The density of dopamine D3 receptors was determined in young (4-month-old) and aged (37-month-old) Fischer-344 x Brown-Norway (F1) male rats using the putative D3 receptor-preferring agonist, [3H](+)-7-hydroxy-2- N,N-di-n-propylamino)tetralin ([3H](+)-7-OH-PAT). In the presence of the non-hydrolyzable GTP analog, 5'-guanylylimidodiphosphate (Gpp(NH)p), the density of dopamine D3 receptors in the striatum and nucleus accumbens was significantly increased (29-102%, respectively) in aged Fischer-344 x Brown-Norway (F1) rats compared to young adults. These findings suggest that dopaminergic activity in aged rats is compromised by increased D3 receptor density, resulting in altered striatal/nucleus accumbens function via presynaptic or postsynaptic modifications.
- Basal forebrain
- Nucleus accumbens