Pancreatic regeneration after partial pancreatectomy.

The ability of the pancreas to regenerate and the effects of trophic hormones on regeneration of the pancreas after partial pancreatectomy are not completely understood. We investigated the effects of the trypsin inhibitor FOY-305 (an agent that stimulates endogenous cholecystokinin) on pancreatic regeneration after partial pancreatectomy in rats. FOY-305 or water was administered for either 13 days or 27 days by gavage feeding, after sham operation or partial pancreatectomy (n = 6 to 8 animals per group). FOY-305 stimulated hypertrophy of the pancreatic remnant at 13 days; prolonged treatment for 27 days produced both hypertrophy and hyperplasia. The magnitude of pancreatic growth after FOY-305 administration was significantly greater at 27 days in the pancreatic remnant than growth of the equivalent pancreatic segment (duodenal and parabiliary) in sham-operated rats treated with FOY-305. Our results suggest that endogenous cholecystokinin released by FOY-305 stimulates regeneration after partial pancreatectomy. The pancreatic remnant is more sensitive to trophic stimulation in comparison to the normal pancreas. FOY-305 may be a useful agent in the treatment of pancreatic insufficiency after extensive subtotal pancreatectomy or chronic pancreatitis.     

Effect of CCK receptor antagonist on growth of pancreatic adenocarcinoma.

Cholecystokinin (CCK) exerts an influential effect on the growth of normal pancreas. It is postulated that carcinoma arising from the pancreas may retain some normal pancreatic properties as far as hormone dependency is concerned. In an effort to examine the effect of CCK on the growth of pancreatic cancer, we evaluated the effect of CCK receptor antagonist on the growth of a transplantable adenocarcinoma of the pancreas. For this study we utilized three groups of hamsters with adenocarcinoma of the pancreas transplanted subcutaneously on the right flank. Group I (n = 15) served as control. Group II (n = 15) received CCK receptor antagonist (L-364,718), 0.1 mg/100 g body wt subcutaneously BID. Group III received CCK receptor antagonist in the same dose but treatment was started after tumors became palpable. All animals were examined daily. Latency for tumor growth, tumor size, and body weight were recorded. Animals were sacrificed after 3 weeks and final tumor volume and weight were measured. CCK receptor antagonist (L-364,718) significantly reduced pancreatic carcinoma growth when given immediately after transplantation and also in animals with established tumor. However, this inhibitory effect of L-364,718 was only partial and effective only for a brief time. This finding suggests CCK may have only a minimal influence on the biologic behavior of exocrine pancreatic cancer.     

Cholecystokinin augmentation of 'surgical' pancreatitis. Benefits of receptor blockade

The management of acute pancreatitis has not changed appreciably throughout several decades. Recent evidence has suggested that cholecystokinin (CCK) may play an important role in pancreatic disease. Investigations into the precise role of CCK in acute pancreatitis have been hampered by the lack of a specific CCK receptor antagonist. Using a newly described, highly potent and specific CCK receptor antagonist, L-364,718, the effect of CCK in two models of acute "surgical" pancreatitis was examined: (1) the bile salt ductal perfusion model in the rat and (2) a traumatic model in the guinea pig. At a suboptimal dose for pancreatic enzyme secretion (25 pmol/kg/h), CCK was found to potentiate the severity of the ensuing pancreatitis in both models. Continuous CCK receptor blockade with L-364,718 (25 nmol/kg/h) improved biochemical, morphologic, and survival indexes. This study suggests that physiologic levels of CCK play an important permissive role in the evolution of acute pancreatitis. The use of L-364,718 as an investigative probe or therapeutic tool for acute pancreatitis is worthy of further consideration.     

The influence of truncal vagotomy or surgical sympathectomy on the pancreatic trophic effect of trypsin inhibitor upon normal rats and major pancreatectomized rats

The influences of truncal vagotomy or surgical sympathectomy on the pancreatic trophic effect of oral administration of synthetic trypsin inhibitor (FOY-305) were examined upon normal rats and 85% major pancreatectomized rats. On normal rats, oral administration of trypsin inhibitor increased pancreatic weight, DNA content RNA content, protein content, pancreatic weight/DNA, RNA/DNA and protein/DNA. This pancreatic trophic effect seemed to be consisted of hyperplasia and hypertrophy of pancreatic acinar cell. Under truncal vagotomy or surgical sympathectomy, this trophic effect was not diminished. On major pancreatectomized rats, oral administration of trypsin inhibitor also caused pancreatic trophic action, consisted of hyperplasia mainly. And truncal vagotomy or surgical sympathectomy did not decrease this action. These results suggested that oral administration of trypsin inhibitor might be a beneficial method for functional recovery of remnant pancreas after major pancreatectomy even under the denervated state.     

