Sarcoidosis with esophageal involvement: an uncommon clinical enigma.

We present the case of a 46-year-old male, a former smoker, with a medical history significant for morbid obesity grade III, hypothyroidism, hyperuricemia, and dyslipidemia. Four months ago, he was diagnosed with sarcoidosis involving mediastinal lymph nodes and is currently undergoing treatment with corticosteroids. The patient presented to the emergency department with persistent epigastric and thoracic pain lasting one week, accompanied by dysphagia and odynophagia intermittently. Laboratory tests showed elevated acute-phase reactants, with no other notable abnormalities. Chest X-ray revealed pre-existing mediastinal adenopathy. Despite an abdominal CT scan with contrast showing no significant findings, esophagogastroduodenoscopy revealed marked extrinsic compression of the esophagus between 25 and 32 cm from the dental arch, with less intensity distally. Although passage of the endoscope through this area caused significant pain, it did not hinder its advancement. A chest CT scan with oral contrast demonstrated filamentous narrowing of the esophagus in the middle third, along with concentric thickening of its walls and multiple paratracheal, parahilar, and periesophageal lymphadenopathies. Following a tapering regimen of corticosteroids, the patient was discharged with a clinical diagnosis of sarcoidosis with mediastinal and esophageal involvement secondary to extrinsic compression. Due to clinical improvement with the prescribed treatment, endoscopic ultrasound and biopsies to assess esophageal wall involvement were deemed unnecessary.

Changing perspectives: unveiling the risks of ashwagandha-induced hepatotoxicity.

Ashwagandha, an herb popular in Ayurvedic medicine, is renowned for its health-enhancing properties. However, its association with liver damage in recent years has raised significant concerns, necessitating careful assessment and management. This case underscores the dangers of Ashwagandha, particularly for individuals with preexisting liver conditions, where it can lead to life-threatening acute-on-chronic liver failure. The lack of solid clinical evidence supporting Ashwagandha's health claims emphasizes the need for an evidence-based approach. Public education is essential to raise awareness of the risks associated with herbal supplements and prevent liver diseases.

Bismuth quadruple three-in-one single capsule three times a day increases effectiveness compared with the usual four times a day schedule: results from the European Registry on Helicobacter pylori Management (Hp-EuReg).

BACKGROUND: The recommended schedule for single capsule bismuth quadruple therapy (scBQT, Pylera) includes a proton pump inhibitor (PPI) two times a day and three scBQT capsules four times a day. Four times a day treatments are inconvenient and reduce adherence. In contrast, adherence improves with three times a day schedules. In clinical practice, many gastroenterologists use four capsule scBQT three times a day. However, the effectiveness and safety of this latter approach remain uncertain. AIM: To assess the effectiveness and safety of scBQT administered three times a day in the patients included in the European Registry on Helicobacter pylori Management (Hp-EuReg). METHODS: All Spanish adult patients registered in the Asociación Española de Gastroenterología Research Electronic Data Capture (REDCap) database from June 2013 to March 2021 receiving 10-day scBQT were analysed. Modified intention-to-treat effectiveness, adherence and the safety of scBQT given three times a day were calculated and compared with the four times a day schedule. A multivariate analysis was performed to determine independent factors predicting cure of the infection. RESULTS: Of the 3712 cases, 2516 (68%) were four times a day and 1196 (32%) three times a day. Mean age was 51 years, 63% were women and 15% had a peptic ulcer. The three times a day schedule showed significantly better overall cure rates than four times a day (1047/1112, 94%; 95% CI 92.7 to 95.6 vs 2207/2423, 91%; 95% CI 89.9 to 92.2, respectively, p=0.002). Adherence and safety data were similar for both regimens. In the multivariate analysis, three times a day dosage, first-line therapy, use of standard or high-dose PPIs and adherence over 90% were significantly associated with cure of the infection. CONCLUSIONS: ScBQT prescribed three times a day was more effective than the traditional four times a day schedule. No differences were observed in treatment adherence or safety.

