Hormone replacement therapy in the menopause: a suitable animal model

Area of Science:

• Endocrinology
• Reproductive Biology
• Gerontology

Background:

• The human climacteric involves hormonal changes and physiological effects.
• Hormone replacement therapy (HRT) is a common treatment for menopausal symptoms.
• Understanding animal models is crucial for studying human menopause and HRT.

Purpose of the Study:

• To investigate the effects of ethynyl oestradiol and oestrone sulphate on female CBA mice.
• To evaluate the suitability of the CBA mouse as a model for human climacteric studies and HRT response.

Main Methods:

• Cyclical oral administration of ethynyl oestradiol or oestrone sulphate to 11-month-old female CBA mice for 3 months.
• Ovarian atrophy assessment.
• Genital tract tissue analysis using electron microscopy.
• Measurement of uterine cytoplasmic oestrogen receptors.
• Monitoring of serum luteinizing hormone levels.
• Evaluation of cortical-endosteal bone remodelling.

Main Results:

• Ovarian atrophy observed in all treated mice.
• Genital tract tissues responded to both oestrogens, with increased cellular metabolic activity in endometrium and urothelium.
• Endometrial hyperplasia occurred, more pronounced with oestrone sulphate.
• Uterine cytoplasmic oestrogen receptors doubled.
• Serum luteinizing hormone levels decreased by 50%, indicating intact hypothalamic-pituitary function.
• Both oestrogens improved skeletal balance via bone remodelling.

Conclusions:

• Ethynyl oestradiol and oestrone sulphate induce significant physiological changes in female CBA mice.
• The CBA mouse model demonstrates responsiveness to oestrogens, mirroring aspects of the human climacteric.
• This mouse model is suitable for research into human menopause and hormone replacement therapy efficacy.