WGhrelin is a hormone produced by enteroendocrine cells of the gastrointestinal tract, especially the stomach, and is often called a "hunger hormone" because it increases food intake. Blood levels of ghrelin are highest before meals when hungry, returning to lower levels after mealtimes. Ghrelin may help prepare for food intake by increasing gastric motility and gastric acid secretion.
WGrowth hormone (GH) or somatotropin, also known as human growth hormone in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. GH also stimulates production of IGF-1 and increases the concentration of glucose and free fatty acids. It is a type of mitogen which is specific only to the receptors on certain types of cells. GH is a 191-amino acid, single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.
WGrowth hormone 1, also known as pituitary growth hormone or simply as growth hormone (GH) or somatotropin, is a protein that in humans is encoded by the GH1 gene.
WGrowth hormone 2 (GH2), also known more commonly as placental growth hormone (PGH) or as growth hormone variant (GH-V), is a protein that in humans is encoded by the GH2 gene. It is produced by and secreted from the placenta during pregnancy, and becomes the predominant form of growth hormone (GH) in the body during this time. Its cogener is growth hormone 1 (GH1), or pituitary growth hormone.
WThe hypothalamic–pituitary–somatotropic axis, or hypothalamic–pituitary–somatic axis, also known as the hypothalamic–pituitary–growth axis, is a hypothalamic–pituitary axis which includes the secretion of growth hormone from the somatotropes of the pituitary gland into the circulation and the subsequent stimulation of insulin-like growth factor 1 production by GH in tissues such as, namely, the liver. Other hypothalamic–pituitary hormones such as growth hormone-releasing hormone, growth hormone-inhibiting hormone, and ghrelin (GHS) are involved in the control of GH secretion from the pituitary gland. The HPS axis is involved in postnatal human growth. Individuals with growth hormone deficiency or Laron syndrome show symptoms like short stature, dwarfism and obesity, but are also protected from some forms of cancer. Conversely, acromegaly and gigantism are conditions of GH and IGF-1 excess usually due to a pituitary tumor, and are characterized by overgrowth and tall stature.
WThe insulin-like growth factors (IGFs) are proteins with high sequence similarity to insulin. IGFs are part of a complex system that cells use to communicate with their physiologic environment. This complex system consists of two cell-surface receptors, two ligands, a family of seven high-affinity IGF-binding proteins, as well as associated IGFBP degrading enzymes, referred to collectively as proteases.
WInsulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults.
WInsulin-like growth factor 2 (IGF-2) is one of three protein hormones that share structural similarity to insulin. The MeSH definition reads: "A well-characterized neutral peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like and mitogenic activities. The growth factor has a major, but not absolute, dependence on somatotropin. It is believed to be a major fetal growth factor in contrast to Insulin-like growth factor 1, which is a major growth factor in adults."
WSomatostatin, also known as growth hormone-inhibiting hormone (GHIH) or by several other names, is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones. Somatostatin inhibits insulin and glucagon secretion.