GH, as a growth hormone, is the most well-known anabolic hormone. Mention GH, you must mention IGF-1, because GH is secreted in the body in the form of a pulse, so if you want to determine whether the level of growth hormone in a person's body is enough, it is necessary to determine the level of IGF-1. IGF-1 is mainly produced by secretory stimulation of GH, therefore, GH acts through IGF-1, and some GH also acts alone. Similarly, IGF-1 mediates the action of GH while having an independent effect independent of GH. The two work synergistically and separately.
With GH and without iGF-1
In a new form of dwarfism, patients have high serum GH values, but they are unable to produce IGF-1. Studies have shown that their GH receptor genes are missing or mutated, resulting in an inability to produce IGF-1 and reduced synthesis of several other IGF-binding proteins (IGFBP). In these patients, who were slightly shorter from birth than the healthy babies, bone maturation and organ growth were delayed throughout the single year. At the same time, the deficiency of IGF-1 can also lead to poor muscle development and weakness.
By knocking out the IGF-1 gene or GH receptor, it was confirmed in mice that growth and bone development were impaired, body size was reduced, and growth rate decreased when IGF-1 was lacking.
After treatment with IGF-1, the mean growth rate of patients increased from 3-4.7cm/year to 8.2-9.1cm/year.
Synergistic effect of IGF-1 and GH
GH stimulates bone growth by stimulating the liver to produce IGF-1, and IGF1 in turn promotes longitudinal bone growth in an endocrine manner.
IGF mediates most of the effects of GH on bone metabolism, promoting cartilage formation and increasing bone formation by regulating the function of differentiated osteoblasts.