Impaired autophagy underlies key pathological responses of acute pancreatitis

The recently discovered HspB8-Bag3 complex participates in protein quality control through a mechanism that requires the activation of the eIF2α signaling pathway and that leads to protein synthesis inhibition and autophagy stimulation. Both processes help to protect the cells against the accumulation of aggregate-prone proteins, which may be relevant in many protein conformational neurodegenerative disorders. Besides, this activity of HspB8-Bag3 may have important implications during viral infection.     

A new model of chronic pancreatitis in rats

This study was designed to examine whether continuous pancreatic ductal hypertension (PDH) plays an important role in the onset and development of chronic pancreatitis (CP). Pancreatic, biliary, and duodenal cannulas were implanted in male Wistar rats. PDH was induced by vertically raising the free end of the pancreatic duct cannula to exert a hydrostatic pressure and maintained for 2 wk. PDH was gradually increased, but when the pancreatic juice (PJ) flow was interrupted, PDH was decreased to restore PJ flow. The induction of PDH resulted in a marked reduction of amylase activity in PJ and an increase in serum amylase activity. At 2 wk after persistent PDH, pancreatic exocrine function was markedly decreased in response to a bolus injection of secretin (100 pmol/kg) compared with the control group. Histological examination revealed interlobular as well as intralobular fibrosis in the form of nodular pancreatitis at 2 wk after the induction of PDH. Immunohistochemistry revealed the expression of fibronectin and collagen types I and III. Quantitative real-time RT-PCR showed an increase in transforming growth factor-beta(1) mRNA expression in the pancreas during PDH. The present results suggest that PDH plays an important role in the onset and development of CP. Furthermore, our animal model seems useful for investigating the mechanisms of CP in rats.     

The inhibitory effects of Nardostachys jatamansi on alcoholic chronic pancreatitis

Nardostachys jatamansi (NJ) belonging to the Valerianaceae family has been used as a remedy for gastrointestinal inflammatory diseases for decades. However, the potential for NJ to ameliorate alcoholic chronic pancreatitis (ACP) is unknown. The aim of this study was to examine the inhibitory effects of NJ on ACP. C57black/6 mice received ethanol injections intraperitoneally for 3 weeks against a background of cerulein-induced acute pancreatitis. During ACP, NJ was ad libitum administrated orally with water. After 3 weeks of treatment, the pancreas was harvested for histological examination. NJ treatment increased the pancreatic acinar cell survival (confirmed by amylase level testing) and reduced collagen deposition and pancreatic stellate cell (PSC) activation. In addition, NJ treatment reduced the activation but not death of PSC. In conclusion, our results suggest that NJ attenuated ACP through the inhibition of PSC activation.     

Development of an animal model of chronic alcohol-induced pancreatitis in the rat

This study was designed to develop an animal model of alcoholic pancreatitis and to test the hypothesis that the dose of ethanol and the type of dietary fat affect free radical formation and pancreatic pathology. Female Wistar rats were fed liquid diets rich in corn oil (unsaturated fat), with or without a standard or high dose of ethanol, and medium-chain triglycerides (saturated fat) with a high dose of ethanol for 8 wk enterally. The dose of ethanol was increased as tolerance developed, which allowed approximately twice as much alcohol to be delivered in the high-dose group. Serum pancreatic enzymes and histology were normal after 4 wk of diets rich in unsaturated fat, with or without the standard dose of ethanol. In contrast, enzyme levels were elevated significantly by the high ethanol dose. Increases were blunted significantly by dietary saturated fat. Fibrosis and collagen alpha1(I) expression in the pancreas were not detectable after 4 wk of enteral ethanol feeding; however, they were enhanced significantly by the high dose after 8 wk. Furthermore, radical adducts detected by electron spin resonance were minimal with the standard dose; however, the high dose increased carbon-centered radical adducts as well as 4-hydroxynonenal, an index of lipid peroxidation, significantly. Radical adducts were also blunted by approximately 70% by dietary saturated fat. The animal model presented here is the first to demonstrate chronic alcohol-induced pancreatitis in a reproducible manner. The key factors responsible for pathology are the amount of ethanol administered and the type of dietary fat.     

