Naturally occurring in the brain and controlling both growth and metabolism, growth hormone, also called somatotropin, can be isolated from cadavers or produced in synthetic form for use as an injectable drug. While somatotropin injections are extremely helpful for individuals with deficiencies of growth hormone, they can also be abused by people who don't have a specific medical need for the hormone.
Biology
The protein growth hormone is produced by the pitutitary gland of the brain and is made up of 190 amino acids, explains Colorado State University Biomedical Hypertexts. The hormone is produced by cells called somatotrophs. In the body, growth hormone binds to growth hormone receptor, causing the cells with this receptor to respond by secreting other hormones or carrying out specific biological activities. In some organs, such as the liver, this binding causes the secretion of another important protein called insulin-like growth factor-1, or IGF-1. The amount of growth hormone produced peaks at puberty and decreases as the individual grows older.
Effects
Direct effects of growth hormone include stimulating fat cells to break down triglycerides and stop taking up new lipids, effectively shutting down fat production in the body, and stimulating the cells that create new bone. Growth hormone also helps keep blood sugar stable. By stimulating the production of IGF-1, growth hormone also has an indirect effect on growth, since this hormone causes additional bone growth, muscle growth and protein production.
Diseases
Too much growth hormone in a child's body can produce a condition called gigantism, a rare disorder that causes affected individuals to grow extremely large for their age. Children with gigantism may also develop unusually large hands and feet, thick facial features and a prominent jaw. If an excess of growth hormone occurs in adults, a different condition, called acromegaly, occurs. People with acromegaly develop oversized bones and muscles in the hands, feet and face along with other symptoms such as headache and fatigue. A growth hormone deficiency causes short stature if it develops in childhood and may result in a loss of bone and muscle mass or changes in cholesterol levels when it occurs in adulthood.
Human Uses
Synthetic human growth hormone is a prescription drug used to treat growth hormone deficiencies and the muscle wasting that accompanies diseases such as AIDS. Because of its ability to increase bone and muscle mass, decrease fat levels and improve the capacity for exercise, some individuals believe it could be used to counter the normal decreases in muscle and bone mass that occur with aging. In sports, growth hormone is used as an illegal performance enhancing drug. Some parents also try using growth hormone in children of normal stature in order to try and increase these kids' height, a use that is considered unethical by most doctors.
Agricultural Uses
Growth hormone is sometimes used in cattle to improve milk production and in pigs to create leaner, more muscular pigs for pork production. The use of growth hormone in agriculture remains controversial, with many people opting not to eat products made from animals given artificial somatotropin injections.
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