Melatonin controls cell proliferation and modulates mitochondrial physiology in pancreatic stellate cells

We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells. In the presence of melatonin (1 mM, 100 µM, 10 µM, or 1 µM), decreases in the phosphorylation of c-Jun N-terminal kinase and of p44/42 and an increase in the phosphorylation of p38 were observed. Cell viability dropped in the presence of melatonin. A rise in the phosphorylation of AMP-activated protein kinase was detected in the presence of 1 mM and 100 µM melatonin. Treatment with 1 mM melatonin decreased the phosphorylation of protein kinase B, whereas 100 µM and 10 µM melatonin increased its phosphorylation. An increase in the generation of mitochondrial reactive oxygen species and a decrease of mitochondrial membrane potential were noted following melatonin treatment. Basal and maximal respiration, ATP production by oxidative phosphorylation, spare capacity, and proton leak dropped in the presence of melatonin. The expression of complex I of the mitochondrial respiratory chain was augmented in the presence of melatonin. Conversely, in the presence of 1 mM melatonin, decreases in the expression of mitofusins 1 and 2 were detected. The glycolysis and the glycolytic capacity were diminished in cells treated with 1 mM or 100 µM melatonin. Increases in the expression of phosphofructokinase-1 and lactate dehydrogenase were noted in cells incubated with 100 µM, 10 µM, or 1 µM melatonin. The expression of glucose transporter 1 was increased in cells incubated with 10 µM or 1 µM melatonin. Conversely, 1 mM melatonin decreased the expression of all three proteins. Our results suggest that melatonin, at pharmacological concentrations, might modulate mitochondrial physiology and energy metabolism in addition to major pathways involved in pancreatic stellate cell proliferation. (AU)

Melatonin controls cell proliferation and modulates mitochondrial physiology in pancreatic stellate cells.

We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells. In the presence of melatonin (1 mM, 100 µM, 10 µM, or 1 µM), decreases in the phosphorylation of c-Jun N-terminal kinase and of p44/42 and an increase in the phosphorylation of p38 were observed. Cell viability dropped in the presence of melatonin. A rise in the phosphorylation of AMP-activated protein kinase was detected in the presence of 1 mM and 100 µM melatonin. Treatment with 1 mM melatonin decreased the phosphorylation of protein kinase B, whereas 100 µM and 10 µM melatonin increased its phosphorylation. An increase in the generation of mitochondrial reactive oxygen species and a decrease of mitochondrial membrane potential were noted following melatonin treatment. Basal and maximal respiration, ATP production by oxidative phosphorylation, spare capacity, and proton leak dropped in the presence of melatonin. The expression of complex I of the mitochondrial respiratory chain was augmented in the presence of melatonin. Conversely, in the presence of 1 mM melatonin, decreases in the expression of mitofusins 1 and 2 were detected. The glycolysis and the glycolytic capacity were diminished in cells treated with 1 mM or 100 µM melatonin. Increases in the expression of phosphofructokinase-1 and lactate dehydrogenase were noted in cells incubated with 100 µM, 10 µM, or 1 µM melatonin. The expression of glucose transporter 1 was increased in cells incubated with 10 µM or 1 µM melatonin. Conversely, 1 mM melatonin decreased the expression of all three proteins. Our results suggest that melatonin, at pharmacological concentrations, might modulate mitochondrial physiology and energy metabolism in addition to major pathways involved in pancreatic stellate cell proliferation.

Green discoloration of the urine following sedation with propofol for colonoscopy.

Propofol (2,6-diisopropylphenol) is the most widely used drug for endoscopic procedures under deep sedation. We present the clinical case of an 83-year-old man who underwent a colonoscopy under sedation with propofol, observing a green discolouration of the urine during the procedure.

Curcumin and curcumoids: hepatoprotection or hepatotoxicity?

Curcumin (Curcuma longa) and curcumin analogues are plant-based drugs used because of their possible antioxidant and anti-inflammatory. Clinical data on the efficacy of curcumin as a hepatoprotectant are limited, with growing concern for formulations that may potentially increase curcumin hepatotoxicity.

