Pharmacology
Summary
Growth hormone (GH) originates from the anterior pituitary, and plays a pivotal role in growth and development, particularly during childhood and adolescence. GH binds to specific receptors on target cells, initiating a signaling cascade involving JAK tyrosine kinase and STATs, forming the JAK-STAT pathway. Along with growth, GH can also influence body composition and carbohydrate, protein, and lipid metabolism. It's also responsible for the stimulation of insulin-like growth factor 1 (IGF-1) production, which is crucial for long bone growth, particularly during puberty.
Disruptions in GH levels can result in conditions such as growth hormone deficiency in children, which can lead to stunted growth, and excess GH leading to gigantism in children and acromegaly in adults. Medications like mecasermin mimic the actions of IGF-1 to address severe IGF-1 deficiency or growth hormone resistance, octreotide inhibits excess growth hormone secretion, and pegvisomant acts as a GH receptor antagonist which reduces IGF-1 levels and is effective for the treatment of acromegaly.
Lesson Outline
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FAQs
Mecasermin is a recombinant form of insulin-like growth factor 1 (IGF-1), a hormone that is stimulated by growth hormone produced in the anterior pituitary. Mecasermin is commonly used for growth hormone deficiency, especially when patients have an inadequate response to growth hormone therapy. Mecasermin effectively replicates the effects of IGF-1, and promotes the growth and development of bones and tissues.
Octreotide is a drug that mimics somatostatin, a hormone in the human body that inhibits the release of growth hormone from the anterior pituitary. Therefore, octreotide is often used in situations where there's an excessive production of growth hormone, such as gigantism and acromegaly.
Pegvisomant is a growth hormone receptor antagonist. In conditions like acromegaly where there is an overproduction of growth hormone, it works by binding to the growth hormone receptor and blocking its activation. By doing so, it prevents the excess growth hormone from activating the JAK-STAT pathway and thus reduces the production of IGF-1, which is responsible for the signs and symptoms seen in acromegaly.
Growth hormone stimulates the JAK-STAT pathway, which contributes to the production of IGF-1 in the liver. IGF-1 is crucial for promoting growth and development in various tissues throughout the body. In growth hormone deficiency, this pathway is under-stimulated, resulting in lower levels of IGF-1. This leads to slower growth and development, which is evident in conditions such as dwarfism.