Effects of the specific cholecystokinin antagonist L 364,718 in experimental acute pancreatitis in the rat

Cholecystokinin (CCK) has been suggested to be involved in the pathogenesis of acute pancreatitis. To test this hypothesis, we administered the highly selective and specific CCK receptor antagonist L 364,718 to rats in which acute experimental pancreatitis had been induced by the use of transduodenal pancreatic duct injection of taurocholate. It was, however, found that despite the use of L 364,718 at a high dose level (1 mg/kg body weight given three times), and also given prior to induction of pancreatitis, the mortality rate, the serum or ascites amylase activity, the pancreatic concentrations of lysosomal enzymes or the morphology of the pancreas were not affected. This suggests that the CCK receptors are not involved in the pathogenesis of acute pancreatitis in this experimental model, and, consequently, that CCK receptor antagonists have no place in the therapy of this condition.     

Stimulation of pancreatic growth. Distal small bowel resection mediated by increased levels of cholecystokinin.

SUMMARY BACKGROUND DATA: Distal, but not proximal, resection of the small bowel induces growth of rat pancreas, but the mechanism of this phenomenon is poorly clarified. The release of cholecystokinin (CCK), a trophic hormone for the pancreas, is regulated by a negative-feedback control of bile salts. The ileum is a major site for reabsorption of bile salts. Thus, unsuppressed release of CCK due to deleted reabsorption of bile salts after distal small bowel resection may be a cause of pancreatic growth. In this study, the authors have examined whether pancreatic growth after distal small bowel resection was mediated by endogenous CCK and have determined whether the mechanism of this pancreatic growth required biosynthesis of polyamine. METHODS: Male Fischer 344 rats underwent 70% distal small bowel resection or transection of the ileum. Beginning 48 hours after surgery, CR1409 (a CCK-receptor antagonist) or saline was injected subcutaneously every 8 hours. All animals were pair-fed and killed 14 days after surgery. The pancreas from each rat was excised, weighed, and assayed for DNA, RNA, protein, and polyamine content. RESULTS: Distal small bowel resection increased pancreatic weight, DNA, RNA, and protein, as well as polyamine levels; all of these increases were significantly suppressed by CR1409. Postprandial release of CCK into the circulation was significantly increased after distal small bowel resection. CONCLUSIONS: Pancreatic growth after distal small bowel resection was associated with the stimulation of polyamine biosynthesis; growth appeared to be mediated by endogenous CCK.     

Pancreatic growth after pancreatico-biliary diversion does not increase the capacity to secrete amylase

BACKGROUND/AIM: Cholecystokinin (CCK) stimulates secretion and evokes a hyperplastic response in the rat pancreas. The aims of this study were to measure the effect of chronic hyperCCKemia induced by pancreatico-biliary diversion (PBD) on pancreatic enzyme concentrations, on amylase secretion by dispersed acinar cells, and on the CCK-stimulated secretion of pancreatic juice in PBD-operated rats. MATERIAL AND METHODS: Forty-five Sprague-Dawley male rats had either PBD or sham operation 4 weeks before sacrifice or additional experiments. In the first study, 25 rats (13 PBD and 12 sham-operated rats) were either freely fed or fasted overnight before sacrifice. The pancreas was dissected out, weighed and analyzed. In the second study, the rats (6 PBD and 7 sham-operated rats) were fasted overnight before pancreatic acini were prepared. Secretion of amylase during stimulation of acini with CCK-8S and carbachol was measured. In the third study (5 sham-operated and 4 PBD rats), the rats were fasted overnight before basal and CCK-stimulated secretion was measured in vivo. RESULTS: PBD-operated rats showed a threefold increase in pancreatic wet weight with increased contents of DNA, protein and water. The concentration of pancreatic amylase was 7-12% of that found in control animals. The concentrations of trypsin and lipase were also lowered. Stimulation of dispersed pancreatic acini with CCK-8S or carbachol resulted in secretion of amylase to a similar extent in PBD and sham-operated rats. There was no difference in the secretion of pancreatic juice in response to CCK, but although the output of amylase from PBD-operated rats increased with CCK, it remained at a low level throughout the study period. CONCLUSION: PBD evoked hyperplastic changes in the rat pancreas and decreased the concentrations of amylase, trypsin and lipase. However, the capacity of acinar cells to secrete amylase remained intact. The stimulated pancreatic secretion was not changed in volume, but the output of amylase was low in PBD-operated rats. The findings are consistent with the idea that the enlargement of the pancreas following PBD does not improve the secretory capacity.     

