Age-correlated loss of dopamine uptake sites labeled with [H]GBR-12935 in human putamen

The effects of age (19–100 years) upon dopamine uptake sites labeled with ³H]GBR-12935 in human postmortem putamen from 20 individuals were studied. There was a 70% decrease in binding density (B_max) over the adult age range. No significant changes in binding affinity (K_d) were detected, the mean K_d being 1.0 ± 0.2 NM (mean ± S.E.M.). Nor were there any changes in binding related to the postmortem delay. Based on the findings that ³H]GBR-12935 labels the uptake site for dopamine, it is suggested that the age-related loss of ³H]GBR-12935 binding in human putamen reflects a degeneration of dopamine neurites.