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Beste Big T.
Hier mijn onderbouwing van het feit dat Nandrolone (Deca) beter bindt aan de AR receptor dan testosteron. Die kans kreeg in niet omdat jij zonodig een slotje moest zetten.
Omdat je mij niet gelooft haal ik maar enkele bronnen aan.
Misschien kun je daarna toegeven dat je er naast zat en ik het alweer goed had?
In de tekst is in vet aangegeven waar het omgaat: Deca bindt beter aan de AR dan testosteron! Feit.
Van Morenature Amsterdam (zie ook bron lijst)
References
1- Biosynthesis of Estrogens, Gual C, Morato T, Hayano M, Gut M and Dorfman R. Endocrinology 71 (1962) 920-25
2- Relative Importance of 5-alpha Reduction for the Androgenic and LH-Inhibiting Activities of Delta-4, 3-Ketosteroids. Steele R, Didato F, Steinets G. Steroids 1977 331-47
3- Relative Binding Affinities of Testosterone, 19-Nortestosterone and their 5-alpha Reduced Derivatives to the Androgen Receptor and to other Androgen-Binding Proteins: A Suggested Role of 5-alpha Reductive Steroid Metabolism in the Dissociation of "Myotropic" and "androgenic" activities of 19-Nortestosterone. Toth M. Zakar T. J. Steroid Biochem 17 (1982) 653-60.
4- Relative binding affinity of anabolic-androgenic steroids: Comparison of the binding to the androgen receptor in skeletal muscle and in prostate, as well as to Sex Hormone-Binding Globulin. Endocrinology 114 (1984) 2100-06
5- Aromatization of androgens to estrogens mediates increased activity of glucose 6-phosphate dehydrogenase in rat levator ani muscle. Endocrinol 106(2):440-43 1980
6- The pentose phosphate pathway in regenerating skeletal muscle. Biochem J 170: 17 1978
7- Binding of 17-alpha-Methyltestosterone In Vitro to Human Sex Hormone Binding Globulin and Rat Ventral Prostate Androgen Receptors. Wiita B, Althea A, Ackerman and Longcope C. Therapeutic Drug Monitoring 17 (1995) 377-80
8- Estrogen Receptor Binding Radiopharmaceuticals: II. Tissue Distribution of 17-alpha-Methylestradiol in Normal and Tumor-bearing Rats. Feenstra A., Vaalburg G., Nolten J., Reiffers A. et al. The Journal of Nuclear Medicine 24 (1983) 522-28
9- Identification of C19 Steroids in Bovine Feces. Miller, W.R., C.W. Turner, D.K. Fukushima and I.I. Salamon: J. Biol. Chem. 1956 220: 221
10- Metabolism of 1-dehydroandrostanes in man. I. Metabolism of 17-beta-hydroxyandrosta-1,4-dien-3-one, 17-beta-cyclopent-1-enyloxyandrosta-1,4-dien-3-one (quinbolone) and androsta-1,4-dien-3-one (1). Galletti F and Gardi R. Steroids 18 (1971) 39-50.
Van Bill Roberts, zie ook mesomorphosis.com
I rest my case!
Hier mijn onderbouwing van het feit dat Nandrolone (Deca) beter bindt aan de AR receptor dan testosteron. Die kans kreeg in niet omdat jij zonodig een slotje moest zetten.
Omdat je mij niet gelooft haal ik maar enkele bronnen aan.
Misschien kun je daarna toegeven dat je er naast zat en ik het alweer goed had?
In de tekst is in vet aangegeven waar het omgaat: Deca bindt beter aan de AR dan testosteron! Feit.
Uit PubMed
Endocrinology. 1984 Jun;114(6):2100-6. Related Articles, Links
Relative binding affinity of anabolic-androgenic steroids: comparison of the binding to the androgen receptors in skeletal muscle and in prostate, as well as to coïtus hormone-binding globulin.
Saartok T, Dahlberg E, Gustafsson JA.
It is unclear whether anabolic steroids act on skeletal muscle via the androgen receptor (AR) in this tissue, or whether there is a separate anabolic receptor. When several anabolic steroids were tested as competitors for the binding of [3H]methyltrienolone (MT; 17 beta-hydroxy-17 alpha-methyl-4,9,11-estratrien-3-one) to the AR in rat and rabbit skeletal muscle and rat prostate, respectively, MT itself was the most efficient competitor. 1 alpha-Methyl-5 alpha-dihydrotestosterone (1 alpha-methyl-DHT; mesterolone) bound most avidly to coïtus hormone-binding globulin (SHBG) [relative binding affinity (RBA) about 4 times that of DHT]. Some anabolic-androgenic steroids bound strongly to the AR in skeletal muscle and prostate [ RBAs relative to that of MT: MT greater than 19-nortestosterone ( NorT ; nandrolone) greater than methenolone (17 beta-hydroxy-1-methyl-5 alpha-androst-1-en-3-one) greater than testosterone (T) greater than 1 alpha-methyl-DHT].
