Axis CRH-ACTH-adrenal glands CRH, corticotropin-releasing hormone Characteristics - CNS stress response modulation (anxiety, food intake) - Functions on periphery (BP, immune system, heart) - a part of system of related peptides - CRH-1R - neocortex, cerebellar cortex, subcortical structures of limbic system, amygdala, ovaries, endometrium, skin - CRH-binding protein Hypothalamo-hypophyseal axis - Fast ACTH secretion Clinical significance - Potential treatment of obesity - CRH-R1 antagonists - anxiety and depression treatment Regulation of secretion - Neural control - various stressors - Hypothalamo-hypophyseal axis activation - Sympathoadrenal axis activation - ADH and oxytocin binding - Ensuring requirements in emergency situations - Inflammation and cytokines - IL-1B and hypothalamo-hypophyseal axis activation - Circadian rhythms - diurnal rhythms Proopiomelanocortin - POMC Characteristics -Adenohypophysis - short transcript -CNS -Placenta -Skin -Gonads -GIT -Liver -Kidneys -Adrenal medulla -Lungs -Lymphocytes — long transcript with synthesis of products regulating energy metabolism Stimulation of expression -CRH, cytokines, ADH, catecholamines, VIP Posttranslational modification - Role of prohormone convertases (PCs) Signal peptide PST ACTH [1-LPH v/m®. '///////////, N-terminal IS3 W////////Á Melanocortin receptor ll-LPH Opiate receptor 999 Functions of P O M C-d e rived peptides Adrenal glands - ACTH - the only POMC hormone with effect on adrenal glands - MC2R receptor for melanocortin) - Glucocorticoids, androgens, (mineralocorticoids) - Mitogennic effect on adrenal glands (N terminal peptide) Skin pigmentation - ACTH, ß-LPH, y-LPH - MC1R - Paracrine regulation (melanocytes, keratinocytes) Regulation of appetite - a-MSH - Inhibition of inhibitory effect of leptin - Activation of MC3R and MC4R (hypothalamus) esia - ß-endorphin Circulating probably without effect on CNS Placental POMC - 2nd trimester - Decrease 3 days after birth - No correlation to ACTH/cortisol of mother - Unknown physiological function Ectopic synthesis of POMC/ACTH Mainly tumors with ability of posttranslational changes Immune functions - a-MSH - Inhibition of leukocyte migration - Inhibition of macrophage functions - Modulation of antigen-presenting and T cells MSH - melanotropins a-MSH: (3-MSH: Asp Y-MSH: Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val Ala-Glu-Lys-Lys-Asp-Glu-Gly-Pro-Tyr-Arg-Met-Glu-^ Tyr-Val-Met-Gly-His-Phe-Arg-Trp-Asp-Arg-Phe-Gly - Pregnancy (+) - Adrenal glands (hypofunction) Clinical significance -Synthetic analogues -Afamelanotide - photoprotection -Melanotan II - increased libido -Bremelanotide - aphrodisiac effect (MC3R and MC4R) ACTH Secretion -Circadian and ultradian rhythms -Rise from 16:00 with peak before 19:00 -Lowest levels between 23:00 and 3:00 -Pulsatile secretion (ca 40/day, higher in males) Very complex - neuroendocrine control of stress response and homeostasis Regulatory molecules - CNS, hypothalamus (CRH, ADH, dopamine) - corticotropic cells Cytokines (IL-6, LIF), growth factors - adenohypophysis - local control (paracrine) Glucocorticoids - Negative feedback mechanism - inhibition of CRH secretion, decrease of basal ACTH secretion - Modulation of somatostatin inhibitory effect (downregulation of R) Dopamine Physiological regulation of secretion - exercise (athletes - hypercortisolism) Function - Adrenal glands size, structure and function - Steroidogenesis stimulation Clinical significance - Deficiency ACTH - Hypersecretion of ACTH - Testing - insulin ACTH and stress - Complex - peripherial and central stress adaptors - Vasovagal and sympathetic activation (catecholamines), cytokine secretion - Pain, infection, inflammation, bleeding, hypovolemia, trauma, hypoglycemia, psychological stress - Higher amplitude of ACTH pluses Adrenal glands Adrenal cortex - Steroid hormones - Glucocorticoids - Mineralocorticoids - Androgens