Melatonin Induces Apoptosis and Modulates Cyclin Expression and MAPK Phosphorylation in Pancreatic Stellate Cells Subjected to Hypoxia.

In certain diseases of the pancreas, pancreatic stellate cells form an important part of fibrosis and are critical for the development of cancer cells. A hypoxic condition develops within the tumor, to which pancreatic stellate cells adapt and are able to proliferate. The consequence is the growth of the tumor. Melatonin, the product of the pineal gland, is gaining attention as an agent with therapeutic potential against pancreatic cancers. Its actions on tumor cells lead, in general, to a reduction in cell viability and proliferation. However, its effects on pancreatic stellate cells subjected to hypoxia are less known. In this study, we evaluated the actions of pharmacological concentrations of melatonin (1 mM-1 µM) on pancreatic stellate cells subjected to hypoxia. The results show that melatonin induced a decrease in cell viability at the highest concentrations tested. Similarly, the incorporation of BrdU into DNA was diminished by melatonin. The expression of cyclins A and D also was decreased in the presence of melatonin. Upon treatment of cells with melatonin, increases in the expression of major markers of ER stress, namely BIP, phospho-eIF2α and ATF-4, were detected. Modulation of apoptosis was noticed as an increase in caspase-3 activation. In addition, changes in the phosphorylated state of p44/42, p38 and JNK MAPKs were detected in cells treated with melatonin. A slight decrease in the content of α-smooth muscle actin was detected in cells treated with melatonin. Finally, treatment of cells with melatonin decreased the expression of matrix metalloproteinases 2, 3, 9 and 13. Our observations suggest that melatonin, at pharmacological concentrations, diminishes the proliferation of pancreatic stellate cells subjected to hypoxia through modulation of cell cycle, apoptosis and the activation of crucial MAPKs. Cellular responses might involve certain ER stress regulator proteins. In view of the results, melatonin could be taken into consideration as a potential therapeutic agent for pancreatic fibrosis.

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.

European Registry on Helicobacter pylori management: Single-capsule bismuth quadruple therapy is effective in real-world clinical practice.

BACKGROUND: There has been resurgence in the use of bismuth quadruple therapy (proton pump inhibitor, bismuth, tetracycline and metronidazole) for treating Helicobacter pylori infection thanks to a three-in-one single-capsule formulation. OBJECTIVE: To evaluate the effectiveness and safety of the single-capsule bismuth quadruple therapy. METHODS: Data were collected in a multicentre, prospective registry of the clinical practice of gastroenterologists on the management of H. pylori infection, where patients were registered at the Asociación Española de Gastroenterologia REDCap database on an electronic case report form until January 2020. Effectiveness by modified intention-to-treat and per-protocol as well as multivariable analysis were performed. Independent factors evaluated were: age, gender, indication, compliance, proton pump inhibitor dose and treatment line. RESULTS: Finally, 2100 patients were prescribed single-capsule bismuth quadruple therapy following the technical sheet (i.e., three capsules every 6 h for 10 days). The majority of these patients were naive (64%), with an average age of 50 years, 64% women and 16% with peptic ulcer. An overall modified intention-to-treat effectiveness of 92% was achieved. Eradication was over 90% in first-line treatment (95% modified intention-to-treat, n = 1166), and this was maintained as a rescue therapy, both in second (89% modified intention-to-treat, n = 375) and subsequent lines of therapy (third to sixth line: 92% modified intention-to-treat, n = 236). Compliance was the factor most closely associated with treatment effectiveness. Adverse events were generally mild to moderate, and 3% of patients reported a severe adverse event, leading to discontinuation of treatment in 1.7% of cases. CONCLUSIONS: Single-capsule bismuth quadruple therapy achieved H. pylori eradication in approximately 90% of patients in real-world clinical practice, both as a first-line and rescue treatment, with good compliance and a favourable safety profile.

European Registry on Helicobacter pylori Management: Effectiveness of First and Second-Line Treatment in Spain.

