Pilot study on the effect of estrogen replacement therapy on brain dopamine transporter availability in healthy, postmenopausal women.

OBJECTIVE: Authors investigated the association between estrogen replacement therapy (ERT) and dopamine transporter (DAT) availability in women.

METHODS: Thirteen postmenopausal women were administered ERT and underwent neuroimaging, using single-photon emission computed tomography (SPECT) and [99mTc]TRODAT-1, a radioligand that binds DAT. In this 6-week pilot study, subjects underwent SPECT before ERT, after 4 weeks of 0.625 mg/day of conjugated estrogens (CEE), and after an additional 2 weeks of 0.625 mg/day CEE plus 10 mg/day of medroxyprogesterone acetate. Specific uptake values (SUVs) of [99mTc]TRODAT-1 were calculated for the caudate and putamen.

RESULTS: When compared with baseline values, [99mTc]TRODAT-1 binding demonstrated a modest, but statistically significant, increase in the left anterior putamen after 4 weeks of CEE. After the 6-week ERT intervention, both the left and right anterior putamen demonstrated an increase in SUVs.

CONCLUSION: Short-term administration of ERT in postmenopausal women is associated with a modest increase in DAT in the putamen. These findings may further the understanding of how ERT is associated with improvement in Parkinson's disease and late-onset schizophrenia.