7/4/2017 Macroscopic Anatomy • Species Differences Bovine Equine Porcine Adrenals Feline Canine Caprine Ovine Embryonic Development • Adrenal Cortex – Derived from coelomic mesoderm • Adrenal Medulla – Derived from neuroectoderm Canine Adrenal Gland Cortex 80% (indented surface) Medulla 20% Rat Adrenal Cortex Cortex:Medulla 2-4:1 Zona Glomerulosa (Arcuata) 20% Zona Fasciculata 65% Zone Reticularis 15% Berlin 2017 Thomas Rosol 1 7/4/2017 Homeostatic Model of Adrenal Glands Adrenocortical Growth • Most common endocrine organ with chemically-induced lesions • Understanding structure and function is important for interpreting the mechanisms and significance of chemically-induced lesions Stem cells (Sf1-, Gli1+) Zona glomerulosa cells (Sf1+) Zona fasiculata cells (Sf1+) Capsule cells (Sf1-) Zona reticularis cells (Sf1+) Progenitor cells (Sf1+) Adrenal Organogenesis Adrenal Organogenesis • Adrenal cortex and gonad: Same primordia • Wnt from capsule targets Dax1 in proliferative cells • Adrenal responds to ACTH; Gonad to LH – Dax1 required for adrenal differentiation • Adrenal rests form in ovary when ACTH is – Cortisol prevents differentiation of proliferative high cells • Sf1 (steroidogenic factor 1): Marker for • High LH can stimulate adrenal proliferation adrenal cortex; required for adrenal after switch to Gata-4 from Gata-6 formation; induces CYP450 expression – Induced by ACTH Normal Stress Zona Glomerulosa (Multiformis) • Histology – Variable between species; glomeruli or arch-like (arcuata) cell cords • Function – Production of mineralocorticoids • Aldosterone Blue=Aldosterone synthase – Preservation of Sodium (Na+) (Blood volume) Green=CYP11-hydroxylase – Excretion of Potassium (K+) Red=Ki-67 • Required for life Chronic stress induces adrenal hyperplasia and hypertrophy (rats), Ulrich-Lai YM, Am J Physiol Endocrinol Metab, 2006, E965. Berlin 2017 Thomas Rosol 2 7/4/2017 Zona Glomerulosa: Endocrine Control • Release of hormone precursor (Renin) from juxtaglomerular apparatus – Stimulus: low blood volume • Angiotensinogen to angiotensin II • Trophic hormone for zona glomerulosa • Increased aldosterone secretion • Target cells in kidney + - – Increased tubular reasorption of Na , Cl , H20 – Blood volume returned to normal Zona Fasiculata Zona Reticularis • Histology • Histology – Columns (fasicles) of cuboidal to – Anastamosing cell cords columnar cells along vascular sinusoids • Function • Function – Production of glucocorticoids – Production of glucocorticoids (not and small amount of sex required for life) steroids (estrogen, •Cortisol androgens, progesterone) • Corticosterone • Endocrine control • Endocrine control – CRH (Hypothalamus) – CRH (Hypothalamus) – ACTH (Adenohypophysis) – ACTH (Adenohypophysis) Blood Supply to Adrenal Gland Blood Supply to Adrenal Gland • Cranial, middle, and caudal adrenal arteries (Phrenic, aorta, renal) – Small branches from the accessory phrenic, lumbar, cranial mesenteric, celiac arteries •Cortex – Capsule arterioles – Capillary bed of cortex – Venules at corticomedullary junction • Medulla – Cortico-medullary portal system from capillary bed of cortex – Medullary arterioles Berlin 2017 Thomas Rosol 3 7/4/2017 