Forebrain implants of estradiol stimulate maternal nest-building in ovariectomized rabbits.
In rabbits, estradiol and progesterone (P) stimulate digging a maternal burrow while P withdrawal promotes straw-carrying. To investigate where such hormones act to regulate those activities, ovariectomized rabbits were implanted with estradiol benzoate (EB; Experiment 1) in the nucleus accumbens (ACC), the principal nucleus of the medial preoptic area or the dorsal hippocampus. Implants were combined with s.c. P injections. In Experiment 2, P (in crystals or dissolved in oil) was implanted in the same regions as in Experiment 1, combined with s.c. injections of EB. Implants of EB into the ACC or MPOA-bed nucleus of the stria terminalis (BNST) stimulated significant digging across the period of P injections in 72% and 67% of females, respectively. Neither EB implants in the hippocampus nor cholesterol implants in the MPOA-BNST were effective in eliciting digging. P withdrawal provoked a rapid decline of digging in all animals; it also stimulated straw-carrying in 53% of females implanted with EB in the MPOA-BNST. P implants failed to stimulate digging in most females injected with EB. Removal of P crystals did not promote straw-carrying. Results support an action of estradiol on the ACC and MPOA-BNST to promote digging while only the MPOA-BNST is involved in stimulating straw-carrying. The failure of P implants to stimulate digging or straw-carrying in EB-treated females suggests that the stimulation of other or additional brain areas by P is necessary to fully activate maternal nest-building.
González-Mariscal
Gabriela
G
Centro de Investigación en Reproducción Animal, CINVESTAV-UAT, Apdo. Postal 62, Tlaxcala, Tlax. 90000, México. gglezm@prodigy.net.mx
Chirino
Rosario
R
Rosenblatt
Jay S
JS
Beyer
Carlos
C
D000818:Animals; D002784:Cholesterol / Q000494:pharmacology; D020667:Diagonal Band of Broca / Q000187:drug effects / Q000502:physiology; D004343:Drug Implants; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D008425:Maternal Behavior / Q000187:drug effects; D009425:Nesting Behavior / Q000187:drug effects*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology; D010052:Ovariectomy; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology; D011374:Progesterone / Q000494:pharmacology; D016548:Prosencephalon / Q000187:drug effects* / Q000502:physiology*; D011817:Rabbits; D012686:Septal Nuclei / Q000187:drug effects / Q000502:physiology
D004343:Drug Implants; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; D002784:Cholesterol