Hormonal protection in acute pancreatitis by ghrelin, leptin and melatonin

Practical application of melatonin for pancreas disorders: protective roles against inflammation, malignancy, and dysfunctions

Melatonin, a hormone primarily produced by the pineal gland, exhibits a range of physiological functions that extend beyond its well-known role in regulating circadian rhythms. This hormone influences energy metabolism, modulates insulin sensitivity, and plays a significant role in controlling sleep patterns and food intake. Notably, melatonin is also synthesized in various peripheral organs, including the gastrointestinal system and pancreas, suggesting its function as a local hormone. The presence of melatonin receptors in the pancreas underscores its relevance in pancreatic physiology. Pancreatic disorders, such as diabetes mellitus (DM), pancreatitis, and pancreatic cancer, often stem from inflammatory processes. The majority of these conditions are characterized by dysregulated immune responses and oxidative stress. Melatonin's anti-inflammatory properties are mediated through the inhibition of pro-inflammatory cytokines and the activation of antioxidant enzymes, which help to mitigate cellular damage. Furthermore, melatonin has demonstrated pro-apoptotic effects on cancer cells, promoting cell death in malignant tissues while preserving healthy cells. Thus, melatonin emerges as a multifaceted agent with significant therapeutic potential for pancreatic disorders. Its ability to reduce inflammation and oxidative stress positions it as a promising adjunct therapy for conditions such as diabetes mellitus, pancreatitis, and pancreatic cancer. By modulating immune responses and enhancing cellular resilience through antioxidant mechanisms, melatonin not only addresses the symptoms but also targets the underlying pathophysiological processes associated with these disorders. This review aims to categorize and summarize the impacts of melatonin on pancreatic functions and disorders, emphasizing its potential as a therapeutic agent for managing pancreatic dysfunctions. Future research should focus on elucidating the precise mechanisms by which melatonin exerts its protective effects on pancreatic tissues and exploring optimal dosing strategies for clinical applications. The integration of melatonin into treatment regimens may enhance existing therapies and offer new hope for individuals suffering from pancreatic dysfunctions.

Antioxidative effect of astragalosides on acute pancreatitis in mice

Introduction

The research examined the antioxidative impact of astragalosides (AST) on experimental acute pancreatitis (AP) in mice. This study aims to assess the correlation between varying doses of astragalosides and superoxide dismutase (SOD) activity in an acute pancreatitis mouse model. By examining the interplay between astragaloside's protective effects and its antioxidant properties, we aim to deepen our understanding of its therapeutic potential in acute pancreatitis.

Methods

The AP model in mice was induced by retrograde injection of sodium deoxycholate into the biliary and pancreatic ducts. Serum amylase activity was monitored at various time points following induction. Furthermore, 24 hours post-induction, levels of serum nitric oxide (NO), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in pancreatic tissue were assessed.

Results

The findings of this study illustrated that AST, while exhibiting a protective effect in experimental AP, could effectively lower the elevated serum NO levels, reduce MDA production, and enhance SOD activity in model mice. AST notably reduced MDA levels in the pancreatic tissue of AP mice, underscoring its ability to inhibit membrane peroxidation induced by oxygen free radicals. Furthermore, AST was observed to elevate SOD activity in scavenging oxygen free radicals in pancreatic tissue.

Conclusion

These findings suggest that AST enhances recovery in an experimental acute pancreatitis mouse model by exerting antioxidative effects.

Melatonin ameliorates multiorgan injuries induced by severe acute pancreatitis in mice by regulating the Nrf2 signaling pathway

Severe acute pancreatitis (SAP) is a complicated inflammatory reaction that impacts the pancreas, often resulting in damage to numerous organs. This disorder encompasses a range of processes such as inflammation, oxidative stress, and pancreatitis. The hormone melatonin (MT) is primarily secreted by the pineal gland and plays a crucial role in mitigating inflammation, countering the harmful effects of free radicals, and regulating oxidative stress. The aim of this research was to investigate the potential protective impact and the underlying mechanism of melatonin in mice afflicted with SAP. The biochemical and histological assessments unequivocally demonstrated that melatonin effectively inhibited necrosis, infiltration, edema and cell death in pancreatic tissues, thereby suppressing acute pancreatitis. Notably, melatonin also alleviated the consequent harm to distant organs, notably the lungs, liver, and kidneys. Furthermore, both preventive and therapeutic administration of melatonin prompted nuclear factor E2-related factor 2 (Nrf2) activation followed by Nrf2 target gene expression. Nrf2 initiates the activation of antioxidant genes, thereby providing defense against oxidative stress. Conversely, Nrf2 reduction may contribute to impaired antioxidant protection in SAP. The beneficial impact of Nrf2 on antioxidants was absent in Nrf2-knockout mice, leading to the accumulation of LDH and exacerbation of cell death. This deterioration in both pancreatitis and injuries in distant organs intensified significantly. The results indicate that melatonin has an enhanced ability to protect against multiorgan damage caused by SAP, which is accomplished through the increase in Nrf2 expression. Additionally, Nrf2 initiates the activation of antioxidant genes that offer defense against cell death.

