scholarly journals Mechanism of galanin's inhibitory action on pancreatic enzyme secretion: modulation of cholinergic transmission--studies in vivo and in vitro.

Gut ◽  
1993 ◽  
Vol 34 (11) ◽  
pp. 1616-1621 ◽  
Author(s):  
K H Herzig ◽  
G Brunke ◽  
I Schon ◽  
M Schaffer ◽  
U R Folsch
Keyword(s):  
Inhibitory Action ◽  
Pancreatic Enzyme ◽  
Enzyme Secretion ◽  
Cholinergic Transmission ◽  
Pancreatic Enzyme Secretion ◽  
Transmission Studies

Biochemical reactions involved in pancreatic enzyme secretion. 2. Inhibitory effects of tetracaine and atropine

1977 ◽  
Vol 55 (3) ◽  
pp. 639-643 ◽  
Author(s):  
J. Morisset ◽  
A. R. Beaudoin
Keyword(s):  
Inhibitory Action ◽  
Pancreatic Enzyme ◽  
Pancreatic Tissue ◽  
Enzyme Secretion ◽  
Inhibitory Effects ◽  
Calcium Efflux ◽  
Inhibitory Potency ◽  
Subsequent Response ◽  
Pancreatic Enzyme Secretion

Pancreatic enzyme secretion induced by urecholine or cholecystokinin–pancreozymin (CCK–PZ) is inhibited by tetracaine. If the pancreatic tissue is preincubated with tetracaine then washed out, the subsequent response to CCK–PZ is not affected while that to urecholine is impaired. In contrast with atropine, tetracaine loses its inhibitory potency once secretion has been initiated by urecholine before the addition of the local anaesthetic. Calcium efflux studies have shown that addition of tetracaine in vitro is associated with release of calcium in the incubation medium. This effect on calcium efflux might explain partly the inhibitory action of the drug.

Pancreatic enzyme secretion: nonspecific stimulation by duodenal mucosal extracts

1981 ◽  
Vol 240 (2) ◽  
pp. G109-G113
Author(s):  
A. La Bella ◽  
R. G. Lahaie ◽  
H. Sarles ◽  
J. C. Dagorn
Keyword(s):  
Pancreatic Enzyme ◽  
Extraction Procedure ◽  
Pancreatic Enzymes ◽  
Enzyme Secretion ◽  
Specific Enzyme ◽  
Pancreatic Enzyme Secretion ◽  
Related Enzyme

Felber et al. (Lancet 2: 185-188, 1974) reported that duodenal extracts obtained from rats fed a given meal induced the specific secretion of related pancreatic enzymes. Such an observation challenges the generally accepted theory of parallel secretion of pancreatic enzymes. Although these experiments were faithfully reproduced, no induction of specific enzyme secretion could be obtained. Moreover, comparison of the secretagogue potency of different preparations of duodenal extract, both in vivo (anesthetized rat) and in vitro (pancreatic lobules), demonstrated that in the original extraction procedure most of the secretagogue activity was lost. Finally, even the fully active extract failed to induce specific enzyme secretion. It is therefore unlikely that duodenal extracts from rats fed a specific meal can induce selective secretion of the related enzyme.

Somatostatin inhibits pancreatic enzyme secretion at a central vagal site

1993 ◽  
Vol 265 (2) ◽  
pp. G251-G257 ◽  
Author(s):  
Y. Li ◽  
C. Owyang
Keyword(s):  
Effective Dose ◽  
Protein Secretion ◽  
Pancreatic Secretion ◽  
Inhibitory Action ◽  
Pancreatic Enzyme ◽  
Enzyme Secretion ◽  
Afferent Pathway ◽  
Pancreatic Enzyme Secretion ◽  
Vagal Afferent ◽  
Somatostatin 14

