Pilot Study on the Effect of Estrogen Replacement Therapy on Brain Dopamine Transporter Availability in Healthy, Postmenopausal Women

Abstract

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