Effects and mechanisms of somatostatin analogs on apoptosis of pancreatic acinar cells in acute pancreatitis in mice

The effect of trimethazidine on mortality in an experimental acute pancreatitis model1

BACKGROUND/AIMS

Acute pancreatitis has a high morbidty and mortality. Its physiopathogenesis has not been enlightened up to the present. This study aims to investigate trimetazidine (antiischemic, antioxidant and cardioprotective agent) 's effects on the acute pancreatitis.

MATERIALS AND METHODS

In this study, four aqual groups are formed with 43 female Spraque-dawley type rats weighed between230-300 gr (mean 265 gr). 0.9% NaCl is injected intraperitoneally after laparotomy to the Group 1 (n=6). Group 2 (n=6) is control group that without any intervention. Acute pancreatitis is formed in Group 3 (n=16) via injection of Na-taurokolat in the common bile duct. Group 4 (n=15) is being formed pancreatitis and treated with Trimetazidine. In group 4 Trimetazidine 10 mg/kg/day drugs were given, 30 minutes, 24 and 72 hours after formation of acute pancreatitis, in three equal doses by orogastric way. In all groups, the rats have been laparatomised 72 hours later under general anesthesia and pancreas tissues has been extracted and studied histopathologically. Amylase, lipase, lactate dehydrogenase, aspartate transaminase, alanine tranaminase levels in the rats serum and superoxide dismutase, catalase, glutathione, malondialdehyde, nitric oxide, protein carbonyl, glutathione peroxidase levels in the rats tissue also have been looked up.

RESULTS

Serum and tissue findings and histopathologically examination of the pancreas tissues show significant decrease in the treatment group compare to study group.

CONCLUSION

Trimetazidine protects pancreas tissue and decreases the mortality by significantly lowering the biochemical and histopathological changes in the early stages of acute pancreatitis.

What we already know about rhubarb: a comprehensive review

Rhubarb (also named Rhei or Dahuang), one of the most ancient and important herbs in traditional Chinese medicine (TCM), belongs to the Rheum L. genus from the Polygonaceae family, and its application can be traced back to 270 BC in "Shen Nong Ben Cao Jing". Rhubarb has long been used as an antibacterial, anti-inflammatory, anti-fibrotic and anticancer medicine in China. However, for a variety of reasons, such as origin, variety and processing methods, there are differences in the effective components of rhubarb, which eventually lead to decreased quality and poor efficacy. Additionally, although some papers have reviewed the relationship between the active ingredients of rhubarb and pharmacologic actions, most studies have concentrated on one or several aspects, although there has been great progress in rhubarb research in recent years. Therefore, this review aims to summarize recent studies on the geographic distribution, taxonomic identification, pharmacology, clinical applications and safety issues related to rhubarb and provide insights into the further development and application of rhubarb in the future.

Phytoceuticals in Acute Pancreatitis: Targeting the Balance between Apoptosis and Necrosis

Despite recent advances in understanding the complex pathogenesis of pancreatitis, the management of the disease remains suboptimal. The use of phytoceuticals (plant-derived pleiotropic multitarget molecules) represents a new research trend in pancreatology. The purpose of this review is to discuss the phytoceuticals with pancreatoprotective potential in acute pancreatitis and whose efficacy is based, at least in part, on their capacity to modulate the acinar cell death. The phytochemicals selected, belonging to such diverse classes as polyphenols, flavonoids, lignans, anthraquinones, sesquiterpene lactones, nitriles, and alkaloids, target the balance between apoptosis and necrosis. Activation of apoptosis via various mechanisms (e.g., inhibition of X-linked inhibitor of apoptosis proteins by embelin, upregulation of FasL gene expression by resveratrol) and/or inhibition of necrosis seem to represent the essential key for decreasing the severity of the disease. Apart from targeting the apoptosis/necrosis balance, the phytochemicals displayed other specific protective activities: inhibition of inflammasome (e.g., rutin), suppression of neutrophil infiltration (e.g., ligustrazine, resveratrol), and antioxidant activity. Even though many of the selected phytoceuticals represent a promising therapeutic alternative, there is a shortage of human evidence, and further studies are required to provide solid basis to justify their use in the treatment of pancreatitis.

Octreotide negates the benefit of galantide when used in the treatment of caerulein-induced acute pancreatitis in mice

BACKGROUND

We have previously shown that galantide, a non-specific galanin receptor antagonist, ameliorates acute pancreatitis (AP) induced in mice. Octreotide, a somatostatin analogue, has been used in the treatment of AP with inconsistent outcomes. This study set out to compare the efficacy of a combined treatment of galantide and octreotide with the efficacy of each agent individually in experimental AP.

METHODS

Acute pancreatitis was induced in mice with 7-hourly caerulein injections. Galantide and/or octreotide were co-administered with each caerulein injection commencing with the first injection. Control animals received galantide, octreotide or saline alone. Pancreata were harvested for histological examination and estimation of myeloperoxidase (MPO) activity. Plasma amylase and lipase activities were measured.

RESULTS

Galantide significantly reduced AP-induced hyperenzymaemia by 39-45%. Octreotide alone, or in combination with galantide, did not significantly alter AP-induced hyperenzymaemia. Plasma enzyme activity in the control groups was comparable with pre-treatment activity. Galantide and octreotide administered individually reduced MPO activity by 79% and 50%, respectively; however their combination was without effect. Galantide, octreotide and their combination significantly reduced the percentage of abnormal acinar cells by 28-45%.

CONCLUSIONS

Treatment with galantide alone ameliorated most of the indices of AP studied, whereas treatment with octreotide reduced pancreatic MPO activity and acinar cell damage. Combining the two peptides appears to negate their individual benefits, which suggests an interaction in their mechanism of action.

Melatonin treatment is beneficial in pancreatic repair process after experimental acute pancreatitis

Current treatment options for acute pancreatitis are supportive and symptomatic. Due to lack of agents targeting the underlying pathophysiology a large amount of experimental work is going on to identify novel therapeutic agents. The present study was carried out to explore if melatonin can modulate the spontaneous regeneration process of the pancreas after experimentally induced acute pancreatitis. Rats were given two i.p. injections of l-arginine in a dose of 200mg/100g at an interval of 1h for induction of pancreatitis. After this rats were randomly divided into three groups i.e. saline, CCK-8 and melatonin. Drug treatment was started 2h after the last l-arginine injection and continued till the day of sacrifice. An additional only saline treated control group was included for comparison. Animals in each group were sacrificed at 24h, days 3, 14 and 28 after pancreatitis induction for determination of biochemical parameters (serum amylase, lipase and IL-10 and pancreatic amylase, total proteins and nucleic acid content) and histological examination. For rate of DNA synthesis and immunohistochemical studies animals were sacrificed at day 3 and day 7. Melatonin treatment was found to be beneficial in acute pancreatitis. Severity of acute pancreatitis was significantly reduced in melatonin group. Nucleic acid content, rate of DNA synthesis, pancreatic proteins and pancreatic amylase content were significantly improved. Histopathological examination showed significantly lower total scores in melatonin group. Results of melatonin group were comparable to that of positive control, CCK-8 group. Thus melatonin treatment was found to promote the spontaneous regeneration process of pancreatic tissue.

Protective effect of resveratrol in severe acute pancreatitis-induced brain injury

OBJECTIVES

The aim of this study was to study the effects of resveratrol on severe acute pancreatitis (SAP)-induced brain injury.

METHODS

Ninety-six male Sprague-Dawley rats were randomly divided into 4 equal groups: sham operation, SAP, resveratrol-treated (RES), and dexamethasone-treated. Each group was evaluated at 3, 6, and 12 hours. Levels of serum myelin basic protein and zonula occludens 1 (Zo-1) were determined by enzyme-linked immunosorbent assay. The brain and pancreatic tissues were examined using electron microscopy. Expressions of Bax, Bcl-2, and caspase-3 were observed using immunohistochemistry, reverse transcriptase polymerase chain reaction, and Western blotting. Cytochrome c was detected using Western blotting alone.

RESULTS

Myelin basic protein and Zo-1 levels of the RES group were lower than the SAP group at all time points (P < 0.05). The RES group had significantly improved pathologic brain, increase in Bcl-2 expression, and decrease in Bax and caspases-3 expressions compared with the SAP group.

CONCLUSIONS

The degradation of Zo-1 is involved in the pathophysiology of brain injury in SAP; MBP can be used as a marker of brain injury in SAP. The protective effect of resveratrol might be associated with the up-regulation of Bcl-2 and down-regulation of Bax and caspase-3.

Effects of arsenic trioxide on the cerulein-induced AR42J cells and its gene regulation

OBJECTIVES

To study the molecular mechanism of arsenic trioxide-induced cell death on cerulein-stimulated AR42J cells.

METHODS

AR42J cells were incubated for 24 hours, and cerulein (10 nmol/L) and different concentrations of arsenic trioxide were added for another 24 hours. The cells were collected and analyzed for apoptosis and oncosis by using rhodamine 123 and propidium iodide staining, and the changes in the genes that related to cell death were detected by a gene chip.

RESULTS

After cerulein stimulation, apoptosis was significantly increased in the AR42J cells. The addition of arsenic trioxide increased the number of apoptotic cells, and the apoptotic index reached its peak in the 1-micromol/L group. Regarding oncosis, low concentrations of arsenic trioxide (0.5, 1, 2, and 4 micromol/L) reduced the development of oncosis, and in the 2-micromol/L group, it was most significant, whereas high concentration of arsenic trioxide (8 micromol/L) promoted the development of oncosis. A total of 96 genes related to apoptosis were detected, and 36 genes were differentially expressed.

CONCLUSIONS

Appropriate concentrations of arsenic trioxide can induce apoptosis in AR42J cells that were induced by cerulein and lead to changes in the expressions of certain genes.

Effects of Baicalin and Octreotide on the serum TNF-alpha level and apoptosis in multiple organs of rats with severe acute pancreatitis

We investigated the effects of Baicalin and Octreotide on the levels of endotoxin and TNF-alpha in blood and the effects of apoptotic changes in multiple organs of SAP rats, and explored the underlying therapeutic mechanisms of Baicalin and Octreotide. In this study, 135 SAP rats were randomly divided into model control, Baicalin treated and Octreotide treated group (n = 45), respectively, the same number of normal rats were included in sham-operated group (n = 45). The above-mentioned groups were further subdivided into 3, 6 and 12 h subgroups, respectively (15 rats in each subgroup). At 3, 6 and 12 h after operation, the mortality rate of rats, endotoxin and TNF-alpha levels in blood as well as the pathological severity scores, expression levels of Bax protein and apoptosis indexes in multiple organs were determined. Compared to model control group (1),both drugs can relieve the pathological injuries of multiple organs and decrease significantly the levels of endotoxin and TNF-alpha in blood and the mortality rate of rats in treated groups (P < 0.05 or P < 0.01); (2) the expression of Bax protein was upregulated in pancreas, lung, intestinal mucosa (P < 0.05 or P < 0.01) but downregulated in spleen and lymph nodes (P < 0.001 and P < 0.05, respectively) in Baicalin treated group; The apoptosis indexes significantly increased in pancreas, intestinal mucosa, lymph nodes and spleen (P < 0.05 or P < 0.01). (3) the expression of Bax protein was upregulated in pancreas and lung but downregulated in spleen and lymph nodes (P < 0.05 or P < 0.01) in Octreotide treated group; The apoptosis indexes significantly increased in lymph nodes and spleen in Octreotide treated group (P < 0.05 or P < 0.01). Baicalin and Octreotide share a similar therapeutic efficacy in the treatment of SAP via a mechanism that is associated with inhibiting the levels of TNF-alpha in blood and induce apoptosis in multiple organs.

The beneficial effects of pentoxifylline on caerulein-induced acute pancreatitis in rats

In this study we aimed to investigate the effect of pentoxifylline on caerulein-induced acute pancreatitis (AP) by detecting oxidative stress markers and performing histopathological examination. Twenty-one adult female Sprague-Dawley rats were divided into three groups as follows: control, caerulein, and caerulein + pentoxifylline groups. Pancreatic tissues of rats from all groups were removed for light and electron microscopic examination and determination of oxidative stress markers. Pancreatic oxidative stress markers were evaluated by the measurements of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and total glutathione (GSH). Serum amylase and lipase levels were determined spectrophotometrically. The pancreatic damage score was significantly increased (P < 0.005) in the caerulein group, whereas it was decreased (P < 0.05) in the caerulein+ with pentoxifylline group. MDA levels, CAT, SOD, GPx, and GSH activities were significantly altered (P < 0.05, P < 0.005) in the caerulein group and indicated increased oxidative stress. Oxidative stress markers were normalized with pentoxifylline administration. Caerulein administration resulted in significant increase (P < 0.05) in amylase and lipase levels; pentoxifylline reduced the levels of these enzymes. Pentoxifylline is potentially capable of limiting pancreatic damage produced during AP by restoring the fine structure of acinar cells and tissue antioxidant enzyme activities. We concluded that pentoxifylline may have beneficial effects in the treatment of caerulein-induced AP.

The prophylactic effect of somatostatin on post-therapeutic endoscopic retrograde cholangiopancreatography pancreatitis: a randomized, multicenter controlled trial

OBJECTIVES

Patients undergoing therapeutic endoscopic retrograde cholangiopancreatography (ERCP) are at a higher risk of developing post-ERCP pancreatitis than patients undergoing diagnostic ERCP. The aim of this study was to evaluate the effectiveness of somatostatin in preventing post-therapeutic ERCP pancreatitis.

METHODS

This placebo-controlled, double-blind, randomized study involved 391 patients in 3 hospitals who required therapeutic ERCP. Patients were assigned to receive either somatostatin or placebo. The incidence of pancreatitis and hyperamylasemia after performing ERCP was compared between the somatostatin and placebo groups.

RESULTS

Pancreatitis occurred in statistically significantly fewer ERCP patients who received somatostatin (7/193: 3.6%) than placebo (19/198: 9.6%; P = 0.02). With regard to the individual ERCP procedures, statistically significant reductions in post-ERCP pancreatitis were seen in patients treated with somatostatin who had stoneremoval (P = 0.04) and endoscopic papillary balloon dilation (P= 0.03). The incidence of hyperamylasemia was lower in the somatostatin group (7.8%) than in the placebo group (12.6%), although this difference was not statistically significant (P > 0.05).

CONCLUSIONS

A significantly lower incidence of post-ERCP pancreatitis occurred in patients who received somatostatin prophylaxis. This finding suggests that the administration of somatostatin is useful in preventing pancreatitis in patients undergoing therapeutic ERCP.

Resveratrol ameliorates hepatic injury via the mitochondrial pathway in rats with severe acute pancreatitis

To gain insight into the processes by which severe acute pancreatitis induced apoptosis takes place in the liver, and to observe the protective effect of resveratrol on hepatic injury, a rat model of severe acute pancreatitis was induced by administering 4% sodium taurocholate through the common biliopancreatic duct. Pancreatic and hepatic injury was assessed by histology. Serum ALT (alanine aminotransferase), AST (aspartate aminotransferase) and total bilirubin were determined by reaction rate assay, and the serum levels of TNF-alpha (tumor necrosis factor-alpha) and IL-6 (interleukin-6) were detected by ELISA (enzyme linked immunosorbent assay). We investigated cytochrome c released from mitochondria and used the RT-PCR (reverse transcription PCR), Western blot technique to evaluate Bax, Bcl-2, and caspase-3 expression levels in hepatic tissue over the time course of apoptosis. Changes in hepatic cell mitochondrial membrane potential were observed by confocal laser scanning microscopy. The majority of cytochrome c release occurred early in apoptosis from mitochondria, which undergo gradual hepatic impairment. The released cytochrome c can be reduced by resveratrol through both up-regulation of Bcl-2 and down-regulation of Bax and caspase-3. These data provide substantial evidence that apoptosis is involved in hepatic injury during the severe acute pancreatitis process and that resveratrol can ameliorate the situation, thus protecting liver function in rats with severe acute pancreatitis.

Induction of apoptosis by artemisinin relieving the severity of inflammation in caerulein-induced acute pancreatitis

AIM

To observe the apoptosis and oncosis of pancreatic acinar cells and secondary inflammatory reaction in pancreatic tissue from rats with acute pancreatitis (AP), and the influences of artemisinin on them.

METHODS

AP was induced by 4 intraperitoneal injections of caerulein at 1 h intervals. To induce apoptosis, solution of artemisinin (50 mg/kg) was given intraperitoneally 1, 12, 24 and 36 h after the last caerulein injection. Histological examination of impairment of pancreatic tissue and detection of serum amylase were performed to evaluate the severity of acute pancreatitis. Apoptosis and oncosis were detected with acridine orange (AO) and ethylene dibromide (EB) staining. Caspase-3 and myeloperoxidase (MPO) activity were measured by colorimetric assay. Nuclear factor-kappa B (NF-kappaB) activation was detected by flow cytometry. Macrophage inflammatory protein-1alpha (MIP-1alpha) protein was measured by Western blot. Interleukin-1beta (IL-1beta) mRNA was detected by RT-PCR.

RESULTS

Addition of artemisinin increased the number of apoptotic cells (11.7% +/- 1.4% vs 6.3% +/- 0.7%, P < 0.05), while reduced the number of oncotic cells (13.0% +/- 2.4% vs 17.5% +/- 2.2%, P < 0.05). The activity of caspase-3 speeded up (1.52 +/- 0.21 vs 1.03 +/- 0.08, P < 0.05), the pancreas pathological impairment was relieved (3.0 +/- 0.5 vs 4.0 +/- 0.5, P < 0.05) and the level of serum amylase decreased (5642 +/- 721 U/dL vs 7821 +/- 653 U/dL, P < 0.05). The activation of NF-kB (29% +/- 4.1% vs 42% +/- 5.8%), MIP-1alpha protein (3.7 +/- 0.5 vs 5.8 +/- 0.7), MPO (0.52 +/- 0.06 U/g vs 0.68 +/- 0.09 U/g), IL-1beta mRNA (1.7 +/- 0.3 vs 2.4 +/- 0.4) in the apoptosis inducing group was obviously decreased (P < 0.05).

CONCLUSION

Inducing apoptosis can relieve pathological impairment and inflammatory reaction in AP rats.

Induction of apoptosis by artemisinin relieving the severity of inflammation in caerulein-induced acute pancreatitis

AIM: To observe the apoptosis and oncosis of pancreatic acinar cells and secondary inflammatory reaction in pancreatic tissue from rats with acute pancreatitis (AP), and the influences of artemisinin on them.

METHODS: AP was induced by 4 intraperitoneal injections of caerulein at 1 h intervals. To induce apoptosis, solution of artemisinin (50 mg/kg) was given intraperitoneally 1, 12, 24 and 36 h after the last caerulein injection. Histological examination of impairment of pancreatic tissue and detection of serum amylase were performed to evaluate the severity of acute pancreatitis. Apoptosis and oncosis were detected with acridine orange (AO) and ethylene dibromide (EB) staining. Caspase-3 and myeloperoxidase (MPO) activity were measured by colorimetric assay. Nuclear factor-kappa B (NF-κB) activation was detected by flow cytometry. Macrophage inflammatory protein-1α (MIP-1α) protein was measured by Western blot. Interleukin-1β (IL-1β) mRNA was detected by RT-PCR.

RESULTS: Addition of artemisinin increased the number of apoptotic cells (11.7% ± 1.4% vs 6.3% ± 0.7%, P < 0.05), while reduced the number of oncotic cells (13.0% ± 2.4% vs 17.5% ± 2.2%, P < 0.05). The activity of caspase-3 speeded up (1.52 ± 0.21 vs 1.03 ± 0.08, P < 0.05), the pancreas pathological impairment was relieved (3.0 ± 0.5 vs 4.0 ± 0.5, P < 0.05) and the level of serum amylase decreased (5642 ± 721 U/dL vs 7821 ± 653 U/dL, P < 0.05). The activation of NF-κB (29% ± 4.1% vs 42% ± 5.8%), MIP-1α protein (3.7 ± 0.5 vs 5.8 ± 0.7), MPO (0.52 ± 0.06 U/g vs 0.68 ± 0.09 U/g), IL-1β mRNA (1.7 ± 0.3 vs 2.4 ± 0.4) in the apoptosis inducing group was obviously decreased (P < 0.05).

CONCLUSION: Inducing apoptosis can relieve pathological impairment and inflammatory reaction in AP rats.

Relationship between expression of gastrin, somatostatin mRNA and cell apoptosis and Bcl-2, Bax in large intestinal carcinoma

AIM: To explore the correlations the between expression of somatostatin (SS), gastrin (GAS) mRNA and cell apoptosis index (AI) and Bcl-2, Bax in large intestinal cancer.

METHODS: The expression of GAS and SS genes were detected in 62 colorectal cancer patients by nested reverse transcription polymerase chain reaction (RT-PCR), and the apoptosis of the cells was detected by TUNEL method. The protein expression of,Bcl-2, Bax, GAS, and SS were detected using immunohistochemical staining (S-P method).

RESULTS: The expression of GAS and SS mRNA and protein were basically consistent. The AI in SS high and moderate expression patients with large intestinal cancer was remarkably higher than that in SS low expression ones (q = 5.06, 3.95, both P < 0.01), while it was just opposite in GAS positive patients (q = 6.66, 6.33, P < 0.01). The positive rates of Bax and Bcl-2 expression had significant difference between SS (or GAS) high, moderate and low expression patients with large intestinal cancer (Bax: χ² = 9.24, 6.91, P < 0.05; Bcl-2: χ² = 7.17, 13.83, P < 0.05). The positive rate of Bax expression in SS high (80%, 8/10) and moderate (76.5%, 13/17) expression patients was notably higher than that in the low expression ones (40.0%, 14/35) (χ² = 5.24, 6.09, P < 0.05), but the rate of Bcl-2 expression was just opposite (χ² = 4.71, 4.70, P < 0.05). The positive rate of Bcl-2 expression in GAS high (90.9%,10/11) and moderate expression patients (86.7%,13/15) was markedly higher than that in the low expression ones (44.4%, 16/36) (χ² = 5.60, 7.69, P < 0.05), but the positive rate of Bax expression in GAS high expression patients (27.3%, 3/8) was obviously lower than that in the low expression ones (69.4%, 25/36) (χ² = 4.59, P < 0.05). Bax expression was not significantly different between moderate and low GAS positive patients. The value of GAS/SS was positively correlated with Bcl-2 expression (r = 0.34, P < 0.01), but negatively with the AI value and Bax expression (r = －0.546, P < 0.01; r = －0.299, P < 0.05).

CONCLUSION: GAS and SS play important roles in the regulation and control of cell apoptosis in large intestinal carcinoma, and the mechanism may be related to the aberrant expression of Bcl-2 and Bax.

Pathophysiology of acute pancreatitis

Acute pancreatitis is a common clinical condition. It is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The exact mechanisms by which diverse etiological factors induce an attack are still unclear. It is generally believed that the earliest events in acute pancreatitis occur within acinar cells. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction. If this inflammatory reaction is marked, it leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies have established the role played by inflammatory mediators in the pathogenesis of acute pancreatitis and the resultant MODS. At the same time, recent research has demonstrated the importance of acinar cell death in the form of apoptosis and necrosis as a determinant of pancreatitis severity. In this review, we will discuss about our current understanding of the pathophysiology of acute pancreatitis.

Correlation between expression of gastrin, somatostatin and cell apoptosis regulation gene bcl-2/bax in large intestine carcinoma

AIM: To explore the correlation between expression of somatostatin (SS), gastrin (GAS) and cell apoptosis regulation gene bcl-2/bax in large intestine carcinoma.

METHODS: Sixty-two large intestine cancer tissue samples were randomly and retrospectively selected from patients with large intestine carcinoma. Immunohistochemical staining for bcl-2, bax, GAS, SS was performed according to the standard streptavidin-biotin-peroxidase (S-P) method. According to the semi-quantitative integral evaluation, SS and GAS were divided into three groups as follows. Scores 1-3 were defined as the low expression group, 4-8 as the intermediate expression group, 9-16 as the high expression group. Bax and bcl-2 protein expressions in different GAS and SS expression groups of large intestine carcinoma were assessed.

RESULTS: The positive expression rate of bax had a prominent difference between SS and GAS high, intermediate and low expression groups (P<0.05, χ²_SS = 9.246; P<0.05, χ²_GAS = 6.981). The positive expression rate of bax in SS high (80.0%, 8/10) and intermediate (76.5%, 13/17) expression groups was higher than that in low expression group (40.0%, 14/35) (P<0.05, χ²_{high vs low} = 5.242; P<0.05,χ²_{middle vs low} = 6.097). The positive expression rate of bax in GAS high expression group (27.3%, 3/8) was lower than that in low expression group (69.4%, 25/36) (P<0.05, χ² = 4.594). However, bax expression in GAS intermediate expression group (46.7%, 7/15) was lower than that in low expression group, but not statistically significant. The positive expression rate of bcl-2 had a prominent difference between SS and GAS high, intermediate and low expression groups (P<0.05, χ²_SS = 7.178; P<0.05, χ²_GAS = 13.831). The positive expression rate of bcl-2 in GAS high (90.9%, 10/11) and intermediate (86.7%, 13/15) expression groups was higher than that in low expression group (44.4%, 16/36) (P<0.05, χ²_{high vs low} = 5.600; P<0.05, χ²_{middle vs low} = 7.695). However, the positive expression rate of bcl-2 in SS high (40.0%, 4/10) and intermediate (47.1%, 8/9) expression groups was lower than that in low expression group (77.1%, 27/35) (P<0.05, χ²_{high vs low} = 4.710; P<0.05, χ²_{middle vs low} = 4.706). There was a significant positive correlation between the integral ratio of GAS to SS and the integral of bcl-2 (P<0.01, r = 0.340). However, there was a negative correlation between the integral ratio of GAS to the SS and bax the integral of (P<0.05, r = -0.299).

CONCLUSION: The regulation and control of gastrin, somatostatin in cell apoptosis of large intestine carcinoma may be directly related to the abnormal expression of bcl-2, bax.

Mechanisms of inhibition of growth of human pancreatic carcinoma implanted in nude mice by somatostatin receptor subtype 2

OBJECTIVES

Several studies reported that somatostatin receptor subtypes, especially subtype 2 (SSTR2), exerted their cytostatic and/or cytotoxic effects on various types of tumors. The aim of this study was to investigate the antitumor effect of SSTR2 gene transfer to the pancreatic cancer cell line PC-3 and the mechanisms involved in this effect.

METHODS

The full-length human SSTR2 cDNA was introduced into pancreatic cancer cell line PC-3 by lipofectamine-mediated transfection; positive clones were screened by G418, and stable expression of SSTR2 was detected by the immunohistochemical SABC method and RT-PCR. Athymic mice were separately xenografted with SSTR2-expressing cells (experimental group), vector control, and mock control cells. TUNEL assay was used to determine the apoptotic index (AI) in the tumors of these groups. The immunohistochemical SP method was used to determine expression of apoptosis-regulating genes Bcl-2 and Bax and re-expression of SSTR2 and to assess intratumoral microvessel density (MVD). Moreover, tumor volume and weight were compared among these 3 groups.

RESULTS

Restoration of SSTR2 was observed in the experimental group both in vitro and in vivo. The AI was significantly higher in the experimental group (3.39 +/- 0.84%) compared with that in the vector control (0.69 +/- 0.08%) and mock control (0.68 +/- 0.09%) (P < 0.05). MVD was significantly lower in the experimental group (6.30 +/- 1.71) than that in the vector control (12.64 +/- 1.69) and mock control (13.50 +/- 1.86) (P < 0.05). Furthermore, a significant decrease in Bcl-2 and increase in Bax protein expression were detected in the experimental group compared with the vector control and mock control (P < 0.05). A significant negative correlation of protein expression between Bcl-2/Bax ratio and SSTR2 was observed in these tumors (P < 0.05). Tumor volume and weight were significantly decreased in the experimental group compared with the vector control and mock control (P < 0.05) groups. However, no significant differences were observed between the vector control and mock control (P > 0.05).

CONCLUSION

Re-expression of the SSTR2 gene, the expression of which is frequently lost in human pancreatic adenocarcinoma, induces apoptosis, which may be mediated via down-regulation of Bcl-2 and up-regulation of Bax (alteration of Bcl-2/Bax ratio) and inhibits tumor angiogenesis in pancreatic carcinoma, resulting in inhibition of tumor growth.

Apoptosis of pancreatic acinar cells in acute pancreatitis: is it good or bad?

Acute pancreatitis is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The events that regulate the severity of acute pancreatitis are, for the most part, unknown. Several recent studies have suggested that the acinar cell response to injury may be an important determinant of disease severity. In these studies, mild acute pancreatitis was found to be associated with extensive apoptotic acinar cell death while severe acute pancreatitis was found to involve extensive acinar cell necrosis but very little acinar cell apoptosis. These observations have led to the hypothesis that apoptosis might be a favorable response to acinar cell and that interventions which favor induction of apoptotic, as opposed to necrotic, acinar cell death might reduce the severity of an attack of acute pancreatitis. This review aims to discuss our current understanding of the contribution of acinar cell apoptosis to the severity of acute pancreatitis.

Mechanisms of Chinese herb emodin and somatostatin analogs on pancreatic regeneration in acute pancreatitis in rats

INTRODUCTION

Studies have revealed that emodin is a potent agent in the management of clinical and experimental acute pancreatitis, but the molecular mechanisms by which emodin produces its biologic effects, especially on pancreatic regeneration after acute pancreatitis, remain unknown. Numerous experimental and clinical studies have shown that somatostatin analogs have favorable effects on acute pancreatitis, but their role in the management of acute pancreatitis remains controversial.

AIM

To investigate mechanisms of the Chinese herb emodin and somatostatin analogs (SSa; Sandostatin) in acute pancreatitis of rats by analyzing the changes in pancreatic tissue cytokine transforming growth factor beta1 (TGFbeta1) and epidermal growth factor (EGF) gene expression, DNA synthesis, total protein content, and the relations between them.

METHODOLOGY

Acute pancreatitis was induced by intraperitoneal infusion of cerulein in rats. Emodin was administered intravenously and Sandostatin was administered subcutaneously at the time of induction of pancreatitis and 24, 48, and 72 hours afterward. Rats were killed at 6, 24, 48, 72, and 96 hours after the operation. The mRNA expression of TGFbeta1 and EGF were evaluated by reverse transcription polymerase chain reaction, and pancreatic tissue DNA synthesis was measured by the 3H-thymidine incorporation method in vitro. Total protein content was detected by Lowry's method.

RESULTS

The serum amylase level was decreased significantly in the emodin-treated and Sandostatin-treated groups in comparison with the nontreated group. Pancreatic tissue DNA synthesis was significantly decreased at 72 hours after the induction of pancreatitis, and a marked increase was observed at 96 hours after treatment with emodin and Sandostatin. Within 48 hours of the induction of pancreatitis, the total protein content in pancreatic tissue declined, but there was a remarkable increase in the emodin-treated group at 96 hours and Sandostatin-treated group at 48 hours. Expression of TGFbeta1 mRNA and EGF mRNA were undetectable in normal pancreas and the nontreated group at 6 hours but was observed from 24 hours to 96 hours after the induction of pancreatitis and reached its maximum at 72 hours. TGFbeta1 mRNA could be detected 6 hours after treatment with emodin and Sandostatin, and its expression was significantly higher in the emodin-treated and Sandostatin-treated groups than in the nontreated group at 24 and 48 hours. The expression of EGF mRNA was significantly higher in the emodin-treated and Sandostatin-treated group than in the nontreated group at 48 hours.

CONCLUSION

It was concluded that mechanisms of the Chinese herb emodin and somatostatin analogs in the management of acute pancreatitis in rats might be ascribed to the upregulation of TGFbeta1 and EGF gene expression, which subsequently increases DNA synthesis and protein content and thus accelerates pancreatic repair and regeneration.