DIFFERENTIAL LOSS OF DOPAMINE D2 RECEPTOR MESSENGER-RNA ISOFORMS DURING AGING IN FISCHER-344 RATS

Effects of aging on the expression of dopamine D2 receptor isoforms (D 2-long and -short) in neostriatal subregions was examined by in situ h ybridization histochemistry. Hybridization of a probe selective for th e D2-long transcript was compared with signal generated by a probe rec ognizing both variants of D2 mRNA. Lateral quadrants of the neostriatu m in old rats appeared to show declines in primarily the long transcri pts. On the other hand, decreases in the expression of D2-short transc ripts appeared to occur during aging in the ventromedial region of the striatum. These data suggest that the mechanisms involved in alternat ive splicing of D2 mRNA may be differentially altered in neostriatal s ubregions during aging.