Effects of antiprogestogen (RU-486) treatment on myometrial and cervical alpha and beta-adrenoceptors in pregnant rabbits.
Oestrogen and progesterone influence myometrial and cervical responses at different levels of the mechanisms regulating uterine contractility. One of these mechanisms could involve alterations in the adrenoceptor concentrations. This study was undertaken to assess the effects of treatment with the antiprogestogen RU-486 on the concentrations of alpha- and beta-adrenoceptors in pregnant rabbit myometrial and cervical membranes by means of a radioligand binding technique. The probable relative oestrogen dominance due to the antiprogestogen treatment selectively decreased the alpha 2-adrenoceptor subtype in the cervix, where an alpha-adrenoceptor dominance was found on day 27 of pregnancy. The results indicate a heterologous regulation of alpha-adrenoceptors by sex steroids, i.e. suppression of the alpha 2-adrenoceptor concentration by antiprogestogen treatment.
Falkay
G
G
Department of Obstetrics and Gynaecology, WHO Collaborative Centre on Clinical Research on Human Reproduction, Albert Szent-Györgyi Medical University Szeged, Semmelweis, Hungary.
D000818:Animals; D002584:Cervix Uteri / Q000378:metabolism; D004082:Dihydroalprenolol / Q000378:metabolism; D005260:Female; D015735:Mifepristone / Q000494:pharmacology*; D009215:Myometrium / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D011247:Pregnancy; D011817:Rabbits; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D015016:Yohimbine / Q000378:metabolism
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D015016:Yohimbine; D015735:Mifepristone; D004082:Dihydroalprenolol; D011224:Prazosin