Fig. 5.

Neurons expressing detectable levels of SP, but not ENK, mRNA express D_1a mRNA at high levels and other dopamine receptor mRNAs at lower levels. A, Photograph of an ethidium bromide-stained agarose gel in which dopamine receptor and peptide mRNA amplicons from a single medium spiny neuron have been separated by electrophoresis. One-tenth of the total cDNA was used for each PCR reaction. Note the presence of SP and D_1aamplicons. B, Summary of the coordinated DA receptor mRNA expression in 10 neurons expressing SP, but not ENK. Coexpression for any set of mRNAs can be deduced by the extent to whichshaded bars in their lanes overlap. C, Photograph of a gel containing amplicons from another neuron in which one-fifth of the total cDNA was used for mRNAs not detected with one-tenth of the starting material (denoted byasterisks). D, Summary of coexpression in four neurons processed in the same manner. E, Photograph of a gel containing amplicons from a single medium spiny neuron in which a multiplex procedure with three-fourths of the total cellular cDNA was used for detection of DA receptor mRNAs. Note that in these amplifications the D_1a primer set yielding the longer amplicon was used. F, Summary of coexpression detected with the multiplex procedure in 16 ENK⁻/SP⁺neurons.