Somatotropin is secreted by endocrine cells, the somatotropes. They are located in a particular structure of the brain, the adenohypophysis which corresponds to the anterior lobe of the pituitary gland. Its secretion is pulsatile and not continuous, leading to a variable blood concentration of the hormone depending on the time of day. Its secretion is regulated by sleep, meals, stress, age or sex. In general, children synthesize more somatotropin daily than adults. Its secretion is mainly regulated by two hormones secreted by the hypothalamus, the brain structure located just above the pituitary gland. Somatoliberin promotes the secretion of somatotropin, while somatostatin produces the opposite effect. These two hormones are released into the bloodstream at the level of the hypothalamic-pituitary portal system and play their role in the secretory neurons of the pituitary gland. The balance between somatoliberin and somatostatin is itself regulated by the rhythm of the day if not there are HGH supplements which can be taken as pills as additional supplements.
Functions of somatotropin
The main role of somatotropin is to promote the growth and multiplication of cells leading to growth in children (hence its name growth hormone). At the molecular level, growth hormone acts by binding to specific cell receptors, which activates a cascade of molecular responses in target cells.
The first action is at the level of the chondrocytes, the multiplication of which is directly stimulated by somatotropin: the growth of the cartilage is then activated.
The secondary functions of somatotropin are numerous and complex, and at present are probably not all known. We can nevertheless cite its lipolytic action (destruction of fat), and protein and muscle synthesis, which makes this hormone anabolic.