The management of Helicobacter pylori infection has to rely on previous local effectiveness due to the geographical variability of antibiotic resistance. The aim of this study was to evaluate the effectiveness of first and second-line H. pylori treatment in Spain, where the empirical prescription is recommended. A multicentre prospective non-interventional registry of the clinical practice of European gastroenterologists concerning H. pylori infection (Hp-EuReg) was developed, including patients from 2013 until June 2019. Effectiveness was evaluated descriptively and through a multivariate analysis concerning age, gender, presence of ulcer, proton-pump inhibitor (PPI) dose, therapy duration and compliance. Overall, 53 Spanish hospitals were included, and 10,267 patients received a first-line therapy. The best results were obtained with the 10-day bismuth single-capsule therapy (95% cure rate by intention-to-treat) and with both the 14-day bismuth-clarithromycin quadruple (PPI-bismuth-clarithromycin-amoxicillin, 91%) and the 14-day non-bismuth quadruple concomitant (PPI-clarithromycin-amoxicillin-metronidazole, 92%) therapies. Second-line therapies were prescribed to 2448 patients, with most-effective therapies being the triple quinolone (PPI-amoxicillin-levofloxacin/moxifloxacin) and the bismuth-levofloxacin quadruple schemes (PPI-bismuth-levofloxacin-amoxicillin) prescribed for 14 days (92%, 89% and 90% effectiveness, respectively), and the bismuth single-capsule (10 days, 88.5%). Compliance, longer duration and higher acid inhibition were associated with higher effectiveness. "Optimized" H. pylori therapies achieve over 90% success in Spain.

Pancreatic stellate cells exhibit adaptation to oxidative stress evoked by hypoxia.

BACKGROUND INFORMATION: Pancreatic stellate cells play a key role in the fibrosis that develops in diseases such as pancreatic cancer. In the growing tumour, a hypoxia condition develops under which cancer cells are able to proliferate. The growth of fibrotic tissue contributes to hypoxia. In this study, the effect of hypoxia (1% O2 ) on pancreatic stellate cells physiology was investigated. Changes in intracellular free-Ca2+ concentration, mitochondrial free-Ca2+ concentration and mitochondrial membrane potential were studied by fluorescence techniques. The status of enzymes responsible for the cellular oxidative state was analyzed by quantitative reverse transcription-polymerase chain reaction, high-performance liquid chromatography, spectrophotometric and fluorimetric methods and by Western blotting analysis. Cell viability and proliferation were studied by crystal violet test, 5-bromo-2-deoxyuridine cell proliferation test and Western blotting analysis. Finally, cell migration was studied employing the wound healing assay. RESULTS: Hypoxia induced an increase in intracellular and mitochondrial free-Ca2+ concentration, whereas mitochondrial membrane potential was decreased. An increase in mitochondrial reactive oxygen species production was observed. Additionally, an increase in the oxidation of proteins and lipids was detected. Moreover, cellular total antioxidant capacity was decreased. Increases in the expression of superoxide dismutase 1 and 2 were observed and superoxide dismutase activity was augmented. Hypoxia evoked a decrease in the oxidized/reduced glutathione ratio. An increase in the phosphorylation of nuclear factor erythroid 2-related factor and in expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1 and heme oxygenase-1 were detected. The expression of cyclin A was decreased, whereas expression of cyclin D and the content of 5-bromo-2-deoxyuridine were increased. This was accompanied by an increase in cell viability. The phosphorylation state of c-Jun NH2 -terminal kinase was increased, whereas that of p44/42 and p38 was decreased. Finally, cells subjected to hypoxia maintained migration ability. CONCLUSIONS AND SIGNIFICANCE: Hypoxia creates pro-oxidant conditions in pancreatic stellate cells to which cells adapt and leads to increased viability and proliferation.

The melatonin receptor antagonist luzindole induces the activation of cellular stress responses and decreases viability of rat pancreatic stellate cells.

