Factors regulating the activity of striatal neurons: new perspectives from in situ hybridization histochemistry.

1. The basal ganglia contain a variety of putative peptide neurotransmitters. In situ hybridization allows changes in the levels of the mRNAs encoding these neuropeptides to be assessed at the cellular level of resolution. 2. Alterations in the activity of pathways within the basal ganglia of the rat produce distinct effects on the different neuropeptide mRNAs. 3. The evidence, where available, suggests that mRNA levels provide an index of peptide turnover. 4. This approach has consequently revealed much new information on the regulation of neuronal activity in the basal ganglia.