Abstract |
Lordosis behavior in ovariectomized guinea pigs is facilitated by the sequential action of estradiol-17 beta (E) and progesterone (P). The present study was designed to explore the possibility that administration of E in a pulsatile manner is more efficacious than a single injection of E with respect to lordosis facilitation in ovariectomized guinea pigs. The data indicate that pulse administration of unesterified E is more effective than a single large dose of E for the facilitation of lordosis behavior. Three injections of as little as 0.5 microgram E at 0, 19 and 28 hr followed by 0.5 mg P at 39 hr was more effective (63.6% responding with lordosis) than a single injection of as much as 15 micrograms E at hr 0 followed by vehicle injections at 19 and 28 hr and 0.5 mg P at 39 hr (0% responding). We also demonstrated that the 19 hr E injection could be eliminated and that two injections of E (0.5 microgram at hr 0 and 1.0 microgram at hr 28 followed by 0.5 mg P at hr 39) was at least as effective (69.0% responding) as three split injections in facilitating lordosis. This behaviorally effective pulse administration of E also resulted in significant induction of cytoplasmic progestin receptors in hypothalamic tissue. Further experiments indicated that a 28 hr interval between E pulses was optimal in terms of percent animals displaying lordosis. The data suggest that pulsatile E stimulation of brain tissues mediating lordosis is a highly effective mode of stimulation, and that an initial pulse of E sensitizes neural tissues to subsequent E administration.
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Authors | J N Wilcox, S R Barclay, H H Feder |
Journal | Physiology & behavior
(Physiol Behav)
Vol. 32
Issue 3
Pg. 483-8
(Mar 1984)
ISSN: 0031-9384 [Print] United States |
PMID | 6463129
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Estrogens
- Receptors, Estrogen
- Receptors, Progesterone
- Estradiol
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Topics |
- Animals
- Brain
(drug effects, physiology)
- Castration
- Cytoplasm
(metabolism)
- Dose-Response Relationship, Drug
- Estradiol
(administration & dosage, pharmacology)
- Estrogens
(administration & dosage, pharmacology)
- Female
- Guinea Pigs
(physiology)
- Receptors, Estrogen
(analysis)
- Receptors, Progesterone
(analysis)
- Sexual Behavior, Animal
(drug effects)
- Time Factors
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