Does anyone treat mice (B6) with tamoxifen to mimic ovarian ablation (ovariectomy)? How much and how long do you treat the mice? Thanks.
Hallo!: I guess the references below may be connected to your query, but I'm a clinician, not a lab person
https://www.ncbi.nlm.nih.gov/pubmed/4567104
https://www.ncbi.nlm.nih.gov/pubmed/20981001
https://www.ncbi.nlm.nih.gov/pubmed/1141814
https://www.ncbi.nlm.nih.gov/pubmed/25187267
https://en.wikipedia.org/wiki/Tamoxifen
Tamoxifen is listed among the Selective Estrogen Receptor Modulators (SERM), you know that Steroid Hormones do act by internalization and binding to specific receptors in the nuclear DNA, this indicating that its action on circulating steroid hormone levels, if any, are indirect.
Tamoxifen doesn't act on Circulating Steroid levels as Aromatase Inhibitors do, regarding this, AIs are similar to ovarian ablation, but Tam competes with the Estrogen Steroids at its receptors. Tam was the first line Hormone manipulation for post-surgical, adjuvant therapy, in pre-menopausal women, although this is changing a bit now. Tamoxifen has some intrinsic estrogen activity early in its dosing, this is in the origin of a short lived 'tumor flare' that is seen immediately upon starting therapy, as with some Prostate cancer drugs having a totally different mechanism of action.
In Prostate cancer, with agents that block the gonadotrophin, and this way, cut the circulating androgen levels, some centers measured periodically, when the time for next dosing approached, the circulating androgen levels (some also SHBG), as these are expensive drugs, and dosing the monthly or the every three months injection only as needed, when Androgens levels start climbing again, decreases number of injections, thus expenses.
Castration androgen or estrogen levels may exist in blood, but not inside tumor, as both tumor and stromal cells can synthesize hormonal steroids from circulating precursor steroids lacking an hormonal action, fatty tissue is active regarding this, and perhaps the different outcome in tumors growing in larger breasts may come from the fat-located hormonal steroid synthesis, secreting tissue is constant along ethnicities and from woman to woman, what makes the difference in breast size is the amount of fatty tissue.
Reports exist about the use of specific anti-prostate cancer drugs in selected Breast cancer cases.
Even if the Serum Steroid levels may have a connection to the clinical activity of Tam, and be affected by Tam, Tam is the choice in most pre-menopausal Hormone Sensible Breast cancer cases, either for adjuvant or advanced cancer use, it doesn't induce direct ovarian ablation, recently, it was shown adding Ovarian Supression to Tamoxifen is beneficial for some selected Breast cancer cases
Good luck! Regards, + Salut
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