Are the metabolic effects of GH and IGF-I separable?

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Growth Hormone & IGF Research
Volume 15, Issue 1 ,
February 2005, Pages 19-27

Review
Are the metabolic effects of GH and IGF-I separable?

Nelly Maurasand Morey W. Haymond


a-Division of Endocrinology, The Department of Pediatrics at the Nemours Children's Clinic, 807 Children's Way, Jacksonville, FL 32207, USA
b-Baylor College of Medicine, Houston, TX, USA

Available online 5 February 2005.

Abstract

IGF-I mediates some, but not all of the metabolic actions of GH and it has both GH-like and insulin-like actions in vivo. GH and IGF-I both have a net anabolic effect in man enhancing whole body protein synthesis over a period of weeks and perhaps months. Both hormones favorably improve body composition in GH deficient subjects with an increase in lean body mass and decreased adiposity. This is also observed when IGF-I is given to patients with GH-receptor mutations. These compounds, however, have divergent effects on carbohydrate metabolism. A potent glucose lowering effect is typically observed after IGF-I administration, with improved insulin sensitivity with marked lowering of circulating insulin concentrations, whereas GH therapy is associated with mild compensatory hyperinsulinemia, a reflection of relative insulin resistance. The latter observation makes IGF-I a potentially more convenient anabolic agent to use in conditions where carbohydrate metabolism is more likely to be impaired. GH increases lipolysis as a direct effect of GH on the adipocyte, as well as lipid oxidation by increasing substrate availability. However IGF-I increases lipid oxidation only when given chronically, most likely as a result of chronic insulinopenia. These compounds have been tried in a variety of catabolic conditions in man and both hormones have been effective in reducing the protein wasting effects of glucocorticosteroids and mitigate some of the catabolic effects of severe hypogonadism in males. A comparison of these and other effects of these hormones is provided in this brief review. Subsequent studies are still needed to fully elucidate the safety and efficacy of IGF-I for use in humans.

Keywords: GH; IGF-I; Protein metabolism; Glucose metabolism; Lipid metabolism; Growth; Glucocorticosteroids; Catabolism; Stable isotopes; Body composition

Quote:

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Originally Posted by oswaldosalcedo

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Subsequent studies are still needed to fully elucidate the safety and efficacy of IGF-I for use in humans.

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I'm starting to see this pop up more and more in recent studies(safety).

Has anyone speculated on what long term side effects could possibly be associated using IGF?Bear in mind,we as BBers only use it 30 days on/30 days off in most cases.The average "Joe" might only run it once a year,or perhaps only once.
So what long term damage could possibly take effect running cycles under the protocol I posted above?

Care to speculate Ossie?

~Pinnacle~

Quote:

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Originally Posted by Pinnacle

I'm starting to see this pop up more and more in recent studies(safety).

Has anyone speculated on what long term side effects could possibly be associated using IGF?Bear in mind,we as BBers only use it 30 days on/30 days off in most cases.The average "Joe" might only run it once a year,or perhaps only once.
So what long term damage could possibly take effect running cycles under the protocol I posted above?

Care to speculate Ossie?

~Pinnacle~

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light side effects.
i think, pinn.

see this study:

(god ! there are some bright minds! ......................lol.............)>
i say that for other persons pinn, no for you, brother..

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"One Year of Insulin-Like Growth Factor I Treatment Does Not Affect Bone Density, Body Composition, or Psychological Measures in Postmenopausal Women1

Anne L. Friedlander, Gail E. Butterfield, Sharon Moynihan, Jeanine Grillo, Margaret Pollack, Leah Holloway, Leah Friedman, Jerome Yesavage, Dwight Matthias, Scott Lee, Robert Marcus and Andrew R. Hoffman


Medical Service, Geriatric Research Education Clinical Center, and Psychiatry Service, Palo Alto Veterans Administration Health Care System, and Departments of Medicine and Psychiatry, Stanford University, Palo Alto, California 94304

Address all correspondence and requests for reprints to: Anne L. Friedlander, Ph.D., Geriatric Research Education Clinical Center Building MB2, 182B, Palo Alto Veterans Administration Health Care System, 3801 Miranda Avenue, Palo Alto, California 94304-1207.

The activity of the hypothalamic-GH-insulin-like growth factor I (hypothalamic-GH-IGF-I) axis declines with age, and some of the catabolic changes of aging have been attributed to the somatopause. The purpose of this investigation was to determine the impact of 1 yr of IGF-I hormone replacement therapy on body composition, bone density, and psychological parameters in healthy, nonobese, postmenopausal women over 60 yr of age. Subjects (n = 16, 70.6 ± 2.0 yr, 71.8 ± 2.8 kg) were randomly assigned to either the self-injection IGF-I (15 µg/kg twice daily) or placebo group and were studied at baseline, at 6 months, and at 1 yr of treatment. There were no significant differences between the IGF-I and placebo groups in any of the measured variables at baseline. Fasting blood IGF-I levels were significantly elevated above baseline values (65.6 ± 11.9 ng/mL) at 6 months (330.0 ± 52.8) and 12 months (297.7 ± 40.8) in the IGF-I treated group but did not change in the placebo subjects. Circulating levels of IGF-binding protein-1 and -3 were unaffected by the IGF-I treatment. Bone mineral density of the forearm, lumbar spine, hip, and whole body [as measured by dual-energy x-ray absorptiometry (DXA)] did not change in either group. Similarly, there was no difference in DXA-measured lean mass, fat mass, or percent body fat throughout the treatment intervention. Muscle strength values (grip, bench press, leg press), blood lipid parameters (cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides), and measures of postmeal glucose disposal were not altered by IGF-I treatment, although postmeal insulin levels were lower in the IGF-I subjects at 12 months. IGF-I did not affect bone turnover markers (osteocalcin and type I collagen N-teleopeptide), but subjects who were taking estrogen had significantly lower turnover markers than subjects who were not on estrogen at baseline, 6 months, and 12 months. Finally, the psychological measures of mood and memory were also not altered by the intervention. Despite the initial intent to recruit additional subjects, the study was discontinued after 16 subjects completed the protocol, because the preliminary analyses above indicated that no changes were occurring in any outcome variables, regardless of treatment regimen. Therefore, we conclude that 1 yr of IGF-I treatment, at a dose sufficient to elevate circulating IGF-I to young normal values, is not an effective means to alter body composition or blood parameters nor improve bone density, strength, mood, or memory in older women."



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none died of cancer..................lol..........



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and:



Effects of Recombinant Human Insulin-Like Growth Factor (IGF)-I and Estrogen Administration on IGF-I, IGF Binding Protein (IGFBP)-2, and IGFBP-3 in Anorexia Nervosa: A Randomized-Controlled Study

Steven Grinspoon, Karen Miller, David Herzog, David Clemmons and Anne Klibanski Neuroendocrine Unit (S.G., K.M., A.K.) and The Eating Disorders Unit (D.H.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114; and Endocrine Division (D.C.), University of North Carolina, Chapel Hill, North Carolina 25799


6 month study.
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but,who knows ?

This drug needs alot more study to see if any long term side effects are possible.I mean not seeing the side effects now,but down the road maybe 5 yrs or so,having something suddenly turn up.
Far to late for me Ossie.I done went to the well possibly a few times too many...lol..and I suppose I'll continue to do so...hahahahahaha

~Pinnacle~

Quote:

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Originally Posted by oswaldosalcedo

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none died of cancer..................lol..........



?

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Not yet anyway...lol....


~Pinnacle~