Expression of mRNAs that encode D2 dopamine receptor subtypes: Anatomical, developmental, and pharmacological studies

We used oligonucleotide probes to isolate cDNAs that encode two subtypes of D2 dopamine receptors ("D2(long)" and "D2(short)"). In situ hybridization histochemistry with cRNA probes derived from these cDNAs revealed relatively high concentrations of D2 receptor mRNA in brain regions associated with the nigrostriatal and mesolimbic dopamine systems. D2 receptor mRNA was also present in several other regions including the oculomotor nucleus and areas of the pons and medulla. Hybridizations with a probe specifically recognizing D2(long) mRNA indicated that the fraction of total D2 receptor mRNA that encodes D2(long) receptors is higher in the nigrostriatal and mesolimbic dopamine systems than in the dorsal tegmental nucleus (of Gudden). Northern blot analysis revealed that developmental changes in D2 receptor mRNA concentrations in whole brain roughly parallel previously documented changes in D2 binding site concentrations. In contrast, Northern blot analysis indicated that D2 mRNA concentrations are unaffected by subchronic administration of the D2 receptor antagonist, haloperidol.