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Elevation of Striatal Dopamine Receptors by Estrogen: Dose and Time Studies
Author(s) -
Hruska Robert E.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb13106.x
Subject(s) - dopamine receptor , dopamine , medicine , endocrinology , receptor , estrogen receptor , estrogen , dopamine receptor d3 , neuroscience , biology , cancer , breast cancer
Administration to male rats of a single dose of 17β‐estradiol valerate (8‐500 μg/rat) or implantation of a pellet containing 17β‐estradiol (0.5‐50 mg/rat) increased serum 17β‐estradiol levels in a dose‐dependent relationship when measured on the sixth day after adminstration. At the same time, after these doses, the serum rat prolactin (rPRL) levels were doubled and the striatal 3,4‐dihydroxyphenyl‐ethylamine (DA, dopamine) receptor densities were increased 20%. A single dose of 17β‐estradiol valerate of 4 μg/ rat or less did not alter serum 17β‐estradiol or rPRL levels or the striatal DA receptor density. After the single injection of 17β‐estradiol valerate (125 μg/rat) the serum 17β‐estra‐diol levels peaked at 1 day, the serum rPRL levels peaked at 2 days, and the striatal DA receptor density elevation peaked from 4 to 8 days. Implantation of a pellet containing 17β‐estradiol (25 mg/rat) produced a constant elevation of serum 17β‐estradiol levels from 1 to 10 days. Whereas the serum rPRL levels were continuously elevated about twofold, the densities of the striatal DA receptors were increased significantly by 20‐25% only from 4 to 8 days after pellet implantation. These results indicate that striatal DA receptor density rises and returns to control levels during the constant elevation of serum 17β‐estradiol and rPRL levels. These results, in comparison with those from the literature, suggest that in male rats the elevation of rPRL levels leads to the increase in striatal DA receptor density and that a substantial sex difference exists in rats in the regulation of striatal DA receptor density after 17β‐estradiol administration.