title: Hormonal regulation of maternal behavior in rats: stimulation following treatment with ectopic pituitary grafts plus progesterone.
abstract: Changes in hormone secretions during pregnancy help to stimulate the onset of maternal behavior at parturition. To date, studies have demonstrated that estradiol (E2) appears to be a necessary component in the hormonal induction of maternal behavior in rats and other mammals. In the present study, we have reevaluated the contribution of E2, progesterone (P), and hormone-secreting pituitary grafts in the rapid induction of maternal behavior by measuring the behavioral effects of exposure to various combinations of P and prolactin-secreting ectopic pituitary grafts in the absence of estrogen. Adult hypophysectomized and nonhypophysectomized nulliparous rats were ovariectomized 2-3 days (Treatment Day 1) after their arrival in our laboratory. In Experiment #1, experimental, hypophysectomized rats were implanted s.c. with 6 P-filled Silastic capsules and given 2 anterior pituitary (AP) glands that were grafted beneath the kidney capsule on Treatment Day 1. Controls were given blank implants and were sham-grafted. P-filled and blank Silastic capsules were removed on Day 11, and behavioral testing was conducted once-a-day beginning on Day 12 for eleven days. Animals treated with P-plus-pituitary grafts displayed full maternal behavior significantly faster than did controls (median latencies of 3.0 and 7.5 days, respectively). In Experiment #2, nonhypophysectomized rats were assigned to one of three treatments. On Treatment Day 1, one group of rats received 6 P-filled Silastic implants and had 2 AP glands grafted under their renal capsules. A second group of animals received 6 P capsules and was sham-grafted, while controls were given blank implants and were sham-grafted.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115.
authors: R S
authors: RS
authors: Bridges
authors: P T
authors: PT
authors: Dunckel
mesh_terms: D000818:Animals; D001835:Body Weight; D004967:Estrogens / Q000502:physiology*; D005260:Female; D007016:Hypophysectomy; D008425:Maternal Behavior; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000502:physiology* / Q000637:transplantation; D011374:Progesterone / Q000502:physiology*; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004967:Estrogens; D011374:Progesterone; D011388:Prolactin