The Efficacy of Chaihu-Guizhi-Ganjiang Decoction on Chronic Non-Atrophic Gastritis with Gallbladder Heat and Spleen Cold Syndrome and Its Metabolomic Analysis: An Observational Controlled Before-After Clinical Trial

Purpose

The aim of this study was to verify the effectiveness and explore the mechanism of Chaihu-Guizhi-Ganjiang decoction (CGGD) in the treatment of chronic non-atrophic gastritis (CNAG) with gallbladder heat and spleen cold syndrome (GHSC) by metabolomics based on UHPLC-Q-TOF/MS.

Patients and Methods

An observational controlled before-after study was conducted to verify the effectiveness of CGGD in the treatment of CNAG with GHSC from January to June 2023, enrolling 27 patients, who took CGGD for 28 days. 30 healthy volunteers were enrolled as the controls. The efficacy was evaluated by comparing the traditional Chinese medicine (TCM) syndrome and CNAG scores, and clinical parameters before and after treatment. The plasma levels of hormones related to gastrointestinal function were collected by ELISA. The mechanisms of CGGD in the treatment of CNAG with GHSC were explored using a metabolomic approach based on UHPLC-Q-TOF/MS.

Results

Patients treated with CGGD experienced a statistically significant improvement in TCM syndrome and CNAG scores (p < 0.01). CGGD treatment evoked the concentration alteration of 15 biomarkers, which were enriched in the glycerophospholipid metabolism, and branched-chain amino acids biosynthesis pathways. Moreover, CGGD treatment attenuated the abnormalities of the gastrointestinal hormone levels and significantly increased the pepsinogen level.

Conclusion

It was the first time that this clinical trial presented detailed data on the clinical parameters that demonstrated the effectiveness of CGGD in the treatment of CNAG with GHSC patients. This study also provided supportive evidence that CNAG with GHSC patients were associated with disturbed branched-chain amino acid metabolism and glycerophospholipid levels, suggesting that CNAG treatment based on TCM syndrome scores was reasonable and also provided a potential pharmacological mechanism of action of CGGD.

Acute pancreatitis: pathogenesis and emerging therapies

Acute pancreatitis is a severe inflammatory disorder with limited treatment options. Improved understanding of disease mechanisms has led to new and potential therapies. Here we summarize what we view as some of the most promising new therapies for treating acute pancreatitis, emphasizing the rationale of specific treatments based on disease mechanisms. Targeted pharmacologic interventions are highlighted. We explore potential treatment benefits and risks concerning reducing acute injury, minimizing complications, and improving long-term outcomes. Mechanisms associated with acute pancreatitis initiation, perpetuation, and reconstitution are highlighted, along with potential therapeutic targets and how these relate to new treatments.

Ameliorative effects of the melatonin on some cytokine levels, NF-κB immunoreactivity, and apoptosis in rats with cerulein-induced acute pancreatitis

Objectives

Investigating the ameliorative effects of melatonin on cytokine levels, apoptosis, and NF-κB immunoreactivity in rats with cerulein-induced acute pancreatitis.

Materials and Methods

Thirthy-two Wistar Albino rats were divided into four groups: Control group which didn't undergo acute pancreatitis induction and was left without treatment, pancreatitis group in which the acute pancreatitis was induced by 2 successive intraperitoneal doses of cerulein at a 2-hour interval (50 µg/kg and then 25 µg/kg), melatonin-treated pancreatitis group which was intraperitoneally administrated with 50 mg/kg of melatonin, 30 min before each cerulein injection, and melatonin group which was intraperitoneally administrated with 2 successive doses of melatonin (50 mg/kg each) at a 2-hour interval. Pancreatic tissue and blood samples were taken from animals of all groups. IL-1β, TNF-α, and IL-10 levels were determined in blood samples. Apoptosis was determined by the TUNEL assay and the NF-κB was detected immunohistochemically in acinar cells of the exocrine pancreatic portion.

Results

IL-1β, TNF-α, and IL-10 levels in the acute pancreatitis group were significantly increased when compared to the control negative group. IL-1β and TNF-α levels in the melatonin-treated pancreatitis group were significantly lower than those of the acute pancreatitis group. While number of apoptotic cells and percentage of NF-κB immunopositive cells in the acute pancreatitis group were significantly increased compared to other groups and it was observed that these parameters were significantly reduced in the melatonin-treated pancreatitis group compared to the acute pancreatitis group.