Adrenal medulla - Catecholamines - Epinephrine (adrenaline) - Norepinephrine (noradrenaline) - Dopamine Corticomedullary portal system Function - Stress response - Na+, K+, ECT - Blood pressure cortex medulla capsule adrenaline » (isoprenaline) a2-adrenergic a2A, a2B, a2C Mainly Got, and Go Decreased activity of AC (antagonistic effect to k (3-AR). Activation of K+ICH, inhibition of Ca2+ ICH. Activation of PLC(3or PLA2. adrenaline = noradrenaline » isoprenaline ßl-adrenergic Gas Activation of AC and increased cAMP concentration Isoprenaline > adrenaline = noradrenaline ß2-adrenergic Gas Activation of AC and increased cAMP concentration Isoprenaline > adrenaline » noradrenaline ß3-adrenergic Gas Activation of AC and increased cAMP concentration Isoprenaline = noradrenaline > adrenaline Dl family Dl, D5 Gas GOlf Activation of AC and increased cAMP concentration dopamine D2 family 02, 03, D4 Got, Inhibition of AC and decreased cAMP concentration dopamine Physiological effects of catecholamines are mediated through G-protein-coupled adrenergic receptors. Catecholamines from adrenal medulla cannot cross HEB and affect peripherial tissues. Main effects of catecholamines - overview Clinical relevance - Antagonistic effect of various a2AR subtypes - A - decresed blood pressure - B - increased blood pressure (vasoconstriction) - Wide use of agonists and antagonists in clinical practice: - Cardiology - Ophthalmology - Internal medicine Mediated by a-AR Mediated by ß-AR Vasoconstriction Vasodilatation (+) inotropy (+) chronotropy Smooth muscle relaxation (GIT) (+) dromotropy Sphincter contraction (GIT) (+) inotropy Mydriasis Smooth muscle relaxation (GIT) Stimulation of saliva and tear secretion Musculus detrusor relaxation Bronchoconstriction Bronchodilatation Ejaculation Calorigenesis, thermogenesis Gluconeogenesis (liver) Glycogenolysis (-) insulin secretion Lipolysis Thrombocytes aggregation (+) renin secretion (+) Na+ reabsorption (kidneys) (+) glucagon secretion Pilomotor muscle contraction Accommodation of distance vision Physiological effects of catecholamines Catecholamine secretion stimuli - Sympathetic stimulation (generally) - Stress response (physical, psychical stress) - Bleeding and blood loss - Hypoglycemia - Trauma - Surgery - Fear - „fight or flight" Acute response to stress stimuli - e.g. bronchodilatation, sphincter contraction, tachycardia, peripherial vasoconstriction and increased peripherial resistance, inhibition of motility (GIT) Ensuring energy requirements - Mobilisation of substrates - liver, muscles, adipose tissue - Glycogenolysis, lipolysis - Effect - increased glycemia, concentration of glycerol, FFA Regulation of adrenergic receptors - Chronic stimulation = changes in sensitivity (biological response) of target tissues - Desensitization of AR (phosphorylation) Internalization of AR - Upregulation: - Glucocorticoids - Thyroid hormones - Different upregulation of various AR receptors! Biochemical aspects - Monitoring of catecholamine secretion - urine Clinical relevance - Changes in target tissue sensitivity during chronic administration of agonists/antagonists - Chronic application of ß-agonists - asthma - Chronic application of a-agonists - tachyphylaxis (intranasal decongestants) - Feochromocytom Dopamine Functions of dopamine outside of CNS : - Hormone, paracrine and autocrine factor - Cannot cross HEB! - Regulation of ECF volume and ion balance - increased GFR - natriuretic effect - Immune function - (-) lymphocyte activation - Endocrine pancreas - (-) insulin secretion - Heart - (+) inotropy - (+) systolic blood pressure - (0) diastolic blood pressure Clinical relevance - i.v. application in newborns - Treatment of acute kidney damage? - Cardiogenic shock - Septic shock DR Family Dl E JL Dl D5 i Family D2 1 D2 D3 D4 -1- (-) ion (-) Na+ and Relaxation transport water in of smooth in GIT kidneys muscle j (-) sympathetic n.s. (CNS) T