Differences in the plasma membrane proteins of chronic alcoholic rat brain

Plasma membranes were isolated from the cerebral cortex of control and chronic ethanol-treated rat brains. Analysis of protein composition by SDS-PAGE and by two-dimensional gel electrophoresis (IEF-SDS-PAGE) revealed significant differences in the membrane protein patterns between control and ethanol-treated rat cerebral cortices, indicating the loss of several proteins in membranes from ethanol-treated rat brains. Plasma membrane-associated protein species are categorized into ethanol-sensitive and -insensitive proteins, based on their response to ethanol. This study reports that ethanol depletes certain intrinsic proteins of membranes that might be responsible for plasma membrane disruption by ethanol.     

Protein kinase D: A therapeutic target in experimental alcoholic pancreatitis

BackgroundAlcohol abuse, a main cause of pancreatitis, has been known to augment NF-κB activation and cell necrosis in pancreatitis. However, the underlying mechanisms are unclear. We recently reported that inhibition of protein kinase D (PKD) alleviated NF-κB activation and severity of experimental pancreatitis. Here we investigated whether PKD signaling mediated the modulatory effects of alcohol abuse on pathological responses in alcoholic pancreatitis.MethodsAlcoholic pancreatitis was provoked in two rodent models with pair-feeding control and ethanol-containing Lieber-DeCarli diets for up to 8 weeks followed by up to 7 hourly intraperitoneal injections of cerulein at 1 μg/kg (rats) or 3 μg/kg (mice). Effects of PKD inhibition by PKD inhibitors or genetic deletion of pancreatic PKD isoform (PKD3Δpanc mice) on alcoholic pancreatitis parameters were determined.ResultsEthanol administration amplified PKD signaling by promoting expression and activation of pancreatic PKD, resulted in augmented/promoted pancreatitis responses. Pharmacological inhibition of PKD or with PKD3Δpanc mice prevented the augmenting/sensitizing effect of ethanol on NF-κB activation and inflammatory responses, cell necrotic death and the severity of disease in alcoholic pancreatitis. PKD inhibition prevented alcohol-enhanced trypsinogen activation, mRNA expression of multiple inflammatory molecules, the receptor-interacting protein kinase activation, ATP depletion, and downregulation of pro-survival Bcl-2 protein in alcoholic pancreatitis. Furthermore, PKD inhibitor CID755673 or CRT0066101, administrated after the induction of pancreatitis in mouse and rat alcoholic pancreatitis models, significantly mitigated the severity of pancreatitis.ConclusionPKD mediates effect of alcohol abuse on pathological process of pancreatitis and constitutes a novel therapeutic target to treat this disease.     

Ameliorative effect of Partysmart in rat model of alcoholic liver disease

Present study was designed to investigate the effect of polyherbal formulation PartySmart in experimental model of alcoholic liver disease in male Wistar strain rats. Alcohol plus fish oil were administered to animals for 8 weeks to induce liver injury. PartySmart was administered at doses of 250 and 500 mg/kg body weight. After 8 weeks, parameters such as liver weight, liver function serum markers alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) and lipid peroxidation were studied. Livers from all the groups were subjected for histological evaluation. Treatment with PartySmart at the dose of 500 mg/kg body weight showed significant reduction in the levels of serum ALT, AST and ALP with a decrease in liver weight as compared to ethanol-fed rats. A significant decrease was also observed in malondialdehyde levels following treatment with PartySmart at 500 mg/kg body weight. Histological profile of liver tissue in PartySmart-treated animals showed lesser vacuolar degeneration and intactness of hepatic architecture along with improved glycogen deposition as demonstrated by PAS staining. PartySmart ameliorated alcohol-induced liver injury by preventing cell membrane disturbances, reduction of oxidative stress by free radical scavenging and antioxidant activity and normalization of altered intracellular redox status. Thus, PartySmart can be beneficial in the treatment of alcohol-induced liver damage.     

Secretory apparatus assessed by analysis of pancreatic secretory stress protein expression in a rat model of chronic pancreatitis

Secretory stress proteins (SSP) are a family of proteins including isoforms of pancreatitis-associated protein (PAP) and pancreatic stone protein (PSP/reg). In vitro exposure to trypsin results in the formation of insoluble fibrillar structures. SSP are constitutively secreted into pancreatic juice at low levels. The WBN/Kob rat is a model for chronic pancreatitis, displaying focal inflammation, destruction of the parenchyma and changes in the architecture of the acinar cell; the synthesis and secretion of SSP are also increased. We have investigated the secretory apparatus by SSP immunohistochemistry at the light- and electron-microscopical (EM) levels. Immunocytochemistry of PSP/reg in Wistar control rats reveals low levels, with individual acinar cells exhibiting high immunoreactivity in zymogen granules. PAP is not detectable. In the WBN/Kob rat, PSP/reg and PAP immunoreactivity is markedly increased. Double immunofluorescence for PSP/reg and PAP I or II demonstrates that these proteins colocalize to the same cell. Acinar cells change their secretory architecture by fusion of zymogen granules and elongation of the fused organelles. The immunogold technique has demonstrated an increase of SSP in zymogen granules in WBN/Kob rats. PSP/reg-positive zymogen granules fuse to form elongated structures with fibrillar contents. An extensive PSP/reg-positive fibrillar network is established in the cytosol. Extracellular fibrils have been observed in several ductules. Thus, SSP-derived fibrils form concomitantly with acinar damage in the WBN/Kob rat. Based on the known tryptic cleavage site of SSP, the in vivo generation of fibrils is presumably the result of premature trypsin activation.     

异丙肾上腺素激发试验在大鼠酒精性心肌病模型评价中的应用

目的:建立大鼠酒精性心肌病模型,采用异丙肾上腺素激发试验评价模型大鼠心功能。方法:成年雄性SD大鼠以20 g/(kg.d)白酒(52°v/v)灌胃15 d。观察大鼠一般状况、心肌标本病理学及超微结构改变;通过左心室插管、异丙肾上腺素试验(IPT),测量大鼠在不同状态下的左心室内压、收缩压、舒张压、最大收缩速度、最大舒张速度。结果:模型组大鼠心脏舒缩功能降低,心力储备明显下降,心血管系统整体调节能力降低。病理见心肌细胞肥大、坏死,炎症细胞浸润;电镜见线粒体肿胀变形,嵴受损,肌原纤维断裂。结论:高度酒灌胃可使大鼠发生酒精性心肌病,该法稳定可靠。异丙肾上腺素试验(IPT)可准确考察心脏心力储备状况,显现潜在心功能减退。     

FH/Wjd大鼠酒精性肝损伤模型探讨

目的对FH/W jd大鼠酒精性肝损伤模型进行探讨。方法 FH/W jd大鼠按体重随机分为饮水组和饮酒组,两组均自由饮食。16周后取血,检测血清ALT、AST、TBIL、TG、CHO;取肝脏,匀浆后检测TG、GSH;流式细胞仪检测肝细胞凋亡率;Western blot检测肝脏组织PPARα蛋白表达;肝脏HE染色观察组织病理学改变。结果与饮水组比较,饮酒组两种性别FH/W jd大鼠血清TBIL、TG含量显著升高,饮酒组雌性大鼠血清ALT、CHO显著降低;饮酒组两种性别大鼠肝脏TG含量显著升高,GSH含量呈现降低趋势;饮酒组两种性别大鼠肝细胞凋亡率亦呈降低趋势;饮酒组肝脏PPARα蛋白表达明显上调;饮酒组组织病理学改变以小泡性脂肪变性为主。结论长期自主摄入酒精可以造成FH/W jd大鼠肝脏损伤。     

Role of fibrosis-related genes and pancreatic duct obstruction in rat pancreatitis models: implications for chronic pancreatitis

Human chronic pancreatitis is characterized by irreversible fibrosis, whereas pancreatic fibrosis in animal models is reversible. In this study, we compare the development of pancreatic fibrosis in the dibutyltin dichloride (DBTC) model, WBN/Kob rats and bile duct-ligated (BDL) rats. DBTC (8 mg/kg) was administered to LEW rats, and the pancreas was histopathologically investigated sequentially. Male and female WBN/Kob rats aged 4, 6 and 8 months were also examined. BDL rats were prepared by ligation of the bile duct at the duodenal portion and sacrificed at 3 or 7 days after ligation. Fibrosis in the DBTC model peaked after 1 week and was limited to the areas around the pancreatic ducts after 2 weeks, and was composed of both type I and type III collagen. In contrast, fibrosis in male WBN/Kob rats peaked at age 4 months, expanded into intralobular area, and was composed of type III collagen. It exhibited almost no type I collagen and a marked tendency to regress. Pancreatic fibrosis in BDL rats was somewhat difficult to induce and required increased stimulation. This suggests that fibrosis in human biliary pancreatitis may gradually form based on weak, continuous stimulation. We conclude that type I collagen may be involved in the progression of irreversible fibrosis. The imbalance between synthesis and degradation of extracellular matrix molecules or degree of stimulation over a certain period may lead to pancreatic fibrosis. Gene expressions of prolyl hydroxylase and tissue inhibitors of matrix metalloproteinase-2 were elevated.     

Enhanced excitability and suppression of A-type K+ current of pancreas-specific afferent neurons in a rat model of chronic pancreatitis

Chronic pancreatitis (CP) is a relatively common disorder, characterized by glandular insufficiency and chronic, often intractable, pain. The mechanism of pain in CP is poorly understood. We have previously developed a model of trinitrobenzene sulphonic acid (TNBS)-induced CP that results in nociceptive sensitization in rats. This study was designed to examine changes in the excitability and alteration of voltage-gated K(+) currents of dorsal root ganglia (DRG) neurons innervating the pancreas. CP was induced in adult rats by an intraductal injection of TNBS. DRG neurons innervating the pancreas were identified by 1,1'-dioleyl-3,3,3',3-tetramethylindocarbocyanine methanesulfonate fluorescence labeling. Perforated patch-clamp recordings were made from acutely dissociated DRG neurons from control and TNBS-treated rats. Pancreas-specific DRG neurons displayed more depolarized resting potentials in TNBS-treated rats than those in controls (P < 0.02). Some neurons from the TNBS-treated group exhibited spontaneous firings. TNBS-induced CP also resulted in a dramatic reduction in rheobase (P < 0.05) and a significant increase in the number of action potentials evoked at twice rheobase (P < 0.05). Under voltage-clamp conditions, neurons from both groups exhibited transient A-type (I(A)) and sustained outward rectifier K(+) currents (I(K)). Compared with controls, the average I(A) but not the average I(K) density was significantly reduced in the TNBS-treated group (P < 0.05). The steady-state inactivation curve for I(A) was displaced by approximately 20 mV to more hyperpolarized levels after the TNBS treatment. These data suggest that TNBS treatment increases the excitability of pancreas-specific DRG neurons by suppressing I(A) density, thus identifying for the first time a specific molecular mechanism underlying chronic visceral pain and sensitization in CP.     

Systemic administration of anti-NGF increases A-type potassium currents and decreases pancreatic nociceptor excitability in a rat model of chronic pancreatitis

We have previously shown that pancreatic sensory neurons in rats with chronic pancreatitis (CP) display increased excitability associated with a decrease in transient inactivating potassium currents (I(A)), thus accounting in part for the hyperalgesia associated with this condition. Because of its well known role in somatic hyperalgesia, we hypothesized a role for the nerve growth factor (NGF) in driving these changes. CP was induced by intraductal injection of trinitrobenzene sulfonic acid (TNBS) in rats. After 3 wk, anti-NGF antibody or control serum was injected intra-peritoneally daily for 1 wk. This protocol was repeated in another set of experiments in control rats (receiving intraductal PBS instead of TNBS). Pancreatic nociceptors labeled with the dye Dil were identified, and patch-clamp recordings were made from acutely dissociated DRG neurons. Sensory neurons from anti-NGF-treated rats displayed a lower resting membrane potential, increased rheobase, decreased burst discharges in response to stimulatory current, and decreased input resistance compared with those treated with control serum. Under voltage-clamp condition, neuronal I(A) density was increased in anti-NGF-treated rats compared with rats treated with control serum. However, anti-NGF treatment had no effect on electrophysiological parameters in neurons from control rats. The expression of Kv-associated channel or ancillary genes Kv1.4, 4.1, 4.2, 4.3, and DPP6, DPP10, and KCHIPs 1-4 in pancreas-specific nociceptors was examined by laser-capture microdissection and real-time PCR quantification of mRNA levels. No significant differences were seen among those. These findings emphasize a key role for NGF in maintaining neuronal excitability in CP specifically via downregulation of I(A) by as yet unknown mechanisms.     

A neural network dynamic model reproducing the output signal of the ganglion cell

A functional model of a neural network reproducing the output signal of the ganglion cell is proposed. The model assumes that receptive fields with antagonistic center and periphery are formed.     

Effects of quorum-sensing on immunoglobulin G responses in a rat model of chronic lung infection with Pseudomonas aeruginosa

Levels of serum antibodies against Pseudomonas aeruginosa were observed for 106 days in a rat model of chronic lung infection. Significantly weaker responses of serum IgG and IgG1 and a lower ratio of IgG1/IgG2a were found in the rats infected with the quorum-signal-deficient mutant, PAO1 (rhlI, lasI), compared with the wild-type PAO1. Four out of 15 rats infected with wild-type PAO1 contained bacteria in the lungs on day 106, whereas no bacteria were found in the mutant PAO1 group. The results indicate that quorum signals contribute to the persistence of the infection and influence the immune response.     

Chemopreventive effects of resveratrol in a rat model of cerulein-induced acute pancreatitis

In the past decades, a greater understanding of acute pancreatitis has led to improvement in mortality rates. Nevertheless, this disease continues to be a health care system problem due to its economical costs. Future strategies such as antioxidant supplementation could be very promising, regarding to beginning and progression of the disease. For this reason, this study was aimed at assessing the effect of exogenous administration of resveratrol during the induction process of acute pancreatitis caused by the cholecystokinin analog cerulein in rats. Resveratrol pretreatment reduced histological damage induced by cerulein treatment, as well as hyperamylasemia and hyperlipidemia. Altered levels of corticosterone, total antioxidant status, and glutathione peroxidase were significantly reverted to control levels by the administration of resveratrol. Lipid peroxidation was also counteracted; nevertheless, superoxide dismutase enzyme was overexpressed due to resveratrol pretreatment. Related to immune response, resveratrol pretreatment reduced pro-inflammatory cytokine IL-1β levels and increased anti-inflammatory cytokine IL-10 levels. In addition, pretreatment with resveratrol in cerulein-induced pancreatitis rats was able to reverse, at least partially, the abnormal calcium signal induced by treatment with cerulein. In conclusion, this study confirms antioxidant and immunomodulatory properties of resveratrol as chemopreventive in cerulein-induced acute pancreatitis.     

Chromosome aberrations and dominant lethals in rat oocytes during acute and chronic alcoholic intoxication

The influence of a single dose and of long-term alcohol administration on cytogenetic processes in the oocytes of Wistar white rats was studied. It is shown that a single dose of alcohol in preovulatory period when the oocytes are in the stage of diakinesismeiosis metaphase I significantly increases the rate of aneuploid gametes and dominant lethality. Analogous effect follows after long-term alcohol administration. Similarity of cytogenetic effects of acute and chronic alcohol intoxication suggests that both types of influence trigger common mechanism which results in chromosome abnormalities and, consequently, in embryonic death, i.e. dominant lethality. Taking into account that alcohol-like colchicine disturbs normal functioning of the spindle filaments, the appearance of pathology under alcohol intoxication may well be induced by disorders occurring in the stage of cell formation.