Estrogen modulates 5-HT(1A) agonist inhibition of lordosis behavior but not binding of [(3)H]-8-OH-DPAT.
Previous studies showed that repeated estrogen treatment reduces the ability of the 5-HT(1A) receptor agonist, 8-hydroxy-2(di-n-propylamino) tetralin (8-OH-DPAT), to inhibit lordosis behavior of female rats. The present study evaluated the effects of repeated estrogen treatment on lordosis behavior and 5-HT(1A) receptor binding and coupling to G protein in the hypothalamus-preoptic area using the agonist ligand [3H]-8-OH-DPAT, which binds selectively to G-protein-coupled 5-HT(1A) receptors. Rats were injected twice with 25 or 50 microg of estradiol benzoate (EB) 7 days apart followed by 500 microg of progesterone (P) 48 h after the second EB injection. Controls received a single injection of 25 or 50 microg EB followed 48 h later by 500 microg of P. Four hours after P, 0.15 mg/kg 8-OH-DPAT was injected, and lordosis behavior examined for 30 min. Rats treated twice with EB showed significantly less 8-OH-DPAT inhibition of lordosis behavior than rats receiving a single EB injection. For receptor binding, rats received EB without P treatment. None of the estrogen treatments reduced [3H]-8-OH-DPAT binding density or affinity in the hypothalamus-preoptic area or hippocampus. These studies suggest that estrogen modulates 5-HT(1A) agonist potency without a measurable change in 5-HT(1A) receptor density or coupling to G protein.
Jackson
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Department of Neuroscience, F113, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Etgen
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D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D005260:Female; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D011187:Posture / Q000502:physiology; D011301:Preoptic Area / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology
D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D019204:GTP-Binding Proteins