Non-steroidal anti-inflammatory drugs increase insulin release from beta cells by inhibiting ATP-sensitive potassium channels

Effect of Phenylbutazone Administration on Insulin Sensitivity in Horses With Insulin Dysregulation

BACKGROUND

Phenylbutazone is prescribed to manage pain caused by hyperinsulinemia-associated laminitis. Phenylbutazone reduces glucose and insulin concentrations in horses with insulin dysregulation (ID) but the underlying mechanism of action is unknown.

HYPOTHESIS/OBJECTIVES

Investigate the effect of phenylbutazone on tissue insulin sensitivity in horses. It is hypothesized that the reduced glucose and insulin concentrations in horses with ID receiving phenylbutazone are mediated by a higher tissue insulin sensitivity.

ANIMALS

Fifteen light breed horses, including seven with ID.

METHODS

Randomized cross-over study. Horses underwent a modified frequently sampled intravenous glucose tolerance test (mFSIGTT) after 8 days of treatment with phenylbutazone (4.4 mg/kg IV daily) or placebo (5 mL 0.9% saline IV daily). After a 10-day washout period, horses received the alternative treatment for 8 days and a second mFSIGTT. Minimal model analysis was performed, and the effects of ID status and phenylbutazone were investigated with p < 0.05 considered significant.

RESULTS

In horses with ID, phenylbutazone increased tissue insulin sensitivity index (median [interquartile range]: 0.39 [0.14-0.74] vs. 0.56 [0.55-1.18] ×10-4 L/mIU/min, p = 0.03), and decreased glucose (21 726 [19 040-24 948] vs. 22 909 [22 496-26 166] mg/dL × min, p = 0.02) and insulin (19 595 [16 147-29 698] vs. 22 752 [20 578-31 826] μIU/mL × min, p = 0.03) areas under the curves. No effect was detected in horses administered placebo.

CONCLUSION AND CLINICAL IMPORTANCE

Phenylbutazone reduces insulin concentration in horses with ID by modulating tissue insulin sensitivity, suggesting that its relevance in the management of ID can extend beyond laminitis-associated pain.

The L-type amino acid transporter 1 enhances drug delivery to the mouse pancreatic beta cell line (MIN6)

l-type amino acid transporter 1 (LAT1) is a membrane transporter responsible for carrying large, neutral l-configured amino acids as well as appropriate (pro)drugs into a cell. It has shown a great potential to improve drug delivery across the blood-brain barrier and to increase cell uptake into several brain and cancer cell types. However, besides the brain, the LAT1-utilizing compounds are also delivered more efficiently into the pancreas in vivo. In this study, we quantified the expression of LAT1 along several other membrane transporters in mouse pancreatic β-cell line (MIN6). Furthermore, we studied the function of LAT1 in MIN6 cells, and its ability to deliver non-steroidal anti-inflammatory drug (NSAID)-derived prodrugs there. The results showed that LAT1 was highly abundant in MIN6 cells, with an even expression on cell pseudoislets. The l-leucine uptake as a probe substrate was efficient, with comparable affinity and capacity to previously studied immortalized mouse microglia (BV2). The NSAID-derived prodrugs utilized LAT1 for their delivery and were uptaken into MIN6 cells 2-300 times more efficiently when compared to their parent drugs. A similar increase in pancreatic delivery was observed also in vivo, where the pancreatic exposure was 2-10 times higher with selected prodrugs, indicating an excellent correlation between in vitro uptake and in vivo pancreatic delivery. Finally, the LAT1-utilizing prodrugs were able to reverse the effects of cytokines on insulin secretion in MIN6 cells, showing that improved delivery via LAT1 can enhance drug effects in the mouse pancreatic β-cell line.

Risk factors and prediction of hypoglycaemia using the Hypo-RESOLVE cohort: a secondary analysis of pooled data from insulin clinical trials

AIMS/HYPOTHESIS

The objective of the Hypoglycaemia REdefining SOLutions for better liVES (Hypo-RESOLVE) project is to use a dataset of pooled clinical trials across pharmaceutical and device companies in people with type 1 or type 2 diabetes to examine factors associated with incident hypoglycaemia events and to quantify the prediction of these events.

METHODS

Data from 90 trials with 46,254 participants were pooled. Analyses were done for type 1 and type 2 diabetes separately. Poisson mixed models, adjusted for age, sex, diabetes duration and trial identifier were fitted to assess the association of clinical variables with hypoglycaemia event counts. Tree-based gradient-boosting algorithms (XGBoost) were fitted using training data and their predictive performance in terms of area under the receiver operating characteristic curve (AUC) evaluated on test data. Baseline models including age, sex and diabetes duration were compared with models that further included a score of hypoglycaemia in the first 6 weeks from study entry, and full models that included further clinical variables. The relative predictive importance of each covariate was assessed using XGBoost's importance procedure. Prediction across the entire trial duration for each trial (mean of 34.8 weeks for type 1 diabetes and 25.3 weeks for type 2 diabetes) was assessed.

RESULTS

For both type 1 and type 2 diabetes, variables associated with more frequent hypoglycaemia included female sex, white ethnicity, longer diabetes duration, treatment with human as opposed to analogue-only insulin, higher glucose variability, higher score for hypoglycaemia across the 6 week baseline period, lower BP, lower lipid levels and treatment with psychoactive drugs. Prediction of any hypoglycaemia event of any severity was greater than prediction of hypoglycaemia requiring assistance (level 3 hypoglycaemia), for which events were sparser. For prediction of level 1 or worse hypoglycaemia during the whole follow-up period, the AUC was 0.835 (95% CI 0.826, 0.844) in type 1 diabetes and 0.840 (95% CI 0.831, 0.848) in type 2 diabetes. For level 3 hypoglycaemia, the AUC was lower at 0.689 (95% CI 0.667, 0.712) for type 1 diabetes and 0.705 (95% CI 0.662, 0.748) for type 2 diabetes. Compared with the baseline models, almost all the improvement in prediction could be captured by the individual's hypoglycaemia history, glucose variability and blood glucose over a 6 week baseline period.

CONCLUSIONS/INTERPRETATION

Although hypoglycaemia rates show large variation according to sociodemographic and clinical characteristics and treatment history, looking at a 6 week period of hypoglycaemia events and glucose measurements predicts future hypoglycaemia risk.