Subcellular Structure/Function Relationships • Lipid droplets (cholesterol esters) • Smooth endoplasmic reticulum • Mitochondria • Minimal storage of hormone • Steroids are hydrophobic molecules diffuse out of cells Steroidogenesis Adrenal Cortex Steroid Hormones • ACTH (cAMP second messenger) • 17-carbon steroid nucleus – ↑StAR protein (steroidogenic acute regulator protein – Cholesterol is precursor • Moves cholesterol to inner mitochondrial membrane • Cytochrome P450 enzymes – ↑Cyp11A1 (Rate limiting step) – Mitochondria, SER, Shuttling • Mitochondria • Secretion – Side chain cleavage (Cyp11A1) – Circadian rhythm – Hydroxylation to Pregnenalone – Nocturnal animals (rats, mice, cats): High at night • SER – Daytime animals (dogs, humans): High in morning – Converted to 11-Deoxycorticosterone – Decreased secretion with age (increased in dogs) • Mitochondria • Bound in serum (90%) to CBG (transcortin) – Hydroxylated to Corticosterone or Cortisol • Metabolized in liver (hydroxylated and conjugated) Acetate ACAT Cholesterol HDL Major Glucocorticoids HO Cholesterol nCEH Esters LDL **CYP11A1** O O O . Cortisol . Corticosterone CYP17 OH CYP17 Pregnenalone 17-OH- . Fish (teleosts) . Amphibians HO HO HO Pregnenalone 3ß-OH-STEROID DE-OH-ASE- 3ß-OH-STEROID Dehydroepiadrosterone . Hamsters . Reptiles DE-OH-ASE- 4,5 ISOMERASE O 4,5 ISOMERASE O O . Dogs (similar to . Birds OH CYP17 CYP17 humans) Progesterone 17-OH- . Rats O O Progesterone O Androstenedione CH OH CYP21 CH2OH CYP21 CH OH . Cats . Mice 2 2 O HO O O O . Nonhuman primates . Rabbits CYP11B2 OH . Humans 11-Deoxy- 11-Deoxycortisol O O corticosteroneO Aldosterone CH OH CYP11B1 CH2OH CYP11B1 2 HO O HO O OH Corticosterone Cortisol O O ACAT: acyl-CoA:cholesterol acyltransferase, nCEH: neutral cholesterol ester hydrolase Berlin 2017 Thomas Rosol 4 7/4/2017 ACTH ACAT Cholesterol HO Cholesterol HO Cholesterol nCEH Esters cAMP CYP11A1 **CYP11A1** O O O O O O CYP17 OH CYP17 CYP17 OH CYP17 Pregnenalone 17-OH- Pregnenalone 17-OH- HO HO HO HO HO HO 3ß-OH-STEROID Pregnenalone Dehydroepiadrosterone 3ß-OH-STEROID Pregnenalone Dehydroepiadrosterone 3ß-OH-STEROID DE-OH-ASE- 3ß-OH-STEROID DE-OH-ASE- DE-OH-ASE- DE-OH-ASE- 4,5 ISOMERASE O 4,5 ISOMERASE O O 4,5 ISOMERASE O 4,5 ISOMERASE O O OH CYP17 OH CYP17 CYP17 CYP17 17-OH- Progesterone 17-OH- Progesterone O O O O O Progesterone O Progesterone Androstenedione CYP21 CH OH CH OH Androstenedione CH OH CYP21 CH OH CH OH CH2OH 2 CYP21 2 2 2 CYP21 2 HO HO O O O O O O O O OH CYP11B2 OH CYP11B2 11-Deoxy- 11-Deoxy- 11-Deoxycortisol O O 11-Deoxycortisol O O corticosteroneO O corticosterone Aldosterone CH OH Aldosterone CYP11B1 CH OH CH OH CYP11B1 CH2OH CYP11B1 2 2 CYP11B1 2 O O HO O HO O HO HO OH OH Corticosterone Cortisol Corticosterone Cortisol O O O O Acetate ACAT Cholesterol Cholesterol HDL HO HO Cholesterol nCEH Esters LDL CYP11A1 **CYP11A1** O O O O O O CYP17 OH CYP17 CYP17 OH CYP17 Pregnenalone 17-OH- Pregnenalone HO HO HO HO 17-OH- HO HO 3ß-OH-STEROID Pregnenalone Dehydroepiadrosterone Pregnenalone 3ß-OH-STEROID DE-OH-ASE- 3ß-OH-STEROID DE-OH-ASE- 3ß-OH-STEROID Dehydroepiadrosterone DE-OH-ASE- DE-OH-ASE- 4,5 ISOMERASE O 4,5 ISOMERASE O O 4,5 ISOMERASE O 4,5 ISOMERASE