Ovariectomy and 17β-estradiol Replacement in Rats and Mice: A Visual Demonstration

Abstract

Estrogens are a family of female sexual hormones with an exceptionally wide spectrum of effects. When rats and mice are used in estrogen research they are commonly ovariectomized in order to ablate the rapidly cycling hormone production, replacing the 17β-estradiol exogenously. There is, however, lack of consensus regarding how the hormone should be administered to obtain physiological serum concentrations. This is crucial since the 17β-estradiol level/administration method profoundly influences the experimental results 1-3 . We have in a series of studies characterized the different modes of 17β-estradiol administration, finding that subcutaneous silastic capsules and per-oral nut-cream Nutella are superior to commercially available slow-release pellets (produced by the company Innovative Research of America) and daily injections in terms of producing physiological serum concentrations of 17β-estradiol [4][5][6] . Amongst the advantages of the nut-cream method, that previously has been used for buprenorphine administration 7 , is that when used for estrogen administration it resembles peroral hormone replacement therapy and is non-invasive. The subcutaneous silastic capsules are convenient and produce the most stable serum concentrations. This video article contains step-by-step demonstrations of ovariectomy and 17β-estradiol hormone replacement by silastic capsules and peroral Nutella in rats and mice, followed by a discussion of important aspects of the administration procedures. Video LinkThe video component of this article can be found at

Histological changes in the vulva and vagina from ovariectomised rats undergoing oestrogen treatment

“…The experimental model of hormone replacement therapy, associated with surgically-induced anoestrus through bilateral ovariectomy in female rats, is wellknown [16,28,31]. In accordance with the validated animal model, the histopathological analysis in group 2 found evident atrophy in the epithelium, chorion and glandular tissues of the vagina and vulva.…”

Elevated Mechanical Loading When Young Provides Lifelong Benefits to Cortical Bone Properties in Female Rats Independent of a Surgically Induced Menopause

“…Surgeries were performed under inhalation anesthesia with the delay between completion of the loading program and surgery used to replicate the clinical scenario of exercise-induced mechanical loading when young followed by menopause later in life. Animals in the OVX group had both ovaries removed via a dorsal approach, as previously described (22). Animals in the sham-OVX group had their ovaries exteriorized but not removed.…”

Regulation of the Mouse Medial Prefrontal Cortical Synapses by Endogenous Estradiol

“…Ovariectomy was performed under ketamine/xylazine anesthesia. Ovaries were removed after making incisions of 5 mm on either sides about 10 mm from the midline (Strom et al, 2012). A control group was subjected to sham surgeries in which the ovaries were exteriorized but remained intact.…”