Effect of catecholestrogens on [3H]-GABA uptake by hypothalamic crude synaptosomes.
Catecholestrogens (CE), 2-hydroxyestradiol, 2-hydroxyestrone and primary estrogens, estradiol and estrone were tested in their ability to compete for the high affinity uptake of [3H]-GABA into crude synaptosomal fractions. Aliquots of the crude synaptosomal fraction obtained from normal rats were incubated for 10 min at 37 degrees C with [3H]-GABA in the presence, or absence, of estrogens and catecholestrogens. Neither estradiol nor estrone modified the specific [3H]-GABA uptake into crude synaptosomal fractions. On the contrary, CE significantly affected the specific [3H]-GABA uptake in a dose-dependent manner: low concentrations of CE enhanced the uptake; this effect disappeared with high concentrations of the compounds. The stimulatory effect of CE on [3H]-GABA uptake was blocked when samples were coincubated with nipecotic acid, thus suggesting that this effect is specific rather than the result of non-specific interactions of CE with the hypothalamic membrane.
CENEXA-Centro de Endocrinología Experimental y Aplicada (UNLP-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
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Etchegoyen
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Del Zotto
D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D002393:Estrogens, Catechol / Q000494:pharmacology*; D004970:Estrone / Q000494:pharmacology; D005260:Female; D006894:Hydroxyestrones / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D066298:In Vitro Techniques; D009557:Nipecotic Acids / Q000494:pharmacology; D011392:Proline / Q000031:analogs & derivatives*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism; D014316:Tritium; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D002393:Estrogens, Catechol; D006894:Hydroxyestrones; D009557:Nipecotic Acids; D014316:Tritium; C030278:nipecotic acid; D004970:Estrone; D004958:Estradiol; D005680:gamma-Aminobutyric Acid; D011392:Proline; C001390:2-hydroxyestradiol; C010983:homoproline; C024980:2-hydroxyestrone