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Secretory activity in isolated rat stomach ECL cells

Lindström, Erik LU (2000)
Abstract (Swedish)
Popular Abstract in Swedish

ECL celler är endokrina (peptid-hormon-producerande) celler belägna i magsäckens syra-producerande del (fundus). Cellerna är av stor betydelse vid regleringen av magens saltsyra produktion och sekretion eftersom de innehåller histamin. Frisatt histamin aktiverar intilliggande parietal celler att utsöndra saltsyra. ECL cellen innehåller också polypeptiden chromogranin A (CGA). I ECL-cellen spjälkas CGA ned till mindre peptid-fragment, bl.a. till pankreastatin, som lagras tillsammans med histamin i s.k. sekretoriska vesikler. Målet med studierna var att först rena fram ECL celler ifrån övriga cell typer i magslemhinnan. Sedan undersöktes vilka hormon eller transmittorer som hade förmågan att... (More)
Popular Abstract in Swedish

ECL celler är endokrina (peptid-hormon-producerande) celler belägna i magsäckens syra-producerande del (fundus). Cellerna är av stor betydelse vid regleringen av magens saltsyra produktion och sekretion eftersom de innehåller histamin. Frisatt histamin aktiverar intilliggande parietal celler att utsöndra saltsyra. ECL cellen innehåller också polypeptiden chromogranin A (CGA). I ECL-cellen spjälkas CGA ned till mindre peptid-fragment, bl.a. till pankreastatin, som lagras tillsammans med histamin i s.k. sekretoriska vesikler. Målet med studierna var att först rena fram ECL celler ifrån övriga cell typer i magslemhinnan. Sedan undersöktes vilka hormon eller transmittorer som hade förmågan att stimulera respektive hämma sekretionen av histamin och/eller pankreastatin. Därefter studerades den intracellulära mekanismen bakom stimuleringen respektive hämningen. Vi har etablerat en metod för upprening av ECL celler från övriga celler från fundus. Elutriering och gradient-centrifugering används för att åstadkomma detta. Vi har lyckats etablera ett protokoll som reproducerbart resulterar i en cell-preparation, där ECL celler utgör mer än 90%. Cellerna odlas 48h innan sekretions-försök påbörjas. Vi har dessutom mätt koncentrationen kalcium (Ca2+) inuti cellen, eftersom Ca2+ är viktig ur sekretions synpunkt. Transport av Ca2+ (och andra joner) över cellmembranen mäts med hjälp av s.k. patch clamp teknik. Vi har visat att både histamin och pankreastatin frisätts som svar på gastrin-stimulering. Även neuropeptiderna PACAP, VIP och PHI, som är belägna i nervfibrer i magslemhinnan, hade förmågan att öka sekretionen från ECL celler. Somatostatin, galanin och prostaglandin E2 (PGE2) däremot kunde effektivt hämma gastrin- och PACAP-inducerad frisättning. Ett arbete visade att ECL cellerna själva kunde producera prostaglandiner som svar på inflammatoriska mediatorer. Vi kunde dessutom tömma cellerna på histamin utan att påverka lagring eller sekretion av pankreastatin. Gastrin och PACAP ökar intracellulärt Ca2+ vid stimulering. Vi har visat att dessa peptider kräver extracellulär Ca2+ för att ECL cellerna skall svara. Gastrin-inducerad frisättning är beroende av Ca2+-inflöde genom s.k. L-typ och N-typ kanaler, medan PACAP-inducerad frisättning är beroende av Ca2+-inflöde genom L-typ och eventuellt andra kanaler. Frisatt kalcium från intracellulära förråd verkar inte påverka sekretionen. Vi kunde bekräfta förekomsten av L-typ och N-typ kanaler med patch clamp teknik. (Less)
Abstract
ECL cells are endocrine/paracrine cells located in the acid-producing part of the stomach. They are important regulators of gastric acid secretion in the stomach by virtue of their histamine synthesizing and secreting capacity. Histamine in turn stimulates parietal cells to secrete acid. The ECL cell also contains the endocrine polypeptide chromogranin A (CGA) and CGA-derived peptides such as pancreastatin. The aim of the study was to identify regulators of secretory activity in isolated and purified ECL cells and to elucidate their signal transduction pathways. The effect of histamine reduction by various mechanisms was studied along with screening of a wide-range of CCK2 receptor antagonists. Gastrin and PACAP stimulated both histamine... (More)
