Human Growth Hormone (HGH)Growth hormone GHalso known as somatotropin or as human growth hormone [hGH or HGH] in its human formis a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. It is a type of mitogen which is specific only to certain kinds decca steroids cells. Growth hormone is a amino acidsingle-chain polypeptide that is human growth hormone where does it come from, stored and coome by somatotropic cells within the lateral wings of the anterior whwre gland. GH is a stress hormone that raises the concentration of glucose and free fatty acids.
Growth hormone - Wikipedia
Growth hormone GH , also known as somatotropin or as human growth hormone [hGH or HGH] 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. It is a type of mitogen which is specific only to certain kinds of cells. Growth hormone is a amino acid , single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.
GH is a stress hormone that raises the concentration of glucose and free fatty acids. A recombinant form of hGH called somatropin INN is used as a prescription drug to treat children's growth disorders and adult growth hormone deficiency. In the United States, it is only available legally from pharmacies, by prescription from a doctor. In recent years in the United States, some doctors have started to prescribe growth hormone in GH-deficient older patients but not on healthy people to increase vitality.
While legal, the efficacy and safety of this use for HGH has not been tested in a clinical trial. At this time, HGH is still considered a very complex hormone, and many of its functions are still unknown. Traditional urine analysis does not detect doping with HGH, so the ban was unenforceable until the early s, when blood tests that could distinguish between natural and artificial HGH were starting to be developed.
GH has been studied for use in raising livestock more efficiently in industrial agriculture and several efforts have been made to obtain governmental approval to use GH in livestock production.
These uses have been controversial. In the United States, the only FDA-approved use of GH for livestock is the use of a cow-specific form of GH called bovine somatotropin for increasing milk production in dairy cows. Retailers are permitted to label containers of milk as produced with or without bovine somatotropin. The names somatotropin STH or somatotropic hormone refer to the growth hormone produced naturally in animals and extracted from carcasses.
Hormone extracted from human cadavers is abbreviated hGH. The main growth hormone produced by recombinant DNA technology has the approved generic name somatropin INN and the brand name Humatrope,  and is properly abbreviated rhGH in the scientific literature. Since its introduction in Humatrope has been a banned sports doping agent,  and in this context is referred to as HGH.
Genes for human growth hormone, known as growth hormone 1 somatotropin; pituitary growth hormone and growth hormone 2 placental growth hormone; growth hormone variant , are localized in the q region of chromosome 17   and are closely related to human chorionic somatomammotropin also known as placental lactogen genes. GH, human chorionic somatomammotropin, and prolactin belong to a group of homologous hormones with growth-promoting and lactogenic activity.
The major isoform of the human growth hormone is a protein of amino acids and a molecular weight of 22, daltons. The structure includes four helices necessary for functional interaction with the GH receptor.
It appears that, in structure, GH is evolutionarily homologous to prolactin and chorionic somatomammotropin. Despite marked structural similarities between growth hormone from different species , only human and Old World monkey growth hormones have significant effects on the human growth hormone receptor.
Several molecular isoforms of GH exist in the pituitary gland and are released to blood. In particular, a variant of approximately 20 kDa originated by an alternative splicing is present in a rather constant 1: Secretion of growth hormone GH in the pituitary is regulated by the neurosecretory nuclei of the hypothalamus.
These cells release the peptides Growth hormone-releasing hormone GHRH or somatocrinin and Growth hormone-inhibiting hormone GHIH or somatostatin into the hypophyseal portal venous blood surrounding the pituitary. GH release in the pituitary is primarily determined by the balance of these two peptides, which in turn is affected by many physiological stimulators e.
Somatotropic cells in the anterior pituitary gland then synthesize and secrete GH in a pulsatile manner, in response to these stimuli by the hypothalamus. A number of factors are known to affect GH secretion, such as age, sex, diet, exercise, stress, and other hormones. In addition to control by endogenous and stimulus processes, a number of foreign compounds xenobiotics such as drugs and endocrine disruptors are known to influence GH secretion and function.
Effects of growth hormone on the tissues of the body can generally be described as anabolic building up. Like most other protein hormones, GH acts by interacting with a specific receptor on the surface of cells. Increased height during childhood is the most widely known effect of GH. Height appears to be stimulated by at least two mechanisms:.
In addition to increasing height in children and adolescents, growth hormone has many other effects on the body:. The most common disease of GH excess is a pituitary tumor composed of somatotroph cells of the anterior pituitary. These somatotroph adenomas are benign and grow slowly, gradually producing more and more GH. For years, the principal clinical problems are those of GH excess. Eventually, the adenoma may become large enough to cause headaches, impair vision by pressure on the optic nerves, or cause deficiency of other pituitary hormones by displacement.
Prolonged GH excess thickens the bones of the jaw, fingers and toes. Resulting heaviness of the jaw and increased size of digits is referred to as acromegaly.
Accompanying problems can include sweating, pressure on nerves e. GH-secreting tumors are typically recognized in the fifth decade of life. It is extremely rare for such a tumor to occur in childhood, but, when it does, the excessive GH can cause excessive growth, traditionally referred to as pituitary gigantism. Surgical removal is the usual treatment for GH-producing tumors.
In some circumstances, focused radiation or a GH antagonist such as pegvisomant may be employed to shrink the tumor or block function. Other drugs like octreotide somatostatin agonist and bromocriptine dopamine agonist can be used to block GH secretion because both somatostatin and dopamine negatively inhibit GHRH-mediated GH release from the anterior pituitary. The effects of growth hormone GH deficiency vary depending on the age at which they occur.