内源性一氧化氮对急性胰腺炎大鼠胰腺微血管通透性的影响

目的 探讨内源性一氧化氮（NO）对急性坏死性胰腺炎大鼠胰腺炎大鼠胰腺微血管通透性的影响。方法 以5%牛磺胆酸钠溶液胰胆管注射（1ml/kg）制成大鼠急性坏死性胰腺炎模型,以工具药L-硝基精氧酸（L-NNA）和内源性NO的阻断Evans Blue的漏出代表微血管的通透性,观察内源性NO对胰腺组织损伤程度、胰腺内Evans Blue漏出等的影响。结果 牛磺胆酸钠胆管注射造成大鼠胰腺组织明显坏死和炎性细胞浸润,以及血清淀粉酶浓度升高、胰腺湿/干重比率产加和明显的胰腺组织内Evans Blue积聚。以L-NNA（12.5mg/kg）阻断内源性NO后,胰腺组织坏死和炎性细胞浸润进一步加重,并使血清淀粉酶浓度升高,胰腺湿/干重比率增加,Evans Blue的漏出率也较之单纯胰腺炎组大鼠明显增加。结论 内源性NO具有胰腺保护作用,其保护机制可能与维持胰腺微血管的完整性有关。     

Effect of somatostatin analogue and cholecystokinin receptor antagonist on bile-induced acute canine pancreatitis.

To determine whether a synthetic somatostatin analogue, octreotide, and a cholecystokinin receptor antagonist, L-364,718, may be beneficial in acute pancreatitis, 33 dogs were assigned to four groups. Each dog underwent laparotomy with injection of autologous bile into the dorsal pancreatic duct. Thirty minutes after the induction of pancreatitis, Group 1 received a subcutaneous injection of octreotide (200 micrograms/kg), Group 2 received an equal volume of the octreotide carrier, Group 3 received an hourly intravenous bolus of L-364,718 (60 micrograms/kg), and Group 4 received an equal volume of the L-364,718 carrier. Hemodynamic profiles, arterial blood gases, plasma glucose, and serum amylase were obtained before laparotomy, at bile injection, and at hourly intervals. The pancreas was removed after 8 hours for gross evaluation, measurement of water content, and histologic examination. A significant decrease in cardiac index and a significant increase in serum amylase and pancreatic edema occurred in all four groups 8 hours after the induction of pancreatitis (P less than 0.05), but there was no statistical difference between any group. Likewise, there was no difference in gross or histologic changes in the pancreas of any group. The somatostatin analogue, octreotide, and the cholecystokinin receptor antagonist, L-364,718, did not ameliorate the effects of severe, bile-induced pancreatitis in dogs.     

Experimental evidence for a vagally mediated and cholecystokinin-independent enteropancreatic reflex.

Truncal vagotomy results in diminished pancreatic protein secretion in response to intraduodenal fat. This diminished secretion may be due, at least in part, to interruption of the vagal reflexes between the intestine and the pancreas that work independently of cholecystokinin (CCK). In five dogs with chronic pancreatic fistulas, plasma CCK concentrations and pancreatic protein secretion in response to an intestinal stimulant (intraduodenal oleate) and to two exogenous peptides (bombesin and CCK-33) were compared before and after bilateral truncal vagotomy. Vagotomy decreased integrated protein secretion by about 50% in response to intraduodenal oleate. In contrast, protein output in response to parenteral stimuli increased after vagotomy. Integrated output of CCK in response to intraduodenal oleate or to exogenous bombesin or CCK was not significantly affected by vagotomy, but release of pancreatic polypeptide was decreased significantly in response to all stimuli after truncal vagotomy. These data provide evidence that truncal vagotomy decreases pancreatic protein secretion in response to intestinal stimulants by interrupting enteropancreatic reflexes mediated by the vagus, while maintaining normal (or supranormal) sensitivity of the pancreas to endogenous and exogenous CCK.     