J Blood pressure regulation Chromogranin A Characteristics - Acidic glycoprotein - Precursor protein for: - Vasostatin-1 - Vasostatin-2 - Pancreastatin - Catestatin - Para statin - Chromaffin cells of AM - p-cells of pancreas - Paraganglia - ECL cells v- ns-Golqi network CHGA Enhances DCG biogenesis by preventing degradation of granule proteins eNOS Inhibits CA secretion by acting on a nicotinic cholinergic receptors Functions and relevance - Cardioprotective effect (catecholamines) - Autoantigen - DM1 - Hormone secerning CgA - marker CA . • • • Mediates sympathoadrenal activity on cardiovascular target cells to Increase blood pressure Adrenomedullin - AMD Characteristics - Hormone, neuromodulator, neurotransmitter - Peptide (partial homology with CGRP) - Receptors - combination of CALCR + RAMP2/3-AM1/2 - Found in: - CNS - Bloodvessels - Myocardium - Tumour tissue Functions - Vasodilatation (cAMP, NO) - Cardioprotection - Protection during oxidative stress - Protection from hypoxic damage -angiogenesis Hypoxia Other stimuli, e.g. cytokines I 1 AdrGFiomedullin AM gene 1 Adrenomedullln/CGHP receptor system CL RAMP 1 RAMP (CGRP Receptor) RAMP 2 (AMI Receptor) RAMP 3 (AM2 Receptor) Ö iiiiii^ G-protem complex GC. PI3K ATP *CAMPGTP • cGMP ndothellal cell , PLC Ras/Rat puk PI MP, 1 MEK. P125FAK- Akt Mgj, Ca I Win PKG I I Migration Vasodilatation Vessel Maturation . r ^ Gr DWth Mtgratl on BIO Bad caspase 8. BCI2 Ras/Rat MEK. ? ERK1/2.? Apoptosls Tut» tormaiion Angiogenesis Increased growth/survival Vessel growth Tumour progression Hormones of adrenal cortex Hormones of adrenal cortex = cholesterol derivates C21 steroids with two carbon chain in position C17 Mineralocorticoids Glucocorticoids C19 steroids with keto- or hydroxyl group in position C17 Androgens C18 steroids with 17-keto or hydroxyl group without angular methyl group in position CIO STAR (Steroid Acute Regulatory) proteins Source of cholesterol - cholesterol esters or plasma membrane i J^j^jcholesterol CYP11A(P450ssc) i '^cS - £j _ ^X^J Pregnenanlone Biosynthesis of Steroid Hormones mineralocorticoids/ ? JJL J Aldosterone Transfer of cholesterol into inner mitochondrial membrane Regulation of synthesis - Acute (minutes) versus chronic 1 7G-HSD J Androste-. nedione ___ [ Testosterone - (Estrogen) & p— . (Androgen) 5a-reductase 1 J 1 Dihyd ro- testosterone Enzyme Location in Cell Mitochondria Smooth Endoplasmic Reticulum Synthesis and secretion of steroid hormones Glucocorticoids - pulsatile character under ACTH stimulation (Cortisol - 10 - 20 mg/day) Mineralocorticoids - ACTH only basal secretion, RAAS - angiotensin II (aldosterone - 100 - 150 |ag/day) Androgens - ACTH (DHEA, DHEAS, androstenedione - 100 - 150 |ag/day) Different expressions of enzymes catalyzing steps in steroid conversions are responsible for synthesis of various steroid hormones in individual zones of adrenal cortex Regulation of synthesis and secretion Glucocorticoids - ACTH - Gas-activation of AC and PAK - Phosphorylation of cholesterol ester hydrolase - Increased availability of cholesterol - Increased STAR synthesis Mineralocorticoids - Angiotensin II and extracellular K+ - ACTH (only basal and acute secretion) - RAAS system - Renin (juxtaglomerular cells) - Conversion of angiotensinogen - Angiotensin II stimulates aldosteron synthesis and secretion - Inhibition also by somatostatin and dopamine Diurnal rhythm 1 Stressors ~ (hypoglycemia, hypotension, ^(yrj Hypothalamus fever, trauma, | surgery) \ CRH ADH Cytokines I Renal arterial pressure t ß-Adrenergic action t Prostaglandins Metabolism Cardiovascular system t Gluconeogenesis T Glycogenolysis t Proteolysis t Lipolysis t Myocardial contractility t Cardiac output t Catecholamine pressor effect ANP Dopamine Extracellular volume Renal arterial pressure Na+ (+ water) retention K+ excretion J 1ECF[K+] Regulation of Cortisol secretion B Angiotensin II -Regulation of