Effect of estrogen on calcium homeostasis and pituitary hormones in the growing chick

• Published in: General and comparative endocrinology Vol. 76; no. 2; pp. 261 - 266
• Main Authors: Sommerville, Barbara A., Scanes, C.G., Swaminathan, R., Care, A.D., Harvey, S., Chadwick, A.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.11.1989; Elsevier
• Subjects: Animals; Biological and medical sciences; CALCIO; CALCIUM; Calcium - metabolism; Chickens - growth & development; CHICKS; Dose-Response Relationship, Drug; ESTROGENOS; Estrogens - pharmacology; Fundamental and applied biological sciences. Psychology; Growth Hormone - blood; GROWTH RATE; Homeostasis - drug effects; HORMONAS PITUITARIAS; HORMONE HYPOPHYSAIRE; INDICE DE CRECIMIENTO; Male; Mixed Function Oxygenases - metabolism; OESTROGENE; OESTROGENS; PITUITARY HORMONES; POLLITO; POUSSIN; Prolactin - blood; Steroid hormones. Cholecalciferol derivatives; TAUX DE CROISSANCE; Vertebrates: endocrinology; Vitamin D - metabolism; Calcium; Growth; STH; Estrogen; Gonadotropin; Inorganic element; Estradiol; Chromatography; Ovarian hormone; Phosphocalcic homeostasis; Dose activity relation; Protein hormone; Vertebrata; Pituitary hormone; Enzymatic activity; Adenohypophyseal hormone; Prolactin; Radioimmunoassay; Cations; Chicken; Aves; Sex steroid hormone
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/0016-6480(89)90157-3

An experiment was carried out to investigate the effect of a range of estradiol (E 2) doses (0.1–6.5 μg/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 μg/g E 2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxy vitamin D 1α-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 μg/g E 2 but there was evidence of a second peak in 1-hydroxylase activity at 6 μg/g E 2. At this high dose rate, the plasma Ca level rose to 8 m M, 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.