title: Endometrial effects of intrauterine levonorgestrel.
abstract: Local intrauterine delivery of levonorgestrel (LNG) results in extensive decidualization of endometrial stromal cells, atrophy of the glandular and surface epithelium and changes in vascular morphology (suppression of spiral artery formation and presence of large dilated vessels). With endometrial exposure to LNG, there is down-regulation of sex steroid receptors in all cellular components. As a consequence of endometrial sex steroid receptor down-regulation, there is perturbation of progesterone-regulated locally acting mediators, and the integrity of blood vessel walls is disturbed. Thus, intrauterine LNG administration results in modulation of local mediators regulating endometrial function. To date, no single factor has been identified where the expression correlates closely with unscheduled breakthrough bleeding (BTB). BTB is a common side effect and reason for discontinuation of LNG-IUS use. Much remains to be determined about the mechanisms involved in suppression of menstruation, BTB episodes and the local endometrial environment with local LNG administration.
authors.affiliation: Division of Reproductive and Developmental Sciences, The Queen's Medical Research Institute, Centre for Reproductive Biology, The University of Edinburgh, EH16 4TJ Edinburgh, UK.
authors.forename: Anja
authors.initials: A
authors.lastname: Guttinger
authors.forename: Hilary O D
authors.initials: HO
authors.lastname: Critchley
mesh_terms: D003271:Contraceptive Agents, Female / Q000494:pharmacology*; D016889:Endometrial Neoplasms / Q000188:drug therapy; D004717:Endometrium / Q000098:blood supply / Q000187:drug effects*; D005260:Female; D006801:Humans; D007436:Intrauterine Devices, Medicated / Q000009:adverse effects; D016912:Levonorgestrel / Q000494:pharmacology*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008796:Metrorrhagia / Q000503:physiopathology; D011987:Receptors, Steroid / Q000187:drug effects / Q000378:metabolism
chemical_list: D003271:Contraceptive Agents, Female; D011987:Receptors, Steroid; D016912:Levonorgestrel; D020782:Matrix Metalloproteinases