Chapter 8 The Mammalian Adrenal Glands: Cortical and Chromaffin Cells Copyright © 2013 Elsevier Inc. All rights reserved

Chapter 8Chapter 8

The Mammalian Adrenal Glands: The Mammalian Adrenal Glands: Cortical and Chromaffin CellsCortical and Chromaffin Cells

Copyright © 2013 Elsevier Inc. All rights reserved.

Figure 8-1 Location of adrenal tissue in the human. Note in addition to the expected location of adrenocortical and chromaffin cells in the adrenal gland heterotopic locations where either tissue may be found in either sex. Adapted with permission from Bethune, J.E. The Adrenal Cortex: A Scope Monograph. Upjohn Co., 1974.)

2Copyright © 2013 Elsevier Inc. All rights reserved.

Figure 8-2 Zonation of the adrenal gland. The cortex consists of an outermost layer of connective tissue (CT); the zona glomerulosa (ZG), which produces aldosterone; the zona fasciculata (ZF), which secretes most of the glucocorticoids (cortisol and/or corticosterone); and the inner zona reticularis (ZR), which specializes in adrenal androgen production (DHEA, DHEA-S, androstenedione). The adrenal medulla is separated from the cortex by another layer of CTand consists primarily of chromaffin cells that secrete epinephrine or norepinephrine. Numerous other secretions have been associated with the adrenal medulla, including dopamine and endogenous opiates (EOPs).


Figure 8-3 Comparison of fetal zone to remainder of adrenal gland in humans. Prior to birth, the bulk of the adrenal consists of the androgensecreting fetal zone that regresses rapidly after birth. Whereas the fetal zone is gone by one year of age, the medulla and cortex continue to grow until puberty. In the actual adrenal gland, the fetal zone appears between the zona reticularis and the medulla but is shown above the cortex here for effect. Adapted with permission from Tsakiri, S.P., Chrousos, G.P., and Margioris, A.N., Molecular development of the hypothalamic-pituitaryadrenal (HPA) axis. In E,A. Euguster and O.H. Pescovitz, eds. "Contemporary Endocrinology: Developmental Endocrinology" From Research to Clinical Practice, Humana Press, Inc., pp 359-380.


Figure 8-4 Adrenarche in humans. After birth, adrenal DHEA (open circles) declines as the fetal zone regresses. Although the fetal zone has regressed completely by age one, production of the adrenal androgen DHEA continues in the zona reticularis (solid circles). DHEA secretion begins to increase at about age five and peaks at puberty. (Adapted with permission from de Peretti, E. and Forest, M.G., Journal of Clinical Endocrinology and Metabolism, 43, 982–991, 1976.)


Figure 8-5 Adrenal androgen secretion during human lifespan. Other adrenal androgens follow the pattern shown here for DHEA-S. Note the marked decline associated with regression of the fetal zone after birth followed by a sharp increase at puberty (adrenarche) and a steady decline after mid-20s (adrenopause). (Adapted with permission from Rainey, W.E. et al., Trends in Endocrinology and Metabolism, 13, 234–239, 2002.)


Figure 8-6 Monitoring of glucocorticoid metabolites in spotted hyenas (Crocuta crocuta). Although fecal samples contain a mixture of glucocorticoid metabolites, extraction of fecal samples and measurement of fecal glucocorticoid metabolites by immunoassay can serve as a noninvasive means for monitoring adrenal activity in wild animal species such as hyenas from which it would be difficult or harmful to collect a blood sample. Changes in fecal glucocorticoid content reflect the adrenal response to ACTH (left) and aggression (right) in both male and female hyenas. (Adapted with permission from Goymann, W. et al., General and Comparative Endocrinology, 114, 340–348, 1999.)


Figure 8-7 Evidence of chronic stress. See discussion in text.


Figure 8-8 Pathways in the response to anticipatory and reactive physiological stressors. Signals regarding anticipatory stressors arise in forebrain and limbic brain structures that project to the PVN. Reactive stressors are perceived subconsciously via sensory nerves entering the brainstem or bloodborne factors such as cytokines that can enter the brainstem via circumventricular organs. Noradrenergic neurons located in the nucleus of the solitary tract (see Figure 4-2) convey information about reactive stressors from the brainstem to the PVN. Preganglionic sympathetic neurons in the intermediolateral (IML) cell column receive signals about both kinds of stressors from both forebrain and brainstem sites and activate epinephrine release from the adrenal medulla.


