Single-cell RT-PCR, in situ hybridization histochemical, and immunohistochemical studies of substance P and enkephalin co-occurrence in striatal projection neurons in rats

Differential localization of the GluR1 and GluR2 subunits of the AMPA-type glutamate receptor among striatal neuron types in rats

“…3C). This observation is consistent with the findings that not all striatal projection neurons contain immunohistochemically detectible CALB in rodents (Wang et al, 2006), nor do large striatal interneurons (Gerfen and Wilson, 1996). In contrast to the ubiquity of GluR2 in calbindinergic striatal neurons, not all striatal projection neurons of the matrix compartment, as identified by their uniform perikaryal Alexa 594 (red) immunolabeling for CALB (Fig 3A), also showed an Alexa 488 (green) cytoplasmic ring of GluR1 immunofluorescence (Fig.…”

“…Note that since striato-GPi and striatonigral neurons send a minor collateral into GPe (Kawaguchi et al, 1990;Wu et al, 2000), the RDA3k injection into GPe may have also labeled some striato-GPi or striatonigral neurons. A prior single-cell RT-PCR study of ours (Wang et al, 2006), however, indicates that no more than 25% of striatal neurons retrogradely labeled from GPe are striato-GPi or striatonigral neurons. Similarly, retrograde tracer injections into GPi might yield labeling of striatonigral neurons via their fibers of passage through the GPi, and retrograde tracer injection into nigra might yield labeling of striato-GPi neurons via their collaterals in the nigra (Kawaguchi et al, 1990;Wu et al, 2000).…”

“…3C). Again, this reflects the findings that not all striatal projection neurons contain detectible CALB in rodents (Wang et al, 2006), and large striatal interneurons lack CALB as well (Gerfen and Wilson, 1996). In particular, the large, intensely GluR1+ perikarya did not label for CALB.…”

“…For example, GluR1 was most prevalent among striatal neurons retrogradely labeled from GPe (71.6%), next most prevalent among those labeled from the nigra (62.2%), and least prevalent among those labeled from the GPi (53.4%). Note that since about 25% of striatal neurons retrogradely labeled from GPe are striato-GPi/nigral neurons labeled via their slight intra-GPe collateral (Wang et al, 2006), and since we found GluR1 frequency to be only 50-60% among striato-GPi/nigral neurons, it seems likely that GluR1 frequency among true striato-GPe neurons is somewhat higher than the 71.6% shown in the table for neurons labeled from GPe. Similarly, striatal neurons labeled from GPi include some striatonigral neurons labeled via their axon passing through GPi, and striatal neurons labeled from the nigra include some striato-GPi neurons labeled via their collateral to the nigra.…”

“…Similarly, retrograde tracer injections into GPi might yield labeling of striatonigral neurons via their fibers of passage through the GPi, and retrograde tracer injection into nigra might yield labeling of striato-GPi neurons via their collaterals in the nigra (Kawaguchi et al, 1990;Wu et al, 2000). Prior studies suggest, however, that any such unintended labeling is not so extensive (about 20% labeled from GPi may be striatonigral and 20% from nigra may be striato-GPi) as to obscure trends for the population intended for retrograde labeling (FigueredoCardenas et al, 1994;Wang et al, 2006).…”