Effects of ibuprofen in the ZDF rat model of type 2 diabetes

We aimed to investigate the therapeutic potential of ibuprofen against type 2 diabetes (T2D) using obese Zucker diabetic fatty (ZDF) rats as type 2 diabetes model. ZDF rats were hyperglycemic, dyslipidemic and expressed proinflammatory markers in contrast to lean controls, thus reflecting the relationship between obesity and chronic inflammation promoting T2D. Chronic treatment with ibuprofen (2-(4-Isobutylphenyl)propanoic acid) was used to study the impact on pathological T2D conditions as compared to metformin (1,1-dimethylbiguanide) treated ZDF as well as lean controls. Ibuprofen decreased A1c but induced a high insulin release with improved glucose tolerance only after early time points (i.g., 15 and 30 min) resulting in a non-significant decline of AUC values and translating into a high HOMA-IR. In addition, ibuprofen significantly lowered cholesterol, free fatty acids and HDL-C. Some of these effects by ibuprofen might be based on its anti-inflammatory effects through inhibition of cytokine/chemokine signaling (i.g., COX-2, ICAM-1 and TNF-α) as measured in whole blood and epididymal adipose tissue by TaqMan and/or upregulation of anti-inflammatory cytokines (i.g., IL-4 and IL-13) by ELISA analysis in blood. In conclusion, our ZDF animal study showed positive effects of ibuprofen against diabetic complications such as inflammation and dyslipidemia but also demonstrated the risk of causing insulin resistance.

Preservation of β-Cells as a Therapeutic Strategy for Diabetes

The preservation of pancreatic islet β-cells is crucial in diabetes mellitus, encompassing both type 1 and type 2 diabetes. β-cell dysfunction, reduced mass, and apoptosis are central to insufficient insulin secretion in both types. Research is focused on understanding β-cell characteristics and the factors regulating their function to develop novel therapeutic approaches. In type 1 diabetes (T1D), β-cell destruction by the immune system calls for exploring immunosuppressive therapies, non-steroidal anti-inflammatory drugs, and leukotriene antagonists. Islet transplantation, stem cell therapy, and xenogeneic transplantation offer promising strategies for type 1 diabetes treatment. For type 2 diabetes (T2D), lifestyle changes like weight loss and exercise enhance insulin sensitivity and maintain β-cell function. Additionally, various pharmacological approaches, such as cytokine inhibitors and protein kinase inhibitors, are being investigated to protect β-cells from inflammation and glucotoxicity. Bariatric surgery emerges as an effective treatment for obesity and T2D by promoting β-cell survival and function. It improves insulin sensitivity, modulates gut hormones, and expands β-cell mass, leading to diabetes remission and better glycemic control. In conclusion, preserving β-cells offers a promising approach to managing both types of diabetes. By combining lifestyle modifications, targeted pharmacological interventions, and advanced therapies like stem cell transplantation and bariatric surgery, we have a significant chance to preserve β-cell function and enhance glucose regulation in diabetic patients.

Effect of phenylbutazone on insulin secretion in horses with insulin dysregulation

BACKGROUND

Phenylbutazone is often prescribed to manage pain caused by hyperinsulinemia-associated laminitis, but in diabetic people nonsteroidal anti-inflammatory drugs increase insulin secretion and pancreatic activity.

HYPOTHESIS/OBJECTIVES

Investigate the effect of phenylbutazone administration on insulin secretion in horses. It was hypothesized that phenylbutazone will increase insulin secretion in horses with insulin dysregulation (ID).

ANIMALS

Sixteen light breed horses, including 7 with ID.

METHODS

Randomized cross-over study design. Horses underwent an oral glucose test (OGT) after 9 days of treatment with phenylbutazone (4.4 mg/kg IV q24h) or placebo (5 mL 0.9% saline). After a 10-day washout period, horses received the alternative treatment, and a second OGT was performed. Insulin and glucose responses were compared between groups (ID or controls) and treatments using paired t test and analyses of variance with P < .05 considered significant.

RESULTS

In horses with ID, phenylbutazone treatment significantly decreased glucose concentration (P = .02), glucose area under the curve (2429 ± 501.5 vs 2847 ± 486.1 mmol/L × min, P = .02), insulin concentration (P = .03) and insulin area under the curve (17 710 ± 6676 vs 22 930 ± 8788 μIU/mL × min, P = .03) in response to an OGT. No significant effect was detected in control horses.

CONCLUSION AND CLINICAL IMPORTANCE

Phenylbutazone administration in horses with ID decreases glucose and insulin concentrations in response to an OGT warranting further investigation of a therapeutic potential of phenylbutazone in the management of hyperinsulinemia-associated laminitis beyond analgesia.

Acute Antiplatelet Effects of an Oleocanthal-Rich Olive Oil in Type II Diabetic Patients: A Postprandial Study

Postprandial dysmetabolism is a common entity of type 2 diabetes mellitus (T2DM) and may act as a daily stressor of the already dysfunctional diabetic platelets. This study aims to investigate whether oleocanthal-rich olive oils (OO), incorporated into a carbohydrate-rich meal, can affect postprandial dysmetabolism and platelet aggregation. Oleocanthal is a cyclooxygenase inhibitor with putative antiplatelet properties. In this randomized, single-blinded, crossover study, ten T2DM patients consumed five isocaloric meals containing 120 g white bread combined with: (i) 39 g butter, (ii) 39 g butter and 400 mg ibuprofen, (iii) 40 mL OO (phenolic content < 10 mg/Kg), (iv) 40 mL OO with 250 mg/Kg oleocanthal and (v) 40 mL OO with 500 mg/Kg oleocanthal. Metabolic markers along with ex vivo ADP- and thrombin receptor-activating peptide (TRAP)-induced platelet aggregation were measured before and for 4 h after the meals. The glycemic and lipidemic response was similar between meals. However, a sustained (90-240 min) dose-dependent reduction in platelets' sensitivity to both ADP (50-100%) and TRAP (20-50%) was observed after the oleocanthal meals in comparison to OO or butter meals. The antiplatelet effect of the OO containing 500 mg/Kg oleocanthal was comparable to that of the ibuprofen meal. In conclusion, the consumption of meals containing oleocanthal-rich OO can reduce platelet activity during the postprandial period, irrespective of postprandial hyperglycemia and lipidemia.

Drug-induced hyperinsulinemic hypoglycemia: An update on pathophysiology and treatment

The initial step for the differential diagnosis of hypoglycemia is to determine whether it is hyperinsulinemic or non hyperinsulinemic. Existing literature discusses drug-related hypoglycemia, but it misses a focus on drug-induced hyperinsulinemic hypoglycemia (DHH). Here we reviewed the association existing between drugs and hyperinsulinemic hypoglycemia. We primarily selected on the main electronic databases (MEDLINE, EMBASE, Web of Science, and SCOPUS) the reviews on drug-induced hypoglycemia. Among the drugs listed in the reviews, we selected the ones linked to an increase in insulin secretion. For the drugs missing a clear association with insulin secretion, we investigated the putative mechanism underlying hypoglycemia referring to the original papers. Our review provides a list of the most common agents associated with hyperinsulinemic hypoglycemia (HH), in order to facilitate both the recognition and the prevention of DHH. We also collected data about the responsiveness of DHH to diazoxide or octreotide.

