(2006)Endocrine Pituitary Gland


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(2006)Endocrine Pituitary Gland

  1. 1. 腦下垂體生理學 ~ Pituitary ~ 1h 授課日期 : 2007/1/2 11:10-12:00 授課教師 : 許勤教授 生理及分子醫學所 連絡 : TEL: 2309 轉 17 E-mail: chinhsu@kmu.edu.tw
  2. 2. Learning issues Hypothalamic control of pituitary gland Hormones of the posterior lobe : Hormones of the anterior lobe : ADH and Oxytocin GH , PRL, ACTH, MSH , TSH, LH, FSH and Beta-LPH (Lipotropin)
  3. 3. Hypothalamic-hypophysial-axis Vander’s Human Physiology, p360
  4. 4. Hypothalamic Control of the Anterior Pituitary
  5. 5. Hypothalamic Control of Posterior Pituitary (ADH) (Oxy)
  6. 6. Anterior pituitary (Adenohypophysis) Posterior pituitary (Neurohypophysis) SON PVN RH: Releasing hormone IH: Inhibiting hormone Hypothalamic control of pituitary gland
  7. 7. ADH (Vasopressin) : 1. Synthesis and storage Hormones of the posterior lobe Review of Medical Physiology, 21 eds, p246
  8. 8. 2. Physiological effects of ADH : <ul><li>The retention of water in excess of solute </li></ul><ul><li>by the kidney </li></ul><ul><li>b. In large doses, vasopressin elevates </li></ul><ul><li>arterial blood pressure </li></ul><ul><li>Causes glycogenolysis in the liver </li></ul><ul><li>Increases ACTH secretion </li></ul>
  9. 9. <ul><li>Control of secretion </li></ul><ul><li>Osmotic stimuli </li></ul><ul><li>Volume effect </li></ul><ul><li>Other stimuli: </li></ul><ul><li>pain </li></ul><ul><li>nausea </li></ul><ul><li>surgical stress </li></ul><ul><li>drugs: morphine </li></ul><ul><li>nicotine </li></ul><ul><li>barbiturate </li></ul><ul><li>alcohol </li></ul><ul><li>opiate antagonist </li></ul>Hypertonicity Hypovolemia Osmoreceptors In OVLT Baroreceptors Angiotensin II Hypothalamus Thirst Review of Medical Physiology, 21 eds, p244
  10. 10. <ul><li>Clinical implications: </li></ul><ul><li>SIADH </li></ul><ul><li>S yndrome of “ i nappropriate” hypersecretion of ADH </li></ul><ul><li>b. Diabetes insipidus </li></ul><ul><li>c. Nephrogenic diabetes insipidus </li></ul><ul><li>(receptor disease) </li></ul>
  11. 11. 2. Physiologic effects of oxytocin: <ul><li>Stimulates contraction of the smooth muscle (myometrium) of the lactating mammary gland (milk ejection ) and myometrium of the uterus. </li></ul><ul><li>b. The sensitivity of the myometrium to exogenous oxytocin during pregnancy increases as pregnancy advances. </li></ul><ul><li>c. Oxytocin plays a role in labor and has been shown to be a useful therapeutic agent in the induction of labor. </li></ul>
  12. 12. “ Positive feedback loop” Oxytocin↑ Uterine contraction Cervix dilation Labor Oxytocin receptor ↑ x100 Estradiol ⊕ ⊕
  13. 13. <ul><li>Control of oxytocin secretion </li></ul><ul><li>Stimuli: </li></ul><ul><li>Stimulation of the “touch receptor” around the nipples </li></ul><ul><li>Milk let-down or “milk ejection reflex” (latent period: 30-60 seconds) </li></ul><ul><li>Genital tract stimulation </li></ul><ul><li>Inhibition: </li></ul><ul><li>Milk let-down can be inhibited by emotional stress and psychic factors such as fright </li></ul><ul><li>NE & Epi inhibit its secretion </li></ul><ul><li>Ethanol </li></ul><ul><li>enkephalins </li></ul>
  14. 14. Paraventricular nucleus Anterior pituitary Hypothalamus Supraoptic nucleus Portal system Posterior pituitary TSH MSH GH Prolactin ACTH Gonadotropins FSH LH Hypothalamo- anterior pituitary portal vessels Hormones of the anterior lobe
  15. 15. Hormones of the anterior lobe
  16. 16. Physiological effects of prolactin (PRL): 1. Causes milk secretion 2. Increase production of casein & lactalbumin 3. Preventing ovulation in lactating women