Alterations in somatomedin can result in growth hormone deficiency with two known mechanisms; failure of tissues to respond to somatomedin , or failure of the liver to produce somatomedin. In adults, somatomedin alteration contributes to increased osteoclast activity, resulting in weaker bones that are more prone to pathologic fracture and osteoporosis.
Adults with GHD "tend to have a relative increase in fat mass and a relative decrease in muscle mass and, in many instances, decreased energy and quality of life". Diagnosis of GH deficiency involves a multiple-step diagnostic process, usually culminating in GH stimulation tests to see if the patient's pituitary gland will release a pulse of GH when provoked by various stimuli. Several studies, primarily involving patients with GH deficiency , have suggested a crucial role of GH in both mental and emotional well-being and maintaining a high energy level.
Adults with GH deficiency often have higher rates of depression than those without. GH has also been studied in the context of cognitive function , including learning and memory. Treatment with exogenous GH is indicated only in limited circumstances,  and needs regular monitoring due to the frequency and severity of side-effects.
GH is used as replacement therapy in adults with GH deficiency of either childhood-onset or adult-onset usually as a result of an acquired pituitary tumor. In these patients, benefits have variably included reduced fat mass, increased lean mass, increased bone density, improved lipid profile, reduced cardiovascular risk factors, and improved psychosocial well-being. GH can be used to treat conditions that produce short stature but are not related to deficiencies in GH. However, results are not as dramatic when compared to short stature that is solely attributable to deficiency of GH.
Examples of other causes of shortness often treated with GH are Turner syndrome , chronic renal failure , Prader—Willi syndrome , intrauterine growth restriction , and severe idiopathic short stature. Higher "pharmacologic" doses are required to produce significant acceleration of growth in these conditions, producing blood levels well above normal "physiologic". Despite the higher doses, side-effects during treatment are rare, and vary little according to the condition being treated.
Off-label prescription of HGH is controversial and may be illegal. Claims for GH as an anti-aging treatment date back to when the New England Journal of Medicine published a study wherein GH was used to treat 12 men over The authors of the study noted that these improvements were the opposite of the changes that would normally occur over a to year aging period.
Despite the fact the authors at no time claimed that GH had reversed the aging process itself, their results were misinterpreted as indicating that GH is an effective anti-aging agent. No other critical factors were affected, such as bone density, cholesterol levels, lipid measurements, maximal oxygen consumption, or any other factor that would indicate increased fitness. This would explain the increase in lean body mass. GH has also been used experimentally to treat multiple sclerosis , to enhance weight loss in obesity , as well as in fibromyalgia , heart failure , Crohn's disease and ulcerative colitis , and burns.
GH has also been used experimentally in patients with short bowel syndrome to lessen the requirement for intravenous total parenteral nutrition.
In , the US Congress passed an omnibus crime bill, the Crime Control Act of , that amended the Federal Food, Drug, and Cosmetic Act , that classified anabolic steroids as controlled substances and added a new section that stated that a person who "knowingly distributes, or possesses with intent to distribute, human growth hormone for any use in humans other than the treatment of a disease or other recognized medical condition, where such use has been authorized by the Secretary of Health and Human Services" has committed a felony.
Sometimes it's used appropriately. This means that the drug has acceptable safety in light of its benefits when used in the approved way. Like every drug, there are several side effects caused by GH, some common, some rare. Injection-site reaction is common. More rarely, patients can experience joint swelling, joint pain, carpal tunnel syndrome , and an increased risk of diabetes.
GH may also be a risk factor for Hodgkin's lymphoma. One survey of adults that had been treated with replacement cadaver GH which has not been used anywhere in the world since during childhood showed a mildly increased incidence of colon cancer and prostate cancer, but linkage with the GH treatment was not established.
The first description of the use of GH as a doping agent was Dan Duchaine's "Underground Steroid handbook" which emerged from California in ; it is not known where and when GH was first used this way.
Athletes in many sports have used human growth hormone in order to attempt to enhance their athletic performance. Some recent studies have not been able to support claims that human growth hormone can improve the athletic performance of professional male athletes. However, because GH is a potent endogenous protein, it is very difficult to detect GH doping. In the United States, GH is legally available only by prescription from a medical doctor. To capitalize on the idea that GH might be useful to combat aging, companies selling dietary supplements have websites selling products linked to GH in the advertising text, with medical-sounding names described as "HGH Releasers".
In the United States, because these products are marketed as dietary supplements it is illegal for them to contain GH, which is a drug. Also, under United States law, products sold as dietary supplements cannot have claims that the supplement treats or prevents any disease or condition, and the advertising material must contain a statement that the health claims are not approved by the FDA.
In the United States, it is legal to give a bovine GH to dairy cows to increase milk production, and is legal to use GH in raising cows for beef; see article on Bovine somatotropin , cattle feeding , dairy farming and the beef hormone controversy. The use of GH in poultry farming is illegal in the United States. Several companies have attempted to have a version of GH for use in pigs porcine somatotropin approved by the FDA but all applications have been withdrawn.
The identification, purification and later synthesis of growth hormone is associated with Choh Hao Li. Genentech pioneered the first use of recombinant human growth hormone for human therapy in Prior to its production by recombinant DNA technology, growth hormone used to treat deficiencies was extracted from the pituitary glands of cadavers.
Attempts to create a wholly synthetic HGH failed. Beck and colleagues in Montreal, in the late s. There was a gain in body weight during both periods.