An experimental study on the effects of selected drugs on pancreatic regeneration after partial pancreatectomy

This study was undertaken to determine the effect of the single and combined administration of caerulein, hydrocortisone, and FOY-305 (camostat) on the regeneration of the remnant pancreas after a 90% pancreatectomy in rats. After undergoing either a sham operation or a 90% pancreatectomy, the rats were administered the three drugs either singly or in combination. After the rats were killed, the pancreas was weighed and examined for tissue amylase activity, tissue protein content and total DNA content. The results were as follows: In the sham operation group, the caerulein among three drugs produced a significant trophic effect. The trophic effect in the combined administration group was greater than that in the single administration group. In the 90% pancreatectomy group, of the three drugs administered, hydrocortisone produced the most significant trophic effect. The trophic effect in the combined administration group was greater than that in the single administration group. These data suggest that the trophic effect of caerulein is significant in mature pancreatic cells while that of hydrocortisone is an immature one and that an additive effect of the three drugs was observed.     

Duodenogastric reflux enhances growth and carcinogenesis in the rat pancreas.

Surgery for peptic ulcer disease may increase the risk of pancreatic cancer. The effect of duodenogastric reflux on pancreatic carcinogenesis was tested, and changes in the circulating levels of cholecystokinin (CCK) and gastrin were measured. Male Wistar rats (n = 40) weighing 250-300 g were randomized to undergo gastrotomy (control) or split gastrojejunostomy (to produce complete duodenogastric reflux) and then to receive azaserine (30 mg/kg/week intraperitoneally) or saline injections for 3 weeks. At 6 months, blood CCK was assayed and the pancreas was excised for quantitative estimation of atypical acinar cell foci (AACF), the precursor lesions of carcinoma. Rats that had undergone split gastrojejunostomy weighed 15-19 per cent less than controls (P < 0.05), but their relative pancreatic weight (mg pancreas per 100 g body-weight) was 52-60 per cent greater (P < 0.001). Acidophilic AACF occurred only in azaserine-treated rats with duodenogastric reflux. Although plasma CCK concentrations were unchanged, split gastrojejunostomy increased basal and postprandial gastrin levels by 98-175 per cent (P < 0.05). Duodenogastric reflux produces sustained hypergastrinaemia and promotes experimental pancreatic carcinogenesis.     

Pancreatic regeneration after subtotal distal resection in rats. Effects of bombesin and octreotide by the in vivo bromodeoxyuridine uptake technique.

Forty male Wistar rats were randomly allocated to four treatment groups after 90% distal pancreatectomy: group A (control) received saline (0.5 ml subcutaneously); group B received bombesin (BBS; 10 microg/kg intraperitoneally); group C received octreotide (2.5 microg/kg subcutaneously), and group D received BBS and octreotide. All substances were injected three times a day until sacrifice after 28 days. BBS increased pancreas weight (p = 0.003) and DNA synthesis (p < 0.001), as measured by a bromodeoxyuridine nuclear-labeling index (BrdU LI). The simultaneous administration of octreotide significantly decreases the remnant pancreas weight (p = 0.016) as compared to group B rats; however the BrdU LI is not significantly reduced in group D as compared to group B. BBS administration promotes regeneration of the remnant pancreas in terms of hypertrophy and hyperplasia. Although octreotide appears to significantly reduce the pancreatic weight increase induced by BBS, it does not reduce DNA synthesis and cell proliferation.     