Lipolysis inhibition as a treatment of clinical ketosis in dairy cows: A randomized clinical trial

Excessive and protracted lipolysis in adipose tissues of dairy cows is a major risk factor for clinical ketosis (CK). This metabolic disease is common in postpartum cows when lipolysis provides fatty acids as an energy substrate to offset negative energy balance. Lipolysis in cows can be induced by the canonical (hormonally induced) and inflammatory pathways. Current treatments for CK focus on improving glucose in blood (i.e., oral propylene glycol [PG], or i.v. dextrose). However, these therapies do not inhibit the canonical and inflammatory lipolytic pathways. Niacin (NIA) can reduce activation of the canonical pathway. Blocking inflammatory responses with cyclooxygenase inhibitors such as flunixin meglumine (FM) can inhibit inflammatory lipolytic activity. The objective of this study was to determine the effects of including NIA and FM in the standard PG treatment for postpartum CK on circulating concentrations of ketone bodies. A 4-group, parallel, individually randomized trial was conducted in multiparous Jersey cows (n = 80) from a commercial dairy in Michigan during a 7-mo period. Eligible cows had CK symptoms (lethargy, depressed appetite, and milk yield) and hyperketonemia (blood β-hydroxybutyrate [BHB] ≥1.2 mmol/L). Cows with CK were randomly assigned to 1 of 3 groups where the first group received 310 g of oral PG once per day for 5 d; the second group received PG for 5 d + 24 g of oral NIA once per day for 3 d (PGNIA); and the third group received PG for 5 d + NIA for 3 d + 1.1 mg/kg i.v. FM once per day for 3 d (PGNIAFM). The control group consisted of cows that were clinically healthy (HC; untreated; BHB <1.2 mmol/L, n = 27) matching for parity and DIM with all 3 groups. Animals were sampled at enrollment (d 0), and d 3, 7, and 14 to evaluate ketone bodies and circulating metabolic and inflammatory biomarkers. Effects of treatment, sampling day, and their interactions were evaluated using mixed effects models. Logistic regression was used to calculate the odds ratio (OR) of returning to normoketonemia (BHB <1.2 mmol/L). Compared with HC, enrolled CK cows exhibited higher blood concentrations of dyslipidemia markers, including nonesterified fatty acids (NEFA) and BHB, and lower glucose and insulin levels. Cows with CK also had increased levels of biomarkers of pain (substance P), inflammation, including lipopolysaccharide-binding protein, haptoglobin, and serum amyloid A, and proinflammatory cytokines IL-4, MCP-1, MIP-1α, and TNFα. Importantly, 72.2% of CK cows presented endotoxemia and had higher circulating bacterial DNA compared with HC. By d 7, the percentage of cows with normoketonemia were higher in PGNIAFM = 87.5%, compared with PG = 58.33%, and PGNIA = 62.5%. At d 7 the OR for normoketonemia in PGNIAFM cows were 1.5 (95% CI, 1.03-2.17) and 1.4 (95% CI, 0.99-1.97) relative to PG and PGNIA, respectively. At d 3, 7, and 14, PGNIAFM cows presented the lowest values of BHB (PG = 1.36; PGNIA = 1.24; PGNIAFM = 0.89 ± 0.13 mmol/L), NEFA (PG = 0.58; PGNIA = 0.59; PGNIAFM = 0.45 ± 0.02 mmol/L), and acute phase proteins. Cows in PGNIAFM also presented the highest blood glucose increment across time points and insulin by d 7. These data provide evidence that bacteremia or endotoxemia, systemic inflammation, and pain may play a crucial role in CK pathogenesis. Additionally, targeting lipolysis and inflammation with NIA and FM during CK effectively reduces dyslipidemia biomarkers, improves glycemia, and improves overall clinical recovery.

Ozonated saline intradermal injection: promising therapy for accelerated cutaneous wound healing in diabetic rats

Introduction

The use of ozonized water is gaining importance in medicine due to its effects on hyperglycemia and wound healing mechanisms.

Methods

This experiment was conducted to assess the impacts of intradermal administration of ozonated water on acute skin wound healing in a diabetic rat model. Sixty-four adult male Wistar rats were randomly divided into two groups: an ozonated water group (O3W) and a control group (CG). Experimental diabetes was chemically induced in the rats by the intraperitoneal administration of 60 mg/kg streptozotocin. One week later, full-thickness skin surgical wounds (1 cm2) were created between the two shoulders of the rats under general anesthesia. The wounds were then daily irrigated with normal saline (CG) or intradermally injected with 1 mL of ozonated water at 10 mg/L O3W. Wound healing was evaluated through macroscopic analysis, measuring wound size, diameter, and percentage of contraction rate before wounding and at 3, 7, 9, 12, 14, 18, 21, 24, and 28 days post-wounding. On days 7, 14, 21, and 28 after induction of the wounds, the body weights and blood glucose levels of rats (8 per group) were measured before the rats were euthanized. Moreover, the morphological structure of the tissue, vascular endothelial and transforming growth factor (VEGF and TGF) affinity and gene expression were examined.

Results

The O3W group had significantly lower blood glucose levels and wound size and gained body weight. Additionally, epithelial vascularization, stromal edema, TGF, and VEGF gene expression significantly improved in the O3W group.

Discussion

Therefore, ozonated water has the potential to enhance and promote cutaneous wound healing in diabetic rats.

