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How does IGF-1 affect muscle mass?

In patients with acromegaly whose serum IGF-1 levels are quite high, skeletal muscle mass is significantly higher than in controls, and it significantly decreases 1 year after pituitary tumor resection [40]. Thus, serum IGF-1 levels are associated with changes in skeletal muscle mass.

What is the normal range of IGF-1?

IGF-1, ng/mL 108.5 (81.5–138.8) Age, years 44.0 (37.0–51.8) BW, kg 113.2 (99.3–134.8) 79.8 (70.6–98.0) <0.0001 BMI, kg/m2

Is there a relationship between IGF-1 and GH secretion?

However, the lipolytic action of GH is direct and not associated with IGF-1 [27, 28, 29, 30]. Serum IGF-1 levels were related to decreased body fat mass in this study, suggesting that IGF-1 reflects GH secretion and lipolytic action. Other studies have also shown a relationship between serum or plasma IGF-1 levels and body fat [31, 32, 33].

Do serum IGF-1 levels reflect the lipolytic effect of human growth hormone?

The results of previous studies and our study indicate that serum IGF-1 levels reflect the lipolytic effect of GH. Patients with sufficient serum IGF-1 levels are considered to adequately maintain GH secretion.

What is the mechanism of action of IGF-1 in skeletal muscle?

Mechanisms of IGF-1-Mediated Regulation of Skeletal Muscle Hypertrophy and Atrophy Insulin-like growth factor-1 (IGF-1) is a key growth factor that regulates both anabolic and catabolic pathways in skeletal muscle. IGF-1 increases skeletal muscle protein synthesis via PI3K/Akt/mTOR and PI3K/Akt/GSK3β pathways.

How does IGF-I affect muscle mass?

Muscle mass increases in proportion to body size during the growth phase. The growth-promoting effects of GH and IGF-I in young animals and humans are well documented, but increases in muscle mass are usually in proportion to the increase in body size.

How does IGF-1 affect myofiber size and function?

IGF-1 can regulate both protein synthesis and degradation pathways, and changes in IGF-1 signaling in skeletal muscle can greatly affect myofiber size and function.

How does aging affect IGF-1 levels?

Both circulating and local IGF-1 levels are reduced in aging [189], with decreased Akt/mTOR/p70S6Kin skeletal muscle [9,189,190]. AAV-mediated IGF-1 gene transfer prevented aging-related muscle changes in old mice [191], and, conversely, deletion of liver-specific IGF-1 at one year of age dramatically impaired health span of the mice [192].

What is the relationship between IGF-1 and growth hormone?

The relationship between IGF-1 and growth hormone begins with GH promoting the production of insulin growth factor 1. It is a complicated process that requires numerous hormones working at maximum potential to complete the feedback loop. The balance of IGF-1 and HGH in the bloodstream begins with the hypothalamus.

Which factors control the secretion of IGF-1 and IGFBPs?

The secretion of IGF-1 and IGFBPs is not only under the control of endocrine and nutritional factors, but also autocrine and paracrine factors ( Voci et al., 1999 ).

How do the GH/IGF-1 axis and the clock system interact?

The GH/IGF-1 axis and clock system may interact further on the metabolism through several pathways in peripheral tissues (e.g., liver, fat). The physiological roles of GH and IGF-1 are also summarized in this figure ( Huang et al., 2020b ).

What is the mechanism of action of growth hormone (GH)?

Whilst growth hormone (GH) is capable of acting directly upon receptors at its target tissues, its downstream effects, like muscle and bone growth, are principally the result of indirect action through IGF-1. GH induces the synthesis and secretion of IGF-1 in the liver.

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