ECL cells are endocrine/paracrine cells located in the acid-producing part of the stomach. They are important regulators of gastric acid secretion in the stomach by virtue of their histamine synthesizing and secreting capacity. Histamine in turn stimulates parietal cells to secrete acid. The ECL cell also contains the endocrine polypeptide chromogranin A (CGA) and CGA-derived peptides such as pancreastatin. The aim of the study was to identify regulators of secretory activity in isolated and purified ECL cells and to elucidate their signal transduction pathways. The effect of histamine reduction by various mechanisms was studied along with screening of a wide-range of CCK2 receptor antagonists. Gastrin and PACAP stimulated both histamine and pancreastatin secretion from isolated ECL cells. VIP, PHI and adrenaline also evoked secretion but to a lesser extent. Muscarinic agonists failed to induce secretion. Gastrin and PACAP-evoked secretion depended upon Ca2+-influx through multiple Ca2+-channels in the cell membrane. Somatostatin, galanin and PGE2 were effective inhibitors of ECL-cell secretion. Histamine did not exert any autoinhibitory effects. The ECL cells synthesized PGE2 in response to inflammatory mediators such as IL-1B, TNF-a and bradykinin. Histamine depletion was evoked by interfering with histamine production using a-FMH or by interfering with intracellular transport using reserpine or bafilomycin A1. Neither pancreastatin storage nor secretion were affected by histamine depletion. The CCK2 receptor antagonists YM022, YF476 and AG041R were the most potent antagonists tested at inhibiting gastrin-evoked secretion. pKB values ranged between 10.4 – 11.3. YM022 and YF 476 acted in a competitive manner. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Dr Prinz, Christian
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Endocrinology, Calcium channels, Adrenaline, Pancreastatin, Prostaglandin E2, Galanin, Somatostatin, Histamine, Gastrin, VIP, PACAP, secreting systems, diabetology, Endokrinologi, sekretion, diabetologi, Pharmacological sciences, pharmacognosy, pharmacy, toxicology, Farmakologi, farmakognosi, farmaci, toxikologi
pages
201 pages
publisher
Erik Lindström, Dept. of Pharmacology, Sölvegatan 10, 223 62 Lund, Sweden,
defense location
Lecture Hall, Dept. of Pharmacology
defense date
2000-05-05 10:15
external identifiers
  • Other:ISRN: LUMEDW/MEFA--1040--SE
language
English
LU publication?
yes
id
68881177-966c-47ee-be22-92ceae632180 (old id 40429)
date added to LUP
2007-07-31 08:12:01
date last changed
2016-09-19 08:45:12
@misc{68881177-966c-47ee-be22-92ceae632180,
  abstract     = {ECL cells are endocrine/paracrine cells located in the acid-producing part of the stomach. They are important regulators of gastric acid secretion in the stomach by virtue of their histamine synthesizing and secreting capacity. Histamine in turn stimulates parietal cells to secrete acid. The ECL cell also contains the endocrine polypeptide chromogranin A (CGA) and CGA-derived peptides such as pancreastatin. The aim of the study was to identify regulators of secretory activity in isolated and purified ECL cells and to elucidate their signal transduction pathways. The effect of histamine reduction by various mechanisms was studied along with screening of a wide-range of CCK2 receptor antagonists. Gastrin and PACAP stimulated both histamine and pancreastatin secretion from isolated ECL cells. VIP, PHI and adrenaline also evoked secretion but to a lesser extent. Muscarinic agonists failed to induce secretion. Gastrin and PACAP-evoked secretion depended upon Ca2+-influx through multiple Ca2+-channels in the cell membrane. Somatostatin, galanin and PGE2 were effective inhibitors of ECL-cell secretion. Histamine did not exert any autoinhibitory effects. The ECL cells synthesized PGE2 in response to inflammatory mediators such as IL-1B, TNF-a and bradykinin. Histamine depletion was evoked by interfering with histamine production using a-FMH or by interfering with intracellular transport using reserpine or bafilomycin A1. Neither pancreastatin storage nor secretion were affected by histamine depletion. The CCK2 receptor antagonists YM022, YF476 and AG041R were the most potent antagonists tested at inhibiting gastrin-evoked secretion. pKB values ranged between 10.4 – 11.3. YM022 and YF 476 acted in a competitive manner.},
  author       = {Lindström, Erik},
  keyword      = {Endocrinology,Calcium channels,Adrenaline,Pancreastatin,Prostaglandin E2,Galanin,Somatostatin,Histamine,Gastrin,VIP,PACAP,secreting systems,diabetology,Endokrinologi,sekretion,diabetologi,Pharmacological sciences,pharmacognosy,pharmacy,toxicology,Farmakologi,farmakognosi,farmaci,toxikologi},
  language     = {eng},
  pages        = {201},
  publisher    = {ARRAY(0x966bdd8)},
  title        = {Secretory activity in isolated rat stomach ECL cells},
  year         = {2000},
}