IGF-I Is a Regulator of 5ar activity

endo.endojournals.org/cgi/conten … /133/2/447

Androgen induction of steroid 5 alpha-reductase may be mediated via insulin-like growth factor-I

The abstract:
The action of added insulin-like growth factor-I (IGF-I) and dihydrotestosterone (DHT) on steroid 5 alpha-reductase (5 alpha R) activity was studied using primary cultures of rat or human scrotal skin fibroblasts. Agents were added to cultured cells (2 x 10(5) cells) for 2 days, and enzyme activity was measured by the percent conversion of [3H] testosterone to DHT over a 4-h period in the absence of fetal calf serum or other growth factors. DHT, but not testosterone, at 10(-7) M significantly increased 5 alpha R activity (rat, 1.5 +/- 0.3% to 3.0 +/- 0.4%; human, 7.6 +/- 1.7% to 11.4 +/- 2.9%; P < 0.01). IGF-I (10(-9)-6.4 x 10(-9) M), but not IGF-II (10(-9)-10(-8) M) or insulin (10(-9)-10(-7) M), increased enzyme activity in a dose-related fashion [i.e. 1.5 +/- 0.5 to 10 +/- 2 in rat and 6.0 +/- 1.1 to 9.8 +/- 1.6% (P < 0.01) in human cells]. No change in cell numbers was observed in any experiment. Since the effect of IGF-I was about 100 times that of androgen, we studied the possibility that androgen induction of the enzyme activity could be via IGF-I production. Addition of a monoclonal antibody against IGF-I significantly reduced the effect of DHT, and simultaneous addition of a specific IGF-I receptor antibody blocked the expected induction of 5 alpha R activity (control, 4.9 +/- 0.5; DHT, 8.0 +/- 1.9; DHT plus IGF-I receptor antibody, 3.7 +/- 0.4%). No effect on 3 alpha-reduction of [3H]DHT to 3 alpha-androstanediol was detected in separate experiments. These studies indicate that IGF-I may be an important regulator of skin 5 alpha R activity and, thus, may influence DHT formation. The previously known androgen induction of this peripheral steroidogenic enzyme may be via paracrine/autocrine production of an IGF-I-type growth factor.

It is possible that if our IGF-I levels are low then 5ar activity is not optimal even though DHT levels are high since IGF-1 has 100 times greater effect on 5ar activity than just DHT

Are there any ways to boost IGF-I?

Great finding, mystory!
Thank you!

Natural ways of boosting IGF1:
Levodopa, arginine, exercise, sugar ingestion, sleep.

Artificial ways:
Testosterone replacement, Growth Hormone replacement.

I am willing to do HGH replacement, i ve tried everything else.

1 Like

Looks like creatine boosts IGF-1 concentrations in muscle tissues.

The purpose of this study was to compare changes in muscle insulin-like growth factor-I (IGF-I) content resulting from resistance-exercise training (RET) and creatine supplementation (CR). Male (n=24) and female (n=18) participants with minimal resistance-exercise-training experience (=1 year) who were participating in at least 30 min of structured physical activity (i.e., walking, jogging, cycling) 3-5 x/wk volunteered for the study. Participants were randomly assigned in blocks (gender) to supplement with creatine (CR: 0.25 g/kg lean-tissue mass for 7 days; 0.06 g/kg lean-tissue mass for 49 days; n=22, 12 males, 10 female) or isocaloric placebo (PL: n=20, 12 male, 8 female) and engage in a whole-body RET program for 8 wk. Eighteen participants were classified as vegetarian (lacto-ovo or vegan; CR: 5 male, 5 female; PL: 3 male, 5 female). Muscle biopsies (vastus lateralis) were taken before and after the intervention and analyzed for IGF-I using standard immunohistochemical procedures. Stained muscle cross-sections were examined microscopically and IGF-I content quantified using image-analysis software. Results showed that RET increased intramuscular IGF-I content by 67%, with greater accumulation from CR (+78%) than PL (+54%; p=.06). There were no differences in IGF-I between vegetarians and nonvegetarians. These findings indicate that creatine supplementation during resistance-exercise training increases intramuscular IGF-I concentration in healthy men and women, independent of habitual dietary routine.

I wish I could read the whole article to figure out the duration of the study.

Has anyone tried creatine with training and noticed any effects? I have used creatine before fin with poor muscle gaining results. I might try it again to boost IGF-1 to see how things go.

I am taking three grams every day after training and I notice a big difference in muscle definition, size and strength.

Cdnuts, any effects on sexual function(side effects)?

I can’t say for sure because I am taking a plethora of different herbs to boost my T production and other things to increase my sexual functioning. I haven’t noticed any negatives from anything that I have been taking. When you are recovering from the state that I was in, even if there were some negatives, they would pale in comparison.

