Fisiología de la Hormona de Crecimiento

Growth Hormone Physiology

• Growth hormone (GH) is a peptide hormone synthesized and secreted primarily by somatotropes in the anterior pituitary gland.
• Its primary function is promoting growth and development in children and adolescents, and maintaining tissue mass in adults.
• GH has diverse metabolic effects, including stimulating protein synthesis, increasing lipolysis, and decreasing glucose uptake by peripheral tissues.

Factors Stimulating GH Secretion

• Exercise, especially resistance training, strongly stimulates GH release. Intense physical activity, particularly during anaerobic conditions, triggers a significant GH surge.
• Sleep, especially deep slow-wave sleep stages, is critical for GH secretion. This nocturnal surge is essential for growth and repair.
• Low blood glucose levels (hypoglycemia) stimulate GH release to maintain blood sugar balance.
• Amino acid levels, particularly arginine and leucine, stimulate GH release, promoting protein synthesis and tissue repair.
• Ghrelin, a hormone produced in the stomach, stimulates GH secretion.
• Stressful stimuli, whether psychological or physiological, can trigger GH release, though the mechanisms are complex.
• Hormones like thyroid hormones and insulin-like growth factor-1 (IGF-1) influence GH secretion.

Factors Inhibiting GH Secretion

• High blood glucose levels (hyperglycemia) inhibit GH release.
• High free fatty acid levels in the blood suppress GH secretion.
• Obesity significantly inhibits GH release, likely due to factors like leptin and adipose tissue.
• Somatostatin, a hypothalamic hormone, strongly inhibits GH release.
• Cortisol, an adrenal hormone, suppresses GH secretion, especially during prolonged stress.
• Insulin-like growth factor-1 (IGF-1) itself exerts negative feedback on GH, reducing pituitary GH production when levels are high.
• Chronic conditions, like malnutrition and chronic illnesses, negatively impact GH secretion.
• Certain medications, such as glucocorticoids and some antipsychotics, reduce GH levels.

GH Actions and Physiological Roles

• GH promotes linear growth by stimulating chondrocyte proliferation and differentiation.
• It contributes to increased body size and tissue mass.
• GH impacts protein metabolism by stimulating protein synthesis and boosting amino acid uptake by cells.
• Regarding fat metabolism, GH stimulates lipolysis (fat breakdown), increasing circulating free fatty acids, providing energy for other tissues.
• In carbohydrate metabolism, GH increases insulin resistance, hindering glucose uptake by peripheral tissues and raising blood glucose levels. This is crucial for maintaining energy balance.
• GH plays a vital role in maintaining tissue health and cellular replacement.

Growth Hormone Disorders

• Excessive GH production (gigantism in children, acromegaly in adults) results in excessive growth and metabolic changes.
• Insufficient GH production (growth hormone deficiency) impairs growth and development, impacting metabolism. Pituitary gland or regulatory mechanism issues may be causative.

Esta evaluación examina la fisiología de la hormona de crecimiento (GH) y los factores que estimulan su secreción. La GH desempeña un papel crucial en el crecimiento y desarrollo, así como en el mantenimiento de la masa tisular. Además, se explorarán los estímulos como el ejercicio, el sueño y los niveles de glucosa que afectan su liberación.