aldosterone secretion Circadian and pulsatile secretion of ACTH and cortiso Glucocorticoid metabolism Lipophilic Conjugates Binding to CBG proteins (transcortin, cortisol-binding globulin) and albumin Half-life 70-90 min Detoxication - Liver - Kidney - Reduction, oxidation, hydroxylation and conjugation - Glucuronides and sulphates Local glucocorticoid metabolism - Tissues with different expression of isoforms of 11(3-hydroxysteroid dehydrogenase type I (conversion cortisone to Cortisol) - Liver, adipose tissue, lungs, skeletal muscle, smooth muscles of blood vessels, gonads, CNS - Tissues with different expression of isoforms of 11(3-hydroxysteroid dehydrogenase type II - Tubular system O en' Cortisol- Free Cortisol Cortisolalbumin -Up to 10% CBG -20-50% -Up to 80% to I-+ —^ O era to Conversion of Cortisol to cortisone is essential for prevention of Cortisol binding to mineralocorticoid receptor. Effects of glucocorticoids 1. Binding of GC on corresponding receptor 2. Conformational change and dissociation of receptor from complex HSP70 and HSP90 3. Migration to nucleus 4. Binding on GRE together with activating protein (API) H binds cytosoiic R 11 ji-Hydroxysteroid dehydrogenase Release regulatory proteins 3L Type 1 NADP(hQ Cortisone w_ Cortisol Expose nuclear locali2ation signals O Type 2 NAD HR complex translocates to nucleus >. Cortisone Glucocorticoids affect intermedial metabolism, stimulate proteolysis and gluconeogenesis, inhibit proteosynthesis (mainly in muscles) and stimulate mobilization of FFAs. Specific for MC High affinity for QC rC>]0 I-*■ MRE II All tissues express glucocorticoid receptors, which causes their wide array of effects. Specificity of MC action Localization of MCR 11 fi-HSD2 in MC target cells Greater affinity of MCR to aldosterone Specific effects of glucocorticoids System Induced gene expression Suppressed gene expression Immune system Inhibitor of NF-kB, haptoglobin, TCR, p21, p27, p57, lipocortin Interleukins, TNF-a, interferon-y, E-selectin, COX-2, iNOS Metabolism PPAR-y, glutamine synthase, glycogen synthase, Glu-6-phosphatase, leptin, y-fibrinogen, cholesterol 7a-hydroxylase Tryptophan hydroxylase, metalloproteases Bone tissue Androgene receptor (AR), calcitonin receptor (CTR), alcalic phosphatase, IGFBP6 Osteocalcin, collagenase Ion channels and transporters ENaC-a, -ß a -y, SGK, aquaporin 1 Endocrine system Basic FGF, VIP, endothelin, RXR, GHRH receptor, receptors for natriuretic peptides GCR, prolactin, POMC/CRH, PTHrP, ADH Growth and development Surfactant proteins A, B, C Fibronectin, a-fetoprotein, NGF, erythropoietin, Gl cyclins and CDKs Effects of glucocorticoids - overview Cardiovascular system: - Increased sensitivity to catecholamines (a2-AR) - Increased sensitivity to angiotensin II - Inhibition of NO-mediated vasodilatation - Stimulation of angiotensinogen synthesis - HSDllB2-activity-dependent increase in Na+ retention in distal tubulus and increased K+ excretion - Increased GFR - Increased resorption of Na+ in proximal tubulus Immune system: - Decrease in lymphocyte count (T more than B) based on redistribution to spleen, lymphatic nodes and bone marrow - Increased number of neutrophils - Decreased number of eosinophils and basophils - Inhibition of monocyte-macrophage differentation - Inhibition of immunoglobulin synthesis - Inhibition of cytokine synthesis - Inhibition of histamine and serotonin secretion from mast cells - Inhibition of Prostaglandine synthesis n —í co DJ en co a. cr o o o. co oo oo —í CO 3 & I! o — oo OJ 3 3 DJ i-+ O -í -o CD 00 00 <■ CO DJ CO CO n Q. Brain/CNS: Depression Psychosis Carbohydrate/lipid metabolism: t Hepatic glycogen deposition t Peripheral insulin resistance tGluconeogenesis t Free fatty acid production Overall diabetogenic effect Adipose tissue distribution: Promotes visceral obesity Bone and calcium metabolism, I Bone formation I Bone mass and osteoporosis