Mechanisms of action of mifepristone and levonorgestrel when used for emergency contraception.
(1/18)
An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely under-utilized worldwide. One of the main barriers to widespread use is concern about the mechanism of action. Recently, treatment with either 10 mg mifepristone or 1.5 mg of levonorgestrel has emerged as the most effective hormonal method for emergency contraception with very low side-effects. However, the knowledge of the mechanism of action of mifepristone and levonorgestrel in humans, when used for contraceptive purposes and especially for emergency contraception, remains incomplete. The objective of this review is to summarize available data on the effects of mifepristone and levonorgestrel on female reproductive functions relevant to the emergency use of the compounds. When summarized, available data from studies in humans indicate that the contraceptive effects of both levonorgestrel and mifepristone, when used in single low doses for emergency contraception, involve either blockade or delay of ovulation, due to either prevention or delay of the LH surge, rather than to inhibition of implantation. (+info)
Ovulation suppression of premenstrual symptoms using oral contraceptives.
(2/18)
Managing premenstrual symptoms at the most fundamental level necessitates careful consideration of female reproductive biology. Inhibiting ovulation using hormonal agents is a reasonable approach for reducing premenstrual symptoms, but the benefits of agents such as gonadotropin-releasing hormone agonists and the synthetic androgen danazol are largely offset by their adverse effects and costs. Combination oral contraceptives provide an alternative that is widely accepted by women experiencing premenstrual symptoms and by their physicians; and newer formulations with lower levels of estrogen and progestin, administered using a monthly regimen with a shortened pill-free interval, appear promising for alleviating patient distress from severe premenstrual symptoms. (+info)
Suppression of menstruation in adolescents with severe learning disabilities.
(3/18)
As girls with severe cognitive developmental delay progress into puberty and become young women with learning disabilities, concerns about menstruation are common amongst carers and health care professionals are often consulted for advice. Very little, however, has been published on this area to guide the practitioner and studies are almost exclusively confined to the gynaecological literature. We aim to give an account of the various therapeutic options available and current practice within the paediatric endocrinology unit at our institution. (+info)
The aryl hydrocarbon receptor is required for normal gonadotropin responsiveness in the mouse ovary.
(4/18)
The aryl hydrocarbon receptor (AHR) mediates the toxicity of a variety of environmental chemicals. Although little is known about the physiological role of the AHR, studies suggest that it plays an important role in regulating ovulation because Ahr deficient (AhRKO) mice have a reduced number of ovulations compared to wild-type (WT) mice. The reasons for the reduced ability of AhRKO mice to ovulate are unknown. Normal ovulation, however, requires estrous cyclicity, appropriate luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels, and LH and FSH responsiveness. Thus, the purpose of this study was to test the hypothesis that Ahr deletion regulates ovulation by altering cyclicity, FSH and LH levels, follicle-stimulating hormone receptor (Fshr) and luteinizing hormone receptor (Lhcgr) levels and/or gonadotropin responsiveness. The data indicate that AhRKO and WT mice have similar levels of FSH and LH, but AhRKO mice have reduced Fshr and Lhcgr mRNA levels compared to WT mice. Furthermore, AhRKO ovaries contain fewer corpora lutea compared to WT ovaries after 5 IU equine chorionic gonadotropin (eCG) treatment. Lastly, both AhRKO and WT mice ovulate a similar number of eggs in response to 5 IU human chorionic gonadotropin (hCG), but AhRKO mice ovulate fewer eggs than WT mice in response to 2.5 IU and 1.25 IU hCG. Collectively, these data indicate that AhRKO follicles have a reduced capacity to ovulate compared to WT follicles and that this is due to reduced responsiveness to gonadotropins. Thus, in addition to mediating toxicity of environmental chemicals, the Ahr is required for normal ovulation. (+info)
Safety and tolerability of depot medroxyprogesterone acetate among HIV-infected women on antiretroviral therapy: ACTG A5093.
(5/18)