1. Chapter 9 Comparative Aspects of Vertebrate Adrenals
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Figure 9-1 Summary of stressor types and effects in vertebrates. Physical, chemical, and perceived stressors induce a state of stress that in turn brings about changes at the brain and pituitary (primary), physiological changes (secondary), and changes at the level of the organism (tertiary). (Adapted with permission from Barton, B.A., Integrative and Comparative Biology, 42, 517–525, 2002.)
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Figure 9-2 Environmental or life history demands: allostasis and homeostasis. Physiological state A represents basic physiological and behavioral processes necessary for simple existence. Homeostatic mechanisms (level A, arrow) operate around specific set points to maintain balance (blue circle). Predictable or manageable demands of the environment or life history events such as reproduction activate allostatic mechanisms that raise the physiological state to B and homeostatic level B (arrow) involving different set points and new maintenance conditions (purple circle). In the face of unpredictable and potentially life-threatening events, additional allostatic mechanisms drive the physiological state to C, and hence new homeostatic mechanisms (level C, arrow) are required to maintain survival conditions (red circle). (Adapted with permission from Landys, M.M. et al., General and Comparative Endocrinology, 148, 132–149, 2006.)
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Figure 9-3 Predictable and unpredictable stressors and effects on glucocorticoid levels. (Adapted with permission from Landys, M.M. et al., General and Comparative Endocrinology, 148, 132–149, 2006.)
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Figure 9-4 Comparative anatomy of adrenal tissues. Comparision of distribution of chromaffin (black) and adrenocortical tissue (clear) associated with the kidneys (stippled) in the vertebrates. Chromaffin tissue is not shown for the ratfish (C) and sturgeon (D). (A) cyclostomes; (B) selachians; (C) holocephalans; (D) chondrosteans; (E) holosteans; (F) dipnoans; (G) teleosts; (H) gymnophionans; (I) anurans; (J) urodeles; (K) chelonians; (L) snakes; (M) lizards; (N) crocodilians; (O) birds; (P) mammals.
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Figure 9-5 Adrenocortical tissue in a teleost head kidney. The larger, clear cells are adrenocortical (interrenal) cells located in clumps among the much smaller and darker lymphoid cells of the head kidney of a brown trout (Salmo trutta).
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Figure 9-6 Amphibian adrenal tissue. (A) Light micrograph from the bullfrog (Lithobates (Rana) catesbeianus) showing adrenocortical (ST), chromaffin (C), and summer or Stilling cells (SM). (B) Electron micrograph from the bullfrog. The cells with the large secretory granules are Stilling cells (SM). The steroidogenic cells contain lipid droplets (LD) and mitochondria with tubular cristae. N, nucleus. (C) Adrenocortical cells in a salamander are located close to kidney tubules (T). (Parts A and B reprinted with permission from Matsumoto, A. and Ishii, S., “Atlas of Endocrine Organs,” Springer- Verlag, Berlin, Part C reprinted with permission from Vinson, G.P. et al., “The Adrenal Cortex.” Prentice-Hall, Englewood Cliffs, NJ, 1993.)
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Figure 9-7 Adrenal gland of the lizard Podacris sicula. (A) Entire adrenal gland. (B) Section from A enlarged to show chromaffin cells (dark green =orepinephrine (NE)-secreting cells; light green = epinephrine (E)-secreting cells) and steroidogenic (GC) cells (light purple cells). Some chromaffin ells are distributed among the steroidogenic cells in addition to being along the surface. Giemsa stain. Photomicrographs courtesy of Salvatore Valiante.