And IGF deficiency also means hypopituitarism. Has anyone tested for it? I think I’m doing it tomorrow with my own money, because every theory leads to this hormone…

I had been looking for some type of connection to a GH deficiency or low IGF-1 and 5ar activity. This certainly makes a lot of sense.

Again this begs the question how do most of our IGF-1 levels look? Many of us have tested our DHT levels and they turn up fine. I would be very interested to see more IGF-1 levels of guys here.

Would GHRP-6 increase IGF levels?

This is just so depressing. I don’t want to see my IGF1 levels. I so hope they’re in range, because I don’t want to have stopped growing.


I did quite a bit of research on this one and it most likely would. I’m not sure if it would be better to just take the HGH or go GHRP-6. I asked a couple of endocrinoligists that I have seen recently about it. They both said they didn’t know a lot about it, as it hasn’t been around that long.

I scoured a couple of the muscle chat boards and many of the body builders have used it and say it works while there were a couple who said they didn’t get a reaction from using it.


just get the test done man. If it is low, it won’t do you any good sitting around hoping it isn’t low.

You of all people under age 20 and still in the possible growing years need to wake up to reality and stop wasting time. Find a doctor as quickly as possible who believes you and is willing to run this test or go pay your own money and get the test done.

hey boston,

as i understand it the major reason that alot of bodybuilders pass over GHRP for old school synthetic GH is, that by injecting GH they can achieve super-physiological levels necessary for accelerated muscle growth were as with GHRP, whilst it will increase your GH levels, it will increase them within the limits of your bodies ability to produce. its important to remember that bodybuilders have different goals that what alot of us are trying to achieve.

so synthetic GH will enable you to achieve GH levels in excess of what your body would ever be capable of producing on its own (not necessarily a good thing) whilst GHRP will increase your levels within your bodies own limits.

i have heard that an advantage of GHRP over traditional GH therapy is also that GHRP will cause your body to release GH in a pulsatile fashion similar to how your body would do it naturally, rather than one big surge you would get by direct injection.

another thing we should be looking at is that GHRP-6 is no the only form of GHRP. I know of at least one other (GHRP-2) which is also available, but i’m not sure about which is best.

i also know that alot of guys who use GHRP are combining it with CJC-1295. i don’t know much about this but it might be worth investigating.


good luck bro,

stay strong.


thanks for the info. My only concern with the GHRP-6 is I take it and sit around waiting for it to work. I just want to be sure I’m not doing something that is wasting more time. I see your point, I agree body buliders want to exceed their bodies levels of GH. I just simply want my body to make a healthy amount of it.

I had mentioned this GHRP-6 to two endo doctors that I saw in the last couple weeks. Neither of them knew much about the product. I was pretty surprised, as one of them is a prominent endo doctor who specializes in pituitary problems. I guess if turns out I am GH deficient, I will discuss both of these options with my endocrinoligst.

I was also thinking it might make sense to take the GH for a period of time just to get my levels back up as we know that would work and then begin to introduce the GHRP-6 to kick in my own bodies production. I just don’t know how long this product takes to work. I’m growing impatient of waiting for things to get back to normal. I have read that most people that use GHRP-6 use it after they have synthetic GH.

Ive tested IGF-1

279 range (160-340)

I have also tested IGF-1:

IGF-1: 310 (90 - 360)

Yeah this sounds like a good idea, i would definitely discuss this with your endo. As you say it’s very strange that the endos you’ve spoken to don’t know much about GHRP. i mean if anyone would know about it you think it would be them.

I found this forum article which has a lot of useful information.

professionalmuscle.com/forum … post435292

Something else to consider is also that i believe synthetic GH is actually quite a bit more expensive than GHRP


yes you would certainly think they would know, which disappointing. I may still explore this as an option. It seems like a remedy that I don’t have to depend forever if it works.

Yea I would definitely think it would be cheaper than the synthetic GH. I have heard 600-800 per month is the cost, for GH. I was surprised to find out that if you do get diagnosed as GH deficient by your endo doctor the Insurance pretty much have to cover the GH. They can decline you, but you can appeal it and eventually take it to the state level and force them to cover it. The bottom line is you have to have the Arginine infusion test done to determine if your GH deficient.

Both of my endo doctors said this is the only test the Insurance companies will consider. They will not accept an IGF-1 blood test, which irononically is considered very realible.

thanks for the link

You and GCAC clearly aren’t GH deficient. THis doesn’t surprise me. This drug has screwed us all up differently. We just need to find guys that have similar hormone profiles and keep track of who makes progress.

my IGF-1 result

Insulin-Like-Growth factor 1 result-180 range 116-358 ng/ml

my result is in lower half of the range is this anything I need to worry about??