Гормоны надпочечников: синтез, функции и нарушения.

Hormones produced by the adrenal cortex
In humans and other animals, the adrenocortical hormones are hormones produced by the adrenal cortex, the outer region of the adrenal gland. These polycyclic steroid hormones have a variety of roles that are crucial for the body's response to stress (for example, the fight or flight response), and they also regulate other functions in the body. Threats to homeostasis, such as injury, chemical imbalances, infection, or psychological stress, can initiate a stress response. Examples of adrenocortical hormones that are involved in the stress response are aldosterone and cortisol. These hormones also function in regulating the conservation of water by the kidneys and glucose metabolism, respectively.

Adrenocortical hormones are divided into three classes by function: mineralocorticoids, glucocorticoids, and androgens. Mineralocorticoid hormones are synthesized in the outermost layer of the adrenal cortex known as the zona glomerulosa. Their function is to regulate the concentration of electrolytes circulating in the blood. Additionally, the ion gradient initiates conservation of water. The glucocorticoid family of hormones is synthesized in the middle layer of the adrenal cortex known as the zona fasciculata. These hormones regulate the processing of proteins, fats, and carbohydrates by the human body. They also play a role in maintaining a normal stress response cycle. Androgens, or sex hormones, are synthesized in the innermost layer of the adrenal cortex known as the zona reticularis. These hormones, such as estrogen in females and testosterone in males, are commonly known for promoting sexual characteristics and the maturation of reproductive organs of the respective gender. The cholesterol backbone consists of four hydrocarbon rings, three cyclohexane rings and one cyclopentane, that contribute to its insolubility in aqueous environments. However, the hydrophobic nature allows them to readily diffuse through the plasma membrane of cells. Though synthesis is initiated inside mitochondria, precursors are shuttled to the endoplasmic reticulum for processing by enzymes present in the endoplasmic reticulum. The precursors are shuttled back to the mitochondria in the region of the adrenal cortex within which synthesis initially began and it is there that synthesis is completed.

Cushing's syndrome arises from the repeated hypersecretion of glucocorticoids. It can be caused by either an adrenal tumor or by hypersecretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary gland. In Cushing's syndrome, this process occurs in excess. Some symptoms of an individual with Cushing's syndrome include low tissue protein levels, due to muscle and bone atrophy, and high blood glucose levels. Sodium levels also see an increase which results in fluid retention in tissues and elevated blood pressure. In addition to hypersecretion of cortisol, excess androgens are secreted. In females, increased secretion of androgens, such as testosterone, results in masculinization which may present as facial hair growth and a deepened voice. The standard treatment for Addison's disease is hormone replacement therapy for the mineralocorticoids and glucocorticoids that are no longer able to be synthesized. [12] Former U. S. President John F. Kennedy is a well known individual who suffered from Addison's disease throughout his presidency. Due to the availability of hormone replacement therapy, he and his staff were able to cover up his condition. The experience of psychological stress activates transcription factors that activate genes. In a study by Cole et al., it was concluded that GABA 1 transcription factor activates the interleukin 6 gene. This gene codes for a protein that activates the inflammatory response which directs an immune response to the site of the inflammation.