Conclusion

These findings suggest that melatonin administration can significantly reduce the severity of acute pancreatitis in rats.

Role of obesity in pathogenesis of acute pancreatitis

Acute pancreatitis (AP) is one of the most common digestive disorders that cause hospitalization. While most of patients with AP have a mild to moderate disease and recover rapidly, about 20% of patients with AP have a severe disease and experience substantial morbidity and mortality from local and/or systemic compli-cations. The incidence of obesity has increased worldwide, and its epidemiological characteristics and rising trend are consistent with those of AP. Therefore, obesity has probably contributed to the increase in the incidence and severity of AP. However, previous studies have generated conflicting results, and some studies demonstrated that obesity is a protective factor in patients with AP. Here we discuss the role of obesity in the pathogenesis of AP and the underlying mechanisms based on clinically relevant studies.

Integrative effects of transcutaneous electrical acustimulation on abdominal pain, gastrointestinal motility, and inflammation in patients with early-stage acute pancreatitis

BACKGROUND/AIMS

Gastrointestinal (GI) dysmotility in acute pancreatitis (AP) aggravates inflammation and results in severe complications. This study aimed to explore effects and possible mechanisms of transcutaneous electrical acustimulation (TEA) on abdominal pain, GI dysmotility, and inflammation in AP patients.

METHODS

Forty-two AP patients were blindly randomized to receive TEA (n = 21) at acupoints PC6 and ST36 or Sham-TEA (n = 21) at sham points for 2 days. Symptom scores, gastric slow waves, autonomic functions (assessed by spectral analysis of heart rate variability), circulatory levels of motilin, ghrelin, and TNF-α were measured before and after the treatment. Sixteen healthy controls (HCs) were also included without treatment for the assessment of gastric slow waves and biochemistry.

KEY RESULTS

Compared with Sham-TEA, TEA decreased abdominal pain score (2.57 ± 1.78 vs. 1.33 ± 1.02, p < 0.05), bloating score (5.19 ± 1.21 vs. 0.76 ± 0.99, p < 0.001), the first defecation time (65.79 ± 19.51 h vs. 51.38 ± 17.19 h, p < 0.05); TEA, but not Sham-TEA, improved the percentage of normal gastric slow waves by 41.6% (p < 0.05), reduced AP severity score (5.52 ± 2.04 vs. 3.90 ± 1.90, p < 0.05) and serum TNF-α (7.59 ± 4.80 pg/ml vs. 4.68 ± 1.85 pg/ml, p < 0.05), and upregulated plasma ghrelin (0.85 ± 0.96 ng/ml vs. 2.00 ± 1.71 ng/ml, p = 0.001) but not motilin (33.08 ± 22.65 pg/ml vs. 24.12 ± 13.95 pg/ml, p > 0.05); TEA decreased sympathetic activity by 15.0% and increased vagal activity by 18.3% (both p < 0.05).

CONCLUSIONS & INFERENCES

TEA at PC6 and ST36 administrated at early stage of AP reduces abdominal pain, improves GI motility, and inhibits inflammatory cytokine, TNF-α, probably mediated via the autonomic and ghrelin mechanisms.

Protective and Healing Effects of Ghrelin and Risk of Cancer in the Digestive System

Ghrelin is an endogenous ligand for the ghrelin receptor, previously known as the growth hormone secretagogue receptor. This hormone is mainly produced by endocrine cells present in the gastric mucosa. The ghrelin-producing cells are also present in other organs of the body, mainly in the digestive system, but in much smaller amount. Ghrelin exhibits a broad spectrum of physiological effects, such as stimulation of growth hormone secretion, gastric secretion, gastrointestinal motility, and food intake, as well as regulation of glucose homeostasis and bone formation, and inhibition of inflammatory processes. This review summarizes the recent findings concerning animal and human data showing protective and therapeutic effects of ghrelin in the gut, and also presents the role of growth hormone and insulin-like growth factor-1 in these effects. In addition, the current data on the possible influence of ghrelin on the carcinogenesis, its importance in predicting the risk of developing gastrointestinal malignances, as well as the potential usefulness of ghrelin in the treatment of cancer, have been presented.

Ghrelin inhibits IKKβ/NF-κB activation and reduces pro-inflammatory cytokine production in pancreatic acinar AR42J cells treated with cerulein

BACKGROUND

Previous studies have provided conflicting results regarding whether the serum ghrelin concentration can reflect the severity of acute pancreatitis (AP). The present study examined the correlation between the serum ghrelin concentration and AP severity in animal models and investigated whether altered ghrelin expression in pancreatic acinar cells influences IKKβ/NF-κB signaling and pro-inflammatory cytokine production.

