Bill, I’m so happy to see a question on estriol
and so sorry
a demanding (evening and week ends) work schedule at the moment doesn't allow me to expound on a topic that has completely captivated me.
First, I have no scientific background and cannot speak adequately, if at all, to your question about the "chemistry". I do think though there is some research suggesting that the estrogen receptor alpha (ERa) may play a protective role in MS. Voskuhl, who led the small UCLA trial on estriol and MS, has also reported that the protective effect that the female sex hormone (? which one) had treating EAE mice was mediated through ER-alpha.
There is also a fascinating article that I personally cannot understand because of its scientific terminology, but it is entitled: Estrogen receptor 1 and estrogen receptor 2 regulate the severity of clinical EAE in male mice.
The first line of the abstract from that article: Estrogens and estrogen-receptor signaling function in establishing and regulating the female immune system and it is becoming increasingly clear that they may play a similar role in males.
(This research was by the group in Oregon that I'll mention later.)
However, on to your other questions, I think I can confidently say that estriol is one form of the hormone generally referred to as estrogen. Estradiol and estrone are two other forms of estrogen.
There was a study by Halina Offner’s group at the Oregon Health and Sciences University in mice with EAE (MS like disease). That study concluded that oral ethinyl estradiol might be a successful candidate as therapy for multiple sclerosis.
Interestingly enough, the ethinyl estradiol suppressed EAE when given at initiation of EAE and also “reduced clinical severity when given after the onset of clinical signs.” (PMID 12538720 Oral feeding with ethinyl estradiol suppresses and treats EAE in SJL mice and inhibits the recruitment of inflammatory cells into the nervous system) Ethinyl estradiol is used in some forms of birth control that are on the market.
If it might help to answer your question about the chemistry that's involved, the actual structure of the steroid hormone molecules, beginning interestingly enough with the cholesterol molecule and ending with the estrone, estradiol and estriol molecules, are diagrammed in the Appendix of a book by John Lee, M.D., What Your Doctor May Not Tell You About Menopause.
The next bit of info is from the MS and Gender article by Patricia Coyle that I referenced in one of my posts on the estriol thread that Finn so kindly hot linked you to. I’m guessing Coyle's article was written before Offner’s research was available.
Oral Contraceptives/Hormone Replacement Therapy
MS is not a contraindication to the use of hormone replacement (HRT) therapy for menopause. In fact, symptoms that worsen postmenopause often respond to HRT. In one study, 75 percent of females with MS on HRT reported improvement in neurological symptoms. In addition, there is no contraindication to the use of oral contraceptives in MS. Such contraceptives have no effect on the risk of developing MS and no adverse effects on the overall disease course. In fact, clinical symptoms of MS are slightly less frequent with use of contraceptives. Another study suggested that young patients taking birth control pills may show less disability. In a study that evaluated menstrually related worsening of symptoms, patients on an oral contraceptive were significantly less likely to note any changes. Given the data suggesting that sex hormones could have a role in the treatment of MS, it would seem that decisions to use oral contraceptives or HRT can be made without regard to MS.
I hope this at least addresses some of your questions. I must confess I haven’t checked out the birth control angle very much since I’m way past the age of needing it.
Seriously though, realizing it may be a week or more before I can respond, please also feel free to PM me with questions if you think I can help. Best wishes to you and your girlfriend and an extra thanks for looking out for her.