Principles of Biochemistry (2+1)

9.1.4.5 Hormones of Adrenal cortex

Hormones secreted by Adrenal cortex are steroids. The secretion is controlled by the hypothalamus. The hypothalamus secretes corticotrophin-releasing hormone, which is sent to the anterior pituitary and stimulates it to release corticotrophin in to the blood.

Corticotrophin binds to receptors on the surface of cells of the adrenal cortex, stimulating them to produce their characteristic steroid hormones. Over 30 steroids are made by adrenal cortex. Collectively called corticoids. They can be grouped into three main classes.

i) Glucocorticoids: The glucocorticoids, of which cortisol is the most important oppose some of the actions of insulin. Cortisol promotes gluconeogenesis from amino acids and glycogen deposition in the liver, increases blood glucose, and decreases peripheral utilization of glucose. It also stimulates utilization of fatty acids and ketogenesis. The glucocorticoids also have remarkable anti–inflammatory and antiallergic action.

ii) Mineralocorticoids: The major corticosteroid of this group is aldosterone. They promote the retention of Na⁺ and Cl^- by the renal tubules, decrease their absorption by sweat glands, salivary glands and the gastrointestinal tract and promote the loss of K⁺ by the kidneys; through these actions these hormones maintain water and salt balance of the body.

iii) Corticosterone : The major hormone of this class is corticosterone. This hormone causes retention of nitrogen, phosphorus, Na, K and Cl.