METHODS

Mild or severe AP was induced in rats by intraperitoneal injection of cerulein or retrograde cholangiopancreatic duct injection of sodium taurocholate, respectively. After successful model induction, serum ghrelin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) concentrations were determined by enzyme-linked immunosorbent assay, and IKKβ/NF-κB activation was assessed by immunohistochemistry. Subsequently, stable overexpression or knockdown of ghrelin in AR42J cells was achieved by lentiviral transfection. After transfected cells and control cells were treated with cerulein for 24 h, the TNF-α and IL-1β levels in the supernatants were determined by enzyme-linked immunosorbent assay, and the expression levels of p-p65, IKKβ, and p-IKKβ were detected by Western blotting.

RESULTS

In rat AP models, AP severity was correlated with increased IKKβ/NF-κB activation, pro-inflammatory cytokine production, and ghrelin secretion. The levels of pro-inflammatory cytokines TNF-α and IL-1β as well as IKKβ/NF-κB signaling activity were increased upon knockdown of ghrelin in the AP acinar cell model and decreased with ghrelin overexpression.

CONCLUSIONS

Serum ghrelin is related to the severity of AP. Ghrelin may play a protective role in the pathogenesis of AP by inhibiting the pro-inflammatory cytokines and the activation of the IKKβ/NF-κB signaling pathway.

Potentiality of ghrelin as antioxidant and protective agent

Background

Oxidative stress is the result of cellular troubles related to aerobic metabolism. Furthermore, this stress is always associated with biological responses evoked by physical, chemical, environmental, and psychological factors. Several studies have developed many approaches of antioxidant defense to diminish the severity of many diseases. Ghrelin was originally identified from the rat stomach, and it is a potent growth hormone-releasing peptide that has pleiotropic functions.

Methods

A systematic review was conducted within PubMed, ScienceDirect, MEDLINE, and Scopus databases using keywords such as ghrelin, antioxidant, oxidative stress, and systemic oxidative stress sensor.

Results

In the last decade, many studies show that ghrelin exhibits protection effects against oxidative stress derived probably from its antioxidant effects. Pieces of evidence demonstrate that systemic oxidative stress increase ghrelin levels in the plasma. The expression of ghrelin and its receptor in ghrelin peripheral tissues and extensively in the central nervous system suggests that this endogenous peptide plays an important role as a systemic oxidative stress sensor

Conclusion

The current evidence confirms that ghrelin and its derived peptides (Desacyl-ghrelin, obestatin) act as a protective antioxidant agent. Therefore, stressor modality, duration, and intensity are the parameters of oxidative stress that must be taken into consideration to determine the role of ghrelin, Desacyl-ghrelin, and obestatin in the regulation of cell death pathways.

Melatonin Modulates the Antioxidant Defenses and the Expression of Proinflammatory Mediators in Pancreatic Stellate Cells Subjected to Hypoxia

Pancreatic stellate cells (PSC) play a major role in the formation of fibrotic tissue in pancreatic tumors. On its side, melatonin is a putative therapeutic agent for pancreatic cancer and inflammation. In this work, the actions of melatonin on PSC subjected to hypoxia were evaluated. Reactive oxygen species (ROS) generation reduced (GSH) and oxidized (GSSG) levels of glutathione, and protein and lipid oxidation were analyzed. The phosphorylation of nuclear factor erythroid 2-related factor (Nrf2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), and the regulatory protein nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha (IκBα) was studied. The expression of Nrf2-regulated antioxidant enzymes, superoxide dismutase (SOD) enzymes, cyclooxygenase 2 (COX-2), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also studied. Total antioxidant capacity (TAC) was assayed. Finally, cell viability was studied. Under hypoxia and in the presence of melatonin generation of ROS was observed. No increases in the oxidation of proteins or lipids were detected. The phosphorylation of Nrf2 and the expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1, heme oxygenase-1, SOD1, and of SOD2 were augmented. The TAC was increased. Protein kinase C was involved in the effects of melatonin. Melatonin decreased the GSH/GSSG ratio at the highest concentration tested. Cell viability dropped in the presence of melatonin. Finally, melatonin diminished the phosphorylation of NF-kB and the expression of COX-2, IL-6, and TNF-α. Our results indicate that melatonin, at pharmacological concentrations, modulates the red-ox state, viability, and the expression of proinflammatory mediators in PSC subjected to hypoxia.

