Growth Hormone

site of origin
1. Pituitary gland
  1. anatomy
    1. anterior lobe
      1. paras anterior
        acidophils
        somatotropes
        secrete GH
        lactotropes
        secrete prolactin
        basophils
        gonadotrophes
        FSH and LH
        cotricotrophes
        ACTH
        thyrotropes
        TSH
        chromophopes
      2. paras intermediate
        colloid filled cysts
        secrete MSH
      3. paras distalis
        portal venules system
        at medial eminence
    2. posterior lobe
      1. paras nervosa
        infundibulum
        medial emenince
    3. infundiblum
      1. connection with
        hypothalamus
release of GH
1. physiology of hormone release
  1. hypothalamic-hypophyseal tract
    1. 1-hypothalamic nucleus secrete hormones
      1. supraoptic--oxytocin
      2. paraventricular -- ADH
        2-released into the axons
        3-stored in paras nervosa to be released when needed
  2. hypophyseal portal system
    1. 1-neuroendocrine cells in the hypothalamus secrete hormones
      1. releasing hormones
      2. inhibiting hormones
        2-released into the axons
        3-at he medial eminence, they get released into the portal venules to be carried to the anterior pituitary to stimulate or inhibit its hormonal releases
    2. factors that regulate GH secretion
      1. pattern of release: pulsatile
actions on the organs level
1. metabolic actions
  1. CHO
    1. hyperglycemic effect
      1. muscles+adipocytes
        -- glucose utilization
        because of decreased sensitivity to insulin due to ++fatty acids level
        GH
      2. liver-++ gluconeogenesis
  2. LIPID
    1. increase lipid catabolism
      1. adipocytyes
        stimulate Hormone sensitive lipase to breakdown the fats
        ++oxidation of fatty acids
      2. liver
        stimulate ketogenesis (because of excess acetyl Coa)
        inhibit lipogenesis
  3. PROTEIN
    1. INCREASE protein anabolism
      1. muscles
        ++ aminoacids transport across membranes
        ++ RNA translation into proteins by ribosomes
        ++ DNA transcription into RNA to make proteins
        DECREASE PROTEIN cataqbolism (protein sparing)
2. growth
  1. go to liver and generate IGF-1
    1. growth of bone
      1. width
        stimulate osteoblasts
        increase bone desposition on the surface
        increase in bone thickness
      2. length
        increase the metabolism of chondrocytes
        increase the secretion of cartilage in the epiphyseal cartilage
        increase the conversion of this cartilage into bone
3. actions in the cell-- 3 signal transduction pathways
  1. JAK/STAT pathway
    1. MAPK and PI3K/PKB pathways
pathologies and their treatment
1. GH excess
  1. before epiphyseal closure
    1. gigantism
      1. increase in length to 8-9 feet
        all tissue of the body growth rapidly
        hypopituitarism
  2. after epiphyseal closure
    1. acromegaly
      1. increase in bone thickness
        growth in soft tissue (heart-kidney)
  3. main cause: GH secreting tumor
  4. treatment
    1. main line is surgery-2nd line: radiation
      1. 3rd line: pharmacological
        Somatostatin analog
        octreoline
        Dopamine agonists
        bromocreptine
        GH receptor antagonists
        pigvisomant
2. GH deficiency
  1. main cause: hypopituitarism
  2. child
    1. pituitary dwarfism
      1. patient becomes very short-sexual functions might be imparied
  3. adult
    1. generalized symptoms
      1. decrease muscle mass - obesity -lack of energy - accelerated aging
  4. treatment
    1. depends on the cause
      1. GH is deficient
        recombinent hGH
        Saizen
      2. IGF-1 is deficient
        rIGF-1
        Mecasermin
      3. Hypothalamic damage
        Synthesitic GHRH
        Sermorelin

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Growth Hormone

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	Created by Yousaf Alabrash over 6 years ago