The mechanisms and site of action of somatostatin-induced inhibition of pancreatic enzyme secretion were investigated using different stimulants of pancreatic secretion acting on different sites in anesthetized rats. Administration of graded doses of somatostatin-14 resulted in a dose-related inhibition of pancreatic protein secretion evoked by 2-deoxy-D-glucose, a central vagal stimulant that acts by stimulating the dorsal vagal nuclei. The lowest effective dose of somatostatin-14 was 1.0 microgram.kg-1 x h-1; maximal effective dose was 25 micrograms.kg-1 x h-1, which resulted in complete inhibition of protein output. Similarly, somatostatin-14 at a dose of 25 micrograms.kg-1 x h-1 also completely inhibited pancreatic protein secretion in response to a physiological concentration of cholecystokinin octapeptide (CCK-8), which acts via a vagal afferent pathway. In contrast, pancreatic protein outputs evoked by bethanechol, which directly stimulates pancreatic muscarinic receptors, or electrical stimulation of the vagal trunk, which activates the vagal efferent pathway, were unaffected by somatostatin-14. In separate studies, we demonstrated that perivagal treatment with the sensory neurotoxin capsaicin impaired pancreatic responses to CCK-8 but had no effect on the inhibitory action of somatostatin-14 on pancreatic secretion evoked by 2-deoxy-D-glucose, ruling out an effect of somatostatin on the vagal afferent pathway. Similarly we also demonstrated that perineural capsaicin treatment of the celiac-superior mesenteric ganglia did not affect the inhibitory action of somatostatin. These findings indicate that somatostatin inhibits 2-deoxy-D-glucose- and CCK-8-evoked pancreatic enzyme secretion via a vagal pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Early Dissociation of Protein Synthesis and Amylase Secretion Following Hormonal Stimulation of the Pancreas

1974 ◽  
Vol 52 (2) ◽  
pp. 198-205 ◽  
Author(s):  
R. Mongeau ◽  
Y. Couture ◽  
J. Dunnigan ◽  
J. Morisset
Keyword(s):  
Protein Synthesis ◽  
Incubation Medium ◽  
Single Injection ◽  
Pancreatic Enzyme ◽  
Amylase Secretion ◽  
Hormonal Stimulation ◽  
Pancreatic Enzyme Secretion ◽  
Metabolic Conditions

The secretion of the various pancreatic enzymes can be increased by hormonal and cholinergic stimulation. However, it is not yet clear among the different investigators if their synthesis remains constant or can be modified according to different metabolic conditions. The secretion and synthesis of the pancreatic proteins were then studied in parallel to evaluate if secretion triggers synthesis or both phenomenons are controlled by separate mechanisms.The approach for these studies consists mainly in a combination of in vivo and in vitro experiments. The stimulants were injected in vivo and the pancreatic secretions were collected for different periods of time. The animals were then sacrificed and protein synthesis was measured in vitro along with the amylase secreted into the incubation medium. The results show that protein synthesis is decreased during the first 15 min after a single injection or infusion of both cholecystokinin–pancreozymin (CCK–PZ) and secretin. This reduction was associated with an increase in amylase secreted into the incubation medium. However, at 30 min after the hormonal stimulation, protein synthesis is increased while secretion into the incubation medium had returned to control levels. This increase in protein synthesis lasts for at least 1 h. These results strongly suggest that pancreatic enzyme secretion and synthesis are dissociated in the early minutes following hormonal stimulation.

Cholecystokinin at physiological levels evokes pancreatic enzyme secretion via a cholinergic pathway

1992 ◽  
Vol 263 (1) ◽  
pp. G102-G107 ◽  
Author(s):  
H. C. Soudah ◽  
Y. Lu ◽  
W. L. Hasler ◽  
C. Owyang
Keyword(s):  
Acetylcholine Release ◽  
Pancreatic Enzyme ◽  
Exocrine Secretion ◽  
Cholinergic Innervation ◽  
Enzyme Secretion ◽  
Healthy Humans ◽  
Cholinergic Pathway ◽  
Pancreatic Enzyme Secretion ◽  
Stimulation Of

The mechanism by which physiological concentrations of cholecystokinin (CCK) evoke pancreatic exocrine secretion in humans was investigated. CCK octapeptide (CCK-8) dose dependently increased trypsin and lipase output in healthy humans. Atropine inhibited CCK-8 (10 ng.kg-1.h-1)-stimulated trypsin output by 84.0 +/- 7.7% and lipase output by 78.6 +/- 9.2%. The inhibition with atropine was much less with a CCK-8 dose of 40 ng.kg-1.h-1 (41.8 +/- 6.6% for trypsin and 46.3 +/- 7.3% for lipase). CCK-8 at 10 ng.kg-1.h-1 produced plasma CCK levels similar to postprandial levels (6.0 +/- 1.3 vs. 6.9 +/- 0.8 pM), whereas the 40-ng.kg-1.h-1 dose produced supraphysiological levels (18.4 +/- 3.1 pM). To evaluate if CCK might act via stimulation of cholinergic nerves, in vitro studies were performed using rat pancreas. CCK-8 (10 nM-10 microM) stimulated [3H]acetylcholine release from pancreatic lobules that was blocked by tetrodotoxin, a calcium-free medium, and the CCK antagonist L364,718. In conclusion, CCK-stimulated pancreatic enzyme secretion is dependent on cholinergic neural and noncholinergic pathways. In humans, CCK infusions, which produce plasma CCK levels similar to those seen postprandially, stimulate the pancreas predominantly via a pathway dependent on cholinergic innervation. Correlative in vitro experiments suggest that CCK may act by stimulation of neural acetylcholine release. In contrast, supraphysiological CCK infusions act in part via noncholinergic pathways.