Identifying target ion channel-related genes to construct a diagnosis model for insulinoma

Background: Insulinoma is the most common functional pancreatic neuroendocrine tumor (PNET) with abnormal insulin hypersecretion. The etiopathogenesis of insulinoma remains indefinable. Based on multiple bioinformatics methods and machine learning algorithms, this study proposed exploring the molecular mechanism from ion channel-related genes to establish a genetic diagnosis model for insulinoma. Methods: The mRNA expression profile dataset of GSE73338 was applied to the analysis, which contains 17 insulinoma samples, 63 nonfunctional PNET (NFPNET) samples, and four normal islet samples. Differently expressed ion channel-related genes (DEICRGs) enrichment analyses were performed. We utilized the protein-protein interaction (PPI) analysis and machine learning of LASSO and support vector machine-recursive feature elimination (SVM-RFE) to identify the target genes. Based on these target genes, a nomogram diagnostic model was constructed and verified by a receiver operating characteristic (ROC) curve. Moreover, immune infiltration analysis, single-gene gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA) were executed. Finally, a drug-gene interaction network was constructed. Results: We identified 29 DEICRGs, and enrichment analyses indicated they were primarily enriched in ion transport, cellular ion homeostasis, pancreatic secretion, and lysosome. Moreover, the PPI network and machine learning recognized three target genes (MCOLN1, ATP6V0E1, and ATP4A). Based on these target genes, we constructed an efficiently predictable diagnosis model for identifying insulinomas with a nomogram and validated it with the ROC curve (AUC = 0.801, 95% CI 0.674-0.898). Then, single-gene GSEA analysis revealed that these target genes had a significantly positive correlation with insulin secretion and lysosome. In contrast, the TGF-beta signaling pathway was negatively associated with them. Furthermore, statistically significant discrepancies in immune infiltration were revealed. Conclusion: We identified three ion channel-related genes and constructed an efficiently predictable diagnosis model to offer a novel approach for diagnosing insulinoma.

Ibuprofen in the Management of Viral Infections: The Lesson of COVID-19 for Its Use in a Clinical Setting

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the management of fever, pain, and inflammation. However, they have always been considered to have a double-faced role, according to their capacity to manage inflammation but also their possible reduction of immune system response and diagnosis delay. This last point could favor a dramatic increase of viral infection diffusion, possibly leading to a more severe outcome. The advent of severe acute respiratory syndrome coronavirus 2 excluded the use of NSAIDs, particularly ibuprofen, and then indicated this drug as the better NSAID to manage infected outpatients and prevent complications. Several authors described the role of NSAIDs and ibuprofen in preventing cytokine storm and modulating the immune system. However, the development of both adverse drug reactions (i.e., gastrointestinal, renal, hepatic, and cardiovascular) and drug interaction recalled the necessity of prescribing the better NSAID for each patient. In this narrative review, we describe the role of NSAIDs, particularly of ibuprofen, in the management of viral symptoms, suggesting that the NSAID may be chosen considering the characteristics of the patient, the comorbidity, and the polytherapy.

Starburst amacrine cells form gap junctions in the early postnatal stage of the mouse retina

Although gap junctional coupling in the developing retina is important for the maturation of neuronal networks, its role in the development of individual neurons remains unclear. Therefore, we herein investigated whether gap junctional coupling by starburst amacrine cells (SACs), a key neuron for the formation of direction selectivity, occurs during the developmental stage in the mouse retina. Neurobiotin-injected SACs coupled with many neighboring cells before eye-opening. The majority of tracer-coupled cells were retinal ganglion cells, and tracer coupling was not detected between SACs. The number of tracer-coupled cells significantly decreased after eye-opening and mostly disappeared by postnatal day 28 (P28). Membrane capacitance (Cm), an indicator of the formation of electrical coupling with gap junctions, was larger in SACs before than after eye-opening. The application of meclofenamic acid, a gap junction blocker, reduced the Cm of SACs. Gap junctional coupling by SACs was regulated by dopamine D1 receptors before eye-opening. In contrast, the reduction in gap junctional coupling after eye-opening was not affected by visual experience. At the mRNA level, 4 subtypes of connexins (23, 36, 43, and 45) were detected in SACs before eye-opening. Connexin 43 expression levels significantly decreased after eye-opening. These results indicate that gap junctional coupling by SACs occurs during the developmental period and suggest that the elimination of gap junctions proceeds with the innate system.

Diclofenac Disrupts the Circadian Clock and through Complex Cross-Talks Aggravates Immune-Mediated Liver Injury-A Repeated Dose Study in Minipigs for 28 Days

Diclofenac effectively reduces pain and inflammation; however, its use is associated with hepato- and nephrotoxicity. To delineate mechanisms of injury, we investigated a clinically relevant (3 mg/kg) and high-dose (15 mg/kg) in minipigs for 4 weeks. Initially, serum biochemistries and blood-smears indicated an inflammatory response but returned to normal after 4 weeks of treatment. Notwithstanding, histopathology revealed drug-induced hepatitis, marked glycogen depletion, necrosis and steatosis. Strikingly, the genomic study revealed diclofenac to desynchronize the liver clock with manifest inductions of its components CLOCK, NPAS2 and BMAL1. The > 4-fold induced CRY1 expression underscored an activated core-loop, and the dose dependent > 60% reduction in PER2mRNA repressed the negative feedback loop; however, it exacerbated hepatotoxicity. Bioinformatics enabled the construction of gene-regulatory networks, and we linked the disruption of the liver-clock to impaired glycogenesis, lipid metabolism and the control of immune responses, as shown by the 3-, 6- and 8-fold induced expression of pro-inflammatory CXCL2, lysozyme and ß-defensin. Additionally, diclofenac treatment caused adrenocortical hypertrophy and thymic atrophy, and we evidenced induced glucocorticoid receptor (GR) activity by immunohistochemistry. Given that REV-ERB connects the circadian clock with hepatic GR, its > 80% repression alleviated immune responses as manifested by repressed expressions of CXCL9(90%), CCL8(60%) and RSAD2(70%). Together, we propose a circuitry, whereby diclofenac desynchronizes the liver clock in the control of the hepatic metabolism and immune response.

BACE1: More than just a β-secretase

β-site amyloid precursor protein cleaving enzyme-1 (BACE1) research has historically focused on its actions as the β-secretase responsible for the production of β-amyloid beta, observed in Alzheimer's disease. Although the greatest expression of BACE1 is found in the brain, BACE1 mRNA and protein is also found in many cell types including pancreatic β-cells, adipocytes, hepatocytes, and vascular cells. Pathologically elevated BACE1 expression in these cells has been implicated in the development of metabolic diseases, including type 2 diabetes, obesity, and cardiovascular disease. In this review, we examine key questions surrounding the BACE1 literature, including how is BACE1 regulated and how dysregulation may occur in disease, and understand how BACE1 regulates metabolism via cleavage of a myriad of substrates. The phenotype of the BACE1 knockout mice models, including reduced weight gain, increased energy expenditure, and enhanced leptin signaling, proposes a physiological role of BACE1 in regulating energy metabolism and homeostasis. Taken together with the weight loss observed with BACE1 inhibitors in clinical trials, these data highlight a novel role for BACE1 in regulation of metabolic physiology. Finally, this review aims to examine the possibility that BACE1 inhibitors could provide a innovative treatment for obesity and its comorbidities.

