Comparison between activation of ornithine decarboxylase and
histidine decarboxylase in rat stomach.
Ding, Xi-Qin, Duan Chen, Elsa Rosengren, Lo Persson, and Rolf
H[angstrom]akanson.
Departments of Pharmacology and Physiology,, University of Lund,
Lund, S-223 62, Sweden
APStracts 2:0202G, 1995.
We compared the responses of rat stomach ornithine decarboxylase (ODC)
and histidine decarboxylase (HDC) to food intake, oral treatment with
antisecretagogues, NaHCO3, and hypertonic NaCl, antrectomy, and
intravenous infusion of gastrin-17, the selective
cholecystokinin(CCK)-B/gastrin receptor antagonist L-365,260, and the
somatostatin analogue RC-160. The serum gastrin concentration and
oxyntic mucosal ODC and HDC activities were higher in freely fed rats
than in fasted rats. Food intake in fasted rats raised the serum
gastrin concentration and the ODC and HDC activities. Ranitidine,
omeprazole and NaHCO3 raised the serum gastrin concentration and
activated ODC and HDC. Hypertonic NaCl raised the ODC activity 200
-fold. Infusion of gastrin-17 activated HDC but not ODC. L-365,260
prevented the activation of HDC but not of ODC in response to food
intake and treatment with omeprazole, NaHCO3 or hypertonic NaCl.
Antrectomy prevented the food- and omeprazole-evoked rise in oxyntic
mucosal HDC activity but not the rise in ODC activity. RC-160
suppressed HDC activity following food intake and treatment with
omeprazole, NaHCO3 or NaCl. In contrast, RC-160 suppressed
omeprazole- and NaHCO3-evoked ODC activation but not that evoked by
food intake or NaCl. The results support the view that HDC in the
oxyntic mucosa is activated by gastrin and suppressed by
somatostatin. The induction of ODC is not mediated by gastrin; ODC
activation appears to be related to acid inhibition per se or to
mucosal maintenance and repair; somatostatin, or rather the lack of
it, might contribute to the induction of ODC following acid blockade.
The mechanism behind the activation of rat stomach ODC seems to
differ depending on the type of stimulus.
Received 18 May 1995; accepted in final form 27 September 1995.
APS Manuscript Number G211-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95