Different effect of age on dopamine transporters in the dorsal and ventral striatum of controls and alcoholics.

It is generally agreed that there is a deterioration in brain dopamine (DA) system with aging. The role of the mesolimbic DA in brain ethanol reinforcement is well established, with nucleus accumbens (NAC) serving as a major terminal area of this system, whereas dorsal striatum is more associated with motor control. The aim of this study was to compare putative age-related alterations of dopamine transporters (DAT) in dorsal and ventral striatum of healthy controls and alcoholics. We studied the effect of age on DAT in caudate (NC), putamen (Pu), and nucleus accumbens (NAC) of eight type 1 and 2 alcoholics and 10 healthy controls by using [(125)I]PE2I as a radioligand for postmortem human whole hemisphere autoradiography. In the type 1 alcoholic group age and DAT density did not correlate significantly with any of the structures studied. The mean densities of DAT declined significantly with age in controls and type 2 alcoholics in dorsal striatum (NC, Pu) (range of correlation coefficient from -0.49 to -0.94), but not statistically significantly in NAC. In type 1 alcoholics the lack of correlation between DAT density and age may indicate a preexisting dopaminergic deficit in this patient group, whereas age-related decline among type 2 alcoholics resembled that of healthy controls. Furthermore, dorsal striatal DAT may be more vulnerable to age-related decline than DAT in NAC. This is supported by the notion that DAT in NAC and dorsal striatum have different molecular weights.