Dus MT beter dan NorT/nandrolon/Deca, die op hun beurt beter dan Methenolone, Methenolone beter dan Testosteron en testo weer beter dan Methyl-DHT !
In other cases, AR binding was weak (RBA values less than 0.05): stanozolol (17 alpha-methyl-5 alpha- androstano [3,2-c]pyrazol-17 beta-ol), methanedienone (17 beta-hydroxy-17 alpha-methyl-1,4-androstadien-3-one), and fluoxymesterolone (9 alpha-fluoro-11 beta-hydroxy-17 alpha-methyl-T). Other compounds had RBAs too low to be determined (e.g. oxymetholone (17 beta-hydroxy-2-hydroxymethylene-17 alpha-methyl-5 alpha-androstan-3-one) and ethylestrenol (17 alpha-ethyl-4- estren -17 beta-ol). The competition pattern was similar in muscle and prostate, except for a higher RBA of DHT in the prostate. The low RBA of DHT in muscle was probably due to the previously reported rapid reduction of its 3-keto function to metabolites, which did not bind to the AR [5 alpha-androstane-3 alpha, 17 beta-diol and its 3 beta-isomer (3 alpha- and 3 beta-adiol, respectively)]. Some anabolic-androgenic steroids (only a few synthetic) bound to SHBG (1 alpha-methyl-DHT much greater than DHT greater than T greater than 3 beta-adiol greater than 3 alpha-adiol = 17 alpha-methyl-T greater than methenolone greater than methanedienone greater than stanozolol). The ratio of the RBA in rat muscle to that in the prostate (an estimate of the myotrophic potency of the compounds) was close to unity, varying only between about 0.4 and 1.7 in most cases.(ABSTRACT TRUNCATED AT 400 WORDS)
PMID: 6539197 [PubMed - indexed for MEDLINE
Van Morenature Amsterdam (zie ook bron lijst)
Comparative effectiveness of nandrolone and boldenone
The closest steroid in appearance (obvious effect to the user) to boldenone would probably be nandrolone. Most athletes use these two drugs under similar conditions, typically when there is a need for lean muscle tissue gain or a drug with fewer side effects in general. For these purposes both are well suited, however there are still some noticeable variances in the effects of both hormones. For example, at promoting overall muscle and strength gains boldenone is often proported to be more effective than nandrolone. This may be because boldenone is somewhat more androgenic in nature than nandrolone, due to the fact that it goes primarily unaltered by the 5-alpha reductase enzyme whereas nandrolone is actually reduced to less active form (dihydronandrolone) (3). While this allows nandrolone to be slightly milder in terms of side effects (except for interfering with libido, which can be much stronger with nandrolone as it is too weak an androgen), the lack of strong activity in crucial areas of the central nervous system may also act to lessen its effectiveness as a muscle and strength promoting anabolic. As boldenone is almost fully resistant to 5-alpha reductase, it retains an equal level of potency in both muscle and androgen target tissues.
We also see that in their respective rates of estrogen conversion both nandrolone and boldenone are similar in that they aromatize much more slowly than does testosterone. That is not to say that are equally resistant to this process however. In fact we see than nandrolone actually converts to estrogen at an even lower rate than boldenone does (1). One might automatically think that this is a more beneficial trait, however this would be assuming estrogen serves us no purpose in terms of muscle growth. Indeed this would be ignoring quite a bit of evidence showing just the opposite. For example, we find Primobolan® (methenolone, a non-aromatizable steroid) and nandrolone activate the androgen receptor with near equal affinity (4), and more avidly than does testosterone.
Yet we know that testosterone is more effective at building muscle size. Were 5-alpha reductase the only cause for this disparity, we would think methenolone would be a similarly or more potent steroid than nandrolone, as it is more androgenic (due to the fact that similar to boldenone, methenolone remains unaltered in the presence of the 5-AR enzyme).
But Primobolan is notably weaker as an anabolic compared to nandrolone, making one question if its inability to convert to estrogen is also a key factor mediating its ability to promote growth. We see an interesting trend here. Testosterone (easily aromatized and the least effective AR agonist of the group) is the most potent muscle builder, whereas nandrolone (weakly aromatized, strong AR agonist) is thought to be roughly half as effective. Methenolone (not aromatizable at all, AR agonist potency near equal to nandrolone) is further known to possess even lower anabolic potency next to nandrolone, to spite its near equal effectiveness at the level of the androgen receptor.