  17. 17. Endocrinopathies Chromophobe adnomas of the anterior pituitary or prolactinoma -> hyperprolactinemia -> “ Galactorrhea” In women: blocking the action of gonadotropins on the ovaries -> hypogonadism -> infertility & amenorrhea and osteoporosis In men: 1. Hypogonadism 2. Decreased libido and impotence Treatment: surgical removal of tumor administration of bromocriptine (by stimulating DA receptor)
  18. 18. Hypogonadism Hypopituitarism: Infertility Pallor Low BMR Intolerance to stress
  19. 19. Galactorrhea A Color Atlas of Endocrinology p22
  20. 20. Control of gonadotropins (LH & FSH) secretion :
  21. 21. Physiological function of GH (somatotropin) : ↑ Linear growth ↑ Lean body mass Adipose tissue ↓ Glucose uptake ↑ Lipolysis ↓ adiposily Kidney, pancreas, intestine, islets, parathyroids, connective tissue, bone, heart, lungs ↑ Protein synthesis ↑ DNA,RNA synthesis ↑ Cell size and number ↑ Organ size ↑ Organ function Growth hormone ↑ Plasma FFA ↑ Plasma glucose ↓ Glucose amino acids ↓ Plasma urea Metabolism Condrocytes ↑ Amino acid uptake ↑ Protein synthesis ↑ DNA,RNA synthesis ↑ Chondroitin sulfate ↑ Cell size and number Muscle ↓ Glucose uptake ↑ Amino acid uptake ↑ Protein synthesis
  22. 22. Control of GH secretion SS GHRH GH IGF-1 Target tissue ⊕ ○ - ⊕ ⊕ - ○ Somatostatin: SS Somatotropin: GH Somatomedin: IGF-1
  23. 23. Actions mediated by GH and IGF-1 Review of Medical Physiology, 21 eds, p407
  24. 24. (C)39. 下列何者會促進第一型類胰島素生長因子 (insulin-like growth factor-1) 的分泌? (A) 糖皮質激素 (glucocorticoid) (B) 胰島素分泌不足 (C) 生長激素 (growth hormone) (D) 氫基皮質酮 (cortisol)
  25. 25. D 21. 下列有關生長激素( growth hormone ) 的作用,何者正確? (A) 降低肝臟產生葡萄糖 (B) 降低血中游離脂肪酸濃度 (C) 增加骨骼肌對葡萄糖的攝取( uptake ) (D) 血中生長激素濃度過高可能造成胰島素 阻抗 (insulin resistance )現象
  26. 26. (B) 胰島素受體 (receptor) 在胰島素 標的細胞 (target cells) 的表現, 在下列何種情況會下降? (A) 長期饑餓 (B) 肢端肥大症 (acromegaly) (C) 腎上腺皮質功能不足 (D) 糖皮質素 (glucocorticoid) 分泌太多
  27. 27. Abnormalities of GH secretion : <ul><li>Dwarfism </li></ul><ul><li>Achondroplasia (FGFR3 mutation) </li></ul><ul><li>Kaspar Hauser syndrome </li></ul><ul><li>(psychosocial dwarfism – </li></ul><ul><li>chronic abuse or neglect) </li></ul><ul><li>Laron dwarfism </li></ul><ul><li>Acromegaly </li></ul><ul><li>Giantism </li></ul>
  28. 28. <ul><li>Dwarfism </li></ul>
  29. 29. Acromegaly A Color Atlas of Endocrinology p15
  30. 30. <ul><li>Acromegaly </li></ul>A Color Atlas of Endocrinology p16
  31. 31. Giantism
  32. 32. Giantism Vander’s Human Physiology, p384
  33. 33. Dimerization is essential for receptor activation Review of Medical Physiology, 21 eds, p404
  34. 34. Review of Medical Physiology, 21 eds, p46 Growth factor ( EGF, PDGF ) Ras Ras Cell membrane TF
  35. 35. GH has two binding sites for receptors Signal transction via the JAK-STAT pathway Review of Medical Physiology, 21 eds, p47
  36. 36. Hormones of the intermediate lobe Pro-opiomelanocortin (POMC) Review of Medical Physiology, 21 eds, p402 NH 2 - -COOH Lipotropin *
  37. 37. MSH (melanotropin; melanocyte-stimulating hormone) melanocytes Melanin synthesis MSH Pigment abnormalities in humans: <ul><li>Hypopigmentation & Hyperpigmentation </li></ul><ul><li>(ACTH has MSH activity) </li></ul><ul><li>2. Albinos (inability to synthesize melanin) </li></ul><ul><li>3. Piebaldism (Congenital) </li></ul><ul><li>4. Vitiligo (Progressive) </li></ul>“ Vitiligo” A Color Atlas of Endocrinology p68 2 types Eumelanin : black, brown Pheomelanin : yellow, red
  38. 38. Summary Hypothalamic control of pituitary gland Posterior lobe : Anterior lobe : ADH: ECF homeostasis Oxytocin: Labor GH: growth PRL: lactation MSH: skin pigmentation