Preconception Alcohol Exposure Increases the Susceptibility to Diabetes in the Offspring

Heavy alcohol drinking alters glucose metabolism, but the inheritability of this effect of alcohol is not well understood. We used an animal model of preconception alcohol exposure in which adult female rats were given free access to 6.7% alcohol in a liquid diet and water for about 4 weeks, went without alcohol for 3 weeks, and then were bred to generate male and female offspring. Control animals were either ad lib-fed rat chow or pair-fed an isocaloric liquid diet during the time of alcohol-feeding in the experimental animals. Our results show that the female rats fed with alcohol in the liquid diet, but not with the isocaloric liquid diet, prior to conception had an altered stress gene network involving glucose metabolism in oocytes when compared with those in ad lib-fed chow diet controls. The offspring born from preconception alcohol-fed mothers showed significant hyperglycemia and hypoinsulinemia when they were adults. These rats also showed increased levels of inflammatory cytokines and cellular apoptosis in the pancreas, altered insulin production and actions in the liver, and a reduced number of proopiomelanocortin neurons in the hypothalamus. Replenishment of proopiomelanocortin neurons in these animals normalized the abnormal glucose to restore homeostasis. These data suggest that preconception alcohol exposures alter glucose homeostasis by inducing proopiomelanocortin neuronal functional abnormalities. Our findings provide a novel insight into the impact of high doses of alcohol on the female gamete that may cause inheritance of an increased susceptibility to diabetes.

Benefits and Risks of Melatonin in Hepatic and Pancreatic Disorders; A Review of Clinical Evidences

Melatonin is the "clock factor" produced from the pineal gland dominating regular circadian rhythm in mammalians. It is an indoleamine with potent multifunctional pharmacological effects, both receptor dependent and non-receptor dependent effects, including antioxidant and anti-inflammatory activities. The aim of this review is to summarize clinical evidence related to melatonin's effectiveness in the treatment of liver and pancreas diseases. Databases including PubMed, Scopus, and Cochran Library were searched up to November 2020.Finally, this review has summarized up-to-date clinical evidence to investigate the efficacy and safety of melatonin for the management of liver and pancreas diseases. Melatonin has been demonstrated to have beneficial effects on the management of Non-alcoholic fatty liver disease (NAFLD), sleep disturbance of cirrhotic patients, prevention of drug/poison induced liver toxicity,and prevention of post endoscopic retrograde cholangiopancreatography pancreatitis (PEP);more data is needed to recommend melatonin administration in the treatment of mentioned disorders.

Pathophysiological and immunohistochemical analysis of pancreas after renal ischemia/reperfusion injury: protective role of melatonin

Objectives: To assess the remote pancreatic injury following renal ischemia/reperfusion (I/R) and to evaluate the effect of pre-treatment with melatonin on pancreatic structure and functions.Methods: 21 rats were divided equally into sham group, renal I/R group, and melatonin pre-treated renal I/R (Mel-I/R) group.Results: Renal I/R significantly increased serum amylase, fasting glucose and decreased serum insulin in I/R versus sham group. Pancreatic levels of malondialdehyde and tumour necrosis factor alpha were significantly increased associated with diminished glutathione. Immunohistochemical and morphometric analysis revealed significant reduction in insulin immune reactivity, β-cell number, β-cells percentage/total islet cell, percentage area of reactive β-cells, and the average area of islets in I/R versus sham group. These changes were alleviated by pre-treatment with melatonin.Conclusion: Renal I/R produces significant impairment of exocrine and endocrine pancreatic functions together with histological, immunohistochemical and morphometric alterations. Pre-treatment with melatonin significantly mitigates such remote pancreatic injury.

Comparing the preventive effect of sodium hydrosulfide, leptin, and curcumin against L-arginine induced acute pancreatitis in rats: role of corticosterone and inducible nitric oxide synthase

OBJECTIVES

Acute pancreatitis (AP) is a life-threatening condition. Using antioxidants in AP is insufficient and conflicting. Therefore, this study compared the effect of hydrogen sulfide (H2S) donor, sodium hydrosulfide (NaHS), leptin or curcumin pretreatment on AP induced by L-arginine.

METHODS

Forty adult male rats were used and classified into: 1) control; 2) AP group [each rat was intraperitoneally (i.p.) injected with 2 doses of L-arginine of 250 mg/100 g body weight (b.w.) with an interval of 1 h]; 3) NaHS+AP group (each rat was i.p. injected with 10 mg/kg b.w. of NaHS 1 h before induction of AP); 4) leptin+AP group (each rat was pretreated with 10 μg/kg b.w. of leptin 30 min before induction of AP; and 5) curcumin+AP group (in which rats were i.p. injected with 150 mg/kg b.w. of curcumin 30 min before induction of AP). Serum amylase, lipase, nitric oxide (NO), tumor necrosis factor alpha (TNF-α), and corticosterone (CORT) levels were assayed. In addition, pancreatic tissues were obtained for histopathological examination and malondialde-hyde (MDA), total antioxidant capacity (TAC), and inducible nitric oxide synthase (iNOS) levels were measured.

