peptides & Gastrointestinal Implications

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I came accross this study which concludes that GI growth does indeed occur in rats who have been adminstered IGF.


http://gut.bmj.com/cgi/content/abstract/37/5/630

Administration of insulin-like growth factor-I (IGF-I) peptides for three days stimulates proliferation of the small intestinal epithelium in rats.
C B Steeb, J F Trahair, L C Read
Cooperative Research Center for Tissue Growth and Repair, North Adelaide, South Australia.

It has previously been shown that longterm administration of insulin-like growth factor-I (IGF-I) or the analogue Long R3 IGF-I (LR3IGF-I) selectively stimulate growth of the gastrointestinal tract in gut resected, dexamethasone treated, and normal rats. In this study, the short-term effects of IGF-I administration on intestinal proliferation have been investigated. Female rats (110 g, five-six/group) were infused for three days with 2.5 mg/kg/day of either IGF-I or LR3IGF-I and compared with vehicle treated or untreated control rats. LR3IGF-I but not IGF-I increased body weight and wet tissue weight of the small and large intestine (+20%), compared with controls. Tissue weight responses were independent of food intake and were reflected in the histology of the tissue. In LR3IGF-I treated animals, duodenal and ileal crypts length were increased by 13 and 22%, respectively, associated with an increase in crypt cell number. No such histological changes were seen in IGF-I treated rats. Tritiated thymidine labelling indices were significantly increased after administration of either IGF-I or LR3IGF-I (up to 14%) in both the duodenum and ileum. In IGF-I treated rats, increased nuclear labelling was not associated with an increase in the crypt compartment. In contrast, LR3IGF-I induced proportional increments in thymidine labelling and crypt size, suggesting that LR3IGF-I is not only more potent than the native peptide but also induced proliferative events more rapidly. In the colon, the thymidine labelling index was low, however, a non-significant increase in the number of cells labelled with thymidine was seen. These results suggest that within a three day treatment period intestinal mitogenesis is more advanced in animals treated with LR3IGF-I. The differences in proliferative response between the two peptides may be accounted for by variations in pharmacokinetics, clearance rates, and interactions with circulating and tissue specific binding proteins.

If I read this correctly, these rats were injected at 2.5 milligrams per kilogram of weight. That would be equal to injecting 2,500mcgs per kilogram... which is like injecting over 200,000mcgs a day!

If this is correct, this study should be taken with a grain of salt and so should anyone who references it to support the assertion that IGF causes extreme GI growth in humans.

It does show that you can deduce that repeated exposure of a large amount over a long period of time will indeed cause intestinal growth. It just occurs more slowly. Just another reason why it is wise to do a short cycle then come off completely.

I think it is more of using large amounts than the amount of time you use it. At large amounts, it seems there is to much spill over into the intestines. If you were to use large amounts for 4 weeks you still have spill over into the gut. You quit for 4 weeks and then start the same thing again. After time all that spill over adds up. I think if you keep your dose low and only use IGF 3 times a week, it would minimize the spill over and you could use IGF for long periods of time. I would not go over 60mcg 3 times a week. I know some people use lots more, but I dread having the huge gut look.

highside said:

I think it is more of using large amounts than the amount of time you use it. At large amounts, it seems there is to much spill over into the intestines. If you were to use large amounts for 4 weeks you still have spill over into the gut. You quit for 4 weeks and then start the same thing again. After time all that spill over adds up. I think if you keep your dose low and only use IGF 3 times a week, it would minimize the spill over and you could use IGF for long periods of time. I would not go over 60mcg 3 times a week. I know some people use lots more, but I dread having the huge gut look.

Click to expand...

I agree.... I think this method gives piece of mind to those concerned about intestinal growth. I know there was a pretty good article out there that emphasized this protocol. I will try to track it down. Of course, there are those that swear by the 80-100 ed or 5on/2off schedule, and they do not seem to have any signs of the "gut". In fact, some pics on this site seem to prove that, but everyone is different.

Some may find this interesting, but the current developing theory out there is that if you are looking for localized muscle growth, then IGF-LR3 is not what you want to use. Instead you should use regular IGF-RH. The reason being is that when you use IGF-LR3, it causes some localized muscle growth, and then it goes into the bloodstream because it doesn't get bound up, thus getting to the intestines and other tissues, making them grow. With IGF-RH, you get localized muscle growth, and then because of its half-life or because it gets bound up it finishes its job, and it's done--no intestinal growth.

Thoughts?

Actually, now that you mention it, I briefly recall reading something along the lines of what you just said. It sounds quite plausible…even likely. Please, post more on this if you come across anything