Association between Non-Steroidal Anti-Inflammatory Drugs Use and the Risk of Type 2 Diabetes Mellitus: A Nationwide Retrospective Cohort Study

Background: Although the link between non-steroidal anti-inflammatory drugs (NSAIDs) and tramadol and symptomatic hypoglycemia has been documented, there is a limited understanding of the associations of NSAIDs and tramadol with the risk of type 2 diabetes mellitus (T2DM). This study was established to evaluate the association between the clinical use of NSAIDs and the risk of T2DM. Patients and methods: A historical cohort study was conducted using the National Health Insurance Research Database in Taiwan dated from 2000 to 2013. Patients who received NSAIDs for at least 3 prescription orders and without co-treatment of tramadol in the exposure period (from 2000 to 2005) were considered as the exposed cohort (n = 3047). In comparison, patients who received tramadol for at least 3 prescription orders and without concomitant use of NSAIDs in the exposure period were considered as the comparison cohort (n = 9141). The primary outcome was the occurrence of T2DM. Multivariable hazard ratios (HRs) with 95% confidence intervals (CIs) derived from the Cox proportional hazard models were applied to determine the association between NSAIDs use and the risk of T2DM. Results: In the average follow-up period of 9.56 years, there were 159 newly diagnosed T2DM, with an incidence rate of 56.96 per 10,000 person years in the exposed cohort. Comparatively, there were 1737 incident T2DM cases, with an incidence rate of 161.23 per 10,000 person years in the comparison cohort. Compared to the comparison cohort, the NSAIDs cohort showed a significantly reduced risk of T2DM with an adjusted HR of 0.31 (95% CI, 0.26–0.36). Conclusions: Our cohort study provides longitudinal evidence that the use of NSAIDs was associated with a reduced risk of T2DM.

NSAIDs Naproxen, Ibuprofen, Salicylate, and Aspirin Inhibit TRPM7 Channels by Cytosolic Acidification

Non-steroidal anti-inflammatory drugs (NSAIDs) are used for relieving pain and inflammation accompanying numerous disease states. The primary therapeutic mechanism of these widely used drugs is the inhibition of cyclooxygenase 1 and 2 (COX1, 2) enzymes that catalyze the conversion of arachidonic acid into prostaglandins. At higher doses, NSAIDs are used for prevention of certain types of cancer and as experimental treatments for Alzheimer’s disease. In the immune system, various NSAIDs have been reported to influence neutrophil function and lymphocyte proliferation, and affect ion channels and cellular calcium homeostasis. Transient receptor potential melastatin 7 (TRPM7) cation channels are highly expressed in T lymphocytes and are inhibited by Mg²⁺, acidic pH, and polyamines. Here, we report a novel effect of naproxen, ibuprofen, salicylate, and acetylsalicylate on TRPM7. At concentrations of 3–30mM, they reversibly inhibited TRPM7 channel currents. By measuring intracellular pH with the ratiometric indicator BCECF, we found that at 300μM to 30mM, these NSAIDs reversibly acidified the cytoplasm in a concentration-dependent manner, and propose that TRPM7 channel inhibition is a consequence of cytosolic acidification, rather than direct. NSAID inhibition of TRPM7 channels was slow, voltage-independent, and displayed use-dependence, increasing in potency upon repeated drug applications. The extent of channel inhibition by salicylate strongly depended on cellular PI(4,5)P₂ levels, as revealed when this phospholipid was depleted with voltage-sensitive lipid phosphatase (VSP). Salicylate inhibited heterologously expressed wildtype TRPM7 channels but not the S1107R variant, which is insensitive to cytosolic pH, Mg²⁺, and PI(4,5)P₂ depletion. NSAID-induced acidification was also observed in Schneider 2 cells from Drosophila, an organism that lacks orthologous COX genes, suggesting that this effect is unrelated to COX enzyme activity. A 24-h exposure to 300μM–10mM naproxen resulted in a concentration-dependent reduction in cell viability. In addition to TRPM7, the described NSAID effect would be expected to apply to other ion channels and transporters sensitive to intracellular pH.

Toxicological Evaluation of Novel Cyclohexenone Derivative in an Animal Model through Histopathological and Biochemical Techniques

Toxicity studies were conducted to provide safety data of potential drug candidates by determining lethal and toxic doses. This study was designed for pre-clinical evaluation of novel cyclohexenone derivative with respect to the acute and sub-acute toxicity along with the diabetogenic potential. Acute and sub-acute toxicity were assessed after intraperitoneal (i.p) injection of the investigational compound through selected doses for 21 days. This was followed by assessment of isolated body organs (liver, kidney, heart and pancreas) via biochemical indicators and histopathological techniques. No signs of toxicity were revealed in the study of acute toxicity. Similarly, a sub-acute toxicity study showed no significant difference in biochemical indicators on 11th and 21st days between treated and control groups. However, in blood urea nitrogen (BUN) and random blood glucose/sugar (RBS) values, significant differences were recorded. Histopathological evaluation of liver, kidney, pancreas and heart tissues revealed mild to severe changes in the form of steatosis, inflammation, fibrosis, necrosis and myofibrillary damages on 11th and 21st days of treatment. In conclusion, the median lethal dose of the tested compound was expected to be greater than 500 mg/kg. No significant change occurred in selected biomarkers, except BUN and RBS levels, but a histopathological study showed moderate toxic effect on liver, kidney, pancreas and heart tissues by the cyclohexenone derivative.

Anti-Diabetic and Angio-Protective Effect of Guluronic Acid (G2013) as a New Nonsteroidal Anti-Inflammatory Drug in the Experimental Model of Diabetes

BACKGROUND

This study aimed to investigate the effects of guluronic acid (G2013) on blood sugar, insulin, and gene expression profile of oxLDL receptors (SR-A, CD36, LOX-1, and CD68) in the experimental model of diabetes.

METHODS

18 Sprague Dawley rats were randomly assigned to three groups of healthy control, diabetic control, and G2013 group. Diabetes was induced through intraperitoneal (IP) injection of 60 mg/kg streptozotocin. The subjects were IP treated with 25 mg/kg of G2013 per day for 28 days. The body weight, food intake, fasting blood glucose and insulin were measured. In addition, the expression of mentioned genes was investigated through quantitative real-time PCR.

