Hypothalamus & pituitary gland. Growth. Hormones Affecting Growth. Growth hormone (GH) GH actions. Suwattanee Kooptiwut, MD., MSc., Ph.D.

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1 Hypothalamus & pituitary gland Suwattanee Kooptiwut, MD., MSc., Ph.D. 1 2 Growth Hormones Affecting Growth Orderly sequences of maturation changes with increased weight and height Factors Genetic Nutrition Infant & child Puberty Thyroid H Parathyroid H Disease Hormones 3 But Sex hormones Accelerate epiphyseal closure 4 Growth hormone () actions Somatotropin from somatotrophs in the anterior pituitary Peptide hormones: 190 amino acids 1. Direct effect: results of binds to its receptor on Targets cells half life < 30 min Children Tissue sensitivity to & Insulin like growth factor (IGFs) 2. Indirect effect: IGFs (Somatomedins)responses 5 6

2 + - actions (indirect effects) Control of secretion Growth promoting action via IGFs Chondrocytes Protein synthesis Cartilage formation Cell proliferation 7 Bone growth 8 Stimulate linear growth Widen epiphyseal cartilage Ossification calcification actions (direct effects) Metabolic effects of Active vitamin D Osteoblasts Hepatic glucose production Lipolysis Blood Ca2+ Calcification Osteocalcin (Bone matrix) 9 Cellular glucose uptake & utilization Blood glucose Glucosostatic effect Blood FFA 10 Anabolic effect Metabolic effects of Metabolic effects of IGFs Anabolic action similar to insulin Amino acid uptake Protein synthesis Protein oxidation Lean body mass Glycogen synthesis ( Lipogenesis Protein synthesis blood glucose) 11 12

3 deficit excess Child Adult Retard growth (dwarfism) (pituitary, resistance) Protein wasting Thinner skin Muscle weakness, osteoporosis Child Gigantism (generalized increased in body & stature) Adult Acromegaly 13 (excess growth of soft tissue & certain bone) 14 Prolactin Hormone 1.Nerve impulses from suckling Secreted from lactotrophs in the anterior pituitary Peptide hormones: 198 amino acids and 3 disulfide bridges Stimulated by PRH and inhibited by dopamine Mammary Gland Development, Milk Production and reproduction Breast feeding mechanism 2.PRL is release into blood stream 3.PRL induces the breasts to secrete milk Prolactin action (1) Prolactin action (2) Mamogenesis Growth and differentiation of labulo-alveolar system Lactogenesis / Milk production Requires estrogen PRL Insulin HPL (pregnancy) Pregesterone Corticosteroids Reproduction Normal PRL is necessary for LH action Ovulation Normal corpus luteum function 17 18

4 Effect on male reproduction Activate LH actions Block synthesis & release of GnRH Sensitivity of gonadotroph to GnRH Testosterone synthesis LH action on gonads - Synthesis of gonadal hormones Maintain structure and function of accessory sex organs Finding - Galactorrhea - Defect in gametogenesis - Infertility 19 - Gynecomastia 20 Thyroid gland Anatomy Relation of Thyroid gland Function before 10 th week Fetus is independent of maternal thyroid hormone but dependent on iodide supply from mother Many follicles, each follicle is lined by a layer of secretory cells & filled with colloid Parafollicular cells (C-cells) secrete Calcitonin Cross section of Thyroid gland Chemical structure of Thyroid H. Thyroid follicle Thyroid H. Thyroid H. are poorly soluble in water Parafollicular cells Thyroid epithelial cell 23 Thyroid binding protein: TBG, transthyrein and albumin 24

5 Coupling T peroxidase Iodination Follicle lumen Metabolism Increase basal metabolism - number and activity of mitochrondria Increase body heat production Thyroglobulin I - - O 2 consumption Iodine trap Lysosome Increase lipid metabolism - Lipolysis Iodine from diet I Increase carbohydrate metabolism - glucose absorption from GI tract - glucose uptake by cell - gluconeogenesis - glucogenolysis Growth Stimulating Development Promote growth and development of the brain during fetal life Other effects Blood glucose 27 Cardiovascular system Heart rate, contractility & cardiac output Vasodilatation Blood flow 28 Central nervous system Alteration mental stage Too little TH mental sluggish Too high TH anxiety & nervousness Reproductive system Regulation of Thyroid Hormone Secretion TH requires for normal reproductive behavior & physiology Too little TH Polymenorrhea Too high TH Amenorrhea 29 30

6 Thyroid Autoregulation Organic I 2 I - uptake Stabilize plasma T 3, T 4 & TSH Response to TSH Organic I 2 I - uptake Response to TSH T 3, T 4 not increase T 3, T 4 not decrease 31 Hyperthyroid Thyroid Dysfunction Hypothyroid: creatinism (mental retardation) Goiter Euthyroid - puberty -pregnancy Hyperthyroid - Graves disease Hypothyroid - I 2 deficiency -Goitrogen 32