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yun tong he que nuo tong geng suan zuo dui ba xi bao yun tong shou ti dong tai fen bu de ying xiang
Pages: 174-182
Year: Issue:  2
Journal: Acta Physiologica Sinica

Keyword:  receptorprogesteronenorethisterone oenanthatenuclearuteruscontraceptive;
Abstract: The mechanism of action of a long-acting steroid contraceptive,norethiste-rone oenanthate,was studied by comparative analysis of its binding characteristicswith both cytosol and nuclear progesterone receptors.Immature female rabbitswere primed with estradiol for five days to enchance the uterine level of proges-terone receptors.Using ~3H-progesterone exchange method,we have measured thereceptor contents in this tissue and its dissociation constants by Scatchard plot.The Kd for cytosol receptor is 4.20±1.59×10~(-9)mol/L and 1.54±0.52×10~(-9)mol/Lfor nuclear receptor.The RBA (relative binding affinity) of norethisterone cenan-thate to progesterone receptor was evaluated by competitive combination analy-sis using ~3H-progesterone.Norethisterone oenanthate was found to be weaker inRBA than that of progesterone.The duration of nuclear retention of progesterone-receptor complex was alsoinvestigated in E_2-primed rabbits.The results demonstrated that the norethiste-rone oenanthate was shown to have a significart longer retention in nuclei (above24 hours) than that of progesterone (above 6 hours).This correlates well with itsbiological activity and it is,therefore,suggested that a close relationship existsbetween the long-acting property and the duration of nuclear retention of the recep-tor complex.
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