal cord specifically expresses high levels of mRNA encoding mGluR1a but not mGluR1b. The expression of mRNAs for mGluRs 5a and 5b was also found at levels roughly comparable to that observed in mGluR5 positive brain areas. mGluR2, mGluR3, mGluR4 and mGluR7 mRN As appeared to be expressed at lower levels, while mGluR6 and mGluR8 m RNAs were not detectable.