We do know a couple of important things about estrogen and muscle growth. This first is that its sodium and water retaining effects of estrogen can greatly enhance the size of muscle tissue. The bulk you see from highly estrogenic steroids is in large part due to intercellular and intracellular water retention, and makes agents like testosterone, Dianabol and Anadrol rapidly acting agents. We also know that the conversion of androgens to estrogens is responsible for enhancing glucose-6-phosphate-dehydrogenase enzyme levels in muscle tissue (5). G6PD is an important regulator of glucose utilization, and plays a vital role in muscle growth and recuperation (6). Clearly the athlete today knows that if you want to put on size, you don't want to get away from estrogen completely. Likewise the low rate of estrogen conversion we see with boldenone may be ideal in that it allows for enough estradiol buildup to help foster muscle growth, yet it should reach a point where we see strong side effects like gynecomastia and excess fat retention.
Boldenone and Dianabol
It is also interesting to point out that boldenone is also structurally almost identical to methandrostenolone (Dianabol), barring that the latter hormone contains an added c-17alpha methyl group to allow for optimal survival during oral administration. The principal achievement with both steroids was again the C1-2 double bond, which markedly increases the ratio of anabolic to androgenic effect in each case. Athletes however usually fail to notice the relationship between these two anabolics, the two drugs varying in outward appearance so much that use of methandrostenolone is usually isolated to bulking cycles while boldenone is accepted as a mild anabolic for cutting phases. Clearly the more active estrogenic nature of methandrostenolone is the cause for such discrepancy, a trait due to the added methyl group. Although we find that c-17 alpha methylation moderately decreases the affinity of this substrate for the aromatase enzyme, the product here is a different form of estradiol (17-alpha methylestradiol). When we look at testosterone for example, we find that a 17alpha-methylated version (methyltestosterone) represents a more potent form of this hormone. This is because the methyl group does not greatly interfere with the ability of the hormone to activate the androgen receptor, however it does allow it have a lower affinity for the serum binding protein SHBG and exist in a more free and active state (7). Sharing use of the same binding protein (SHBG is also referred to as Testosterone-Estradiol Binding Globulin) and knowing that 17-methylestradiol is near in potency to estradiol (8), it seems logical to conclude that 17-methylestradiol would be similarly more active (and explain the greater estrogenic potency of drugs such as methyltestosterone, methandrostenolone and norethandrolone). The structural and characteristic similarities between these two hormones however remain evident.
High Oral Efficacy and Legal Status:
Although one might think 1,4-androstadienedione would be a synthetic hormone at first glance, it has clearly been demonstrated to occur in nature (9). This allows it to be is protected by the Dietary Supplement Health and Education Act (DSHEA), and legal for sale as a nutritional supplement in the U.S. To support the belief that a 1,4-androstadienedione supplement really works as an effective precursor to boldenone in humans and not just on paper, we can take note of a 1971 study in which an unusually high amount of 17beta hydroxylated metabolites (as high as 22% of the given dose) were recovered in urine after oral administration of 100mg (10). Remember that in order to become active its 17-keto group must be converted to a 17-beta hydroxyl group. In fact 7.1% and 11.1% of the given dose was actually recovered in the form of intact boldenone in the two subjects of this investigation, indicating an extremely notable capacity for this hormone to convert to active form in the human body after oral dosing. It also demonstrates the ability for the C1-2 double bond to resist 17-ketosteroid reduction, a trait far different from testosterone, which produces 17-hydroxy metabolites in much smaller amounts.
Clearly boldenone has a firmly rooted place in the world of bodybuilding pharmaceuticals, standing out as a mild yet potent anabolic for the promotion of lean muscle tissue growth. It has likewise always been in high demand on the black market. The inclusion of a highly efficient steroidal precursor to this potent anabolic steroid in the world of legally available nutritional supplements will undoubtedly come to represent a welcome expansion in choices for the consumer.
References
1- Biosynthesis of Estrogens, Gual C, Morato T, Hayano M, Gut M and Dorfman R. Endocrinology 71 (1962) 920-25
2- Relative Importance of 5-alpha Reduction for the Androgenic and LH-Inhibiting Activities of Delta-4, 3-Ketosteroids. Steele R, Didato F, Steinets G. Steroids 1977 331-47
3- Relative Binding Affinities of Testosterone, 19-Nortestosterone and their 5-alpha Reduced Derivatives to the Androgen Receptor and to other Androgen-Binding Proteins: A Suggested Role of 5-alpha Reductive Steroid Metabolism in the Dissociation of "Myotropic" and "androgenic" activities of 19-Nortestosterone. Toth M. Zakar T. J. Steroid Biochem 17 (1982) 653-60.
