DIFFERENTIAL EXPRESSION OF MGLUR5 METABOTROPIC GLUTAMATE-RECEPTOR MESSENGER-RNA BY RAT STRIATAL NEURONS

Metabotropic glutamate receptors (mGluRs) mediate the effects of gluta mate neurotransmission on intracellular second messenger systems. Amon g the seven distinct mGluR receptor isoforms currently identified, the mGluR5 isoform is expressed particularly prominently in the striatum, where it may contribute to neuronal plasticity, motor behaviors, and excitotoxic injury. mGluR5 mRNA expression in striatal enkephalinergic , somatostatinergic, and cholinergic neurons was examined using double label in situ hybridization techniques. mGluR5 expression is abundant in a large number of medium-sized striatal cells but is absent in a s ignificant minority of neurons. Double label in situ hybridization wit h S-35-dATP- and digoxygenin-dUTP-tailed oligonucleotide probes demons trated that mGluR5 message is highly expressed by enkephalinergic stri atal neurons but is not detectable in cholinergic or somatostatin inte rneurons. In addition, some nonenkephalin, presumably substance P, neu rons were also strongly labeled for mGluR5. The differential expressio n of mGluR5 in striatal projection neurons vs. interneurons may contri bute to the selective vulnerability of these neurons to disease proces ses. (C) 1995 Wiley-Liss, Inc.