RESULTS

All AP treated groups showed significant decrease in serum levels of pancreatic enzymes, NO, and TNF-α, and pancreatic MDA and iNOS levels, while TAC levels were significantly increased. NaHS caused more limitation of inflammation than leptin and curcumin by affecting iNOS. Leptin was more potent than curcumin due to the stimulatory effect of leptin on glucocorticoid release to counteract inflammation.

CONCLUSIONS

NaHS was more effective in AP amelioration than the leptin and curcumin.

Ghrelin potentiates cardiac reactivity to stress by modulating sympathetic control and beta-adrenergic response

Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress.

AIMS

In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats.

MAIN METHODS AND KEY FINDINGS

Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol.

SIGNIFICANCE

Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors.

Tetradecyl 2,3-Dihydroxybenzoate Improves the Symptoms of Diabetic Mice by Modulation of Insulin and Adiponectin Signaling Pathways

Background: Tetradecyl 2,3-dihydroxybenzoate (ABG-001) derived from Chinese medicine, gentiana regescens Franch is a leading compound with NGF mimic effect, it can induce neurite outgrowth of PC12 cells via the IGF-1/PI3K/ERK signaling pathway. Thus, we inferred that this compound had anti-diabetic effect and used streptozocin (STZ)-induced diabetic mice to indicate it. Methods: ABG-001 was synthesized with 2,3-dihydroxybenzoic acid and tetradecyl alcohol under certain reaction conditions. STZ-induced diabetic mice were used to investigate anti-diabetic effect. Oral glucose tolerance test, insulin tolerance test, RT-PCR, Western blot, ELISA assays and histological section were performed to do the analysis of action mechanism. Results: ABG-001 showed anti-diabetic effect in STZ-induced diabetic mice. In diabetic mice, the anti-diabetic effect of ABG-001 at a dose of 20 mg/kg was equal with metformin at a dose of 140 mg/kg. Moreover, glucose tolerance and insulin sensitivity were significantly improved on diabetic mice. The plasma insulin, adiponectin and leptin were notably increased, whereas glucagon remarkably decreased. The gene expressions of adiponectin and leptin in adipose tissue, glucose transporter 4 and adiponectin receptor 1 in liver and gastrocnemius, ADR2 in hypothalamus and pancreas were obviously increased. Conclusion: ABG-001 exerts antidiabetic effects via modulation of insulin and adiponectin signaling pathways. This new type of molecule could be a promising drug candidate for treatment of diabetes.

Effects of Ghrelin miRNA on Inflammation and Calcium Pathway in Pancreatic Acinar Cells of Acute Pancreatitis

OBJECTIVES

The study investigated the effects of endogenous targeted inhibition of ghrelin gene on inflammation and calcium pathway in an in vitro pancreatic acinar cell model of acute pancreatitis.

METHODS

Lentiviral expression vector against ghrelin gene was constructed and transfected into AR42J cells. The mRNA and protein expression of each gene were detected by reverse transcription polymerase chain reaction, Western blotting, or enzyme-linked immunosorbent assay. The concentration of intracellular calcium ([Ca]i) was determined by calcium fluorescence mark probe combined with laser scanning confocal microscopy.

RESULTS

Compared with the control group, cerulein could upregulate mRNA and protein expression of inflammatory factors, calcium pathway, ghrelin, and [Ca]i. mRNA and protein expression of inflammatory factors increased significantly in cells transfected with ghrelin miRNA compared with the other groups. Intracellular calcium and expression of some calcium pathway proteins decreased significantly in cells transfected with ghrelin miRNA compared with the other groups.

CONCLUSIONS

Targeted inhibition of ghrelin gene in pancreatic acinar cells of acute pancreatitis can upregulate the expression of the intracellular inflammatory factors and alleviate the intracellular calcium overload.

Serum ghrelin, but not obestatin, is a potential predictor of acute pancreatitis severity

