Sex differences in the striatal dopamine D2 receptor binding characteristics in vivo.
OBJECTIVE
The authors investigated whether striatal dopamine D2 receptor binding characteristics in vivo are similar in men and women and whether there are sex-related differences in the decline in D2 receptor density due to aging.


METHODS
Striatal D2 receptor density (Bmax), affinity (Kd), and binding potential (Bmax/Kd) were measured with positron emission tomography and [11C]raclopride in 54 healthy subjects (33 men and 21 women).


RESULTS
Women had generally lower D2 receptor affinity than men, and this difference was statistically significant in the left striatum. Bmax and Bmax/Kd tended to decline with age twice as fast in men as in women, but the difference did not reach statistical significance.


CONCLUSIONS
These results confirm the age-related reduction of D2 receptor density and binding potential in both sexes in vivo. The lower D2 receptor affinity suggests an increased endogenous striatal dopamine concentration in women. This may have implications for the differential vulnerability of men and women to psychiatric disorders like schizophrenia and alcohol and substance dependence.
Pohjalainen
T
T
Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland.
Rinne
J O
JO
Någren
K
K
Syvälahti
E
E
Hietala
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism; D000437:Alcoholism / Q000378:metabolism; D002250:Carbon Radioisotopes; D003342:Corpus Striatum / Q000737:chemistry / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008593:Menopause / Q000378:metabolism; D008875:Middle Aged; D020891:Raclopride; D011869:Radioligand Assay; D011954:Receptors, Dopamine / Q000032:analysis / Q000378:metabolism*; D012457:Salicylamides; D012737:Sex Factors; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D011954:Receptors, Dopamine; D012457:Salicylamides; D020891:Raclopride