RESULTS

The data showed that the final weight increased significantly in the G2013-treated subjects compared to the diabetic control (p < 0.05). The results indicated that final food intake significantly reduced in the G2013-treated subjects compared to the diabetic control (p < 0.05). The study findings also suggested that the final fasting blood glucose significantly reduced in the G2013-treated group, whereas the final fasting serum insulin level significantly increased in this group compared to the diabetic control (p < 0.05). Moreover, the gene expression levels of SR-A, CD36, LOX-1, and CD68 in the G2013 group significantly reduced compared to the diabetic control (p < 0.05).

CONCLUSION

This study showed that G2013, could reduce blood glucose and increase insulin levels and reduce the gene expression level of oxLDL receptors. In addition, it may probably play an important role in reducing the severity of diabetes-induced inflammatory symptoms.

Neurexin-1α regulates neurite growth of rat hippocampal neurons

The growth of neurites underlies the axonal pathfinding and synaptic formation during neuronal development and regeneration. Neurite growth is regulated by specific interactions between growth cone receptors and their ligands that function as molecular cues existing in microenvironments. Neurexins (NRXNs) are concentrated on growth cones and they may function to constrain axonal branches of invertebrate neurons. The present study explored the role of NRXN-1α in regulating neurite growth of mammalian neurons. Results showed that transfecting an effective NRXN-1α siRNA to cultured rat hippocampal neurons significantly increased neurite length. Adding NRXN-1α ligands including neuroligin (NLGN) peptide and/or α-latrotoxin (α-LTX) to the culture media largely decreased neurite growth of naïve neurons in a Ca²⁺-dependent manner, but had no effect on neurite growth of neurons transfected with NRXN-1α siRNA. Our results suggest that NRXN-1α regulates neurite development of mammalian neurons.

Common inpatient hypoglycemia phenotypes identified from an automated electronic health record-based prediction model

PURPOSE

Common inpatient hypoglycemia risk factor patterns (phenotypes) from an electronic health record (EHR)-based prediction model and preventive strategies were identified.

METHODS

Patients admitted to 2 large academic medical centers who were in the top fifth percentile of a previously developed hypoglycemia risk score and developed hypoglycemia (blood glucose [BG] of <50mg/dL) were included in the study. Frequencies of all combinations of ≥4 risk factors contributing to the risk score among these patients were determined to identify common risk patterns. Clinical pharmacists developed clinical vignettes for each common pattern and formulated medication therapy management recommendations for hypoglycemia prevention.

RESULTS

A total of 401 admissions with a hypoglycemic event were identified among 1,875 admissions whose hypoglycemic risk was in the top fifth percentile among all admissions that received antihyperglycemic drugs and evaluated. Five distinct phenotypes emerged: (1) frail patients with history of hypoglycemia receiving insulin on hospital day 1, (2) a rapid downward trend in BG values in patients receiving an insulin infusion or with a history of hypoglycemia, (3) administration of insulin in the presence of an active nothing by mouth order in frail patients, (4) repeated low BG level in frail patients, and (5) inadequate night-time BG monitoring for patients on long-acting insulin. The 5 themes jointly described 53.0% of high-risk patients who experienced hypoglycemia.

CONCLUSION

Five distinct phenotypes that are prevalent in patients at greatest risk for inpatient hypoglycemia were identified.

Zafirlukast promotes insulin secretion by increasing calcium influx through L-type calcium channels

The zafirlukast has been reported to be anti-inflammatory and widely used to alleviate the symptoms of asthma. However, its influence on insulin secretion in pancreatic β-cells has not been investigated. Herein, we examined the effects of zafirlukast on insulin secretion and the potential underlying mechanisms. Among the cysteinyl leukotriene receptor 1 antagonists, zafirlukast, pranlukast, and montelukast, only zafirlukast enhanced insulin secretion in a concentration-dependent manner in both low and high glucose conditions and elevated the level of [Ca²⁺ ]_i , further activating Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) signaling. These effects were nearly abolished by the L-type Ca²⁺ channel antagonist nifedipine, while treatment with thapsigargin, a sarco/endoplasmic reticulum Ca²⁺ ATPase inhibitor, did not have the same effect, suggesting that zafirlukast primarily induces the entry of extracellular Ca²⁺ rather than intracellular Ca²⁺ from the endoplasmic reticulum. Zafirlukast treatment resulting in a significant drop in glucose levels and increased insulin secretion in C57BL/6J mice. These findings will contribute to an improved understanding of the side effects of zafirlukast and potential candidate for a therapeutic intervention in diabetes.

miR-204 is associated with an endocrine phenotype in human pancreatic islets but does not regulate the insulin mRNA through MAFA

miR-204 has been proposed to modulate insulin expression in human pancreatic islets by regulating the expression of the MAFA transcript, and in turn insulin transcription. We investigated miR-204 expression in pancreatic endocrine tumors (PET), a panel of human tissues, tissues derived from pancreatic islet purification, and in induced pluripotent stem cells (iPSCs) differentiated towards a pancreatic endocrine phenotype by quantitative real time RT-PCR or droplet digital PCR (ddPCR). In addition, we evaluated the effect of miR-204 up- or down-regulation in purified human islets and in the EndoC-βH1 cell line, as an experimental model of human pancreatic β cells. Our results confirm that miR-204 was enriched in insulin producing PET, in β cells within healthy pancreatic islets, and highly expressed in EndoC-βH1 cells. Moreover, in iPSCs miR-204 increased stepwise upon stimulated differentiation to insulin producing cells. However, up- or down-regulation of miR-204 in human islets and in EndoC-βH1 cells resulted in modest and not significant changes of the MAFA and INS mRNAs measured by ddPCR or c-peptide release. Our data confirm the association of miR-204 with a β cell endocrine phenotype in human pancreatic islets, but do not support its direct role in regulating the levels of insulin mRNA through MAFA.

The pathogenesis of diclofenac induced immunoallergic hepatitis in a canine model of liver injury

Hypersensitivity to non-steroidal anti-inflammatory drugs is a common adverse drug reaction and may result in serious inflammatory reactions of the liver. To investigate mechanism of immunoallergic hepatitis beagle dogs were given 1 or 3 mg/kg/day (HD) oral diclofenac for 28 days. HD diclofenac treatment caused liver function test abnormalities, reduced haematocrit and haemoglobin but induced reticulocyte, WBC, platelet, neutrophil and eosinophil counts. Histopathology evidenced hepatic steatosis and glycogen depletion, apoptosis, acute lobular hepatitis, granulomas and mastocytosis. Whole genome scans revealed 663 significantly regulated genes of which 82, 47 and 25 code for stress, immune response and inflammation. Immunopathology confirmed strong induction of IgM, the complement factors C3&B, SAA, SERPING1 and others of the classical and alternate pathway. Alike, marked expression of CD205 and CD74 in Kupffer cells and lymphocytes facilitate antigen presentation and B-cell differentiation. The highly induced HIF1A and KLF6 protein expression in mast cells and macrophages sustain inflammation. Furthermore, immunogenomics discovered 24, 17, 6 and 11 significantly regulated marker genes to hallmark M1/M2 polarized macrophages, lymphocytic and granulocytic infiltrates; note, the latter was confirmed by CAE staining. Other highly regulated genes included alpha-2-macroglobulin, CRP, hepcidin, IL1R1, S100A8 and CCL20. Diclofenac treatment caused unprecedented induction of myeloperoxidase in macrophages and oxidative stress as shown by SOD1/SOD2 immunohistochemistry. Lastly, bioinformatics defined molecular circuits of inflammation and consisted of 161 regulated genes.

