MULTIPLICITY OF GLUTAMATE-RECEPTOR SUBUNITS IN SINGLE STRIATAL NEURONS - AN RNA AMPLIFICATION STUDY

The RNA amplification technique was used to examine the pattern of coe xpression of mRNAs encoding 16 subtypes/subunits of the glutamate rece ptor (GluR) in acutely dissociated neurons from adult rat striata. The signal intensity for each mRNA varied within single neurons, but the general pattern of low versus high expression signals was similar amon g neurons, except for the GluR4 subunit of the lpha-amino-3-hydroxy-5- methyl-4-isoxazolepropionic acid (AMPA) receptor. The mRNAs for GluR1- 3 subunits of the AMPA receptor were present in all cells, with the si gnal intensity of GluR1 mRNAs usually the lowest. The kainate receptor subunit mRNAs (GluR5-7) were present in most neurons, and the signal intensity for GluR6 mRNA was the highest. The signals for N-methyl-D-a spartate (NMDA)R1 and NMDAR2B mRNAs were high in most neurons; however , NMDAR2A and NMDAR2C mRNAs gave low or undetectable signals. For mRNA s encoding metabotropic GluRs (mGluRs), signals for mGluR1, mGluR2, an d mGluR3 mRNAs were low or undetectable, whereas mGluR4 and mGluR5 mRN A signals were high in most neurons. In most cases (12 of 16 mRNAs), t he results agreed with data from in situ hybridization experiments in which individual mRNAs were examined. All neurons expressed subtypes/s ubunits mRNAs for all four types of GluRs; however, there were differe nces in the relative intensity of the mRNA signals detected in individ ual cells, suggesting that these receptors could exist in various comb inations within individual neurons and thus confer synapse-specific fu nction for information processing in the striatum.