Estrogen receptor in purified nuclei from deciduomata of the pseudopregnant rat

• Published in: Journal of steroid biochemistry Vol. 9; no. 12; pp. 1149 - 1154
• Main Authors: Glenn Armstrong, E., Villee, Claude A.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.12.1978
• Subjects: Animals; Cell Nucleus - metabolism; DNA - metabolism; Estradiol - metabolism; Female; Kinetics; Pseudopregnancy - metabolism; Rats; Receptors, Estrogen - metabolism; Uterus - metabolism
• ISSN: 0022-4731
• DOI: 10.1016/0022-4731(78)90004-3

A specific estrogen receptor was identified in purified nuclei from deciduomata of pseudopregnant rats. Sucrose density gradient centrifugation of 0.4 M KCl extracts of deciduomal nuclei from rats injected with [ 3H]-17β-estradiol ([ 3H]-17β-E 2) revealed the presence of saturable estrogen-receptor complexes sedimenting at 4.6 S. A nuclear exchange assay was used to determine the association constant ( K a ) for the binding of 17β-E 2 by purified deciduomal nuclei and the concentrations of specific nuclear estrogen receptor sites on different days of decidualization. The mean K a of nine determinations was 4.0 × 10 9 M −1 indicating that deciduomal nuclei bind 17β-E 2 with high affinity. The concentration of specific estrogen receptor sites in deciduomal nuclei on day 3 of decidualization was determined to be 0.21 pmol/mg DNA or approximately 1300 sites/nucleus. Between days 3 and 7 of decidualization there is a significant linear decrease ( P < 0.01) in the number of estrogen receptor sites in deciduomal nuclei; on day 7 there are approximately 60% as many sites as on day 3. The significance of the nuclear estrogen receptor and its decrease as a function of decidualization time are discussed with regard to the growth and regression of deciduomata.