Altogether, the mechanism of diclofenac induced liver hypersensitivity reactions involved oxidative stress, macrophage polarization, mastocytosis, complement activation and an erroneous programming of the innate and adaptive immune system.

Prognostic impact of hyperglycemia at onset of methicillin-sensitive Staphylococcus aureus bacteraemia

Previous reports have associated hyperglycemia to poor outcome among aged and comorbid Staphylococcus aureus bacteraemia (SAB) patients. However, the prognostic impact of hyperglycemia in SAB irrespective of age and underlying conditions including a diagnosis of diabetes has received little attention. The objective here was to evaluate the prognostic relevance of hyperglycemia at onset of methicillin-sensitive SAB (MS-SAB). It was a retrospective study of MS-SAB patients. Blood glucose was measured within 24 h of positive blood cultures. The patient cohort was analyzed en bloc and by categorization according to age, underlying conditions and a diagnosis of diabetes. Altogether 161 patients were identified. High initial blood glucose levels were observed among diabetics (p < 0.001), patients with deep infections (p < 0.05) and poor outcome at 28- or 90-days (p < 0.05). Receiver operating characteristics presented the glucose cut-off level of 7.2 mmol/L as a significant predictor of mortality with an area under the curve of 0.63 (95% CI 0.52-0.75, p < 0.05). Blood glucose ≥7.2 mmol/L connected to higher 28- (9 vs. 20%, p < 0.05) and 90-day (14 vs. 29%, p < 0.01) mortality. In Cox proportional hazard regression the blood glucose cut-off value of 7.2 mmol/L significantly predicted 90-day mortality (HR, 2.12; 95% CI, 1.01-4.46; p < 0.05). Among young and healthy non-diabetics the negative prognostic impact of high glucose was further accentuated (HR 7.46, p < 0.05). High glucose levels had no prognostic impact among diabetics. Hyperglycemia at SAB onset may associate to poor outcome. The negative prognostic impact is accentuated among young and healthy non-diabetics.

Drugs of environmental concern modify Solea senegalensis physiology and biochemistry in a temperature-dependent manner

The alerted presence in recent decades of pharmaceuticals has become an issue of environmental concern, and most of the mechanisms of biotransformation and biochemical and physiological responses to them in fish are still unknown, as well as the influence of water temperature in their ability to cope with them. This study aims to detect the main effects of two of the most widespread drugs on a set of physiological and biochemical markers in Solea senegalensis. Sole juveniles acclimatized at 15 and 20 °C were administered an intraperitoneal injection of the non-steroidal anti-inflammatory drug ibuprofen (IB; 10 mg/kg) and the anti-convulsant drug carbamazepine (CBZ; 1 mg/kg). Two days after the injection, liver, muscle and plasma were sampled. Liver enzymatic activities of 15 °C acclimated fish were more responsive to pharmaceuticals than those acclimated at 20 °C, especially for CYP450-related activities (7-ethoxyresorufin (EROD), 7-methoxyresorufin (MROD), 3-cyano-7-ethoxycoumarin (CECOD) and 7-benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD)) and uridine diphosphate glucuronosyltransferase (UDPGT). Cytosolic anti-oxidant enzyme activities and glutathione S-transferase (GST) did not show a clear effect of temperature. Glucose and transferase activities in plasma were not affected by the treatments, while ammonium, osmolality and lactate were affected by both pharmaceuticals. Plasma triglycerides were affected in a temperature-dependent manner, and creatinine was only responsive to CBZ injection. HSP70 levels in muscle were only affected by CBZ injection. Some of the physiological identified responses to IB and CBZ are proposed as endpoints in further chronic studies.

High dose of aspirin moderates diabetes-induced changes of heart glycogen/glucose metabolism in rats

Aspirin (ASA), as a multifunctional drug has been used as a hypoglycaemic agent in the treatment of diabetes and severe hyperglycaemia and has been established as a secondary strategy which may prevent many cardiovascular events. In this study we investigated high dose (100 mg/kg b.w./i.p) and time-dependent (2, 7 and 14 days) effects of ASA on the heart key enzymes and substrates from glycogen/glucose metabolism in control and diabetic rats. The results accomplished demonstrated that ASA significantly potentiates glycogen accumulation, as well as decreased blood glucose level and heart glycolytic potential in control rats. The treatment of diabetic rats with ASA caused moderation of the diabetic complication-significant inhibition of glycogen accumulation, lowering of blood glucose, as well as elevation of glycolytic potential. In conclusion, we propose that use of high-dose of ASA has anabolic effects in control rats and reduces heart glycogen glucose complications in diabetic rats. The moderation of diabetes-induced changes is time-dependent and involves reduction of glycogenogenesis and inhibited depression of glycolysis, with a tendency to maintenance control values.

Meclofenamic acid blocks the gap junction communication between the retinal pigment epithelial cells

AIM

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to manage the pain and inflammation. NSAIDs can cause serious side effects, including vision problems. However, the underlying mechanisms are still unclear. Therefore, we aimed to investigate the effect of meclofenamic acid (MFA) on retinal pigment epithelium (RPE).

MATERIALS AND METHODS

In our study, we applied image analysis and whole-cell patch clamp recording to directly measure the effect of MFA on the gap junctional coupling between RPE cells.

RESULTS

Analysis of Lucifer yellow (LY) transfer revealed that the gap junction communication existed between RPE cells. Functional experiments using the whole-cell configuration of the patch clamp technique showed that a gap junction conductance also existed between this kind of cells. Importantly, MFA largely inhibited the gap junction conductance and induced the uncoupling of RPE cells. Other NSAIDs, like aspirin and flufenamic acid (FFA), had the same effect.

CONCLUSION

The gap junction functionally existed in RPE cells, which can be blocked by MFA. These findings may explain, at least partially, the vision problems with certain clinically used NSAIDs.

