Mouse model of metformin-induced diarrhea

Relationship Between Hemoglobin A1c and Fecal Incontinence in a Nationwide Cohort Study

INTRODUCTION

Gastrointestinal manifestations of diabetes include a variety of symptoms, including fecal incontinence (FI). We investigated the relationship between hemoglobin A1c and FI among US adults in a large, population-based survey.

METHODS

We identified adults (≥ 20 years) who completed the bowel health questionnaire and had A1c data in the National Health and Nutrition Examination Survey from 2005 to 2010 (N = 13,787). FI was defined as any involuntary loss of mucus, liquid, or solid stool during the last 30 days. Adjusted odds ratios (aORs) for FI were estimated in a multivariable logistic model according to A1c. Subgroup analyses examined relevant characteristics.

RESULTS

We identified 1283 (9.3%) adults with FI. A1c was associated with a 26% increase in the odds of FI (crude OR 1.26, 95% CI 1.20-1.33), which persisted after stepwise adjustment for age, demographic factors, and comorbidities (aOR 1.09, 95% CI 1.01-1.17). In subgroup analyses, A1c was associated with FI in diabetes (aOR 1.13, 95% CI 1.01-1.26), women (aOR 1.15, 95% CI 1.02-1.3), those < 65 years of age (aOR 1.17, 95% CI 1.09-1.25), overweight/obesity (aOR 1.1, 95% CI 1.02-1.20), non-white (aOR 1.1, 95% CI 1.01-1.20), and those with solid stool FI (aOR 1.17, 95% CI 1.04-1.32).

CONCLUSION

Increasing A1c was associated with an increased odds of FI. Our study provides insights into subgroups of patients who may benefit from interventions aimed at glucose control to reduce this risk of FI.

Evaluation of metformin's effect on the adult and juvenile stages of Schistosoma mansoni: an in-vitro study

Metformin (Met), a well-known anti-diabetic drug with a potent autophagy induction property, has been proven to be effective against several parasitic diseases. In the present in vitro study, the effect of Met on the viability and ultrastructure of Schistosoma mansoni adults and juveniles in comparison with the standard anti-schistosomal drug, praziquantel (PZQ), was investigated. Adults and juveniles were treated in vitro with 5 µM PZQ and/or 10 mM Met. The viability of the treated worms was screened over a three-day period by light microscopy and recorded as mortality rates (MR). The alterations in the ultrastructure were verified using scanning and transmission electron microscopy. Met showed significant anti-schistosomal activity against both adults and juveniles and resulted in severe tegumental damage in the form of loss of integrity and architecture, with evident vacuolation suggestive of increased autophagy. Met might be a potential drug either alone or as an adjuvant to PZQ for the treatment of schistosomiasis mansoni and warrant its further assessment in animal models of disease.

Zingiber striolatum phytochemicals ameliorated hyperglycemia symptoms by modulating gut microbial communities in mice with type 2 diabetes mellitus

Introduction

Prolonged hyperglycemia caused by type 2 diabetes mellitus (T2DM) can lead to liver injury and disrupt the community of the gut microbiota that pose significant risks to human health. As a food rich in a variety of active ingredients, Zingiber striolatum (Z. striolatum) exhibits hypoglycemic and hypolipidemic effects. However, the regulatory influence of Z. striolatum ethanol extract (ZSE) on the gut microbiota of T2DM mice or its potential relationship with T2DM pathology remains unexplored.

Methods

After a one-week acclimation period, 12 mice were randomly selected as the normal group. The remaining 48 mice were employed T2DM model, and then randomly assigned to four groups: the model group, a low-dose ZSE group (ZSE-L, 100 mg/kg/day), a high-dose ZSE group (ZSE-H, 300 mg/kg/day), and a positive control group treated with metformin hydrochloride (MET, 100 mg/kg/day).

Results

After a 4-week intervention, the results revealed that ZSE significantly ameliorated fasting blood glucose (FBG), area under the curve of oral glucose tolerance test (AUC of OGTT) and glycated serum protein (GSP) in T2DM mice. Moreover, the high-dose (ZSE-H) treatment increased the relative abundance of beneficial bacteria such as Faecalibaculum, while reducing harmful bacteria such as Bilophila, thereby alleviating insulin resistance. Additionally, ZSE-H demonstrated superior efficacy over low-dose (ZSE-L) in improving FBG, AUC of OGTT, and other hypoglycemic parameters. Predictive analysis of the correlation between gut microbiota and hypoglycemic parameters identified Dubosiella, Bacillus, and Mailhella as potential microbial biomarkers for further investigation into the pathogenesis of T2DM.

Conclusion

ZSE plays a pivotal role in mitigating hyperglycemia in T2DM mice through the modulation of intestinal microbiota communities.

Effects of metformin on binge-like ethanol drinking and adenosine monophosphate kinase signaling in inbred high drinking in the dark line 1 mice

BACKGROUND

Adenosine monophosphate-activated protein kinase (AMPK) signaling plays a vital role in regulating cellular metabolism and energy throughout the body. Ethanol and cocaine both reduce AMPK activity in addiction-related brain regions. Though AMPK activation has been found to reduce cocaine seeking, its role in harmful drinking and alcohol use disorder (AUD) progression remains unclear. We asked whether metformin, a first-line type 2 diabetes medication that targets AMPK, can reduce binge-like ethanol intake in inbred High Drinking in the Dark Line-1 (iHDID-1) mice, a genetic risk model for drinking to intoxication. We then determined whether metformin altered ethanol clearance in iHDID-1 mice. Next, we tested whether metformin and/or ethanol altered AMPK signaling in the nucleus accumbens (NAc), a brain region critically important for harmful drinking.

METHODS

We measured the effects of metformin [0 or 250 mg/kg; intraperitoneal injection (i.p.)] on binge-like ethanol intake in separate acute (Experiment 1) and chronic (Experiment 3A) drinking studies (n = 6-8 iHDID-1 mice/sex/treatment/experiment). The effect of metformin (0 or 250 mg/kg) on ethanol (2.0 g/kg, i.p.) clearance was tested in iHDID-1 mice (Experiment 2; n = 7-9/sex/treatment). Lastly, we measured NAc AMPK and phosphorylated AMPK (pAMPK) levels in response to chronic ethanol (or water) drinking (n = 6 iHDID-1 mice/sex/treatment/fluid type; Experiment 3B) and an intoxicating dose of ethanol (2.0 g/kg; i.p.; Experiment 4).

RESULTS

Metformin reduced binge-like ethanol drinking intake in acute and chronic studies in both male and female iHDID-1 mice (p's < 0.05). We found no significant changes in ethanol clearance in response to metformin. Moreover, no differences in AMPK or pAMPK levels in the NAc were observed with either ethanol or metformin.

CONCLUSIONS

These findings provide early support for the repurposing of metformin, an affordable and safe diabetes medication, to reduce harmful ethanol intake and lay a foundation for testing its efficacy to treat individuals with AUD.

Acupuncture and Drug Combination Therapy for Abnormal Glucose Metabolism: Exploring Synergistic Enhancement and Reduced Toxicity Mechanisms

This review examines the impact of combining acupuncture with drug therapy on abnormal glucose metabolism and investigates their underlying mechanisms. Conditions like diabetes pose significant health risks due to irregular glucose metabolism. Traditional drug treatments often encounter challenges related to side effects and drug resistance. Acupuncture, as a non-pharmacological intervention, is thought to enhance glucose metabolism and mitigate medication side effects. We selected the relevant studies of acupuncture or electroacupuncture combined with drugs in the treatment of abnormal glucose metabolism in the past five years, and the results indicate that the combination of acupuncture or electroacupuncture and drug therapy markedly enhances glucose metabolism and mitigates medication-related side effects such as gastrointestinal discomfort and hypoglycemia. Overall, this review underscores the synergistic benefits of acupuncture and drug therapy in improving treatment efficacy and reducing adverse effects, offering promising new approaches for managing abnormal glucose metabolism. Our review provides evidence for the potential benefits of combining acupuncture with drug therapy for abnormal glucose metabolism, which could lead to improved treatment outcomes and reduced side effects for patients with type 2 diabetes mellitus.

l-Malic Acid Facilitates Stem Cell-Driven Intestinal Epithelial Renewal through the Amplification of β-Catenin Signaling by Targeting Frizzled7 in Chicks

l-Malic acid (l-MA) contributes to energy metabolism and nutrient digestion, which is an alternative to antibiotics for livestock; however, it is not clear whether l-MA can replace antibiotics to promote intestinal development in chicks. To investigate the effects of l-MA on intestinal stem cells (ISCs) driving epithelial renewal, we employed in vivo chick feeding experiments, chick intestinal organoid (IO) models, and in vitro chick intestinal epithelial cell models. The results showed that the feed conversion rate and diarrhea scores were decreased with improved jejunal morphology and barrier function in the 0.5% l-MA group. l-MA promoted the proliferation and differentiation of ISCs, inhibited the cell apoptosis, increased the IO formation efficiency, surface area, budding efficiency, and number of buds, suggesting that l-MA promoted the expansion of ISCs. Furthermore, l-MA treatment dramatically upregulated the Wnt/β-catenin signaling pathway in the jejunum. Importantly, Wnt transmembrane receptor Frizzled7 (FZD7) mRNA abundance was increased in response to dietary 0.5% l-MA. In addition, molecular docking analysis using Autodock software and isothermal titration calorimetry revealed that l-MA binds to Lys91 of FZD7 with high affinity, indicating a spontaneous interaction. The chick intestinal epithelial cells treated with 10 μM l-MA significantly increased cell viability, and the Wnt/β-catenin signaling pathway was activated, but l-MA failed to upregulate the Wnt/β-catenin signaling when treated with the FZD7-specific inhibitor Fz7-21 in chick intestinal epithelial cells, indicating that FZD7 is indispensable for l-MA activation of the Wnt/β-catenin signaling. Collectively, l-MA stimulated β-catenin signaling by targeting transmembrane receptor FZD7, which promoted ISC expansion and inhibited cell apoptosis to accelerate intestinal epithelial renewal in chicks.

Increased expression of glucagon-like peptide-1 and cystic fibrosis transmembrane conductance regulator in the ileum and colon in mouse treated with metformin

Metformin, an oral medication, is prescribed to patients with type 2 diabetes mellitus. Although the efficacy, safety, and low economic burden of metformin on patients have long been recognized, approximately 5% of the patients treated with this drug develop severe diarrhea and discontinue the treatment. We previously reported that 1,000 mg·kg^-1·day^-1 of metformin induced diarrhea in diabetic obese (db/db) mice and wood creosote (traditional medication for diarrhea) ameliorated the symptoms. In this study, we attempted to elucidate the molecular mechanisms by which metformin induces diarrhea. Cystic fibrosis transmembrane conductance regulator (CFTR) is a key ion (chloride) channel in cyclic adenosine monophosphate (cAMP)-induced diarrhea. Metformin treatment increased bile flow (bile acids and bilirubin) in the ileum of mice. In addition, the treatment was accompanied by an increase in mRNA and protein levels of CFTR in the mucosa of the ileum and colon in both wild-type (C57BL/6J) and db/db mice. Glucagon-like peptide-1 (GLP-1), as well as cholic acid, induces CFTR mRNA expression in human colon carcinoma Caco-2 cells through cAMP signaling. Although wood creosote (10 mg/kg) ameliorated diarrhea symptoms, it did not alter the mRNA levels of Glp-1 or Cftr. Similar to overeating, metformin upregulated GLP-1 and CFTR expression, which may have contributed to diarrhea symptoms in mice. Although we could not identify db/db mouse-specific factors associated with metformin-induced diarrhea, these factors may modulate colon function. Wood creosote may not interact with these factors but ameliorates diarrhea symptoms.

Amelioration of type 2 diabetes by the novel 6, 8-guanidyl luteolin quinone-chromium coordination via biochemical mechanisms and gut microbiota interaction

INTRODUCTION

Luteolin is a plant-derived flavonoid that exhibits a broad range of pharmacological activities. Studies on luteolin have mainly focused on its use for hyperlipidaemia prevention, whereas the capacity of the flavonoid to hinder hyperglycaemia development remains underexplored.

OBJECTIVES

To probe the anti-hyperglycemic mechanism of 6,8-guanidyl luteolin quinone-chromium coordination (GLQ.Cr), and to assess its regulatory effect on intestinal microbiota in type 2 diabetes mellitus (T2DM) mice.

METHODS

High-sucrose/high-fat diet-induced and intraperitoneal injection of streptozotocin was used to develop a T2DM model. Glycometabolism related indicators, histopathology, and gut microbiota composition in caecum samples were evaluated, and RNA sequencing (RNA-seq) of liver samples was conducted. Faecal microbiota transplantation (FMT) was further used to verify the anti-hyperglycemic activity of intestinal microbiota.

RESULTS

The administration of GLQ.Cr alleviated hyperglycaemia symptoms by improving liver and pancreatic functions and modulating gut microbe communities (Lactobacillus, Alistipes, Parabacteroides, Lachnoclostridium, and Desulfovibrio). RNA-seq analysis showed that GLQ.Cr mainly affected the peroxisome proliferative activated receptor (PPAR) signalling pathway in order to regulate abnormal glucose metabolism. FMT significantly modulated the abundance of Lactobacillus, Alloprevotella, Alistipes, Bacteroides, Ruminiclostridium, Brevundimonas and Pseudomonas in the caecum to balance blood glucose levels and counteract T2DM mice inflammation.

CONCLUSION

GLQ.Cr improved the abnormal glucose metabolism in T2DM mice by regulating the PPAR signalling pathway and modulating intestinal microbial composition. FMT can improve the intestinal microecology of the recipient and in turn ameliorate the symptoms of T2DM-induced hyperglycaemia.

Metformin Inhibits Na+/H+ Exchanger NHE3 Resulting in Intestinal Water Loss

Glycemic control is the key to the management of type 2 diabetes. Metformin is an effective, widely used drug for controlling plasma glucose levels in diabetes, but it is often the culprit of gastrointestinal adverse effects such as abdominal pain, nausea, indigestion, vomiting, and diarrhea. Diarrhea is a complex disease and altered intestinal transport of electrolytes and fluid is a common cause of diarrhea. Na+/H+ exchanger 3 (NHE3, SLC9A3) is the major Na+ absorptive mechanism in the intestine and our previous study has demonstrated that decreased NHE3 contributes to diarrhea associated with type 1 diabetes. The goal of this study is to investigate whether metformin regulates NHE3 and inhibition of NHE3 contributes to metformin-induced diarrhea. We first determined whether metformin alters intestinal water loss, the hallmark of diarrhea, in type 2 diabetic db/db mice. We found that metformin decreased intestinal water absorption mediated by NHE3. Metformin increased fecal water content although mice did not develop watery diarrhea. To determine the mechanism of metformin-mediated regulation of NHE3, we used intestinal epithelial cells. Metformin inhibited NHE3 activity and the effect of metformin on NHE3 was mimicked by a 5'-AMP-activated protein kinase (AMPK) activator and blocked by pharmacological inhibition of AMPK. Metformin increased phosphorylation and ubiquitination of NHE3, resulting in retrieval of NHE3 from the plasma membrane. Previous studies have demonstrated the role of neural precursor cell expressed, developmentally down-regulated 4-2 (Nedd4-2) in regulation of human NHE3. Silencing of Nedd4-2 mitigated NHE3 inhibition and ubiquitination by metformin. Our findings suggest that metformin-induced diarrhea in type 2 diabetes is in part caused by reduced Na+ and water absorption that is associated with NHE3 inhibition, probably by AMPK.

Efficient Stool Collection Methods for Evaluating the Diarrhea Score in Mouse Diarrhea Models

BACKGROUND/AIM

The mouse diarrhea score is usually determined by evaluating stool consistency and shape. Thus, defecated stools should be collected without damage or contamination. The study aimed to develop improved mouse stool collection methods and diarrhea-scoring criteria.

MATERIALS AND METHODS

We developed improved stool collection methods (paper towel methods) and compared them with previously used ones (stool collection using regular cages containing bedding chips or filter paper and metabolic cages).

RESULTS

Compared to previously used methods, paper towel methods collected stools without bedding chips-induced contamination, mouse body/foot-induced damage, or sampling errors. When using paper towel methods, wet stools create water marks (diarrhea marks) on paper towels with strong water absorption capacity, by which diarrheal severity can be analyzed semi-quantitatively. To improve the objectivity in determining diarrhea scores, practical diarrhea-scoring criteria were also proposed.

CONCLUSION

These results would be helpful to researchers facing difficulties in evaluating the mouse diarrhea score.

Metformin: A Prospective Alternative for the Treatment of Chronic Pain

Metformin (biguanide) is a drug widely used for the treatment of type 2 diabetes. This drug has been used for 60 years as a highly effective antihyperglycemic agent. The search for the mechanism of action of metformin has produced an enormous amount of research to explain its effects on gluconeogenesis, protein metabolism, fatty acid oxidation, oxidative stress, glucose uptake, autophagy and pain, among others. It was only up the end of the 1990s and beginning of this century that some of its mechanisms were revealed. Metformin induces its beneficial effects in diabetes through the activation of a master switch kinase named AMP-activated protein kinase (AMPK). Two upstream kinases account for the physiological activation of AMPK: liver kinase B1 and calcium/calmodulin-dependent protein kinase kinase 2. Once activated, AMPK inhibits the mechanistic target of rapamycin complex 1 (mTORC1), which in turn avoids the phosphorylation of p70 ribosomal protein S6 kinase 1 and phosphatidylinositol 3-kinase/protein kinase B signaling pathways and reduces cap-dependent translation initiation. Since metformin is a disease-modifying drug in type 2 diabetes, which reduces the mTORC1 signaling to induce its effects on neuronal plasticity, it was proposed that these mechanisms could also explain the antinociceptive effect of this drug in several models of chronic pain. These studies have highlighted the efficacy of this drug in chronic pain, such as that from neuropathy, insulin resistance, diabetic neuropathy, and fibromyalgia-type pain. Mounting evidence indicates that chronic pain may induce anxiety, depression and cognitive impairment in rodents and humans. Interestingly, metformin is able to reverse some of these consequences of pathological pain in rodents. The purpose of this review was to analyze the current evidence about the effects of metformin in chronic pain and three of its comorbidities (anxiety, depression and cognitive impairment).