Decrease in human striatal dopamine D2 receptor density with age: a PET study with [11C]raclopride.
The effect of age on human striatal dopamine D2 receptors was investigated with positron emission tomography (PET) using [11C]raclopride as a radioligand. Twenty-one healthy volunteers aged from 20 to 81 years were studied. An equilibrium method was applied and two separate PET scans with different specific activities of [11C]raclopride were performed. The maximal number of receptors (Bmax) and their dissociation constant (Kd) were calculated using Scatchard analysis. There was an age-dependent decline in the Bmax (r = -0.49; p = 0.02) of striatal D2 receptors while the Kd remained unchanged. The results show that there is an age-related loss of striatal D2 receptors, which, together with other changes in the brain nigrostriatal dopaminergic system, may contribute to extrapyramidal symptoms associated with aging.
Rinne
J O
JO
Department of Neurology, University of Turku, Finland.
Hietala
J
J
Ruotsalainen
U
U
Säkö
E
E
Laihinen
A
A
Någren
K
K
Lehikoinen
P
P
Oikonen
V
V
Syvälahti
E
E
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002250:Carbon Radioisotopes; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000378:metabolism; D065127:Dopamine D2 Receptor Antagonists; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012457:Salicylamides; D013378:Substantia Nigra / Q000000981:diagnostic imaging / Q000378:metabolism*; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride