title: Effect of estrogen on calcium homeostasis and pituitary hormones in the growing chick.
abstract: An experiment was carried out to investigate the effect of a range of estradiol (E2) doses (0.1-6.5 micrograms/g body wt/day) on vitamin D metabolism and the plasma levels of growth hormone (GH) and prolactin (PRL) in the growing chick. Doses of 0.5-0.7 microgram/g E2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxyvitamin D 1 alpha-hydroxylase (1-hydroxylase) and 24-hydroxylase activities, and an increase in plasma GH level. These parameters leveled off or fell over the dose range 1-2 micrograms/g E2 but there was evidence of a second peak in 1-hydroxylase activity at 6 micrograms/g E2. At this high dose rate, the plasma Ca level rose to 8 mM, as it does in the laying hen; 24-hydroxylase activity, growth rate, and plasma GH and plasma PRL levels all decreased. It was concluded that the dose response to estrogen in the growing chick is not linear and, in the case of 1-hydroxylase activity, may even be biphasic.
authors.affiliation: Department of Animal Physiology and Nutrition, University of Leeds, Yorkshire, United Kingdom.
authors.forename: B A
authors.initials: BA
authors.lastname: Sommerville
authors.forename: C G
authors.initials: CG
authors.lastname: Scanes
authors.forename: R
authors.initials: R
authors.lastname: Swaminathan
authors.forename: A D
authors.initials: AD
authors.lastname: Care
authors.forename: S
authors.initials: S
authors.lastname: Harvey
authors.forename: A
authors.initials: A
authors.lastname: Chadwick
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002645:Chickens / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D006706:Homeostasis / Q000187:drug effects*; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D014807:Vitamin D / Q000378:metabolism
chemical_list: D004967:Estrogens; D014807:Vitamin D; D011388:Prolactin; D013006:Growth Hormone; D006899:Mixed Function Oxygenases; D002118:Calcium