O O OHCYP17 OH CYP17 CYP17 CYP17 17-OH- 17-OH- Progesterone Progesterone O O Progesterone O O O Progesterone O CH OH CYP21 CH OH CH OH Androstenedione CH OH CYP21 CH OH CH OH Androstenedione 2 2 CYP21 2 2 2 CYP21 2 HO HO O O O O O O O O OH CYP11B2 OH CYP11B2 11-Deoxy- 11-Deoxy- 11-Deoxycortisol 11-Deoxycortisol O O O O O corticosteroneO corticosterone Aldosterone CH OH CH OH CYP11B1 CH2OH CYP11B1 2 Aldosterone CH2OH CYP11B1 2 O O O O HO HO HO HO Angiotensin II OH OH + K Corticosterone Cortisol Corticosterone Cortisol O O O O Cynomolgus Monkey 17-HSD: 17-hydroxysteroid dehydrogenase Berlin 2017 Thomas Rosol 5 7/4/2017 Cynomolgus Monkey: CYP17A IHC Cynomolgus Monkey: CYP11B2 IHC Cynomolgus Monkey: Ki-67 Fetal Adrenal Cortex: Function Fetal Maturation • Lung maturation – Surfactant production • Enzyme induction – Fetal gut, retina, pancreas, thyroid gland, brain • Glycogen deposition –Liver Fetal Adrenal Cortex Fetal Adrenal Cortex Primates, Mice, Sloth, Armadillo • Histology • 80% of cortex in humans – Typical histology in fetus • 90% of cortex in fetal armadillo – Fetal glucocorticoid production • ‘X-Zone’ in mice – Primates • Large cells with abundant, eosinophilic • Fetal cortex undergoes apoptosis & atrophy after cytoplasm birth • Degenerates after birth and is replaced by –Mice the definitive cortex with proliferation in the • Fetal cortex undergoes degeneration and atrophy after birth (X-zone) zona fasciculata Berlin 2017 Thomas Rosol 6 7/4/2017 Fetal Adrenal Cortex: Tamarin Neonate X-Zone in Mice • Zonation is complete at birth (ZG, ZF, no ZR) • X-zone is adjacent to the medulla • Degeneration – Males: Near puberty, fatty degeneration – Virgin Females: Slow regression – Pregnant Females: Regresses during first pregnancy • Vacuolar degeneration • Function is unknown, may catabolize progesterone, may be remnant of adrenal primordia X-Zone in Neonatal Mice Adrenal Dysplasia Cloned Calves • Japanese Black and other breeds Adrenal Cortex: • Prolonged gestation • Heavy birthweights Pathology • Stillborn calves • High neonatal mortality Berlin 2017 Thomas Rosol 7 7/4/2017 Adrenal: Normal Adrenal Dysplasia Cloned Calves Cloned Calves Accessory Adrenal Tissue Accessory Adrenal Tissue: Cat Mesosalpinx • All species, prominent in horses • Near adrenal or gonads (ovary or testes) • Only consists of cortex; all three layers • No medulla Accessory Adrenal Tissue: Foal Accessory Adrenal Tissue: Mare Gonad Ovary Berlin 2017 Thomas Rosol 8 7/4/2017 Peracute Adrenocortical Hypoadrenocorticsm Insufficiency • Diffuse cortical necrosis/hemorrhage • Peracute adrenocortical insufficiency – Trauma: Calves; dystocia – Overexertion: Horses, wild animals – Waterhouse-Friedrickson Syndrome – Septicemia: Calves • Thrombosis of adrenal vessels • Chronic adrenocortical insufficiency – Bacterial or parasitic emboli – Addison’s Disease • Toxemia – Intestinal disease • Necrotizing inflammation; torsion – Certain drugs (O,P’-DDD, Lysodren, mitotane) Septic Infarct - Dog Chronic Hypoadrenocorticism Pathogenic Mechanisms Chronic Hypoadrenocorticism • Diffuse, bilateral destruction of the Serum Electrolytes* adrenal cortex (all 3 layers) HYPOAC NORMAL –Inflammation (Adrenalitis)