Administration of estradiol-17 beta in pulses to female guinea pigs: self-priming effects of estrogen on brain tissues mediating lordosis.

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.

• 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.)

Chemical References

• Estrogens
• Receptors, Estrogen
• Receptors, Progesterone
• Estradiol

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