Inhibition of the stimulated exocrine pancreas by absorbed amino acids

Intravenous infusion of amino acids is known to inhibit the stimulated pancreas and it has been suggested that this may act as a feedback mechanism in pancreatic regulation. To investigate this, chronic pancreatic fistula dogs were studied to determine if postprandial levels of hyperaminoacidemia inhibit the stimulated pancreas. Duplicate dose-response experiments using exogenous cholecystokinin (CCK) and intraduodenal amino acids were performed with and without a simultaneous intravenous infusion of mixed amino acids, which simulated postprandial hyperaminoacidemia. Significant (P < 0.05), though minor, inhibition of pancreatic responses to both endogenous and exogenous CCK was noted with the simultaneous infusion of amino acids. It was concluded that, while amino acids may exert some inhibitory influence on pancreatic secretion after absorption, this is unlikely to be an important physiological mechanism.     

Expression of epidermal growth factor receptor after partial pancreatectomy in adult rats: an immunohistochemical study.

The expression and localization of epidermal growth factor (EGF) were investigated immunohistochemically using an anti-EGF receptor antibody in the pancreas of partial pancreatectomized and sham-operated adult rats. In the sham-operated pancreas, immunoreactive products against EGF receptor were only slightly positive in the pancreatic acinar cells. In the partial pancreatectomized pancreas on the fifth day after operation, EGF receptor immunoreactivity was intensely positive in the acinar cells, in some cells lining the intercalated ducts and some basal cells of the acinus, but it was not detected in the pancreas when exogenous EGF was given to the rat after partial pancreatectomy for three days. The present results suggest that EGF receptor is expressed in the regenerating pancreatic tissue, and EGF could be involved in the mechanism of pancreatic regeneration in rats.     

区域动脉灌注5-FU诱导大鼠急性胰腺炎腺泡细胞凋亡及Caspase-3表达

目的 探讨区域动脉灌注（regional arterial infusion,RAI）5-氟尿嘧啶（5-fluorouracil,5-FU）对大鼠急性胰腺炎（acute pancreatitis,AP）胰腺腺泡细胞凋亡的影响及其对急性胰腺炎的治疗作用。方法 18只健康成年SD大鼠随机分成3组：对照组（C组）、急性胰腺炎组（AP组）和5-FU治疗组（5-FU组）。各组均行胃左动脉置管,AP组和5-FU组以大剂量雨蛙素（每小时腹腔注射50 μg/kg,连续6 h）诱导建立大鼠急性胰腺炎模型,对照组注射同等剂量的生理盐水。5-FU组在第一次腹腔注射雨蛙素1 h后立即区域动脉灌注5-FU（40 mg/kg）治疗,C组和AP组区域动脉灌注等量的生理盐水。建模成功后3 h取标本并处死大鼠,检测血淀粉酶浓度,RT-PCR法检测胰腺组织内TNF-α、IL-1β、IL-6 mRNA表达水平,胰腺标本送病理学检查,Western blotting法检测胰腺组cleaved Caspase-3的蛋白表达,同时TUNEL法检测大鼠胰腺腺泡细胞凋亡情况。结果 与AP组比较,5-FU组血淀粉酶浓度明显降低（P＜0.05）;胰腺组织内TNF-α、IL-1β、IL-6  mRNA表达水平下降（P＜0.05）;胰腺组织病理学改变减轻;胰腺组织cleaved Caspase-3的蛋白表达增加;胰腺腺泡细胞凋亡增加（P＜0.05）。结论 区域动脉灌注5-FU对大鼠急性胰腺炎有改善作用,其作用机制可能与诱导胰腺腺泡细胞凋亡有关。     

Trophic effects of gastrin on the exocrine pancreas in rats

In three groups of hypergastrinemic rats with gastrojejunostomy and gastric antrum transplanted to the colon (AT), pancreatic structure and function were studied 2, 6, or 16 weeks postoperatively. Fasting serum gastrin was 658 ± 88 pg/ml in AT animals compared with 87 ± 12 pg/ml in sham-operated controls. Another group of rats prepared with antrectomy and gastrojejunostomy (A) had low serum gastrin concentrations; they were studied 12 weeks postoperatively. Pancreatic juice was collected after iv secretin or CCK and was analyzed for [HCO₃^?], [Cl^?], and protein. Pancreas histology and DNA/RNA per milligram of pancreatic protein was the same in all groups. A twofold increase in [HCO₃^?] and volume of secretion at 2 weeks in AT animals suggested that gastrin exerted a trophic effect on the ducts. By 6 weeks pancreas weight had increased, probably reflecting acinar growth. By 16 weeks pancreatic secretion was qualitatively similar to the control group, but the pancreas weights were 35% greater and absolute secretory capacities were 50% greater. In the A animals, pancreas weights and protein secretion were unchanged, but HCO₃^? secretion was impaired. We conclude that chronic endogenous hypergastrinemia produced functionally significant hyperplasia of both the duct and acinar cells.     

