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CORTISOL (HYDROCORTISONE) MICHAEL MONREAN CORTISOL - Cortisol is a steroid hormone derived from cholesterol. - - When used as a synthetic made drug it is referred to as hydrocortisone. Steroid hormones can be grouped into two classes - 1. Corticosteroids - - Produced in the adrenal cortex 2. Sex Steroids - Produced in the gonads or placenta - Cortisol is classified as a corticosteroid - Within these two classes there are multiple types depending on the receptors that the steroid binds to. - Cortisol is thus classified as a glucocorticoid GLUCOCORTICOID - Glucocorticoid (GLUCOse + CORTex + sterOID) - - Named for their role in glucose metabolism, where they are synthesized (adrenal cortex), and for their structure Anti-inflammatory - Allergy Suppressant - Immune Suppressant - Released in response to stressors or low blood glucose - Best known for their temporary increase in energy production from fight or flight response Hypothalamopituitary adrenal (HPA) axis: Negative Immune Feedback system: External altered Stressors Hypothalamus CRH Anterior Pituitary Gland (-) Posterior Pituitary Gland ACTH Glucocorticoids, Adrenals Catecholamines, etc.. Kidney Muscle: Net loss of amino Acids (glucose) Liver: Deamination of proteins into amino acids, gluconeogenesis (glucose) Fat Cells: Free fatty acid mobilization Heart rate: Increased STEROIDOGENESIS CORTISOL CHO 21 30 5 GLUCOCORTICOID RECEPTOR - Effect cell by binding to the GR - - When bound, activated GR complex upregulates the expression of anti-inflammatory proteins in the nucleus (transactivation) Down regulates the expression of pro-inflammatory proteins in the cytosol by preventing translocation of many transcription factors from the cytosol into the nucleus (transrepression) - - Allows/disallows gene expression of certain transcription factors Play an important role in pulmonary maturation during fetal development surfactant EFFECTS OF CORTISOL RELEASE - Metabolic Response - Cortisol stimulates gluconeogenesis and glycogenolysis in the liver and the muscles. - - - Deamination of proteins into amino acids - Extreme conditions may lead to proteolysis Glycogen to glucose and glucose-1-phosphate Immune Response - Prevents release of substances in the body causing inflammation - - Treats conditions resulting from over activity of B-cell mediated antibody response i.e. inflammatory diseases such as eczema, rheumatoid arthritis, allergies Prevents proliferation and growth of T-cells - With large exposure can weaken the immune system ADDITIONAL EFFECTS - - Cortisol reduces bone formation by reducing Ca2+ absorption in the small intestine - Long term exposure = possible osteoperosis Down regulates formation of collagen - - Important connective tissue. Effected by deleterious effect of immune system Negative effect on wound healing - Acts as a diuretic - - Effects electrolyte balance by increasing glomerular filtration rate and plasma flow - Consequently promotes potassium excretion and sodium retention Can effect memory retrieval and long term memory - Works with adrenaline to produce emotional flash bulb memories DIURNAL RELEASE CYCLE - There exists a normal release cycle in humans - - At highest levels early in the morning At lowest levels 3-5 hours after sleep onset Cycle believed to be regulated by light/dark cycle and information sent to suprachiasmatic nuclei of the hypothalamus via the retina. - Important to receive adequate sleep so as not to be overexposed to higher cortisol levels CORTISOL DISORDERS Cushing’s Syndrome - high corticosteroid levels in the blood - changes in protein and carbohydrate metabolism - buffalo hump or moon face - free fatty acids mobilized to periphery Addison’s Disease or Nelson’s Syndrome - inadequate secretion of glucocorticoids - hypoglycemia, Na+ and K+ imbalance, dehydration, hypotension, rapid weight loss and general weakness - tints or shades of deep amber or brown skin (due to the stimulation of melanocytes from high ACTH secretion). This results from inadequate negative feedback from low glucocorticoid levels - John F. Kennedy had Addison’s Disease
