Glucocorticosteroids Flashcards
Ant. Pituitary Hormones
Hypothalamus - CRH -
ACTH (Adrenal Cortex; Diurnal variation) - Cholesterol to Pregnenolone - Cortisol (Feedback on Hypothalamus, Reduce CRH), Aldosterone, Androgens, Estrogens
Adrenal Gland Hormones
Cortisol (Glucocorticoid - Zona fasciculata)
Aldosterone (Mineralocorticoid - Zona glomerulosa)
Adrenal Androgens (Androstenedione and Dehydroepiandrosterone - DHEA - Zona reticularis)
Epinephrine (Adrenaline)
Enkephalin (Both in Medulla)
Inner Medulla and Outer Cortex - Cortex from Mesoderm and Medulla from NC Cells
Inhibited by Ketoconazole
17a-hydroxylase
17,20 lyase
Adrenal Steroids Pharmacokinetics
Cortisol and Progesterone - Bind Corticosteroid-Binding Globulin (CBG) also called Transcortin and Albumin
CBG w/ high affinity for cortisol but low capacity
Albumin w/ low affinity for cortisol but high capacity
Unbound cortisol exterts biologic activity - Affinity and capacity of plasma proteins regulate availability and activity
Amt of transcortin in plasma elevates by female sex hormones (estrogens) and lowered by liver disease, amyloid disease or multiple myeloma
Aldosterone, dehydroepiandrosterone and androstenedione transported diff from cortisol - Bound to albumin
Liver and kidney responsible for cortisol metabolism
Cortisol reduced in liver and conjugated to glucuronic acid and excreted in kidney
Cortisol activity regulated by 11beta-hydroxysteroid dehydrogenase (Liver and adipose tissue w/Type I, Kidney collecting duct cells w/Type 2)
11 Beta-Hydroxysteroid Dehydrogenase
Type I - Liver - Ketone to Hydroxygroup
Type II - Kidney - Hydroxygroup to Ketone
Inactive Metabolites
Peripheral tissues and by liver
Conversion to inactive tetrahydro-derivatives
Conjugated to glucuronic or sulfuric acid and excreted in urine
Genomic Glucocorticoids Action
Increase blood glucose, Gluconeogenesis, Brain activity, Stress resistance, Decrease Inflammation, Immune response
(Also increase resistance to stress, Increase WBC, Decrease water excretion;
Permissive effects - allow Epi/NE to work better)
Nongenomic Glucocorticoids Action
Occur fast (<5min)
Not stopped blocking MR and GR
Effect don’t rely on protein synthesis
Effect on receptors other than MR or GR
Described in brain, lungs, liver, muscle, fat, kidney and immune system;
Behavior aggression, Memory, Risk taking, Mood (Euphoria-depression)
Alter membrane fluidity
Effect on ion channels (Ca++)
Neurotransmitter release
Intracellular but non-nuclear proteins, kinases
Glucocorticoid importers and CBG
Cortisol
Glucocorticoid
Counter-regulatory to insulin
Elevates blood glucose and promotes Gluconeogenesis (Inhibits peripheral protein synthesis and stimulates breakdown of muscle protein; Amino acids then available for liver Gluconeogenesis)
Induces synthesis of gluconeogenic enzymes in liver
Increases glycogen deposition and glucose release by liver
Physiologic Effect of Glucocorticoids - Inflammation
Antiinflammatory
Decrease NFkB - Decrease cytokine from immune cells
Suppress genes for IL 1-6,8, IFN-y leading to decrease Tcell proliferation
Stimulate Lipocortin (Annexin A1) production which inhibit PLA2 - Inhibit 2 products of inflammation, prostaglandins and leukotrienes - Inhibit various leukocyte inflammatory events and suppress COX expression
Physiologic Effect of Glucocorticoids - Development
Promote maturation of lung and production of surfactant necessary for extra-uterine lung function
Physiologic Effect of Glucocorticoids - Brain Function
Form memories w/emotion
Arousal and alertness
Adrenal insufficiency w/ depression
Increase initial cause euphoria and insomnia then depression
ACTH treat infantile spasms w/hypsarrythmia
Physiologic Effect of Glucocorticoids - Bone
Inhibit bone formation (Reduce osteoblasts)
Increase RANK - Increase osteoclasts
Decrease osteoblast function directly and indirect through modulation of growth factor expression, receptor binding or binding protein levels
GIOP treat w/bisphosphonates, anabolic hormones and PTH
Adverse Effects of Glucocorticoids
Endocrine - Decrease GH, Decrease TSH, LH, FSH
GI - Peptic ulcers
Brain - CNS depression, Psychosis
Bone - Decrease bone formation, Decrease bone mass, Osteoporosis
Skeletal m./CT - Protein catabolism, Muscle atrophy, Collagen breakdown, Skin thicken
Eye - Cataract, Glaucoma
Carb - Increase Gluconeogenesis, Free FA production, Increase insulin resistance, Increase hepatic glycogen deposition, Visceral fat
Cardio/Renal - Increase BP, Salt and water retention
Growth - Decrease linear growth
Immune system - Immunosuppressive, Antiinflammatory
Adrenal Androgens
Anabolic
Increase protein synthesis in peripheral tissues
Opposite of cortisol
Pubertal growth spurt in F
Masculinization if excessive (Adrenal tumor)
Androstenedione - Substrate for estrogen synthesis in adipose tissue and estrogen-secreting endocrine glands