Estradiol effects on the dopamine transporter - Protein levels, subcellular location, and function

Cheryl S. Watson, Rebecca A. Alyea, Bridget Hawkins, Mary L. Thomas, Kathryn Cunningham, Adrian A. Jakubas

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Background: The effects of estrogens on dopamine (DA) transport may have important implications for the increased incidence of neurological disorders in women during life stages when hormonal fluctuations are prevalent, e.g. during menarche, reproductive cycling, pregnancy, and peri-menopause. Results: The activity of the DA transporter (DAT) was measured by the specific uptake of 3H-DA. We found that low concentrations (10-14 to 10-8M) of 17β-estradiol (E2) inhibit uptake via the DAT in PC12 cells over 30 minutes, with significant inhibition taking place due to E2 exposure during only the last five minutes of the uptake period. Such rapid action suggests a non-genomic, membrane-initiated estrogenic response mechanism. DAT and estrogen receptor-α (ERα) were elevated in cell extracts by a 20 ng/ml 2 day NGFβ treatment, while ERβ was not. DAT, ERα and ERβ were also detectable on the plasma membrane of unpermeabilized cells by immunocytochemical staining and by a fixed cell, quantitative antibody (Ab)-based plate assay. In addition, PC12 cells contained RNA coding for the alternative membrane ER GPR30; therefore, all 3 ER subtypes are candidates for mediating the rapid nongenomic actions of E2. At cell densities above 15,000 cells per well, the E2-induced inhibition of transport was reversed. Uptake activity oscillated with time after a 10 nM E2 treatment; in a slower room temperature assay, inhibition peaked at 9 min, while uptake activity increased at 3 and 20-30 min. Using an Ab recognizing the second extracellular loop of DAT (accessible only on the outside of unpermeabilized cells), our immunoassay measured membrane vs. intracellular/nonvesicular DAT; both were found to decline over a 5-60 min E2 treatment, though immunoblot analyses demonstrated no total cellular loss of protein. Conclusion: Our results suggest that physiological levels of E2 may act to sequester DAT in intracellular compartments where the transporter's second extramembrane loop is inaccessible (inside vesicles) and that rapid estrogenic actions on this differentiated neuronal cell type may be regulated via membrane ERs of several types.

Original languageEnglish (US)
Article number5
JournalJournal of Molecular Signaling
Volume1
DOIs
StatePublished - Dec 5 2006

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Dopamine Plasma Membrane Transport Proteins
Estrogen Receptors
Estradiol
Membranes
PC12 Cells
Assays
Dopamine
Menarche
Antibodies
Nerve Growth Factor
Cell membranes
Menopause
Cell Extracts
Nervous System Diseases
Immunoassay
Estrogens
Cell Count
Cell Membrane
RNA
Staining and Labeling

ASJC Scopus subject areas

  • Cell Biology
  • Biochemistry
  • Molecular Biology

Cite this

Estradiol effects on the dopamine transporter - Protein levels, subcellular location, and function. / Watson, Cheryl S.; Alyea, Rebecca A.; Hawkins, Bridget; Thomas, Mary L.; Cunningham, Kathryn; Jakubas, Adrian A.

In: Journal of Molecular Signaling, Vol. 1, 5, 05.12.2006.

Research output: Contribution to journalArticle

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