{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,17]],"date-time":"2025-09-17T16:14:21Z","timestamp":1758125661476},"reference-count":0,"publisher":"Oxford University Press (OUP)","issue":"6","content-domain":{"domain":["eje.bioscientifica.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1994,6]]},"abstract":"<jats:p>Yamamoto T, Tamura T, Kitawaki J, Osawa Y, Okada H. Suicide inactivation of aromatase in human placenta and uterine leiomyoma by 5\u03b1-dihydronorethindrone, a metabolite of norethindrone, and its effect on steroid-producing enzymes. Eur J Endocrinol 1994;130:634\u201340. ISSN 0804\u20134643<\/jats:p>\n        <jats:p>Norethindrone (NET; 17\u03b1-ethynyl-19-nortestosterone), a progestogen component of the contraceptive pill, irreversibly inhibits aromatase activity in human placental microsomes. However, it is known also to be aromatized in vitro and in vivo to produce a biologically very active estrogen called ethynylestradiol (EE<jats:sub>2<\/jats:sub>). It is therefore inappropriate to administer a high dose of NET to estrogendependent cancer patients for a prolonged time period. In this study, we focused on 5\u03b1-dihydronorethindrone (5\u03b1-DHNET), a metabolite of NET that is not aromatizable, and the inhibitory effects of 5\u03b1-DHNET on human placental and uterine leiomyoma microsomal aromatase and other steroid synthetases. 5\u03b1-Dihydronorethindrone showed weak affinity for both estrogen and progestogen receptors. It inhibited significantly human placental aromatase activity in a dose-dependent manner (K<jats:sub>i<\/jats:sub> = 9.0 \u03bcmol\/l; Kinact = 0.024\/min), as well as that of uterine leiomyoma, but did not influence cholesterol side-chain cleavage or 17\u03b1-hydroxylase, 21-hydroxylase or 11\u03b2-hydroxylase activities. These results suggest that 5\u03b1-DHNET may be useful as an aromatase inhibitor, whose use in large doses is expected to reduce the size of estrogen-dependent tumors.<\/jats:p>\n        <jats:p>Takara Yamamoto, Department of Obstetrics and Gynecology, Kawaramachi-Hirokoji, Kamikyo-Ku, Kyoto 602, Japan<\/jats:p>","DOI":"10.1530\/eje.0.1300634","type":"journal-article","created":{"date-parts":[[2008,12,15]],"date-time":"2008-12-15T21:19:42Z","timestamp":1229375982000},"page":"634-640","update-policy":"http:\/\/dx.doi.org\/10.1530\/crossmarkpolicy-1","source":"Crossref","is-referenced-by-count":7,"title":["Suicide inactivation of aromatase in human placenta and uterine leiomyoma by 5\u03b1-dihydronorethindrone, a metabolite of norethindrone, and its effect on steroid-producing enzymes"],"prefix":"10.1093","volume":"130","author":[{"given":"Takara","family":"Yamamoto","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takaya","family":"Tamura","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jo","family":"Kitawaki","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoshio","family":"Osawa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroji","family":"Okada","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"286","container-title":["European Journal of Endocrinology"],"original-title":[],"link":[{"URL":"https:\/\/eje.bioscientifica.com\/view\/journals\/eje\/130\/6\/eje_130_6_017.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/eje.bioscientifica.com\/view\/journals\/eje\/130\/6\/eje_130_6_017.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,2,14]],"date-time":"2023-02-14T16:18:59Z","timestamp":1676391539000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/ejendo\/article\/130\/6\/634\/6750728"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1994,6]]},"references-count":0,"journal-issue":{"issue":"6"},"URL":"https:\/\/doi.org\/10.1530\/eje.0.1300634","relation":{},"ISSN":["0804-4643","1479-683X"],"issn-type":[{"value":"0804-4643","type":"print"},{"value":"1479-683X","type":"electronic"}],"subject":[],"published":{"date-parts":[[1994,6]]}}}