The roles of ghrelin and obestatin in AP remain controversial.This study investigates the effects and the predictive value of serum ghrelin and obestatin levels in the early stage of AP.A total of 193 consecutive patients with AP and 24 healthy controls were included. Patients were divided into mild acute pancreatitis (MAP), moderately severe acute pancreatitis (MSAP), and severe acute pancreatitis (SAP) groups. Serum levels of ghrelin and obestatin were measured on the first, third, and fifth days of hospitalization. The predictive value of serum ghrelin and obestatin levels on the first day in AP was examined using receiver-operating characteristic (ROC) curves.On the first day of hospitalization, the mean serum ghrelin level was significantly lower in patients with AP than in controls (P < .01). The serum ghrelin concentration decreased with increasing AP severity and was lower in patients with SAP than in those with MAP and MSAP (P < .05). It increased gradually from the first to the fifth day after treatment. ROC curves demonstrated that the serum ghrelin level on the first day had some predictive value for AP severity (area under the ROC curve = 0.646), with an optimal cut-off value of 87.83 pg/mL. Logistic regression showed that the serum ghrelin level had independent predictive value for non-MAP (odds ratio = 10.94; 95% confidence interval, 5.08-23.55; P < .01). The serum obestatin level did not differ significantly between patients with AP and controls and had the limited predictive value for non-MAP (area under the ROC curve = 0.564). However, the serum obestatin concentration showed a "warning" effect regarding AP etiology; on the first day of treatment, it was significantly lower in patients with AP of hypertriglyceridemic etiology than in those with AP of biliary, alcohol-related, and other etiologies (P = .05, P = .031, and P = .029, respectively).Serum ghrelin and obestatin levels may be related to the progression of AP in the early stage. Only the serum ghrelin level is a potential predictor of AP severity in the early stage. Obestatin may be involved in the pathogenesis of AP caused by hypertriglyceridemia.

Distribution and developmental changes of ghrelin-immunopositive cells in the pancreas of African ostrich chicks (Struthio camelus)

Ghrelin, the endogenous ligand for the growth hormone secretagogue receptor (GHS-R), is produced by multiple cell types and affects feeding behavior, metabolic regulation, and energy balance. In the mammalian pancreas, the types of endocrine cells that are immunoreactive to ghrelin vary. However, little was known about its distribution and developmental changes in the pancreas of African ostrich chicks (Struthio camelus). In the present study, the distribution, morphological characteristics, and developmental changes of ghrelin-immunopositive (ghrelin-ip) cells in the pancreas of African ostrich chicks were investigated using immunohistochemistry. Ghrelin-ip cells were found in both the pancreatic islets and acinar cell regions. The greatest number of ghrelin-ip cells were found in the pancreatic islets, and were primarily observed at the periphery of the islets; some ghrelin-ip cells were also located in the central portion of the pancreatic islets. Interestingly, from postnatal d 1 to d 90, there was a steady decrease in the number of ghrelin-ip cells in the pancreatic islets and acinar cell regions. These results clearly demonstrated that ghrelin-ip cells exist and decreased with age in the African ostrich pancreas from postnatal d 1 to d90. Thus, these findings indicated that ghrelin may be involved in the development of the pancreas in the African ostrich.

Effects of Melatonin and Its Analogues on Pancreatic Inflammation, Enzyme Secretion, and Tumorigenesis

Melatonin is an indoleamine produced from the amino acid l-tryptophan, whereas metabolites of melatonin are known as kynuramines. One of the best-known kynuramines is N¹-acetyl-N¹-formyl-5-methoxykynuramine (AFMK). Melatonin has attracted scientific attention as a potent antioxidant and protector of tissue against oxidative stress. l-Tryptophan and kynuramines share common beneficial features with melatonin. Melatonin was originally discovered as a pineal product, has been detected in the gastrointestinal tract, and its receptors have been identified in the pancreas. The role of melatonin in the pancreatic gland is not explained, however several arguments support the opinion that melatonin is probably implicated in the physiology and pathophysiology of the pancreas. (1) Melatonin stimulates pancreatic enzyme secretion through the activation of entero-pancreatic reflex and cholecystokinin (CCK) release. l-Tryptophan and AFMK are less effective than melatonin in the stimulation of pancreatic exocrine function; (2) Melatonin is a successful pancreatic protector, which prevents the pancreas from developing of acute pancreatitis and reduces pancreatic damage. This effect is related to its direct and indirect antioxidant action, to the strengthening of immune defense, and to the modulation of apoptosis. Like melatonin, its precursor and AFMK are able to mimic its protective effect, and it is commonly accepted that all these substances create an antioxidant cascade to intensify the pancreatic protection and acinar cells viability; (3) In pancreatic cancer cells, melatonin and AFMK activated a signal transduction pathway for apoptosis and stimulated heat shock proteins. The role of melatonin and AFMK in pancreatic tumorigenesis remains to be elucidated.

