Differential loss of dopamine D2 receptor mRNA isoforms during aging in Fischer-344 rats

Effects of aging on the expression of dopamine D2 receptor isoforms (D2-long and -short) in neostriatal subregions was examined by in situ hybridization histochemistry. Hybridization of a probe selective for the D2-long transcript was compared with signal generated by a probe recognizing both variants of D2 mRNA. Lateral quadrants of the neostriatum in old rats appeared to show declines in primarily the long transcripts. On the other hand, decreases in the expression of D2-short transcripts appeared to occur during aging in the ventromedial region of the striatum. These data suggest that the mechanisms involved in alternative splicing of D2 mRNA may be differentially altered in neostriatal subregions during aging.