Effects on serum lipid profiles of continuous 17β-estradiol, intermittent norgestimate regimens versus continuous combined 17β-estradiol/ norethisterone acetate hormone replacement therapy

Purpose: The purpose of this study was to analyze the effects of estrogen deficiency and hormone replacement therapy (HRT) on fibrinolytic activity in a rat mode of surgically-induced menopause. Methods: Twelve-week-old, sexually mature female Sprague-Dawley rats, each weighing 200–250 g, were randomly divided into four groups: (1) sham-operated group, (2) ovariectomy group, (3) ovariectomy group followed by oral administration of daily 17β-estradiol (0.02 mg/kg/day) (E2) + norethisterone acetate (0.01 mg/kg/day), and (4) ovariectomy group followed by oral administration of daily 17β-estradiol (0.01 mg/kg/day) + drospirenone (0.02 mg/kg/day). Tissue plasminogen activator (tPA) antigen, plasminogen activator inhibitor-1 (PAI-1) antigen, and PAI-1/tPA levels were measured as markers of fibrinolysis in plasma and liver and brain tissue. Results: Compared with sham-operated rats, ovariectomized rats showed higher levels of fibrinolytic activity; however, the increased fibrinolytic activity in plasma and liver tissue was significantly reduced by HRT regimens. No change was observed in the levels of fibrinolytic activity in brain tissue. Conclusions: HRT showed beneficial effects by decreasing fibrinolytic activity related to surgically-induced menopause. Short-term HRT treatment was associated with a shift in the procoagulant-anticoagulant balance toward a procoagulant state.

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Less Carcinogenic Chlorinated Estrogens Applicable to Hormone Replacement Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms22137222 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7222

Author(s):

Yoshinori Okamoto ◽

Hideto Jinno ◽

Shinji Itoh ◽

Shinya Shibutani

Keyword(s):

Hormone Replacement Therapy ◽

Replacement Therapy ◽

Hormone Replacement ◽

Metabolic Activation ◽

Ovariectomized Rats ◽

Estrogenic Potential ◽

Carcinogenic Potential ◽

Induced Tumors ◽

Carcinogenic Effects ◽

17Β Estradiol

Human estrogens prescribed for hormone replacement therapy (HRT) are known to be potent carcinogens. To find safer estrogens, several chlorinated estrogens were synthesized and their carcinogenic potential were determined. A pellet containing either 2-chloro-17β-estradiol (2-ClE2) or 4-chloro-17β-estradiol (4-ClE2) was implanted subcutaneously for 52 weeks into August Copenhagen Irish (ACI) rats, a preferred animal model for human breast cancer. 17β-Estradiol (E2) frequently induced mammary tumors while both 2-ClE2 and 4-ClE2 did not. Their 17α-ethinyl forms, thought to be orally active estrogens, were also synthesized. Neither 2-chloro-17α-ethinylestradiol (2-ClEE2) nor 4-chloro-17α-ethinylestradiol (4-ClEE2) induced tumors. The less carcinogenic effects were supported by histological examination of mammary glands of ACI rats treated with the chlorinated estrogens. A chlorine atom positioned at the 2- or 4-position of E2 may prevent the metabolic activation, resulting in reducing the carcinogenicity. 2-ClE2 and 4-ClE2 administered subcutaneously and 2-ClEE2 and 4-ClEE2 given orally to ovariectomized rats all showed uterotrophic potency, albeit slightly weaker than that of E2. Our results indicate that less carcinogenic chlorinated estrogens retaining estrogenic potential could be safer alternatives to the carcinogenic estrogens now in use for HRT.

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