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Peptide Pharmacology course

Peptide Pharmacology course. 703B January to April 2011. PEPTIDES. What are they? Organic substances in which the molecules are structurally like those of proteins, but smaller Some are short (the enkephalins have five amino acids), others longer (glucagon has 29 amino acids)

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Peptide Pharmacology course

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  1. Peptide Pharmacology course 703B January to April 2011

  2. PEPTIDES • What are they? • Organic substances in which the molecules are structurally like those of proteins, but smaller • Some are short (the enkephalins have five amino acids), others longer (glucagon has 29 amino acids) • A rigid definition of peptide would consider as protein anything above a MW of 10,000 Daltons • In this course, we will consider as a peptide any signaling molecule with a peptide chain which is secreted

  3. PEPTIDES (2) • What do they do? • Peptides act either as • hormones (vasopressin, glucagon, insulin), • local hormones (bradykinin) • neurotransmitters/neuromodulators (substance P) • trophic factors (nerve growth factor)

  4. Peptides • Neuropeptides (produced by neurons): • Substance P and related tachykinins • Opioid peptides (enkephalins, dynorphin, β-endorphin, etc) • Calcitonin-gene-related peptide (CGRP) • Neurotensin • Somatostatin • Vasopressin and oxytocin • Others

  5. Peptides (cont) • Vasoactive peptides: • Angiotensin II (8 amino acids long) – increases blood pressure • Kinins (e.g., bradykinin) – potent vasodilators • Natriuretic peptides: • Atrialnatriuretic peptide (28 amino acid long) – decreases blood pressure and increases sodium excretion • Brain natriuretic peptide • Endothelins – vasoconstrictor effect (from endothelia) • Some neuropeptides have action on blood vessels as well: • Vasopressin or antidiuretic hormone • Substance P • Calcitonin-gene-related peptide (CGRP) – in C cell of thyroid gland and in neurons. • Neurotensin – in CNS but also in the gut and in circulation. • Neuropeptide Y – in CNS and PNS.

  6. Peptides (cont) • Gastrointestinal peptides: • Gastrin – stimulates gastric secretion • Secretin – stimulates pancreatic secretion • Glucagon – produced in A cells of pancreas and in gut.

  7. WHY WILL I FOCUS ON PEPTIDES IN THE NERVOUS SYSTEM? • Because the nervous system represents an ideal prototype to cover all aspects of peptide-mediated cell to cell communication, ranging from their general trophic action to specialized synaptic transmission • More precisely, in neurons we can cover several mechanisms, both short and long term, related to the activation of peptide receptors: coupling to membrane ion channels, second messenger systems, gene-induction

  8. HISTORICAL ASPECTS ABOUT NEUROPEPTIDES • The peptide hormones of the neurohypophysis, vasopressin and oxytocinwere the first peptides to be have their amino-acid sequence identified over 50 years ago. • Interest in neuropeptides was much increased about 30 years ago when the peptidergic nature of the hypothalamic releasing and inhibitor factors was understood. Example: somatostatin. • Then came the sequencing of substance P (1971) and the understanding that it was a putative pain transmitter. • Particularly important was the isolation of two endogenous morphines, the enkephalins in 1975. This suggested that at least some neuropeptides could have a function related to neurotransmission. • In recent years, characterization and cloning of most of the receptors for neuropeptides. • Most neuropeptidereceptors belong to the G protein-coupled receptor superfamily, as many receptors of more classical transmitters (e.g., the acetylcholine muscarinic).

  9. WHY ARE OTHER PEPTIDES ALSO EXTREMELY IMPORTANT? • This will be covered next by Dr. Zingg

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