Figure 8-9 Glucocorticoid receptors (GR) bound to glucocorticoids may directly interact with AP-1 and NF-κB to cause mutual repression inside inflammatory cells. See text for explanation of abbreviations. (Adapted with permission from Barnes, P.J., Clinical Science (London), 94, 557–572, 1998.)


Figure 8-10 Pathways for glucocorticoid feedback on CRH neurons. (A) Glucocorticoids (CORT) act on membrane receptors to initiate endocannabinoid (EC) synthesis. ECs travel backwards (retrograde) through the synapse to inhibit glutamate (GLU) release. (B) CORT reduces the stability of RNA encoding the prohormone for glucagon-like peptide 1 neurons in the nucleus of the solitary tract (NTS) in the brainstem, thereby short-circuiting ascending signals from sensory areas of the brainstem. (C) CORTacts through the glucocorticoid receptor to activate glutaminergic neurons in the prefrontal cortex (PFC) that travel to the bed nucleus of the stria terminalis (BnST) and hypothalamus to excite inhibitory GABAergic neurons that shut off CRH secretion. GLP-1, glucagon-like peptide 1. (Adapted with permission from Myers, B. et al., Cellular and Molecular Neurobiology, 32, 683–694, 2012.)


Figure 8-11 Schematic representation of the juxtaglomerular apparatus. The red structures represent a portion of the vasculature of the nephron including the afferent arteriole bringing blood to the glomerulus (a capillary bed) housed in Bowman’s capsule of the nephron and exiting via the efferent arteriole prior to entering the peritubular capillaries (not shown). The juxtaglomerular apparatus consists of the renin-secreting juxtaglomerular cells embedded in the walls of the afferent arteriole and the macula densa, which consists of modified cells in the distal convoluted portion of the nephron.


Figure 8-12 Generalized actions of angiotensins. The major endocrine actions of angiotensins are included but not its vasopressor action. In humans, the major angiotensin is angiotensin-II (Ang-II), and angiotensin-III (Ang-III) has a local depressor action (see text).


Figure 8-13 The renin–angiotensin system and blood pressure regulation. The roles of angiotensin III and natriuretic peptides on blood pressure are not included. See text for explanation. TPR, total peripheral resistance.


Figure 8-14 Role of ACE2. See text for details. AT1, angiotensin type 1 receptor; MAS, MAS protooncogene receptor. (Reprinted with permission from Simões, E. et al., Pediatric Nephrology, 27(10), 1835–1845, 2011.)


Figure 8-15 Natriuretic peptides. Three forms have been identified: ANP, BNP, and CNP. Shared amino acids are highlighted in purple. Amino acid designations can be found in Appendix C. (Adapted with permission from Samson, W.K., Trends in ndocrinology and Metabolism, 3, 86–90, 1992. © Elsevier, Inc.)


Figure 8-16 Relationship between excess aldosterone secretion and insulin action. See text for explanation. IR, insulin receptor. (Adapted from Giacchetti, G. et al., Trends in Endocrinology and Metabolism, 16, 120–126, 2005.)


Box Figure 8A-1 Salivary cortisol during the day in workers from the Whitehall II study with lower and higher socioeconomic status. Cortisol levels show the characteristic higher level at waking with a decline during the workday. Men with a lower pay grade showed elevated cortisol throughout the day compared to men of a higher pay grade after smoking and alcohol consumption were factored out. Salivary cortisol levels were no different between the groups after work. (Adapted with permission from Steptoe, A. et al., Psychosomatic Medicine, 65, 461–470, 2003.)


Box Figure 8A-2 Salivary cortisol is lower on weekends than on work days in male (blue) and female (pink) British civil servants examined from the Whitehall II study. Participants were from higher, intermediate, and lower occupational grades. (Adapted with permission from Kunz- Ebrecht, S.R. et al., Psychoneuroendocrinology, 29, 516–528, 2004.)


Box Figure 8C-1 The marked skin discoloration associated with Addison’s disease is evident in James Wooten, Addison’s first patient. (Reproduced with permission from Graner, J.L., Canadian Medical Association Journal, 133, 855–880, 1985.)


Box Figure 8D-1 Jokichi Takamine was a Japanese scientist who moved to the United States and was the first to purify adrenaline in the early 1900s.


Documents

Chapter 8 The Mammalian Adrenal Glands: Cortical and Chromaffin Cells Copyright © 2013 Elsevier Inc. All rights reserved