Constitutive photomorphogenesis protein 1 (COP1) and COP9 signalosome, evolutionarily conserved photomorphogenic proteins as possible targets of melatonin

The ubiquitin proteasome system has been proposed as a possible mechanism involved in the multiple actions of melatonin. COP1 (constitutive photomorphogenesis protein 1), a RING finger-type ubiquitin E3 ligase formerly identified in Arabidopsis, is a central switch for the transition from plant growth underground in darkness (etiolation) to growth under light exposure (photomorphogenesis). In darkness, COP1 binds to photomorphogenic transcription factors driving its degradation via the 26S proteasome; blue light, detected by cryptochromes, and red and far-red light detected by phytochromes, negatively regulate COP1. Homologues of plant COP1 containing all the structural features present in Arabidopsis as well as E3 ubiquitin ligase activity have been identified in mice and humans. Substrates for mammalian (m) COP1 include p53, AP-1 and c-Jun, p27(Kip1) , ETV1, MVP, 14-3-3σ, C/EBPα, MTA1, PEA3, ACC, TORC2 and FOXO1. This mCOP1 target suggests functions related to tumorigenesis, gluconeogenesis, and lipid metabolism. The role of mCOP1 in tumorigenesis (either as a tumor promoter or tumor suppressor), as well as in glucose metabolism (inhibition of gluconeogenesis) and lipid metabolism (inhibition of fatty acid synthesis), has been previously demonstrated. COP1, along with numerous other ubiquitin ligases, is regulated by the COP9 signalosome; this protein complex is associated with the oxidative stress sensor Keap1 and the deubiquitinase USP15. The objective of this review was to provide new information on the possible role of COP1 and COP9 as melatonin targets. The hypothesis is based on common functional aspects of melatonin and COP1 and COP9, including their dependence on light, regulation of the metabolism, and their control of tumor growth.

Potential benefits of melatonin in organ transplantation: a review

Organ transplantation is a useful therapeutic tool for patients with end-stage organ failure; however, graft rejection is a major obstacle in terms of a successful treatment. Rejection is usually a consequence of a complex immunological and nonimmunological antigen-independent cascade of events, including free radical-mediated ischemia-reperfusion injury (IRI). To reduce the frequency of this outcome, continuing improvements in the efficacy of antirejection drugs are a top priority to enhance the long-term survival of transplant recipients. Melatonin (N-acetyl-5-methoxytryptamine) is a powerful antioxidant and ant-inflammatory agent synthesized from the essential amino acid l-tryptophan; it is produced by the pineal gland as well as by many other organs including ovary, testes, bone marrow, gut, placenta, and liver. Melatonin has proven to be a potentially useful therapeutic tool in the reduction of graft rejection. Its benefits are based on its direct actions as a free radical scavenger as well as its indirect antioxidative actions in the stimulation of the cellular antioxidant defense system. Moreover, it has significant anti-inflammatory activity. Melatonin has been found to improve the beneficial effects of preservation fluids when they are enriched with the indoleamine. This article reviews the experimental evidence that melatonin is useful in reducing graft failure, especially in cardiac, bone, otolaryngology, ovarian, testicular, lung, pancreas, kidney, and liver transplantation.

Ghrelin and gastroparesis as early predictors of clinical outcomes in acute pancreatitis

BACKGROUND

Impaired motor and hormonal gastrointestinal functions have been implicated in the pathogenesis of acute pancreatitis. The aim of the present study was to investigate the predictive value of the Gastroparesis Cardinal Symptom Index and serum ghrelin in the development of clinically meaningful outcomes in patients with acute pancreatitis.

METHODS

This was a prospective clinical study. The Gastroparesis Cardinal Symptom Index and serum ghrelin were measured for 48 h after hospitalization. Univariate and multivariate logistic regression analyses were conducted.

RESULTS

The Gastroparesis Cardinal Symptom Index total score alone on day 2 was a significant predictor of oral feeding intolerance in both unadjusted (odds ratio 1.21 (1.01-1.46), P = 0.04) and adjusted (odds ratio 1.30 (1.01-1.69), P = 0.05) analyses. Adding ghrelin to Gastroparesis Cardinal Symptom Index further improved prediction in both unadjusted (odds ratio 1.26 (1.02-1.56), P = 0.03) and adjusted (odds ratio 1.53 (1.00-2.35), P = 0.05) analyses.

CONCLUSION

This pilot study demonstrates that the Gastroparesis Cardinal Symptom Index has a potential to be used as a predictor of oral feeding intolerance. Ghrelin, when combined with the Gastroparesis Cardinal Symptom Index, may further improve the predictive accuracy. These findings need to be confirmed in larger studies.

Diagnostic and therapeutic value of Ghrelin in digestive diseases

Ghrelin is a 28 amino-acid multi-functional peptide hormone, which was identified as a natural ligand of growth hormone secretagogue receptor (GHS-R). Ghrelin has been found in the stomach, intestine, pancreas and liver. In recent years, the application value of Ghrelin in digestive system diseases has attracted wide attention, especially in the protection of liver damage, assessment of the severity of pancreatitis, and evaluation of the activity and prognosis of peptic ulcer, gastritis and inflammatory bowel disease, and the occurrence and progression of gastrointestinal cancer. In this paper, we review the recent advance in understanding the role of Ghrelin in digestive diseases.