Plasma is increased in pregnancy and with oestrogen treatment (e.g. In the circulation, glucocorticoids are mainly protein bound (~90%), chiefly to CBG (cortisol-binding globulin or transcortin). Glucocorticoids are also involved to some extent in regulating sodium and water homeostasis and the inflammatory and stress responses. Lipolysis is increased in adipose tissue, and proteolysis and amino acid release promoted in muscle. In the liver, cortisol stimulates gluconeogenesis, amino acid uptake and degradation, and ketogenesis. Glucocorticoids have widespread metabolic effects on carbohydrate, fat and protein metabolism. Sex steroid production also occurs in the adrenal cortex, mainly in the zona reticularis and to some extent in the zona fasciculata. The deeper layers of the cortex, the zona fasciculata and zona reticularis, synthesise glucocorticoids, of which cortisol is the most important in man. The outermost zona glomerulosa is the site of synthesis of aldosterone, the principal mineralocorticoid. ![]() Three zones can be recognised in the adrenal cortex ( Figure 9.1). ![]() Regulation of adrenal steroid hormone synthesis and secretion
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