Skin/muscle/connective tissue: Protein cataboiism/collagen breakdown Skin thinning Muscular atrophy Endocrine system: I LH, FSH release ITSH release I GH secretion Eye: Glaucoma Gl tract: Peptic ulcerations Cardiovascular/renal: Salt and water retention Hypertension Growth and development: J Linear growth Immune system: Anti-inflammatory action Immunosuppression Glucocorticoids - clinical aspects Field Utilization Endocrinology Substitution therapy Dermatology Dermatitis Haematology hematooncology Leukemia, lymphoma, haemolytic anemia, immune thrombocytopenic purpura Gastroenterology Ulcerative colitis, Crohn's disease Internal medicine, Infectious diseases Chronic active hepatitis, transplantation, nephrotic syndrome, vasculitis Neurology Cerebral edema, increased intracranial pressure Pneumology Asthma, angioedema, anaphylaxis, sarcoidosis, obstructive pulmonary diseases Rheumatology Systemic lupus erythematosus, arteritis, rheumatoid arthritis Long-term glucocorticoid application: - Steroid diabetes - Secondary osteoporosis - Dexamethasone test - Metyrapone test - CRH stimulation test Glucocorticoids are characteristic by not only glucocorticoid, but also mineralocorticoid activity a by ability to affect axis CRH ACTH-GC by feedback loop. Glucocorticoids - clinical aspects Cushing syndrom Addison disease Mineralocorticoids - regulation of aldosteron secretion ■I Pfasma volume T T Angiotensin T Adrenals t Aldosterone release Vasculature T Vasoconstriction Cortical collecting ducts T Na+ reabsorption T K+ secretion T Restore pfasma volume Effects of mineralocorticoids Receptors - Limited distribution - Keratinocytes - Neurons (CNS) - Myocytes - Smooth muscle cells in large blood vessels Main effects of aldosterone - Stimulation of epithelial Na transport - Distal tubulus and collecting duct - Distal colon - Salivary glands Mechanism of effect - (+) synthesis of Na+IK - (+) synthesis of Na+/K+-ATPase - (+) activity of Na+/K+-ATPase - (+) synthesis of H+-ATPase - (+) synthesis of CI/HC03-exchanger o To if) Principal cells (PC) t Na+ transport enzyme synthesis & activity ENaCs {Amflcride-sensitive Na+ channels) (AM) Estrogenic 3Na^/2K+-ATPase (BM) CL 3 HCO r- Intercalated cells (IC) ATPase '- • ' 1 f-ATPase proton pump (apical) • CryHCOg- exchanger (basoiateral) Adrenal gland androgens DHEA is important precursor for sex hormones synthesis Conversion by enzymes from (3-hydroxysteroid dehydrogenase group and aromatase in peripherial tissues Possible presence of CASH (cortical androgen-stimulating hormone) Possible functions of adrenal gland androgens - Libido and its ^regulation" - Cardioprotective effects in men - Possible protective role from ovarial and breast carcinoms in premenopausal women - Neuroprotection - Effect on synthesis and secretion: - IGF-1 - Testosterone and dihydrotestosterone - Estradiol STS DHEAS DHEA-ST DHEA 313-HSD Anrtrostertedione 17^HSD Testosterone 5u -Reductase 5it- D itiy d rotestoste ro ne Aromatase Aromatase Estrone 170-HSD 17|J-Estradiol Androgens produced in adrenal glands represent more than 50 % of circulating androgens in premenopausal women. In men dominates the testicular production. Clinical aspects Congenital adrenal hyperplasia (CAH) - prenatal virilization (high androgen concentration in utero) - Deficit of 21ß-hydroxylase, „salt wasting form" - Deficit of llß-hydroxylase, ^hypertensive form" - Deficit of 3ß-hydroxysteroid dehydrogenase II - Deficit of 17a-hydroxylase Congenital lipoid adrenal hyperplasia - Defective conversion of cholesterol to pregnenolone Adrenogenital syndrome Hyperaldosteronism - Primary hyperaldosteronism - Secondary hyperaldosteronism with increased renin level Secondary adrenal insufficiency (ACTH) Tertiary adrenal insufficiency (CRH) Hyporeninemic hypoaldosteronism Pseudohypoaldosteronism Apparent mineralocorticoid excess syndrome - Inhibition or absence of llß-hydroxysteroid dehydrogenase II