Pituitary adenylate cyclase-activating polypeptide modulates gastric enterochromaffin-like cell proliferation in rats.
OBJECTIVE
Gastric carcinoids (types I and II) involve the transformation of naive enterochromaffin-like (ECL) cells to the neoplastic state and are associated primarily with hypergastrinemia. In this study, we evaluated the effects of two related neuropeptides, pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP), on ECL cell proliferation and characterized the receptor subtype(s) and signal transduction pathways that mediate this effect.


METHODS
Purified rat ECL cells were analyzed in culture for DNA synthesis as measured by 24-hour 5-bromo-2-deoxyuridine (BrdU) uptake. Reverse-transcription polymerase chain reaction (RT-PCR) with gene-specific oligonucleotide primers was performed to characterize the PACAP/VIP receptor subtype(s).


RESULTS
PACAP/VIP neuropeptide-stimulated BrdU uptake was significantly greater (3.4-3.8-fold greater than control) than that at the maximal dose of gastrin (2.2-fold greater than control). PACAP-stimulated ECL cell proliferation (EC50, approximately 3 x 10(-)14 mol/L) was approximately 100-fold more potent than VIP (EC50, approximately 3x 10(-)12 mol/L). The stimulated BrdU uptake by both PACAP and VIP was competitively inhibited by PACAP-receptor antagonist (IC50, 10(-)9 mol/L, 3 x 10(-)9 mol/L, respectively) and VIP-receptor antagonist (IC50, 3 x 10(-)7 mol/L, 5 x 10(-)7 mol/L, respectively). RT-PCR identified the presence of the PACAP-specific but not PACAP/VIP receptor subtypes. The PACAP-stimulated BrdU uptake was inhibited (70%-80%) by inhibitors of adenosine 3',5'-cyclic monophosphate, phosphatidylinositol 3 kinase, and protein tyrosine kinase as well as mitogen-activated protein kinase.


CONCLUSIONS
PACAP/VIP-related peptides are more potent modulators of ECL cell proliferation than gastrin, and their effect is mediated by a PACAP-specific receptor whose activation is transduced by multiple intracellular messenger systems.
Gastric Pathobiology Research Group, Department of Surgery, Yale University School of Medicine and West Haven Veterans Administration Medical Center, New Haven, Connecticut, USA.
J M
JM
Läuffer
I M
IM
Modlin
T
T
Hinoue
M
M
Kidd
T
T
Zhang
S W
SW
Schmid
L H
LH
Tang
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D004759:Enterochromaffin Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005753:Gastric Mucosa / Q000166:cytology* / Q000502:physiology; D005755:Gastrins / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology; D015282:Octreotide / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone / Q000096:biosynthesis / Q000235:genetics*; D018005:Receptors, Vasoactive Intestinal Peptide / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D016593:Terfenadine / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D000077191:Wortmannin
C495401:ADCYAP1 protein, human; C495403:Adcyap1 protein, rat; D000730:Androstadienes; D005419:Flavonoids; D005755:Gastrins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D010446:Peptide Fragments; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; C075647:pituitary adenylate-cyclase-activating-peptide (6-38); D005576:Colforsin; D014660:Vasoactive Intestinal Peptide; D016593:Terfenadine; D004247:DNA; D019833:Genistein; D015282:Octreotide; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin