Effects of bombesin on pancreatic digestive enzyme gene expression.

We examined the effects of bombesin on rat pancreatic digestive enzyme gene expression using cloned complementary DNA probes for amylase, trypsinogen I, chymotrypsinogen B, and lysophospholipase. Rats were injected sc three times daily with 5 nmol/kg body wt bombesin. Pancreata were investigated after 6, 12, 24, 48, and 120 h of hormone treatment. Bombesin administration resulted in a time-dependent increase of pancreatic weight, as well as DNA and protein concentration. Cellular hypertrophy became evident after 48 h, and pancreatic hyperplasia occurred after 5 days of hormone treatment. Bombesin administration resulted in a time-dependent parallel decrease of amylase and lysophospholipase messenger RNA (mRNA) concentrations with maximal inhibition occurring after 120 h of bombesin treatment (13 +/- 1% and 14 +/- 3% of control, respectively, P less than 0.05, n = 6). In contrast, chymotrypsin and trypsin mRNA levels remained unaltered after bombesin treatment for up to 5 days. Amylase and chymotrypsin enzyme levels did not correlate with their respective mRNA concentrations. Both decreased to approximately 50% of control after 12 h and increased to 126 +/- 38% of control and 388 +/- 109% of control (P less than 0.05, n = 6), respectively, after 5 days of bombesin treatment. To test whether the bombesin regulation was mediated by the release of cholecystokinin (CCK), the specific CCK receptor antagonist L-364,718 (1 mg/kg body wt) was injected ip either alone, or 15 min before each bombesin injection for 5 days. Although the antagonist alone significantly reduced the mRNA concentrations for trypsin, chymotrypsin, and lysophospholipase to approximately 50%, it did not block the effects of bombesin on pancreatic digestive enzyme levels. These data therefore indicate that bombesin regulates pancreatic digestive enzyme mRNA and protein concentrations in a nonparallel manner; furthermore, CCK is not involved in mediating the bombesin effects on pancreatic gene expression.

A cholecystokinin-metabolizing enzyme in rat intestine.

Acid extracts of rat intestine contain a material which metabolizes cholecystokinin-33 (CCK-33) to CCK-12. Soybean trypsin inhibitor had little effect on CCK metabolism by the intestinal material. The molecular weight of the CCK-metabolizing activity, estimated by gel filtration, was 34,000. These data suggest rat intestine contains a nontrypsin CCK-metabolizing enzyme. Results from gel filtration also suggest that large CCK forms can be artifactually degraded to smaller ones during chromatography.

Effects of selective cholecystokinin antagonists L364,718 and L365,260 on food intake in rats.

The selective type A and B cholecystokinin (CCK) receptor antagonists L364,718 and L365,260 were used to identify the receptor subtype that mediates the satiety effect of endogenous CCK. Male rats (n = 12-13/group), fed ground rat chow ad lib, received L364,718 (0, 1, 10, 100, or 1000 micrograms/kg IP) or L365,260 (0, 0.1, 1, 10, 100, 1000, or 10,000 micrograms/kg IP) 2 h after lights off, and food intake was measured 1.5, 3.5, and 5.5 h later. L364,718 significantly stimulated 1.5-h food intake by more than 40% at 10 micrograms/kg and higher doses; cumulative intake at 3.5 and 5.5 h remained elevated by about 20% at 1000 and 100 micrograms/kg of L364,718, respectively. In contrast, L365,260 had no significant stimulatory effect on feeding at any dose. The potency of L365,260 for antagonizing gastrin-stimulated gastric acid secretion was examined in unanesthetized rats. Male rats (n = 14), prepared with gastric and jugular vein cannulas, received doubling doses of gastrin (G-171) (0.16-5 nmol/kg/h IV), each dose for 30 min, and gastric juice was collected for each 30-min period. G-171 stimulated gastric acid output dose dependently; the minimal effective dose was 0.16 nmol/kg/h, while maximal output (5-fold above basal) occurred at 5 nmol/kg/h. L365,260 (0, 1, 10, 100, 1000, or 10,000 micrograms/kg IV), administered 30 min before continuous infusion of G-171 (1.25 or 5 nmol/kg/h), significantly inhibited acid output only at 10,000 micrograms/kg; cumulative 60-min output was decreased by 60%. These results suggest that CCK acts at CCK-A receptors to produce satiety during the dark period in ad lib-feeding rats.

Mechanism of bombesin-induced pancreatic secretion in unanesthetized rats.

It is unclear whether stimulation of pancreatic enzyme secretion by intravenously administered bombesin is a direct effect on acinar cells or is mediated by release of CCK; this distinction is important for defining the potential role of bombesin-like peptides as regulators of pancreatic secretion. The role of CCK in bombesin-induced pancreatic secretion was examined in rats using CCK radioimmunoassay and the CCK receptor antagonist L-364,718. A biphasic pancreatic response occurred to sequential doubling doses of bombesin (31 to 2000 pmol/kg/h, each for 30 min; n = 9 rats); amylase secretion increased to peak at 250 pmol/kg/h (11.5 +/- 1.7 kU/30 min; 4.2 +/- 0.6 kU/30 min, basal) and then declined to basal levels at 2000 pmol/kg/h. The ED50 dose of bombesin for stimulation was 31 pmol/kg/h, and the maximal response did not differ significantly from that to exogenous CCK-8 (10.6 +/- 1.5 kU/30 min) in the same rats. When single doses of bombesin were infused for 2 h (31, 62, 125, 250 pmol/kg/h; one dose per day; order randomized; n = 8), a similar dose-response relationship was seen, both for peak amylase response and cumulative output over basal. L-364,718 (0.5 mg/kg IV) had no effect on the pancreatic response to ED50 or maximal doses of bombesin. Neither dose of bombesin altered plasma CCK levels. In contrast, other stimulants of pancreatic secretion (food ingestion, soybean trypsin inhibitor) caused marked elevations in plasma CCK levels. These results indicate that the potent stimulation of pancreatic secretion by exogenous bombesin in rats is not mediated by CCK, similar to findings in humans.

Structure and receptor binding of PYY analogs.

Differences in the structure of PYY and two important analogs, PYY [3-36] and [Pro34]PYY, are evaluated. Y-receptor subtype ligand binding data are used in conjunction with structural data to develop a model for receptor subtype selective agonists. For PYY it is proposed that potent binding to Y1, Y4 and Y5 receptors requires the juxtaposition of the two termini while Y2 binding only requires the C-terminal helix. Further experiments that delineate between primary and tertiary structure contributions for receptor binding and activation are required to support the hypothesis that tertiary structure is stable enough to influence the expression of PYY's bioactivity.

Chemical characterization of rat cholecystokinin-58.

Cholecystokinin-58 (CCK-58) was purified from rat intestines using an extraction method that yields large amounts of this peptide. Greater than 30% of total CCK immunoreactivity eluted before CCK-39 upon gel permeation chromatography (Sephadex G-50) if extracts were loaded onto Sep Pak cartridges before freezing. If the extracts were frozen and stored at -70 degrees C for six weeks, only 20% of the material eluted in this region and total immunoreactivity was reduced by 50%, suggesting that proteases were active under these storage conditions. This early eluting peak was purified by reverse phase and ion-exchange HPLC to a single absorbance peak. Microsequence analysis of this peak detected AVLRPDSEP which is the amino terminus of rat CCK-58 predicted from the rat preprocholecystokinin cDNA. Because degradation of CCK-58 occurred in these extracts, it is possible that CCK-58 is the predominant molecule form in the rat small intestine.

Effects of potent bombesin antagonist on exocrine pancreatic secretion in rats.

Recent synthesis of specific, potent bombesin receptor antagonists allows examination of the role of bombesin-like peptides in physiological processes in vivo. We characterized effects of [D-Phe6]bombesin(6-13)-methyl-ester (BME) on pancreatic enzyme secretion stimulated by the C-terminal decapeptide of gastrin releasing peptide (GRP-10), food intake, and diversion of bile-pancreatic juice in rats. In isolated pancreatic acini, BME had no agonistic effects on amylase secretion but competitively inhibited responses to GRP-10, yielding a pA2 value of 8.89 +/- 0.19. In conscious rats with gastric, jugular vein, bile-pancreatic, and duodenal cannulas, basal enzyme secretion (bile-pancreatic juice recirculated) was not affected by the antagonist. Maximal amylase response to GRP-10 (0.5 nmol/kg/h) was inhibited dose dependently by BME, reaching 97% inhibition at a dose of 400 nmol/kg/h. The dose response curve of amylase secretion stimulated by GRP-10 was shifted to the right by 40 nmol/kg/h BME, but maximal amylase response was unaltered, suggesting competitive inhibition in vivo. Liquid food intake and bile-pancreatic juice diversion caused substantial increases in amylase secretion; neither response was altered during administration of 400 pmol/kg/h BME. These results demonstrate that BME is a potent, competitive antagonist of pancreatic responses to bombesin-like peptides in vitro and in vivo. Lack of effect of BME on basal pancreatic secretion or responses to liquid food intake or diversion of bile-pancreatic juice in rats suggests that endogenous bombesin-like peptides do not act either directly or indirectly to mediate these responses.

Effect of somatostatin immunoneutralization on gastric acid and pancreatic enzyme secretion in anesthetized rats.

The involvement of somatostatin in urethane-anesthesia-evoked suppression of gastric acid secretion has been described. The present study has examined the role of endogenous somatostatin in diminished pancreatic enzyme secretion during anesthesia, while monitoring acid secretion concurrently. Rats were anesthetized with either urethane or sodium pentobarbital. An indwelling catheter was placed into the right jugular vein. The esophagus and the pylorus were ligated, and the stomach was perfused with saline. The common bile duct was ligated at the hepatic hilum, and cannulated at the duodenal end of the duct for collecting pure pancreatic juice. Purified somatostatin monoclonal antibody (CURE.S6) or control antibody (keyhole limpet hemacyanin, KLH) was injected iv in increasing doses (0.05; 0.15; 0.5; and 1.5 mg) every 30 min (n = 6). Gastric acid and pancreatic amylase secretions were measured. The effect of the antibodies on CCK-8-stimulated (0.25-2.50 nmol/kg/h) pancreatic amylase secretion was also tested. During urethane anesthesia somatostatin antibody induced a dose-dependent increase in acid output, while control antibody did not change it. Basal pancreatic amylase secretion was not affected by either somatostatin or by control antibody. Pancreatic secretory responses to high but not to low doses CCK-8 were found to be significantly increased following immunoneutralization of somatostatin. In sodium pentobarbital-anesthetized rats somatostatin antibody stimulated basal acid secretion but did not affect basal pancreatic amylase secretion. Our data indicate that in anesthetized rats endogenous somatostatin mediates suppression of basal gastric acid secretion but not that of basal pancreatic amylase secretion, and this action does not depend on the type of anesthesia. Furthermore, endogenous somatostatin may play a physiological role in modulating stimulated pancreatic enzyme secretion in this species.

Exocrine pancreatic secretion in response to a new CCK-analog, CCK33 and caerulein in dogs.

We studied the relative molar potencies of a newly synthetized cholecystokinin nonapeptide [Thr28,Nle31]CCK[25-33], natural porcine CCK33 and synthetic caerulein in conscious dogs with chronic gastric and pancreatic fistulas. Peptides were dissolved in albumin-containing solutions to prevent loss from solution. The three peptides were found to be equipotent on a molar basis in stimulating exocrine pancreatic secretion. As [Thr28,Nle31]CCK9 is a peptide less susceptible to oxidation than other forms of CCK, it is an interesting analog with many uses for medical and biological research.

Development of cholecystokinin radioimmunoassay using synthetic CCK-10 as immunogen.

Using an antiserum generated against synthetic CCK-10, we have developed a radioimmunoassay specific for the carboxyl-terminus of cholecystokinin (CCK). Three rabbits were immunized with synthetic sulfated carboxy-terminal CCK decapeptide (CCK-10) conjugated to keyhole limpet hemocyanin. Using 125I-CCK-39 prepared by the Iodogen method as a tracer, we found that all immunized rabbits produced antibodies against the conjugate. Antiserum R016 had the highest titer (1:225,000 after four immunizations) and was studied most extensively. R016 recognizes all molecular forms of CCK, including unsulfated and oxidized forms, but has negligible cross-reactivity with gastrin and other peptides. Using CCK-8 as a standard, the assay has a minimum detection limit of 0.5 pM and an ED50 of 11.5 pM. Serial dilutions of water/acid extracts of canine intestine were parallel to serial dilutions of sulfated CCK-8, CCK-33 and CCK-39. The assay was used to measure CCK concentrations in canine plasma after C18 Sep-Pak extraction; the concentration of immunoreactive CCK increased from a basal value of 7.8 +/- 1.0 to 9.5 +/- 1.2 and 11.1 +/- 1.2 pM 30 and 60 min postprandially (P less than 0.05 by paired analysis). This sensitive and uniquely specific CCK radioimmunoassay should be useful in characterizing several aspects of CCK physiology and the method for generating CCK antisera should be of value to other investigators.

Effects of chronic administration of somatostatin on rat exocrine pancreas.

We studied the effects of somatostatin on synthesis of pancreatic DNA, RNA and protein and on pancreatic weight and contents of DNA, protein, amylase and chymotrypsinogen in rats. In short term synthesis studies, rats were injected with 100 micrograms . kg-1 somatostatin or 0.15 M NaCl (control) at times 0, 8 and 16 h. Eight rats from each treatment group were killed 2, 4, 8, 12, 16, 20 and 24 h after beginning treatment. Incorporation rates in vivo of [3H]thymidine into DNA, [3H]uridine into RNA and [14C]phenylalanine into total protein were significantly depressed by somatostatin. In long term studies, four groups of 12 rats were injected every 8 h for 5 days with 0.15 M NaCl or 11, 33 or 100 micrograms . kg-1 somatostatin. Body weight was unaffected but pancreatic contents of DNA, protein and enzymes were significantly decreased by somatostatin. Administration of somatostatin inhibits DNA, RNA and protein synthesis in exocrine pancreas with resulting decreases in DNA and enzyme contents.

CCK stimulates growth of six human pancreatic cancer cell lines in serum-free medium.

The growth responses of six human pancreatic cancer cell lines (SW-1990, PANC-1, MIA PaCa-2, BxPC-3, RWP-2 and CAPAN-2) to cholecystokinin (CCK) were evaluated in serum-free medium (SFM). In each experiment cells were initially plated in media containing fetal calf serum (FCS) grown for 48-72 h, and then washed with saline. Cells were incubated for an additional 72 to 96 h in medium devoid of FCS in the absence (control) or presence of synthetic CCK analogue (Thr4,Nle7)CCK9 (10(-13) to 10(-9) M), or CCK8 (10(-12) to 10(-9) M), or CCK39 (10(-12) to 10(-9) M). Viable cell counts were performed with a hemocytometer. Growth of each cell line was stimulated in the presence of CCK in serum-free medium, although the magnitude of responses differed. The concentrations of (Thr4,Nle7)CCK9 which stimulated the greatest increase in cell counts as compared to controls for each cell line were: SW-1990, 39% (10(-12) M, P less than 0.05); PANC-1, 45% (10(-9) M, P less than 0.005); MIA PaCa-2, 42% (10(-12) M, P less than 0.005); BxPC-3, 32% (10(-13) M, P less than 0.05); RWP-2, 37% (10(-11) M, P less than 0.005). Maximal response to CCK8 occurred at the 10(-9) M dose for each cell line: MIA PaCa-2, 40% (P less than 0.025); PANC-1, 85% (P less than 0.001); RWP-2, 68% (P less than 0.001) and CAPAN-2, 52% (P less than 0.001). The maximal increase in cell count with CCK39 ranged from 44-74% and occurred with either 10(-11) or 10(-10) M. CCK8 in SFM also stimulated cell growth as well as or better than FCS alone in three out of four pancreatic cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of neurotensin with caerulein or secretin on digestive tract growth in rats.