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Figure 9-8 Glucocorticoid receptor distribution compared to areas of neurodegeneration and amyloid deposition in the spawning salmon brain. (A) Distribution of glucocorticoid receptors in brain of Kokanee salmon. (B) Sites of neurodegeneration and deposition of –amyloid in the spawning Kokanee salmon brain. The OT, VC, POA, and SCN exhibit both GR and amyloid as do additional sites not named here (purple areas); green indicates a common olfactory region exhibiting both GR and amyloid whereas the orange areas are unrelated sites positive for GR (in A) and amyloid only in (B), respectively. Abbreviations: OC, optic chiasm; OT, optic tectum; PIT, pituitary; POA, preoptic area; SCN, suprachiasmatic nucleus; VC, valvula cerebelli. (Part A adapted with permission from Carruth, L.L. et al., General and Comparative Endocrinology, 117, 66–76, Part B adapted with permission from Maldonado, T.A. et al., Brain Research, 858, 237–251, © Elsevier Science, Inc.)
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Figure 9-9 Amyloid deposition in the salmon brain. Brains of spawning Pacific salmon are characterized by extensive neurodegeneration and the deposition of immunoreactive –amyloid as shown in the optic tectum (A) compared to an adjacent section of the same brain that was pretreated with immune serum (B). Staining in the optic tectum of a prespawning animal would resemble the immune control. (Reprinted with permission from Maldonado, T.A. et al., Brain Research, 858, 237–251, © Elsevier Science, Inc.)
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Figure 9-10 Corticosterone and stress in captive and free-ranging birds. Resting plasma corticosterone levels and the response to stress in captive birds are blunted as compared to free-ranging birds. Note also the seasonal differences in the sensitivity to a stressor. (Reprinted with permission from Romero, L.M. and Wingfield, J., Comparative Biochemical and Physiology B, 12, 13–20, 1999.)
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Figure 9-11 The juxtaglomerular apparatus in non-mammals. (A) Teleost (Carassius auratus). (B) Bullfrog (Lithobates (Rana) catesbeianus). (C) Snake (Elpahe quadrivirgata). (D) Domestic chicken. Abbreviations: AA, afferent arteriole; DCT, distal convoluted tubule; EA, efferent arteriole; G, glomerulus; JGC, juxtaglomerular cells; PCT, proximal convoluted tubule; MD, macula densa. (Adapted with permission from Matsumoto, A. and Ishii, S., “Atlas of Endocrine Organs,” Springer-Verlag, Berlin, 1989.)
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Figure 9-12 Natriuretic peptides in nonmammals. Comparison of dogfish shark and chicken CNPs to some mammalian CNPs as well as human (h) ANP and BNP. (Adapted with permission from Fowkes, R.C. and McArdle, C.A., Trends in Endocrinology and Metabolism, 11, 333–338, © Elsevier Science, Inc.)
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Figure 9-13 Distribution of natriuretic peptides among tetrapod vertebrates. This figure stresses the absence of ANP in most reptiles and in all birds suggesting that the gene was lost prior to the evolution of the modern Lepidosauria (squamates and the tuatara) and the archosaurs (crocodilians and birds). Bony and chondrichthyean fishes have the ANP gene, although it is absent from cyclostomes. (Adapted with permission from Trajanovska, S. and Donald, J.A., General and Comparative Endocrinology, 156, 339–346, 2008.)
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Box Figure 9A-1 Effects of cadmium exposure on HPA axis of brown trout. Fish living their entire life in cadmium-contaminated water exhibit a delayed response in cortisol secretion to confinement stress but catch up to trout from an uncontaminated reference site by 3 hours; however, after 12 hours of confinement, cadmium-exposed trout can no longer maintain a high level of cortisol secretion. (Data used with permission from Norris, D.O. et al., General and Comparative Endocrinology, 113, 1–8, 1999.)
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Box Figure 9A-2 ACTHresponse to stress in cadmium-exposed brown trout and reference-site brown trout. A significantly greater amount of ACTH secretion is necessary for trout chronically exposed to cadmium to maintain normal cortisol secretion in response to confinement stress. After 12 hours, these fish can no longer maintain ACTH secretion and cortisol secretion also decreases. (Data used with permission from Norris, D.O. et al., General and Comparative Endocrinology 113, 1–8, 1999.)
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