Decreased striatal D2 dopamine receptors in obese Zucker rats: changes during aging.

The specific binding of [3H]YM-09151-2 was used to investigate the possible differences in age-associated changes in striatal D2 dopamine (DA) receptor properties in genetically obese (fa/fa) Zucker rats and their lean (Fa/?) littermates. The maximal binding sites (Bmax) of D2 DA receptors was found to decline with age in both obese and lean rats; the rate of decline in receptor Bmax was slightly higher in lean than obese rats. However, the Bmax of D2 DA receptor in 6-, 12- and 18-month-old obese rats was significantly lower compared to the age-matched lean rats. These data indicate that obesity decreases the number of striatal D2 DA receptors without affecting the rate at which receptor number decreases with age.