4- Relative binding affinity of anabolic-androgenic steroids: Comparison of the binding to the androgen receptor in skeletal muscle and in prostate, as well as to Sex Hormone-Binding Globulin. Endocrinology 114 (1984) 2100-06
5- Aromatization of androgens to estrogens mediates increased activity of glucose 6-phosphate dehydrogenase in rat levator ani muscle. Endocrinol 106(2):440-43 1980
6- The pentose phosphate pathway in regenerating skeletal muscle. Biochem J 170: 17 1978
7- Binding of 17-alpha-Methyltestosterone In Vitro to Human Sex Hormone Binding Globulin and Rat Ventral Prostate Androgen Receptors. Wiita B, Althea A, Ackerman and Longcope C. Therapeutic Drug Monitoring 17 (1995) 377-80
8- Estrogen Receptor Binding Radiopharmaceuticals: II. Tissue Distribution of 17-alpha-Methylestradiol in Normal and Tumor-bearing Rats. Feenstra A., Vaalburg G., Nolten J., Reiffers A. et al. The Journal of Nuclear Medicine 24 (1983) 522-28
9- Identification of C19 Steroids in Bovine Feces. Miller, W.R., C.W. Turner, D.K. Fukushima and I.I. Salamon: J. Biol. Chem. 1956 220: 221
10- Metabolism of 1-dehydroandrostanes in man. I. Metabolism of 17-beta-hydroxyandrosta-1,4-dien-3-one, 17-beta-cyclopent-1-enyloxyandrosta-1,4-dien-3-one (quinbolone) and androsta-1,4-dien-3-one (1). Galletti F and Gardi R. Steroids 18 (1971) 39-50.
Van Bill Roberts, zie ook mesomorphosis.com
Nandrolone (Deca Durabolin®)
Description
by Bill Roberts - This drug is unique (so far as I know) in that 5a -reductase, the enzyme which converts testosterone to the more-potent DHT, actually converts nandrolone to a less-potent compound. Therefore this AAS is somewhat deactivated in the skin, scalp, and prostate, and these tissues experience an effectively-lower androgen level than the rest of the body. Therefore, for the same amount of activity as another drug at the androgen receptors (ARs) in muscle tissue, Deca gives less activity in the scalp, skin, and prostate. Thus, it is the best choice for those particularly concerned with these things.
Its effectiveness at the androgen receptor of muscle tissue is superior to that of testosterone: it binds better. Yet, it gives only about half the muscle-building results per milligram. This I think is a result of its being less effective or entirely ineffective in non-AR-mediated mechanisms for muscle growth.
It also appears less effective or entirely ineffective in activity on nerve cells, certainly on the nerve cells responsible for erectile function. Use of Deca as the sole AAS often results in complete inability to perform coïtusually.
These problems can be solved by combining with a drug that does supply the missing activity: e.g. testosterone.
Nandrolone is proven to be a progestin. This fact is of clear importance in bodybuilding, because while moderate Deca-only use actually lowers estrogen levels as a consequence of reducing natural testosterone levels and thus allowing the aromatase enzyme less substrate to work with, Deca nonetheless can cause gyno in some individuals. Furthermore, just as progesterone will to a point increase coïtus drive in women, and then often decrease it as levels get too high, high levels of progestogenic steroids can kill coïtus drive in male bodybuilders, though there is a great deal of individual variability as to what is too much.
Incidentally, this progestogenic activity also inhibits LH production, and contrary to common belief, even small amounts of Deca are quite inhibitory, approximately as much so as the same amount of testosterone.
To some extent, nandrolone aromatizes to estrogen, and it does not appear that this can be entirely blocked by use of aromatase inhibitors – indeed, aromatase may not be involved at all in this process (there is no evidence in humans that such occurs) with the enzyme CYP 2C11 being in my opinion the more likely candidate for this activity. In any case, Cytadren, an aromatase inhibitor, has not been found effective in avoiding aromatization of nandrolone.
The drug is moderately effective at doses of 400 mg/week. The long half-life of nandrolone decanoate makes it unsuited to short alternating cycles, but suitable for more traditional cycles, with a built-in self-tapering effect in the weeks following the last injection.
I rest my case!
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