Order of magnitude differences between methods for maintaining physiological 17β-estradiol concentrations in ovariectomized rats
2008 (English)In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, Vol. 68, no 8, 814-822 p.Article in journal (Refereed) Published
The use of animal, especially rat, models, is crucial for elucidating the biological effects and mechanisms of the widely used hormone 17β-estradiol. Unfortunately there is a lack of consensus on optimal means of obtaining and maintaining physiological 17β-estradiol concentrations in plasma. This may be the reason for varying results in several studies including the disagreement on whether 17β-estradiol is neuroprotective or not. Very few studies have been devoted to investigating the characteristics and biological relevance of different methods of 17β-estradiol administration. We therefore ovariectomized 75 Sprague-Dawley rats and, following a 2 weeks wash-out period, administered 17β-estradiol using three different methods; daily injections (10 µg 17β-estradiol/kg), slow-release pellets (0.25 mg 60 day-release pellets, 0.10 mg 90 day-release pellets) and silastic capsules (with/without wash-out periods) (silastic laboratory tubing, inner/outer diameter: 1.575/3.175 mm, filled with 20 mm columns of 180 µg 17β-estradiol/mL sesame oil). Further 45 animals were used as ovariectomized and native controls, studied in different parts of the estrous cycle. Silastic capsules produced concentrations of 17β-estradiol within the physiological range for 4-5 weeks independent of whether a prior wash-out period was included or not. The slow-release pellets, irrespective of dose or release period, resulted in initial concentrations which were an order of magnitude above physiological concentrations during the first two weeks followed by a substantial decrease. Daily injections resulted in increasing 17β-estradiol concentrations, however within physiological levels. Silastic capsules are conveniently manufactured and used, and are superior to pellets and injections in reliably producing long-term 17β-estradiol concentrations within the physiological range.
Place, publisher, year, edition, pages
2008. Vol. 68, no 8, 814-822 p.
Estrogens, Injections, Pharmacokinetics, Silastic capsules, Slow-release pellets, Wash-out
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-15389DOI: 10.1080/00365510802409703OAI: oai:DiVA.org:liu-15389DiVA: diva2:114091
Original publication: Jakob O. Ström, Elvar Theodorsson and Annette Theodorsson, Order of magnitude differences between methods for maintaining physiological 17β-estradiol concentrations in ovariectomized rats, 2008, Scandinavian Journal of Clinical and Laboratory Investigation.http://dx.doi.org/10.1080/00365510802409703. Copyright © Taylor & Francis Group, an informa business2008-11-052008-11-052012-05-08Bibliographically approved