Retinal toxicity associated with high dose of meclofenamic acid

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used medications because they provide effective relief of chronic pain and inflammation through inhibition of cyclooxygenase (COX). However, visual side effects also have been reported, such as temporary blindness, visual field defect, blurred vision, scotomata, and color vision changes subsequent to short- or long-term use. Our aim was to investigate the effect of a high dose of meclofenamic acid (MFA) on the retina. In our study, we applied electroretinography (ERG) and histologic examination to study functional and morphological damage of the retina in rabbits after MFA treatment. We reveal that MFA markedly decreased the amplitudes of b-wave of Rod-response and a- and b-wave of the scotopic standard combined ERG, respectively, and induced morphological destruction of the retina, especially photoreceptor cells. We conclude that a high dose of MFA causes retinal toxicity and impairs visual transduction. These findings may explain, at least partially, the vision problems of certain clinically used NSAIDs.

GABA coordinates with insulin in regulating secretory function in pancreatic INS-1 β-cells

Pancreatic islet β-cells produce large amounts of γ-aminobutyric acid (GABA), which is co-released with insulin. GABA inhibits glucagon secretion by hyperpolarizing α-cells via type-A GABA receptors (GABA(A)Rs). We and others recently reported that islet β-cells also express GABA(A)Rs and that activation of GABA(A)Rs increases insulin release. Here we investigate the effects of insulin on the GABA-GABA(A)R system in the pancreatic INS-1 cells using perforated-patch recording. The results showed that GABA produces a rapid inward current and depolarizes INS-1 cells. However, pre-treatment of the cell with regular insulin (1 µM) suppressed the GABA-induced current (I(GABA)) by 43%. Zinc-free insulin also suppressed I(GABA) to the same extent of inhibition by regular insulin. The inhibition of I(GABA) occurs within 30 seconds after application of insulin. The insulin-induced inhibition of I(GABA) persisted in the presence of PI3-kinase inhibitor, but was abolished upon inhibition of ERK, indicating that insulin suppresses GABA(A)Rs through a mechanism that involves ERK activation. Radioimmunoassay revealed that the secretion of C-peptide was enhanced by GABA, which was blocked by pre-incubating the cells with picrotoxin (50 µM, p<0.01) and insulin (1 µM, p<0.01), respectively. Together, these data suggest that autocrine GABA, via activation of GABA(A)Rs, depolarizes the pancreatic β-cells and enhances insulin secretion. On the other hand, insulin down-regulates GABA-GABA(A)R signaling presenting a feedback mechanism for fine-tuning β-cell secretion.

Fenamates as TRP channel blockers: mefenamic acid selectively blocks TRPM3

BACKGROUND AND PURPOSE

Fenamates are N-phenyl-substituted anthranilic acid derivatives clinically used as non-steroid anti-inflammatory drugs in pain treatment. Reports describing fenamates as tools to interfere with cellular volume regulation attracted our attention based on our interest in the role of the volume-modulated transient receptor potential (TRP) channels TRPM3 and TRPV4.

EXPERIMENTAL APPROACH

Firstly, we measured the blocking potencies and selectivities of fenamates on TRPM3 and TRPV4 as well as TRPC6 and TRPM2 by Ca(2+) imaging in the heterologous HEK293 cell system. Secondly, we further investigated the effects of mefenamic acid on cytosolic Ca(2+) and on the membrane voltage in single HEK293 cells that exogenously express TRPM3. Thirdly, in insulin-secreting INS-1E cells, which endogenously express TRPM3, we validated the effect of mefenamic acid on cytosolic Ca(2+) and insulin secretion.

KEY RESULTS

We identified and characterized mefenamic acid as a selective and potent TRPM3 blocker, whereas other fenamate structures non-selectively blocked TRPM3, TRPV4, TRPC6 and TRPM2.

CONCLUSIONS AND IMPLICATIONS

This study reveals that mefenamic acid selectively inhibits TRPM3-mediated calcium entry. This selectivity was further confirmed using insulin-secreting cells. K(ATP) channel-dependent increases in cytosolic Ca(2+) and insulin secretion were not blocked by mefenamic acid, but the selective stimulation of TRPM3-dependent Ca(2+) entry and insulin secretion induced by pregnenolone sulphate were inhibited. However, the physiological regulator of TRPM3 in insulin-secreting cells remains to be elucidated, as well as the conditions under which the inhibition of TRPM3 can impair pancreatic β-cell function. Our results strongly suggest mefenamic acid is the most selective fenamate to interfere with TRPM3 function.

Drug-induced hypoglycaemia: an update

Drugs are the most frequent cause of hypoglycaemia in adults. Although hypoglycaemia is a well known adverse effect of antidiabetic agents, it may occasionally develop in the course of treatment with drugs used in everyday clinical practice, including NSAIDs, analgesics, antibacterials, antimalarials, antiarrhythmics, antidepressants and other miscellaneous agents. They induce hypoglycaemia by stimulating insulin release, reducing insulin clearance or interfering with glucose metabolism. Several drugs may also potentiate the hypoglycaemic effect of antidiabetic agents. Administration of these agents to individuals with diabetes mellitus is of most concern. Many of these drugs, and depending on clinical setting, may also induce hyperglycaemia. Drug-induced hepatotoxicity and nephrotoxicity may lead in certain circumstances to hypoglycaemia. Some drugs may also induce hypoglycaemia by causing pancreatitis. Drug-induced hypoglycaemia is usually mild but may be severe. Effective clinical management can be handled through awareness of this drug-induced adverse effect on blood glucose levels. Herein, we review pertinent clinical information on the incidence of drug-induced hypoglycaemia and discuss the underlying pathophysiological mechanisms, and prevention and management.

Dimethyl amiloride improves glucose homeostasis in mouse models of type 2 diabetes

Dimethyl amiloride (DMA) enhances insulin secretion in the pancreatic beta-cell. DMA also enhances time-dependent potentiation (TDP) and enables TDP to occur in situations where it is normally absent. As we have demonstrated before, these effects are mediated in part through inhibition of neuronal nitric oxide synthase (nNOS), resulting in increased availability of arginine. Thus both DMA and arginine have the potential to correct the secretory defect in diabetes by enabling or enhancing TDP. In the current study we have demonstrated the ability of these agents to improve blood glucose homeostasis in three mouse models of type 2 diabetes. The pattern of TDP under different conditions indicates that inhibition of NOS is not the only mechanism through which DMA exerts its positive effects. Thus we also have explored another possible mechanism through which DMA enables/enhances TDP, via the activation of mitochondrial alpha-ketoglutarate dehydrogenase.