Because neurotensin may potentiate exocrine pancreatic secretory responses to cholecystokinin and secretin, we examined interactions of neurotensin with caerulein or secretin on growth of pancreas, stomach, small intestine, and colon. Rats were injected with saline, neurotensin (100 micrograms/kg), caerulein (0.67 micrograms/kg), secretin (100 micrograms/kg), or neurotensin plus caerulein or secretin every 8 h for 5 days. Pancreas, stomach, small intestine, and colon were weighed and assayed for DNA, protein, and digestive enzymes. Although neurotensin increased pancreatic weight (P less than 0.01), DNA (P less than 0.01), and protein content (P less than 0.05) by 20-30%, it had less than additive effects on responses to caerulein and secretin. Neurotensin had no effects on pancreatic enzymes or on responses to caerulein or secretin. Neurotensin alone had no effects on growth of the oxyntic gland area or antrum but inhibited increases in antral weight, DNA, and protein caused by secretin. Neurotensin increased small intestine weight (9%, P less than 0.05) and protein content (23%, P less than 0.01). Secretin also increased weight (22%), DNA (29%), and protein content (48%) of the small intestine (all P less than 0.01), but neurotensin and secretin together had less than additive effects. Our results suggest that neurotensin inhibits rather than potentiates certain growth effects of caerulein or secretin on the pancreas and other organs.

Negative control by Sandostatin on pancreatic and duodenal growth: a possible implication of insulin-like growth factor I.

This study was undertaken to evaluate the effects of Sandostatin, a potent somatostatin analogue, on pancreatic and intestinal growth and plasma and pancreatic levels of insulin-like growth factor I, a known growth factor. Rats weighing 320-330 g, equipped with an intravenous cannula were infused with either bovine serum albumin or Sandostatin at a dose of 5 micrograms kg-1 h-1 for 7 days. Sandostatin caused significant reductions in pancreatic and intestinal weights accompanied by decreases in total DNA, RNA in both organs and total protein in the intestine while total pancreatic enzymes were increased. Plasma cholecystokinin and insulin-like growth factor I were reduced whereas total insulin-like growth factor I pancreatic content was increased. It is suggested that Sandostatin may reduce growth of these two organs by decreasing cholecystokinin and insulin-like growth factor release and their specific effects at the pancreatic and duodenal cellular level.

Cholecystokinin, vasoactive intestinal peptide and peptide histidine methionine responses to feeding in anorexia nervosa.

Anorexia nervosa (AN) is a syndrome of unknown cause characterized by voluntary starvation. Cholecystokinin has been implicated as a neuroendocrine regulatory factor in control of satiety. Relatively little information is known about gastrointestinal hormone responses to feeding in subjects with anorexia nervosa. In the present studies, we examine fasting and postprandial levels of cholecystokinin (CCK), vasoactive intestinal peptide (VIP) and peptide histidine methionine (PHM) in anorexia nervosa subjects and in control individuals. Results of these studies indicate that plasma CCK response to a liquid meal (Ensure Plus) in untreated AN subjects was distinctly different from that observed in healthy controls, both in terms of temporal pattern of peptide released and the amount of CCK secreted into the circulation. Peak levels of CCK release occurred at 30 min following meal ingestion in AN patients and at 60 min in control subjects. Integrated CCK release in untreated AN patients was approximately twice that measured in control individuals. Renutrition therapy was associated with reversion of the pattern of CCK release to that observed in control subjects. Plasma VIP levels were unchanged following meal ingestion in both control and anorexic subjects. In contrast, PHM levels in AN subjects were significantly greater than that observed in control individuals. The pattern of PHM release following liquid meal ingestion was similar to that observed with plasma CCK; namely, peak release of peptide was observed at 30 min which was significantly greater than corresponding control values (P less than 0.05). In conclusion, these results demonstrate distinctive differences in plasma CCK and PHM levels in response to feeding in AN subjects when compared to control individuals. These findings suggest that the earlier and greater rise in plasma CCK levels in AN subjects following meal ingestion may contribute to the abnormal sensation of satiety in this condition.

