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Suppression of reproductive function in autoimmune NZB/W mice: effective doses of four contraceptive steroids
1Department of Medicine, University of Missouri-Columbia.
Abstract:
Oral contraceptives have been implicated in causing flares of systemic lupus erythematosus in humans, and studies of these agents in the NZB/W mouse model of lupus may help to elucidate mechanisms responsible for disease activation. To define doses which effectively suppress reproductive function in NZB/W mice, we implanted groups of NZB/W females with Silastic capsules containing increasing doses of four compounds: norethindrone (NE) 0.5-5.0 mg, norgestrel (NG) 1.0-7.5 mg, medroxyprogesterone (MP) 0.5-20.0 mg, and ethinyl estradiol (EE) 0.5-5.0 mg. Controls received empty implants. Serum concentrations of LH and FSH, uterine weight, endometrial proliferation, and luteal tissue were assessed after 3 weeks of treatment. Based upon these parameters, we determined that effective doses were 5.0 mg NE, 7.5 mg NG, and 0.5 mg EE given as single implants and 10.0 mg MP given in two 5.0-mg implants. This is the first dosing study of contraceptive steroids in a murine model of lupus. Effective, nontoxic doses of these drugs can now be employed in studies of interactions between gonadal hormones and autoimmunity.
Insights
This study determined effective, non-toxic doses of contraceptive steroids in a mouse model of lupus. These findings will help research the interactions between gonadal hormones and autoimmune diseases like lupus.
Area of Science:
- Immunology
- Endocrinology
- Pharmacology
Background:
- Oral contraceptives are linked to systemic lupus erythematosus (SLE) flares in humans.
- The NZB/W mouse model is crucial for studying lupus pathogenesis and disease activation mechanisms.
Purpose of the Study:
- To establish effective and safe dosages of contraceptive steroids in NZB/W mice.
- To identify doses that suppress reproductive function without causing toxicity.
- To facilitate future research on the interplay between hormones and autoimmunity.
Main Methods:
- NZB/W female mice were implanted with Silastic capsules containing varying doses of norethindrone, norgestrel, medroxyprogesterone, and ethinyl estradiol.
- Control groups received empty implants.
- Hormonal levels (LH, FSH), uterine weight, and endometrial proliferation were assessed after three weeks.
Main Results:
- Effective doses were identified as 5.0 mg norethindrone, 7.5 mg norgestrel, 0.5 mg ethinyl estradiol, and 10.0 mg medroxyprogesterone.
- These doses successfully suppressed reproductive function in the murine model.
- The study established the first dosing parameters for contraceptive steroids in a lupus mouse model.
Conclusions:
- This research provides essential dosing information for contraceptive steroids in NZB/W mice.
- The identified effective, nontoxic doses enable further investigation into gonadal hormone and autoimmunity interactions.
- This study lays the groundwork for understanding how hormonal contraceptives influence lupus activity.