Role of bombesin on gut mucosal growth.

OBJECTIVE: The authors examined the effects of exogenous bombesin (BBS) on gut mucosal growth in chow-fed rats and the mucosal regeneration after gut atrophy brought about by feeding an elemental diet and after intestinal injury produced by methotrexate (MTX). SUMMARY BACKGROUND DATA: Bombesin is one of many gastrointestinal peptides implicated in the regulation of gut mucosal growth. Although BBS is known to stimulate growth of normal pancreatic tissue, the trophic effect of BBS on gut mucosa is less clear and its exact role in gut mucosal regeneration and repair is not known. METHODS: Rats were fed a regular chow diet (control) or an elemental diet plus either saline or BBS (10 micrograms/kg). In another experiment, rats fed a chow diet and treated with saline or BBS were given MTX (20 micrograms/kg) or a single intraperitoneal injection. In all experiments, small and large bowel mucosa and pancreas were removed and analyzed for BBS-mediated proliferation. RESULTS: Bombesin produced significant mucosal proliferation of the small bowel at day 14, but not at day 7, in rats fed regular chow. In contrast, BBS treatment for 7 days produced significant proliferation in both the atrophic and injured gut mucosa of rats given elemental diet or MTX. CONCLUSIONS: Bombesin may be an important enterotrophic factor for normal mucosal proliferation and may be clinically beneficial as an agent to restore or maintain gut mucosa during periods of atrophy or injury.     

急性胰腺炎大鼠TNF-α mRNA、IL-10 mRNA表达和胰腺细胞凋亡的研究

目的 探讨大鼠急性胰腺炎早期胰腺组织中TNF－αmRNA、IL－10mRNA的表达和细胞凋亡的变化规律。方法 以牛磺胆酸钠诱导20只大鼠急性水肿性胰腺炎（AEP）模型,20只急性坏死性胰腺炎（ANP）模型,另取10只正常大鼠作为对照。术后12h各处死10只大鼠,检测血清和胰腺组织中的TNF－α和IL－10水平,分析两者在胰腺组织中的mRNA较录水平,检测胰腺细胞的凋亡率。结果 正常、AEP和ANP组的细胞凋亡率分别为2．98％、17．29％和8．39％。制模后TNF－αm和IL－10增强ANP大鼠TNF－α表达增强。结论 急性胰腺炎大鼠胰腺组织中的TNF－α和IL－10的表达与其在血清和胰腺中的浓度成正比,胰腺本身可能就是产生细胞因子的主要器官。胰腺细胞凋亡率与疾病的严重程度呈负相关,凋亡是对胰腺损伤的良好反应。     

The relation between apoptosis of acinar cells and nitric oxide during acute rejection of pancreas transplantation in rats

Apoptosis is an important mechanism of immune-mediated graft damage. Nitric oxide (NO) generated by inducible NO synthase (iNOS) has been demonstrated to induce apoptosis. This study investigated whether apoptosis occurs during pancreas allograft rejection and examined the relationship of apoptosis of acinar cells and NO. The rats were divided into three groups: untreated isograft group, untreated allograft group and aminoguanidine (AG)-treated group. The pancreatic grafts were harvested on the post-transplantation day 3, 5 and 7 and were used to detect the histopathological rejection grade, the expression of iNOS and the apoptotic index (AI) of the graft. iNOS presented faint positive in the acinar cells of untreated isografts and did not change greatly after transplantation (P>0.05), the level of iNOS in the untreated allografts increased progressively (P<0.01) and at the same time point was significantly higher than that of untreated isograft group and AG-treated group (P<0.01). The transferase-mediated dUTP nick end labeling showed that the apoptotic cells were mainly acinar cells. A significant correlation between AI and iNOS was noted (P<0.01, r=0.611). Therefore, NO-mediated apoptosis of acinar cells plays an important role in acute rejection of pancreas transplantation, AG can mitigate the damage of pancreas allografts.