当前位置： SCI文献检索 > DOMESTIC ANIMAL ENDOCRINOLOGY期刊下所有文献 > Effects of steroid hormone treatment on mammary development in prepubertal heifers.

Effects of steroid hormone treatment on mammary development in prepubertal heifers.

Abstract：

:The objective of this study was to determine the effects of steroid hormone implantation in heifer calves on the ability of mammary tissue to develop subsequently in organ culture. Twenty-four calves were paired by date of birth and assigned to groups (eight calves/group). At 4, 7, or 10 mo of age, calves were implanted subcutaneously (s.c.) with pellets containing cholesterol or cholesterol, 17 beta-estradiol, and progesterone for 9 or 18 d. The calves were euthanized and uteri and mammary glands were removed and weighed. Slices of mammary parenchymal tissue were incubated for 5 d at 37 degrees C in a 50% O2, 5% CO2 humidified atmosphere in Waymouth's 752/liter medium supplemented with insulin (5.0 micrograms/ml) or lactogenic hormone complex insulin (5.0 micrograms/ml), aldosterone (0.1 microgram/ml), hydrocortisone (0.1 microgram/ml), and prolactin (1.0 microgram/ml) in the presence or absence of epidermal growth factor (EGF) (0.06 microgram/ml) to promote lobulo-alveolar development. Tissue sections were stained and mounted on slides for morphologic and histologic analysis or prepared to evaluate expression of beta-casein mRNA. There were no morphologic differences in slices from calf mammary tissues despite age, steroid hormone priming, or hormones used in tissue culture. The 4-mo-old calves required steroid priming followed by incubation of the tissue slices with the lactogenic complex with or without epidermal growth factor to induce cytological changes associated with lactogenesis but did not express beta-casein mRNA. At 7 mo of age, steroid hormone priming was not necessary for induction of alveolar formation and secretion. Incubation of the tissue slices from 7-mo-old calves with the lactogenic complex was sufficient to induce alveolar formation and secretion. However, beta-casein mRNA was not expressed. At 10 mo of age, exposure of tissue from calves to the lactogenic hormones caused histologic changes reminiscent of the ability to secrete milk regardless of hormone priming. However, estrogen and progesterone priming was necessary before incubation of the tissue slices with the lactogenic hormones to induce beta-casein mRNA expression. When epidermal growth factor was added to the lactogenic hormone complex, beta-casein mRNA expression decreased. These data support the concept that there is a sequential development of responsiveness of the mammary gland to various hormones. By 10 mo of age, prepubertal heifers reach a stage of maturity where steroid hormone priming followed by incubation of tissue slices with the lactogenic hormones is sufficient to induce both structural and functional differentiation.

journal_name

Domest Anim Endocrinol

journal_title

Domestic animal endocrinology

authors

Maple RL,Akers RM,Plaut K

doi

10.1016/s0739-7240(98)00037-x

subject

Has Abstract

pub_date

1998-11-01 00:00:00

pages

489-98

issue

eissn

0739-7240

issn

1879-0054

pii

S073972409800037X

journal_volume

pub_type

杂志文章

在线工具

Effects of steroid hormone treatment on mammary development in prepubertal heifers.