Endocrinologia 3 - Hormônio do Crescimento

Summary

This video discusses the growth hormone (GH), also known as somatotropin, highlighting its release during all life stages with a peak during puberty. It explores factors influencing GH release, including fasting, stress, and exercise, as well as the role of the hypothalamus in regulating GH. GH promotes growth in bones, tissues, and muscles, and can affect glucose levels in the bloodstream. The video covers the intricate signaling pathways involving GH and its receptor interactions, leading to various physiological responses such as lipolysis and protein synthesis. Finally, it touches on conditions related to GH deficiencies or excess, like gigantism and acromegaly.

Takeaways

• 😀 Growth hormone (GH), also known as somatotropin, is released throughout life but has a significant peak during puberty.
• 😀 Various factors regulate GH release, including fasting, stress, and cortisol levels.
• 😀 GH concentration is high in individuals with protein deficiency, a condition known as Kwashiorkor, and treatment with carbohydrates does not alter GH release, while protein treatment reduces it.
• 😀 GH has a circadian rhythm, with the highest release occurring during the first hours of sleep.
• 😀 Stress and physical exercise stimulate GH release, as do several other factors like hypoglycemia and fasting.
• 😀 GH interacts with receptors on the hypothalamus, where GHRH stimulates GH release, while somatostatin (GHIH) inhibits it.
• 😀 GH stimulates growth in bones, muscles, and connective tissues by binding to its receptors, promoting protein synthesis, and enhancing glucose metabolism.
• 😀 GH also increases the concentration of glucose in the blood by stimulating gluconeogenesis in the liver and reducing glucose uptake in muscle and adipose tissue.
• 😀 GH's effects are mediated by IGF-1 (Insulin-like Growth Factor 1), which promotes bone and tissue growth.
• 😀 Excess GH during childhood causes gigantism (before epiphyseal fusion), while excess in adulthood causes acromegaly (after epiphyseal fusion).
• 😀 Deficiency of GH leads to growth retardation, while treatment with GH can increase linear growth and reduce adiposity, as demonstrated in clinical cases.

Q & A

What is the main hormone discussed in the transcript?

The main hormone discussed in the transcript is Growth Hormone (GH), also known as somatotropin.

How is Growth Hormone (GH) regulated?

The release of GH is regulated by factors such as fasting, stress, cortisol levels, and certain other hormones. The hypothalamus plays a key role in regulating GH release through the secretion of Growth Hormone-Releasing Hormone (GHRH) and somatostatin.

What role does GH play in the body?

GH promotes the growth of bones and tissues, especially in the musculoskeletal system. It also stimulates the production of insulin-like growth factor (IGF-1), which aids in bone and tissue growth.

What is the effect of GH on glucose metabolism?

GH increases glucose concentration in the blood by reducing glucose uptake in muscles and adipose tissue and stimulating gluconeogenesis in the liver.

What happens when there is a deficiency of GH?

A deficiency of GH can lead to stunted growth and reduced development of muscles and bones. It is often associated with conditions like dwarfism or growth retardation.

How does exercise influence GH release?

Exercise is one of the factors that stimulates GH release. Physical activity leads to an increase in GH levels, contributing to muscle growth and repair.

What are the effects of excess GH during childhood versus adulthood?

Excess GH in childhood leads to gigantism, where growth plates remain open, causing excessive linear growth. In adulthood, after the closure of growth plates, excess GH causes acromegaly, leading to abnormal enlargement of bones and tissues, especially in the hands, feet, and jaw.

How does GH interact with somatostatin?

Somatostatin, also known as GH-inhibiting hormone (GHIH), inhibits the release of GH. It acts on the somatotrophs in the pituitary to reduce GH secretion.

What is the function of IGF-1 in the body?

IGF-1, produced in the liver in response to GH, is responsible for promoting the growth of bones, cartilage, and other tissues. It plays a critical role in stimulating linear growth and tissue repair.

What is the feedback mechanism that regulates GH release?

GH release is regulated by a negative feedback loop. IGF-1 stimulates the release of somatostatin, which inhibits the release of GHRH and GH, ensuring that GH levels do not rise too high.