In this study, we have examined the effects of luzindole, a melatonin receptor-antagonist, on cultured pancreatic stellate cells. Intracellular free-Ca2+ concentration, production of reactive oxygen species (ROS), activation of mitogen-activated protein kinases (MAPK), endoplasmic reticulum stress and cell viability were analyzed. Stimulation of cells with the luzindole (1, 5, 10 and 50 µm) evoked a slow and progressive increase in intracellular free Ca2+ ([Ca2+ ]i ) towards a plateau. The effect of the compound on Ca2+ mobilization depended on the concentration used. Incubation of cells with the sarcoendoplasmic reticulum Ca2+ -ATPase inhibitor thapsigargin (1 µm), in the absence of Ca2+ in the extracellular medium, induced a transient increase in [Ca2+ ]i . In the presence of thapsigargin, the addition of luzindole to the cells failed to induce further mobilization of Ca2+ . Luzindole induced a concentration-dependent increase in ROS generation, both in the cytosol and in the mitochondria. This effect was smaller in the absence of extracellular Ca2+ . In the presence of luzindole the phosphorylation of p44/42 and p38 MAPKs was increased, whereas no changes in the phosphorylation of JNK could be noted. Moreover, the detection of the endoplasmic reticulum stress-sensor BiP was increased in the presence of luzindole. Finally, viability was decreased in cells treated with luzindole. Because cellular membrane receptors for melatonin have not been detected in pancreatic stellate cells, we conclude that luzindole could exert direct effects that are not mediated through its action on melatonin membrane receptors.

Melatonin modulates proliferation of pancreatic stellate cells through caspase-3 activation and changes in cyclin A and D expression.

In this study, the effects of melatonin (1 µM-1 mM) on pancreatic stellate cells (PSC) have been examined. Cell viability and proliferation, caspase-3 activation, and the expression of cyclin A and cyclin D were analyzed. Our results show that melatonin decreased PSC viability in a time- and concentration-dependent manner. This effect was not inhibited by treatment of cells with MT1, MT2, calmodulin, or ROR-alpha inhibitors prior to melatonin addition. Activation of caspase-3 in response to melatonin was detected. The expression of cyclin A and cyclin D was decreased in cells treated with melatonin. Finally, changes in BrdU incorporation into the newly synthesized DNA of proliferating cells were also observed in the presence of melatonin. We conclude that melatonin, at pharmacological concentrations, modulates proliferation of PSC through activation of apoptosis and involving crucial regulators of the cell cycle. These actions might not require specific melatonin receptors. Our observations suggest that melatonin, at high doses, could potentially exert anti-fibrotic effects and, thus, could be taken into consideration as supportive treatment in the therapy of pancreatic diseases.

Melatonin modulates red-ox state and decreases viability of rat pancreatic stellate cells.

In this work we have studied the effects of pharmacological concentrations of melatonin (1 µM-1 mM) on pancreatic stellate cells (PSC). Cell viability was analyzed by AlamarBlue test. Production of reactive oxygen species (ROS) was monitored following CM-H2DCFDA and MitoSOX Red-derived fluorescence. Total protein carbonyls and lipid peroxidation were analyzed by HPLC and spectrophotometric methods respectively. Mitochondrial membrane potential (ψm) was monitored by TMRM-derived fluorescence. Reduced (GSH) and oxidized (GSSG) levels of glutathione were determined by fluorescence techniques. Quantitative reverse transcription-polymerase chain reaction was employed to detect the expression of Nrf2-regulated antioxidant enzymes. Determination of SOD activity and total antioxidant capacity (TAC) were carried out by colorimetric methods, whereas expression of SOD was analyzed by Western blotting and RT-qPCR. The results show that melatonin decreased PSC viability in a concentration-dependent manner. Melatonin evoked a concentration-dependent increase in ROS production in the mitochondria and in the cytosol. Oxidation of proteins was detected in the presence of melatonin, whereas lipids oxidation was not observed. Depolarization of ψm was noted with 1 mM melatonin. A decrease in the GSH/GSSG ratio was observed, that depended on the concentration of melatonin used. A concentration-dependent increase in the expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1 and heme oxygenase-1 was detected in cells incubated with melatonin. Finally, decreases in the expression and in the activity of superoxide dismutase were observed. We conclude that pharmacological concentrations melatonin modify the redox state of PSC, which might decrease cellular viability.

