Please Scroll Down to See Forums Below
Does GH really increase internal organs?
- Thread starter hardone899
- Start date
Nandi12......always intelligent stuff from you! So, I think you are saying that you agree with me.....at least the 2 of the studies you cited (Yarasheski and Barrett) find that whole body protein synthesis is not affected by exogenous GH.
Actually, in Yarasheski's more recent studies (published in the same journal) he states that "lean body mass was increased, but again, this wasn't muscle mass, but probably a combination of water retention, organ mass, and connective tissue instead."
The real answer to the "gut" issue may lie in the relationship between GH and IGF-1 as is suggested in the "mice" study you mentioned. As Ney states in his 1999 study, in addition to the systemic effects of liver IGF-1, IGF can act locally. GH binding to cells can lead to what is called peripheral conversion of IGF-1. At this specific location (skeletal muscle for example), IGF-1 acts in an autocrine or paracrine fashion to promote its effects. This means that unlike GH, which has endocrine function (it is produced in the pituitary and travels elsewhere to do its work), IGF-1 can both be produced in, and promote changes in, the same tissue or those immediately adjacent to it.
Perhaps the most relevant effect of IGF-1 is the ability of IGF-1 to increase protein synthesis by increasing cellular mRNA formation (mRNA makes protein) as well as increasing uptake of amino acids. This effect on protein synthesis can lead to increased lean mass. The research indicates that this effect is dependent on GH presence as well. So IGF-1 alone does not promote such effects. Nor does GH. It appears the combination of the two most consistently lead to increased protein synthesis.
One thing is for sure....the research is contradictory.
Actually, in Yarasheski's more recent studies (published in the same journal) he states that "lean body mass was increased, but again, this wasn't muscle mass, but probably a combination of water retention, organ mass, and connective tissue instead."
The real answer to the "gut" issue may lie in the relationship between GH and IGF-1 as is suggested in the "mice" study you mentioned. As Ney states in his 1999 study, in addition to the systemic effects of liver IGF-1, IGF can act locally. GH binding to cells can lead to what is called peripheral conversion of IGF-1. At this specific location (skeletal muscle for example), IGF-1 acts in an autocrine or paracrine fashion to promote its effects. This means that unlike GH, which has endocrine function (it is produced in the pituitary and travels elsewhere to do its work), IGF-1 can both be produced in, and promote changes in, the same tissue or those immediately adjacent to it.
Perhaps the most relevant effect of IGF-1 is the ability of IGF-1 to increase protein synthesis by increasing cellular mRNA formation (mRNA makes protein) as well as increasing uptake of amino acids. This effect on protein synthesis can lead to increased lean mass. The research indicates that this effect is dependent on GH presence as well. So IGF-1 alone does not promote such effects. Nor does GH. It appears the combination of the two most consistently lead to increased protein synthesis.
One thing is for sure....the research is contradictory.
Similar threads
