From my perspective I think it is the SERMS cause the receptors in the pituitary to be more sensitive to GnRH.
I personally feel clomid works best for any single SERM.
Good post. You are correct. It inspired me to do some serious researching on the subject. Here is one of particular interest.
Effects of Estradiol and Some Antiestrogens
(Clomiphene , Tamoxifen, and Hydroxytamoxifen) on
Luteinizing Hormone Secretion by Rat Pituitary Cells
in Culture*)
G. E m o n s , O. O r t m a n n , Sabine Thi e s s en, and R . K n u p p e n
link:
SpringerLink - Archives of Gynecology and Obstetrics, Volume 237, Number 4
This is an
in vitro study with isolated rat pituitary cells. You're totally right in that SERMs can have a direct effect on the pituitary to release FSH and LH without the presence of estrogen. However, it turns out from this study and several others that estrogen itself, the thing we are trying to block, has an even more potent
positive effect on releasing LH and FSH than any of the SERMs do. So estrogen can be beneficial in the pituitary in increasing the sensitivity to GnRH. This result really got me confused, so I did some more digging. It turns out the regulation of this system is more complicated than I ever imagined. Estrogen can have mixed effects. Estrogen has a strong inhibitory effect on the release of GnRH from the hypothalamus, so overall, estrogen is negative. SERMs can also have a positive and negative effect on the pituitary. It all depends on timing, dosing, the state of the body's hormones, sensitivity, etc., etc., etc.... Most of the studies are
in vitro, as in a petri dish, to isolate the effects in specific environments. Since it's so damn complicated, it's easier to just look at human
in vivo studies, as in an actual person, so that all the complications are taken into account. Specifically, for post-cycle body builders, we can look at hypogonadal and oligozoospermic men whose HPG axis is below normal levels. All we want to see is if on a SERM, the Testosterone, LH, and FSH levels are increased within the ~4 weeks time a traditional PCT lasts. I found one study that studied this general concept.
Hormonal effects of an antiestrogen, tamoxifen, in normal and oligospermic men.
The administration of tamoxifen, 20 mg/day for 10 days, to normal males produced a moderate increase in luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and estradiol levels, comparable to the effect of 150 mg of clomiphene citrate (Clomid). However, whereas Clomid produced a decrease in the LH response to LH-releasing hormone (LHRH), no such effect was seen after the administration of tamoxifen. In fact, prolonged treatment (6 weeks) with tamoxifen significantly increased the LH response to LHRL. Treatment of patients with "idiopathic" oligospermia for 6 to 9 months resulted in a significant increase in gonadotropin, testosterone, and estradiol levels. A significant increase in sperm density was observed only in subjects with oligospermia below 20 X 10(6)/ml and normal basal FSH levels. When basal FSH levels were increased or oligospermia was moderate (greater than 20 X 10(6)/ml); no effect on sperm density was seen. As sperm density increased, FSH levels decreased, suggesting an inhibin effect. Sperm motility was not improved by tamoxifen treatment. In five boys with delayed puberty, tamoxifen treatment appeared to activate the pituitary-gonadal axis and pubertal development.
SERMs definitively increase LH, FSH, and Test. This happens through a ridiculously complicated positive and negative feedback pathway which is still not fully understood. Also, they help to reduce gynecostemia, so it's always good to have on hand in case symptoms flair up. After all my research, the topic is still debatable to me, but the evidence seems to suggest that a PCT would still be useful in a nonaromitzable cycle whether it directly effects the pituitary or indirectly prevents the hypothalamus's inhibition by estrogen. Anyway I'm still planning Tamoxifen as PCT for four weeks. Better to have it and not need it than to need it an not have it.
This post was not a direct reply to anyone's post specifically, but more of just me ranting in general about the complications of SERMs, their effects, and whether they're needed in the first place. |