Dose-related involvement of CCK in bombesin-induced pancreatic growth.

We examined the role of CCK in bombesin-induced pancreatic growth in rats using the CCK receptor antagonist L-364,718. Rats (155 +/- 1 g, 8-10 per group) received subcutaneous injections every 8 h for 5 days with bombesin (0.6, 1.7 and 5 nmol/kg) or bombesin in combination with L-364,718 (1 mg/kg). After 5 days the pancreas was removed and pancreatic weight, protein content, DNA, amylase and chymotrypsin contents were determined. Bombesin produced a significant increase (48-475%) of pancreatic weight, tissue contents of protein, DNA, amylase and chymotrypsinogen (F = 82, P less than 0.001). When a large dose of bombesin (5 nmol/kg) was combined with L-364,718 a significant inhibition (up to 70%) of all tissue parameters was observed (P less than 0.001). L-364,718 did not affect the growth response to a small dose of bombesin (0.6 nmol/kg). Plasma CCK levels 15 min after a single injection of bombesin (0.6, 1.7 and 5 nmol/kg) were significantly increased in response to the 5 nmol/kg dose (2.0 +/- 0.7 to 3.4 +/- 0.8 pM, F = 6.9, P less than 0.01). No increases of CCK plasma levels were found in response to the 0.6 and 1.7 nmol/kg doses of bombesin, corresponding to the lack of effects of L-364,718 on growth parameters at these doses. Measuring the time-course of CCK plasma levels after a single injection of 5 nmol/kg bombesin revealed an increase from basal values of 1.4 +/- 0.3 pM to maximal levels of 3.5 +/- 0.5 pM after 15 min (F = 7.1, P less than 0.001). Values returned to basal after 60 min. These results suggest that low doses of bombesin act directly at the acinar cell or through release of non-CCK growth factors whereas high doses of bombesin act in part through CCK release.

Role of gastrin and cholecystokinin receptors in regulation of peptone-stimulated gastric acid secretion in conscious rats.

With the availability of selective gastrin/CCKB (L365,260) and CCKA (L364,718) receptor antagonists the present study was designed to investigate the role of gastrin and cholecystokinin (CCK) receptors in meal-stimulated gastric acid secretion. Gastric acid output was measured by continuous intragastric titration in conscious rats. Vehicle (dimethylsulfoxide/saline, 3:1), L365,260 (3 or 9 mg/kg), or L364,718 (1 mg/kg) was given by i.v. bolus injection. Basal acid output was strongly inhibited by both doses of L365,260 while L364,718 had no effect. Intragastric peptone (4%, w/v) increased acid secretion 40-65% of the response to a maximal dose (2.5 nmol/kg per h) of gastrin-17. L365,260 completely abolished gastrin-17 stimulated acid secretion and partially inhibited peptone-induced acid secretion. Blockade of CCKA receptors by L364,718 did not affect peptone-stimulated acid output. This study demonstrates that gastrin/CCKB receptors are important in regulating basal acid secretion in the conscious rat while CCKA receptors do not appear to influence basal or peptone-stimulated gastric acid secretion. Blockade of gastrin/CCKB receptors partially inhibits intragastric meal-stimulated acid secretion indicating that the gastrin/CCKB receptor has a physiological role as mediator of food-stimulated acid secretory response in conscious rats.

Effect of neurotensin on pancreatic and gastric secretion and growth in rats.

