jenab123
New member
Control of aging and longevity by IGF-I signaling.
Yang J,
Anzo M,
Cohen P.
Division of Pediatric Endocrinology, Mattel Children's Hospital at UCLA, David Geffen School of Medicine, Los Angeles, CA 90095, USA.
Animal models have established the IGF-I signaling pathway as a key modulator of aging in rodents and invertebrates. Considerable evidence suggests that reduced exposure of tissue to IGF-I is associated with an extended lifespan in these species. In humans, IGF-I is linked to various age-related diseases that are limiting factors for youthful longevity. On one hand, reduced IGF-I activity is associated with significant morbidity in adulthood with an increased risk of developing cardiovascular disease, diabetes, osteoporosis and neurodegenerative diseases. On the other hand, elevated IGF-I levels have been linked to cancer risk given the role of IGF in mediating normal and malignant tissue growth. Thus, IGF is clearly involved in modulating disease of aging; however, the mechanism appears to be complex and interdependent on additional modulating factors. It is attractive to hypothesize that maximal human survival depends on tight regulation of the GH-IGF axis and maintenance of optimal IGF-I action in order to prevent morbidities associated with either deficient or excessive state. Specifically, it is possible that lower levels of IGF-I during early adulthood followed by higher levels of IGF-I later in life may be most beneficial for human longevity by addressing age-specific morbidities.
PMID: 16154307 [PubMed - indexed for MEDLINE]
Then there is lots of evidence both direct and indirect as to IGF, aging and early onset of age-related diseases. We know that one of the main mechanisms of action for green tea is that it suppresses IGF-1 levels likely giving Asian populations the lower risk for cancer that is seen. Lower levels of diabetes, heart disease and other inflammatory diseases are also related to this, and of course, to a cleaner diet in general.
Also, IGF's similarity to insulin is such that it simply needs to be at a balanced level. Too much insulin..deadly, not enough..deadly and this is likely the case for IGF-1 as well. IGF is even more powerful than insulin on many fronts.
So yes, bigger animals and people have more stressers on them and certainly IGF-1 levels can play a role in this.
This is a very intersting study and its conclusions point to what I was really trying to say, which is that IGF-1 levels play a very complicated and often contradictory role in age related illness. Note the last sentence, specifically, which is my personal view of IGF and GH:
"Specifically, it is possible that lower levels of IGF-I during early adulthood followed by higher levels of IGF-I later in life may be most beneficial for human longevity by addressing age-specific morbidities"
To assert only the negatives as that doctor was doing was irresponsible. Also, as some of the studies PA posted up on another thread show, IGF-1 and LR3IGF-1 have very differnt modes of action and target tissues. The fact that LR3 does not bind to transport mechanisms is significant. And the brotelligence saying IGF has a shorter half life than LR3 is wrong turns out, and that LR3 is much more hypoglycemic than regular IGF.
Anyway, bodybuilders will continue to experiment, no one to my knowledge has keeled over from just moderate GH or IGF related illnesses, even the top pros who use ridiculous amounts of the stuff.
What is clear is its mechanism of action on skeletal muscle vs. visceral organs is not completely understood. An that does worry me, so smaller doses EOD or E3D and periods of time off would be wise.