Loss of D2 receptors during aging is partially due to decreased levels of mRNA.

Corpora striata of old rats (24-25 months) contain only about half as much mRNA for D2 dopamine receptors as those of young (6 months) counterparts. This reduction can be observed by in situ hybridization of brain slices as well as with Northern and dot blot analyses of striatal extracts. Decreased levels of D2 receptor mRNA as described in this study are consistent with reductions in receptor containing neurons (20%) and receptor biosynthesis (40%), as previously observed in this and other laboratories. Thus, age related changes in D2 receptor gene expression appear to be partially responsible for loss of these receptors.