HCG & testicular aromatase


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The reason for a significant increase of estrogen when Human Chorionic Gonadotropin ( Human Chorionic Gonadotropin (HCG) ) is used is stimulation of testicular aromatase activity.
Aromatase inhibitors will work fine to correct that.

Endocrinol Jpn 1975 Aug;22(4):287-96 Related Articles, Links

Plasma estradiol concentrations and effect of Human Chorionic Gonadotropin ( Human Chorionic Gonadotropin (HCG) ) on plasma estradiol and testosterone in normal subjects and patients with endocrine disorders

...In the study of stimulation with human chorionic gonadotropin ( Human Chorionic Gonadotropin ( Human Chorionic Gonadotropin (HCG) ) ), 3,000 IU daily for three days in ten normal men, the peripheral concentrations of estradiol showed maximum and fourfold increases 24 hours after the 1st injection of Human Chorionic Gonadotropin ( Human Chorionic Gonadotropin (HCG) ). The testosterone levels, on the other hand, increased stepwise and reached a maximum of about two times preinjection levels 24 hours after the 3rd injection.

Endocrinology 1979 Feb;104(2):285-8 Related Articles, Links

Testicular aromatization in immature rats: localization and stimulation after gonadotropin administration in vivo.

Canick JA, Makris A, Gunsalus GL, Ryan KJ.

Aromatization was measured in testicular microsomal preparations obtained from rats treated 3--4 days with FSH, hCG, or vehicle, hCG, but not FSH, was found consistently to stimulate testicular aromatase activity at least 10-fold. As a marker for FSH action, epididymal androgen-binding protein was assayed and found to be 3 times higher in FSH-treated rats than in either hCG or control rats. hCG, but not FSH or vehicle, stimulated serum testosterone levels more than 100-fold. In all groups, aromatase activity in the microsomal fraction was at least 6 times higher than that found in the mitochondrial fraction. In experiments in which testicular compartments were separated, microsomal preparations from interstitial tissue of hCG-treated rats had 5--7 times more aromatase activity than microsomes from seminiferous tubules and 2--3 times more activity than microsomes from whole testes. It is concluded the hCG administered in vivo can stimulate testicular aromatase activity in immature rats, and the increase in activity is localized in the interstitial tissue.

Nippon Hinyokika Gakkai Zasshi 1997 Jul;88(7):649-57 Related Articles, Links

[A study on testicular aromatase activity--spermatogenic damage in high testicular E2 models of rat]

Akiyama H.

Department of Urology, Okayama University Medical School.

(BACKGROUND): In order to study the influence of testicular estrogen concentration on spermatogenesis, we conducted the following experiments. (METHODS): Eight-week-old male Sprague-Dawley rats were used and two kinds of experiments were prepared. In experiment one (intraperitoneal injection), five groups were set up: control (saline solution), estradiol (E2), human chorionic gonadotropin (hCG), aromatase inhibitor (A.I.) and hCG+A.I. group. In experiment two (intratesticular injection), two groups were set up: control (saline solution) and E2 microcrystal suspension (Emcs) group. The experimental period was 28 days. At sacrifice, we evaluated the concentrations of serum testosterone (T) and E2, testicular T and E2, testicular aromatase activity and the seminiferous tubular diameter. (RESULTS): Exp. 1: In the hCG group, the rate of testicular aromatase activity and testicular E2 level were higher and the diameter of seminiferous tubules was smaller than in the control group. However, these changes were not observed in the hCG+A.I. group. Exp. 2: In the Emcs group, testicular E2 level showed an increase without elevation of serum E2 level, and the diameter of seminiferous tubules was atrophic. (CONCLUSION): It was suggested that the increase of the rate of testicular aromatase activity and the following elevation of testicular E2 level is possibly one of the causes of male infertility.
Some people don't know if they can use aromatase inhibitors to prevent an estrogen increase when on HCG....
These studies show that the estrogen increase when on Human Chorionic Gonadotropin (HCG) is not caused by test. alone (estrogen increase was greater than test increase in study 1, and it was caused by stimulation of testicular aromatase activity )...
That is good to know! I was only using N-dex, but if A-dex or letrozole will work to, thats even better!
Be careful, though, to not drop E levels too low with the Arimidex. That is bad, too. I do think, though, that we are extrapolating too far in the practical application of these data. No one should be using Human Chorionic Gonadotropin (HCG) at that daily dose (I mean, we ALL know better, don't we?). It's like that infamous Belgian study where they compared a normal dose of Nolvadex against three times more Clomid than would be comparable.