AGING-RELATED CHANGES IN RAT STRIATAL D-2 RECEPTOR MESSENGER-RNA-CONTAINING NEURONS - A QUANTITATIVE NONRADIOACTIVE IN-SITU HYBRIDIZATION STUDY

In situ hybridization of a digoxigenin-labeled oligonucleotide probe combined with computer-assisted image assessment was used to directly visualize D-2 receptor mRNA-containing neurons in rat striata, and quantify age-related changes in the sizes and relative mRNA content of these neurons. It was found that: (1) numbers of D-2 mRNA-containing neurons appear to decrease in striata of aged rats, (2) relative amounts of D-2 receptor mRNA decrease in striatal neurons of aged rats, and (3) neurons of all sizes appear to be lost, with the greatest absolute decrease in those smaller than 90 mu m(2). These data confirm the well documented age-associated loss of D-2 dopamine receptors, and further suggest that both neuronal death and reduced transcription contribute to this decrement.