In order to determine the role of biogenic monoamines in the control of pancreatic secretion, the metabolism and disposition of 5-hydroxytryptamine (5-HT) and dopamine in rat exocrine pancreas was studied. Pancreatic acinar cells contained 5-HT which was located exclusively in the zymogen granule fraction. Aromatic amino acid decarboxylase activity was located exclusively in the cytosol of acinar cells and was substrate specific for the L-isomers of hydroxylated aromatic amino acids 3,4-dihydroxyphenylalanine(L-DOPA) and 5-hydroxytryptophan (L-5-HTP). Each substrate competitively inhibited the decarboxylation of the other. When incubated with {('14)C}5-HT dispersed acinar cells took up the amine and concentrated it in zymogen granules. These cells also took up {('14)C}5-HTP, decarboxylated it and stored the {('14)C}5-HT produced in zymogen granules. 5-HTP decarboxylation and 5-HT concentration into zymogen granules occurred in the pancreas, but not in the parotid gland. When pancreatic acinar cells pre-labelled with {('14)C}5-HT and {('3)H}Leucine were stimulated with caerulein, there was a synchronous increase in secretion of amylase activity, {('14)C}5-HT and {('3)H}protein. Pancreatic acinar cells took up L-DOPA, decarboxylated it but the dopamine was not retained by the granules and dopamine secretion from the cells incubated with caerulein could not be demonstrated. The results indicate that (1) in the acinar cell of rat pancreas 5-HT is a normal component of zymogen granule; (2) pancreatic acinar cells possess a single aromatic amino acid decarboxylase specific for DOPA and 5-HTP; (3) zymogen granule 5-HT and zymogen granule protein are released together when the cells are stimulated to secrete protein.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.71898 |
| Date | January 1983 |
| Creators | Yu,Edward Wing-Tung. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Pharmacology and Therapeutics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000186981, proquestno: AAINK66637, Theses scanned by UMI/ProQuest. |
Page generated in 0.0019 seconds