Biochemical Reactions Involved in Pancreatic Enzyme Secretion. I. Activation of the Adenylate Cyclase Complex

1974 ◽  
Vol 52 (2) ◽  
pp. 174-182 ◽  
Author(s):  
A. R. Beaudoin ◽  
C. Marois ◽  
J. Dunnigan ◽  
J. Morisset
Keyword(s):  
Adenylate Cyclase ◽  
Pancreatic Enzyme ◽  
Pancreatic Tissue ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Enzyme Secretion ◽  
Amylase Secretion ◽  
Biochemical Reactions ◽  
Pancreatic Enzyme Secretion

Pancreatic amylase secretion was studied using an in vitro system. Secretion was increased by urecholine and cholecystokinin–pancreozymin (CCK–PZ). Addition of tetracaine and dibucaine to the medium abolished secretion stimulated by urecholine and decreased by 75% that stimulated by CCK–PZ. In contrast, an increase in enzyme secretion was observed after dibutyryl cyclic AMP; this was potentiated by tetracaine added to the medium. Oxygen uptake by pieces of pancreatic tissue was not affected by tetracaine. Adenylate cyclase activity, increased in vitro when CCK–PZ was added to a pancreas homogenate, was inhibited by 15% by tetracaine at 2 mM and by 67.5% at the 10 mM concentration.From data known on biochemical reactions associated with the process of secretion and the results described in the present paper, we propose a model for the activation of the pancreatic adenylate cyclase complex. Associated to the depolarization of the acinar cell plasma membrane by urecholine and CCK–PZ and an inward movement of sodium and calcium, there is an immediate rise in adenylate cyclase activity within 10 s which is timed with the initiation of amylase secretion.

Action of pancreatic polypeptide on rat pancreatic secretion: in vivo and in vitro

1985 ◽  
Vol 249 (4) ◽  
pp. G489-G495 ◽  
Author(s):  
D. S. Louie ◽  
J. A. Williams ◽  
C. Owyang
Keyword(s):  
Protein Secretion ◽  
Pancreatic Polypeptide ◽  
Pancreatic Secretion ◽  
Specific Binding ◽  
Pancreatic Enzyme ◽  
Enzyme Secretion ◽  
Amylase Release ◽  
Pancreatic Acini

The biological activity of bovine pancreatic polypeptide (BPP) on rat exocrine pancreatic secretion was compared in vivo and in vitro. In anesthetized rats prepared with a bile-pancreatic duct cannula, BPP inhibited cholecystokinin (CCK)-stimulated (10 IDU . kg-1 X h-1) protein secretion in a dose-related manner (P less than 0.001). CCK, from 5-20 IDU . kg-1 X h-1, did not alter the degree of inhibition by BPP at 40 micrograms . kg-1 X h-1, suggesting a nonsurmountable inhibition. Analogues of BPP, including rat pancreatic polypeptide, neuropeptide Y, peptide YY, and the C-terminal hexapeptide of PP, also inhibited CCK-stimulated protein secretion. To determine whether BPP acts directly on acinar cells to suppress enzyme secretion, in vitro studies were performed. BPP and its analogues did not suppress octapeptide of CCK (CCK-8)-stimulated amylase release from either isolated rat pancreatic acini or preparations of pancreatic lobules. Specific binding of 125I-BPP to pancreatic acini was also not observed. From our data we conclude that BPP acts to inhibit pancreatic enzyme secretion in the rat in a noncompetitive manner. Absence of an effect by BPP or its analogues in vitro coupled with an absence of 125I-BPP binding to acini suggest that the inhibitory action of PP on exocrine pancreatic function is mediated by indirect mechanisms.

