Lecture 9

Lecture 9 - NPB 101, Autumn 2008 Endocrinology 2...

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1/7/10 NPB 101, Autumn 2008 Endocrinology 2 Hypothalamo-pituitary unit Anterior pituitary
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1/7/10 Hypothalamus Anterior pituitary Posterior pituitary Neurosecretory neurons Systemic arterial inflow Hypothalamic-hypophyseal portal system System venous outflow = Hypophysiotropic = Anterior pituitary hormone Fig. 18-9, p.
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1/7/10 Hormones of the Pars distalis Growth hormone and prolactin (polypeptides) Glycoproteins: thyroid-stimulating hormone (TSH), luteinizing hormone (LH) follicle-stimulating hormone (FSH) Proopiomelanocortin (POMC): adrenocorticotropin (ACTH), melanocyte-stimulating hormone (MSH) and endorphin
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1/7/10 Immunocytochemical staining of pituitary cells Growth hormone ACTH Prolacti n Growth hormone FS H LH
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1/7/10 Growth hormone Prolactin GH and PRL comparisons. Both have considerable overlap in amino acids. GH has two disulphide bonds and PRL has three
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1/7/10 Prolactin Prolactin is synthesized as a prohormone. Following cleavage of the signal peptide, the length of the mature hormone is between 194 and 199 amino acids, depending on species Structure is stabilized by three intramolecular disulfide bonds It is secreted by so-called lactotrophs in the anterior pituitary Prolactin is secreted by a broad range of other cells in the body, most prominently various immune cells, the brain and the decidua of the pregnant uterus
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1/7/10 Actions of prolactin Over 300 known Actions related to reproduction Somatotropic effects (e.g. growth) Osmoregulation Actions on the integument and its derivatives Interactions with steroid hormones Interactions with the immune system
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1/7/10 Signal transduction pathways involved in prolactin regulation Positive regulators of prolactin release include vasoactive intestinal peptide (VIP), estrogen, and thyrotropin- releasing hormone (TRH) VIP exerts its effects by G-protein mediated activation of adenylate cyclase (AC) and its downstream effectors cAMP and protein kinase A (PKA). These activate a protein kinase cascade that culminates in gene expression and subsequent release of prolactin. TRH induces prolactin secretion through activation of the phospholipase C (PLC) signaling pathway. Activation of PLC cleaves phosphatidylinositol 4,5-phosphate (PIP) to form diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3). These release intracellular calcium from endoplasmic reticulum (ER) and release of prolactin by exocytosis.
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1/7/10 Signal transduction pathways involved in prolactin regulation Negative regulators include dopamine and thyroid hormone Dopamine binds to the D2 dopamine receptor and decreases AC activity. Thyroid hormone can directly inhibit the prolactin promotor again through a genomic receptor.
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1/7/10
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1/7/10 Growth, growth hormone and growth factors
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1/7/10 G O G 1 S G 2 M The mammalian cell cycle. Go = a fully mature cell (specialized or resting), not dividing. G1 is the growth phase preparatory to S, the synthetic stage when DNA is duplicated. G2 is of short duration (only 3 - 4 hours and involving
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1/7/10 Types of growth Cells may enlarge (hypertrophy) and intracellular products may change as a result Cells may increase in number (hyperplasia), e.g. organ
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This note was uploaded on 01/06/2010 for the course NPB idk taught by Professor Wingfield during the Spring '09 term at UC Davis.

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Lecture 9 - NPB 101, Autumn 2008 Endocrinology 2...

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