Article

Effect of estradiol and progesterone on rat dopamine uptake sites

School of Pharmacy, Laval University, Québec, Québec, Canada.
Brain Research Bulletin (Impact Factor: 2.97). 10/1990; 25(3):419-22. DOI: 10.1016/0361-9230(90)90231-N
Source: PubMed

ABSTRACT Striatal dopamine (DA) uptake sites labelled with [3H]GBR-12935 binding were investigated in ovariectomized (OVX) rats acutely treated with 17 beta-estradiol (E2) or progesterone (P). One injection of E2 (100 ng, SC) to OVX rats increased plasma levels of this steroid after 15 min while plasma prolactin (PRL) levels remained unchanged. The E2 injection left striatal [3H]GBR-12935 binding affinity unchanged while the maximum density increased 15 and 30 min after the injection (+24% and +18%, respectively). One injection of P (110 micrograms, SC) to OVX rats increased this steroid plasma level from 15 to 120 min while plasma PRL levels remained unchanged. [3H]GBR-12935 binding density and affinity remained unchanged up to 120 min after the injection. Thus, acutely, E2 but not P, modulated striatal DA uptake sites in OVX rats. The effect of E2 appeared in coincidence with the peak of this steroid plasma concentration. This increase was rapid and is probably nongenomic and suggests a causal effect relationship as well as a presynaptic site of action of E2.

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    • "[19] [34] [38]) but numerous studies have also identified mechanisms through which E 2 can rapidly alter these systems. For instance, estradiol rapidly increases the activity of tyrosine hydroxylase, the enzyme that constitutes the limiting step in the synthesis of catecholamines [72], the DA turnover [31], the number of DA re-uptake sites [63] and the DA release as measured by in vivo microdialysis [18] and in vivo voltammettry [80]. Within similarly short latencies, E 2 also uncouples and down-regulates dopamine D2 receptors [53]. "
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