Definition of the profiles of hepatitis C virus patients based on the identification of risky practices in Spain

The absolute number of patients infected with the hepatitis C virus and its prevalence in Spain according to risk practices are not precise. The objective of the study was to estimate the current direct-action antiviral candidates, according to risky practices. The exposed population was determined according to each risky practice and age, based on the data obtained in two epidemiological studies and other bibliographic sources. The overall prevalence of positive serology for the Hepatitis C virus according to the analyzed data was 1.1% (41% with an active infection). The most at-risk group are intravenous drug users (60,368-82,454). It is estimated that between 37,387 to 51,065 patients would be infected via sexual transmission, between 55,505 and 75,812 patients following a blood transfusion and around 18,528 to 25,307 patients by socio-family transmission. According to these data, more than half (55-79%) of the subjects with risky practices would have significant fibrosis (≥ F2). It is estimated that more than half a million people have a positive serology for the Hepatitis C virus and 144,191 to 227,773 antiviral treatments are expected in the coming years. The identification of people with risky practices is key to increase the percentage of diagnosed cases

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Definition of the profiles of hepatitis C virus patients based on the identification of risky practices in Spain.

The absolute number of patients infected with the hepatitis C virus and its prevalence in Spain according to risk practices are not precise. The objective of the study was to estimate the current direct-action antiviral candidates, according to risky practices. The exposed population was determined according to each risky practice and age, based on the data obtained in two epidemiological studies and other bibliographic sources. The overall prevalence of positive serology for the Hepatitis C virus according to the analyzed data was 1.1% (41% with an active infection). The most at-risk group are intravenous drug users (60,368-82,454). It is estimated that between 37,387 to 51,065 patients would be infected via sexual transmission, between 55,505 and 75,812 patients following a blood transfusion and around 18,528 to 25,307 patients by socio-family transmission. According to these data, more than half (55-79%) of the subjects with risky practices would have significant fibrosis (≥ F2). It is estimated that more than half a million people have a positive serology for the Hepatitis C virus and 144,191 to 227,773 antiviral treatments are expected in the coming years. The identification of people with risky practices is key to increase the percentage of diagnosed cases.

The melatonin receptor antagonist luzindole induces Ca2+ mobilization, reactive oxygen species generation and impairs trypsin secretion in mouse pancreatic acinar cells.

BACKGROUND: In this work we studied the effects of the melatonin receptor-antagonist luzindole (1 µM-50 µM) on isolated mouse pancreatic acinar cells. METHODS: Changes in intracellular free-Ca2+ concentration, reactive oxygen species production and trypsin secretion were analyzed. RESULTS: Luzindole induced increases in [Ca2+]i that diminished CCK-8 induced Ca2+ mobilization, compared with that observed when CCK-8 was applied alone. Treatment of cells with thapsigargin (1 µM), in the absence of Ca2+ in the extracellular medium, evoked a transient increase in [Ca2+]i. The additional incubation of cells with luzindole (10 µM) failed to induce further mobilization of Ca2+. In the presence of luzindole a concentration-dependent increase in ROS generation was observed that decreased in the absence of Ca2+ or by pretreatment of cells with melatonin (100 µM). Incubation of pancreatic acinar cells with luzindole (10 µM) impaired CCK-8-induced trypsin secretion. Melatonin was unable to revert the effect of luzindole on CCK-8-induced trypsin secretion. CONCLUSION: The melatonin receptor-inhibitor luzindole induces Ca2+-mediated pro-oxidative conditions and impairment of enzyme secretion, which creates a situation in pancreatic acinar cells that might compromise their function. GENERAL SIGNIFICANCE: The effects of luzindole that we have observed, might be unspecific and could mislead the observations when it is used to study the actions of melatonin on the gland. Another possibility is that melatonin receptors exhibit a basal or agonist-independent activity in pancreatic acinar cells, which might be modulated by melatonin or luzindole.