Dispersed mammary epithelial cells. Receptors of lactogenic hormones in virgin, pregnant, and lactating rabbits.

Détails

ID Serval
serval:BIB_72E06524C161
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Dispersed mammary epithelial cells. Receptors of lactogenic hormones in virgin, pregnant, and lactating rabbits.
Périodique
Journal of Biological Chemistry
Auteur(s)
Suard Y.M., Kraehenbuhl J.P., Aubert M.L.
ISSN
0021-9258
Statut éditorial
Publié
Date de publication
10/1979
Peer-reviewed
Oui
Volume
254
Numéro
20
Pages
10466-10475
Langue
anglais
Notes
Publication types: Comparative Study ; Journal Article
Résumé
The number and affinity of binding sites for lactogenic hormones have been determined in dispersed mammary cells from virgin, pregnant, and lactating rabbits. Dispersed epithelial cells, prepared from mammary glands by enzyme digestion, calcium chelation, and gentle shearing, were separated from nonepithelial cells by density centrifugation. 125I-labeled ovine prolactin (oPRL) and 125I-labeled human growth hormone (/GH) were used as tracers. Association and dissociation of 125I-oPRL or 125I-hGH were time- and temperature-dependent. The rate of association followed a second order reversible reaction with a rate constant of approximately 0.5 at 4 degrees C, approximately 2.0 at 23 degrees C, and approximately 9 x 10(7) M-1 min-1 at 37 degrees C. Maximum binding was achieved after 120 h at 4 degrees C, 48 h at 23 degrees C, and 2 to 4 h at 37 degrees C. Dissociation of 125I-oPRL or hGH from cells by unlabeled oPRL was complete at 4 degrees C after 160 h, following a first order reaction (5-1 = 9.9 x 10(-5) min) and incomplete at 23 degrees C and 37 degrees C even after prolonged time. Internalization of receptor-bound 125I-oPRL was studied by quantitative electron microscope autoradiography. Grain distribution over- and volume densities of cellular organelles was analyzed as a function of time and temperature. At 37 degrees C, there was a rapid and specific translocation of lactogenic hormones to intracellular organelles. Autoradiographic grains were found associated with vesicles, Golgi elements, lysosome-like structures, and the nucleus. One class of high affinity binding sites was estimated from Scatchard plot and direct kinetic analyses at 4 degrees C. Whereas the apparent affinity constant (approximately 10(10) M-1) did not change significantly throughout pregnancy and early lactation, the number of receptors extrapolated from Scatchard plots at 4 degrees C varied in an inverse relation to serum progesterone concentration. Thus, approximately 1900 sites were detected in virgin rabbits (progesterone, approximately 200 pg/ml), and midpregnancy (progesterone, approximately 15,000 pg/ml), and approximately 1800 during early lactation (progesterone, approximately 500 pg/ml). The binding properties of lactogenic hormones to dispersed cells was compared with those to Triton X-100 solubilized microsomal membrane preparations. Good correlation between the two systems was found indicating that cell dispersion did not alter binding properties. Our results indicate that dispersed mammary cells bind lactogenic hormones in a saturable and reversible process, that the number of exposed receptors varies throughout gestation and lactation, and finally that lactogenic hormones are internalized following interaction with their membrane receptors.
Mots-clé
Animals, Epithelium/metabolism, Female, Growth Hormone/metabolism, Kinetics, Lactation, Mammary Glands, Animal/metabolism, Mammary Glands, Animal/ultrastructure, Pregnancy, Pregnancy, Animal, Prolactin/metabolism, Rabbits, Receptors, Cell Surface/metabolism
Pubmed
Web of science
Création de la notice
25/01/2008 16:05
Dernière modification de la notice
03/03/2018 18:18
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