The endocrine system of someone going for a sex change

[Obscurity]

I'm rather curious, I know that people who undergo sex changes would have to go for HRT(Hormonal replacement therapy) but I have a few questions about it:

How would it work since the additional hormones would have to override the natural body system?

I mean, for lets say a person changing sex from male to female, s/he would have to take estrogens/anti androgens but the thing I do not know is will the body produce a negative feedback and produce more testosterone until the levels of testosterone and estrogen equal out such that a plateau is reached?

(I know that people taking anabolic steroids would produce a similar effect with the hormone cortisol and would result in Cusher's syndrome. This as a result would limit the effect of the anabolic steroid since an increased amount of cortisol in the bloodstream would compete for the receptors on the cell surface and so a greater amount of anabolic steroid would have to be administered to have an effect)

and would anti-androgens block the release of more testosterone into the bloodstream?

[Obscurity]

Something I found in relation to the subject:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15288677&query_hl=1

 

Bone Metabolism Unit, Endocrinology Service, University Hospital 12 de Octubre, Madrid, Spain.

 

The effects of chronic administration of estrogens on the lipid profile in males are not fully understood. We have studied the effect of chronic administration of estrogens on the lipid profile in a group of transsexual (TS) Canarian men who were taking estrogens and anti-androgens for a minimum of 3 years. In this cross-sectional study of cases (n=27) and controls (n=26), plasma lipid profile and selected biochemical and hormonal features were studied. TS subjects had shorter stature than controls, and, after adjusting for height and weight, we found that they had lower values of serum free testosterone (FT) and higher estradiol (E2) levels than controls. The TS group had lower total and low-density lipoprotein (LDL) cholesterol and lower apoprotein B (Apo B) levels than the control group. Biochemistry was similar in both groups. The distribution of estrogen receptor gene polymorphisms (ER-Pvu and ER-Xba) was also similar in both groups. Serum Apo B concentration was related to ER-Xba polymorphism. No other association between lipid profile and the distribution of ER-Pvu and ER-Xba was found. We conclude that the chronic administration of estrogens in men could produce an increase in serum estradiol, a decrease in free testosterone levels, and a reduction in total cholesterol, LDL-cholesterol, and Apo B levels. The ER-Xba polymorphism may influence the Apo B response to exogenous estrogen in males.

So does that mean that no negative feedback would occur?

However note that those people who were on HRT were also on anti androgens. So what about having only estrogen?