Methods for long-term 17β-estradiol administration to mice

Area of Science:

• Endocrinology and reproductive biology
• Pharmacology and drug delivery systems
• Animal models in biomedical research

Background:

• 17β-estradiol is crucial for understanding biological mechanisms.
• Long-term administration methods for 17β-estradiol in rodents require thorough evaluation.
• Accurate dosing is essential as 17β-estradiol effects vary with concentration.

Purpose of the Study:

• To assess and compare different long-term 17β-estradiol administration methods in mice.
• To identify reliable and physiologically relevant delivery systems for 17β-estradiol research.
• To evaluate novel peroral and established subcutaneous methods against commercial pellets.

Main Methods:

• 169 ovariectomized female C57BL/6 mice received 17β-estradiol via subcutaneous pellets, silastic capsules, or a novel peroral method.
• Control groups included ovariectomized and intact mice.
• Serum 17β-estradiol levels were measured weekly for five weeks using radioimmunoassay.

Main Results:

• The peroral method maintained steady, mostly physiological 17β-estradiol concentrations.
• Silastic capsules produced predominantly physiological levels, with transient peaks up to threefold the range.
• Commercial pellets resulted in supra-physiological initial concentrations (0.18 mg) or extremely high levels (0.72 mg).

Conclusions:

• Peroral and silastic capsule methods are reliable for 17β-estradiol administration in mice.
• These methods offer superior control over serum concentrations compared to commercial pellets.
• Validated administration regimens are critical for accurate 17β-estradiol research in rodent models.