Effect of CCK antagonist L 364718 on meal-induced pancreatic secretion in rats

1990 ◽  
Vol 258 (2) ◽  
pp. G179-G184 ◽  
Author(s):  
M. F. O'Rourke ◽  
R. D. Reidelberger ◽  
T. E. Solomon
Keyword(s):  
Pancreatic Secretion ◽  
Competitive Inhibition ◽  
Pancreatic Enzyme ◽  
Enzyme Secretion ◽  
Amylase Secretion ◽  
Liquid Meal ◽  
Amylase Output ◽  
Pancreatic Enzyme Secretion ◽  
Cck Receptor Antagonist

The specific cholecystokinin (CCK)-receptor antagonist L 364718 was used to examine the role of CCK in meal-induced pancreatic secretion. Unanesthetized rats with gastric, jugular vein, bilepancreatic, and duodenal cannulas were used; bile-pancreatic juice was recirculated. Basal amylase secretion (30% of maximal) was not inhibited by L 364718 doses of 0.5 or 2 mg/kg intravenously. L 364718 (0.02 to 2 mg/kg) caused dose-related inhibition of the maximal amylase response to CCK-8 (200 pmol.kg-1.h-1), with greater than 80% inhibition at doses greater than or equal to 0.5 mg/kg. L 364718 (0.5 mg/kg) shifted the dose-response curve to CCK-8 (25-3,200 pmol.kg-1.h-1) to the right (ED50 increased 10-fold) but did not alter maximal amylase output consistent with competitive inhibition of CCK in vivo. Ingestion of liquid food significantly increased amylase output threefold above basal. L 364718 (0.5 mg/kg) completely blocked this response. These results suggest that although CCK does not regulate basal pancreatic enzyme secretion, it is the primary mediator of pancreatic enzyme secretion in response to a liquid meal.

Central CGRP inhibits pancreatic enzyme secretion by modulation of vagal parasympathetic outflow

1998 ◽  
Vol 275 (5) ◽  
pp. G957-G963 ◽  
Author(s):  
Ying Li ◽  
Yi Cheng Jiang ◽  
Chung Owyang
Keyword(s):  
Nervous System ◽  
Protein Secretion ◽  
Pancreatic Secretion ◽  
Inhibitory Action ◽  
Pancreatic Enzyme ◽  
Enzyme Secretion ◽  
Intravenous Route ◽  
Neural Pathways ◽  
Vagus Nerves ◽  
Pancreatic Enzyme Secretion

Calcitonin gene-related peptide (CGRP) is a potent inhibitor of pancreatic enzyme secretion in vivo. Recent studies have shown that CGRP exerts its inhibitory action at a central vagal site. The present study investigates the mechanism responsible for the central action of CGRP. Rats were fitted with lateral cerebroventricular cannulas, using stereotaxic instruments, 4 days before pancreatic secretion studies. In anesthetized rats, administration of 2-deoxy-d-glucose (2-DG) (75 mg/kg iv) or CCK-8 (40 pmol ⋅ kg−1 ⋅ h−1) produced a 100 and 75% increase in protein secretion, respectively, which was completely blocked by atropine. Intracerebroventricular (ICV) administration of CGRP (0.03–0.6 nmol/h) resulted in a dose-related inhibition of pancreatic protein secretion evoked by 2-DG or CCK-8. CGRP administered by the ICV route was 10–40 times more potent than CGRP given by the intravenous route. In contrast, ICV administration of CGRP had no significant effect on pancreatic protein secretion evoked by electrical vagal stimulation or bethanechol, which directly activates the pancreatic muscarinic receptor. Chemical sympathectomy induced by pretreatment with guanethedine (20 mg/kg ip, 2 days) or α-adrenergic receptor blockade with phentolamine did not alter the inhibitory effects of CGRP. We recently demonstrated that CCK stimulated the enteropancreatic neural pathways to mediate pancreatic secretion in rats with a chronic vagotomy. ICV-administered CGRP did not affect CCK-stimulated pancreatic secretion in rats with a chronic vagotomy. In conclusion, CGRP in the central nervous system inhibits pancreatic enzyme secretion stimulated by 2-DG and CCK-8, which act through vagal pathways. The inhibitory action of CGRP is not mediated by the sympathetic nervous system but appears to depend on intact vagus nerves.

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