Plasma levels of neurotensin are increased by ingestion of fat, making this peptide a candidate for mediation of pancreatic adaptation to dietary fat. We examined the effects of doses of neurotensin on pancreatic secretion and growth to determine whether doses stimulating secretion also increased pancreatic growth and lipase content in rats. Because neurotensin inhibits gastric secretion in other species, we also measured its effects on gastric secretion and growth. In conscious rats, neurotensin (33, 100, and 300 micrograms kg-1 subcutaneously in gelatin) produced dose-related increases in pancreatic amylase output and decreases in basal gastric secretion. Duration of acid inhibition by neurotensin was longer than stimulation of amylase secretion. Chronic administration of the same doses of neurotensin to groups of rats every 8 h for 5 days produced small but statistically significant trophic effects on the pancreas. The highest dose of neurotensin significantly increased pancreatic weight (16%) and content of DNA (12%), protein (17%), and chymotrypsinogen (60%) but did not affect amylase or lipase content. There were no effects of neurotensin on any measurement of oxyntic or pyloric gland area growth. We conclude that although neurotensin stimulates both pancreatic secretion and growth, it is not the mediator of fat-induced pancreatic adaptation.

Comparative effects of caerulein on food intake and pancreatic secretion in dogs.

We compared effects of the CCK analog caerulein on feeding and pancreatic secretion. Nine fasted mongrel dogs with gastric and pancreatic fistulas received scalar doses of caerulein (0, 6.25, 12.5, 25, 50, 100, 200, 400 pmol/kg-hr, each for 30 min). The D50 dose for stimulation of pancreatic secretion was 15 pmol/kg-hr. Effects of intravenous caerulein (0 to 800 pmol/kg-hr; 15 min before and during a 45 min test meal) on food intake were examined in 8 beagles under 4 feeding conditions: 1 meal/day (22 hr fast), 2 meals/day (4 hr fast), 2 meals/day (19 hr fast), and after ad lib access to food followed by a 4 hr fast. The lowest doses that inhibited feeding were: 400 pmol/kg-hr for feeding condition, 200 pmol/kg-hr for and, and 150 pmol/kg-hr for. We conclude: the potency of caerulein for inhibition of food intake is dependent upon feeding condition; these results do not support a role for CCK as a satiety hormone, since the lowest dose of caerulein for inhibition of feeding was 10 times larger than the D50 dose of caerulein for stimulation of pancreatic secretion.

Bile and pancreatic juice replacement ameliorates early ligation-induced acute pancreatitis in rats.

BACKGROUND: In healthy rats, combined bile and pancreatic juice diversion from gut has a synergistic rather than additive effect on stimulation of exocrine pancreatic protein secretion. We hypothesized that exclusion of combined bile and pancreatic juice from gut exacerbates bile and pancreatic-duct ligation-induced acute pancreatitis in rats to a greater extent than exclusion of either bile or pancreatic juice alone. METHODS: Bile and pancreatic juice (obtained fresh from donor rats) were replaced, separately or together, via a duodenal fistula beginning immediately before 6 hours of duct ligation. Pancreatic morphologic changes were evaluated with an acute pancreatitis histology score and morphometric quantitation of acinar-cell necrosis. Plasma amylase and cholecystokinin concentrations and pancreatic subcellular distribution of cathepsin B activity were determined. Characteristics of bile and pancreatic juice obtained from donor rats were also studied. RESULTS: Combined bile and pancreatic juice replacement limited the increase in acute pancreatitis histology score by 77%, acinar cell necrosis by 95%, hyperamylasemia by 77%, and hypercholecystokininemia by 99%, while preventing subcellular redistribution of cathepsin B. Amelioration of pancreatic morphologic changes was significantly greater with combined bile and pancreatic juice replacement than with replacement of either bile or pancreatic juice alone. CONCLUSION: In this experimental corollary of early gallstone-induced acute pancreatitis, combined bile and pancreatic juice exclusion from gut contributes to disease pathogenesis to a greater extent than exclusion of either bile or pancreatic juice alone.