AMPK pathway: an emerging target to control diabetes mellitus and its related complications

Differential Regulation of PKM2, AMPK, and mTOR in Response to Insulin and Dietary Management

Gestational diabetes mellitus (GDM) affects placental metabolism, influencing both maternal and fetal outcomes. This study investigated the expression of metabolic regulators-Pyruvate Kinase M2 (PKM2), AMP-activated protein kinase (AMPK), and mTOR pathway components-in placental tissues from GDM pregnancies managed with either insulin (GDM-I) or dietary interventions (GDM-D). We hypothesize that metabolic adaptation in GDM is differentially regulated by treatment modality. This study analyzed 30 cases, including 10 control pregnancies,10 GDM-D cases, and 10 GDM-I cases. Analytical methods included immunofluorescence and immunoblotting. We observed an upregulation of PKM2 in both GDM-I and GDM-D placentas, suggesting enhanced glycolytic adaptation under GDM-induced metabolic stress. AMPK expression was significantly elevated in GDM-I and moderately increased in GDM-D placentas, potentially compensating for insulin resistance by promoting glucose uptake and energy homeostasis. Furthermore, mTOR pathway activation differed by treatment type, suggesting a treatment-specific mTOR response. The metabolic changes observed suggest that treatment modality in GDM may have direct implications for maternal and fetal health. Our findings indicate that while insulin and dietary management support metabolic adaptation in GDM, they do so through distinct mechanisms. These findings support a personalized approach in GDM treatment, where patient-specific metabolic responses should guide therapeutic decisions.

Natural products targeting AMPK signaling pathway therapy, diabetes mellitus and its complications

Diabetes mellitus (DM) ranks among the most prevalent chronic metabolic diseases, characterized primarily by a persistent elevation in blood glucose levels. This condition typically stems from either insufficient insulin secretion or a functional defect in the insulin itself. Clinically, diabetes is primarily classified into type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), with T2DM comprising nearly 90% of all diagnosed cases. Notably, the global incidence of T2DM has surged dramatically over recent decades. The adenylate-activated protein kinase (AMPK) signaling pathway is crucial in regulating cellular energy metabolism, marking it as a significant therapeutic target for diabetes and related complications. Natural products, characterized by their diverse origins, multifaceted bioactivities, and relative safety, hold considerable promise in modulating the AMPK pathway. This review article explores the advances in research on natural products that target the AMPK signaling pathway, aiming to inform the development of innovative antidiabetic therapies.

Administration of AICAR, an AMPK Activator, Prevents and Reverses Diabetic Polyneuropathy (DPN) by Regulating Mitophagy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes in both Type 1 (T1D) and Type 2 (T2D). While there are no specific medications to prevent or treat DPN, certain strategies can help halt its progression. In T1D, maintaining tight glycemic control through insulin therapy can effectively prevent or delay the onset of DPN. However, in T2D, overall glucose control may only have a moderate impact on DPN, although exercise is clearly beneficial. Unfortunately, optimal exercise may not be feasible for many patients with DPN because of neuropathic foot pain and poor balance. Exercise has several favorable effects on health parameters, including body weight, glycemic control, lipid profile, and blood pressure. We investigated the impact of an exercise mimetic, 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), on DPN. AICAR treatment prevented or reversed experimental DPN in mouse models of both T2D and T1D. AICAR in high-fat diet (HFD-fed) mice increased the phosphorylation of AMPK in DRG neuronal extracts, and the ratio of phosphorylated AMPK to total AMPK increased by 3-fold (HFD vs. HFD+AICAR; p < 0.001). Phospho AMP increased the levels of dynamin-related protein 1 (DRP1, a mitochondrial fission marker), increased phosphorylated autophagy activating kinase 1 (ULK1) at Serine-555, and increased microtubule-associated protein light chain 3-II (LC3-II, a marker for autophagosome assembly) by 2-fold. Mitochondria isolated from DRG neurons of HFD-fed had a decrease in ADP-stimulated state 3 respiration (120 ± 20 nmol O2/min in HFD vs. 220 ± 20 nmol O2/min in control diet (CD); p < 0.001. Mitochondria isolated from HFD+AICAR-treated mice had increased state 3 respiration (240 ± 30 nmol O2/min in HFD+AICAR). However, AICAR's protection in DPN in T2D mice was also mediated by its effects on insulin sensitivity, glucose metabolism, and lipid metabolism. Drugs that enhance AMPK phosphorylation may be beneficial in the treatment of DPN.

Identification of Bioactive Compounds from the Roots of Rehmannia glutinosa and Their In Silico and In Vitro AMPK Activation Potential

Rehmannia glutinosa Libosch., which belongs to the Orobanchaceae family, is a perennial herb found in China, Japan, and Korea. In traditional medicine, it is used to cool the body, improve water metabolism in the kidney, and provide protection from metabolic diseases such as type 2 diabetes mellitus (T2DM) and obesity. In this study, three new compounds were isolated from the roots of R. glutinosa, along with eighteen known compounds. Structure elucidation was performed with spectroscopic analyses including nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. As the AMP-activated protein kinase (AMPK) signaling pathway is reportedly related to metabolic diseases, AMPK activation studies were conducted using in silico simulations and in vitro assays. Among the isolated compounds, 1 showed a potential as an AMPK activator in both in silico simulations and in vitro experiments. Our findings expand the chemical profiles of the plant R. glutinosa and suggest that one newly found compound (1) activates AMPK.

Cellular and Molecular Pathophysiology of Gestational Diabetes

Gestational diabetes (GD) is a metabolic disorder characterized by glucose intolerance during pregnancy, significantly impacting maternal and fetal health. Its global prevalence is approximately 14%, with risk factors including obesity, family history of diabetes, advanced maternal age, and ethnicity, which are linked to cellular and molecular disruptions in glucose regulation and insulin resistance. GD is associated with short- and long-term complications for both the mother and the newborn. For mothers, GD increases the risk of developing type 2 diabetes, cardiovascular diseases, and metabolic syndrome. In the offspring, exposure to GD in utero predisposes them to obesity, glucose intolerance, and metabolic disorders later in life. This review aims to elucidate the complex cellular and molecular mechanisms underlying GD to inform the development of effective therapeutic strategies. A systematic review was conducted using medical subject headings (MeSH) terms related to GD's cellular and molecular pathophysiology. Inclusion criteria encompassed original studies, systematic reviews, and meta-analyses focusing on GD's impact on maternal and fetal health, adhering to PRISMA guidelines. Data extraction captured study characteristics, maternal and fetal outcomes, key findings, and conclusions. GD disrupts insulin signaling pathways, leading to impaired glucose uptake and insulin resistance. Mitochondrial dysfunction reduces ATP production and increases reactive oxygen species, exacerbating oxidative stress. Hormonal influences, chronic inflammation, and dysregulation of the mammalian target of rapamycin (mTOR) pathway further impair insulin signaling. Gut microbiota alterations, gene expression, and epigenetic modifications play significant roles in GD. Ferroptosis and placental dysfunction primarily contribute to intrauterine growth restriction. Conversely, fetal macrosomia arises from maternal hyperglycemia and subsequent fetal hyperinsulinemia, resulting in excessive fetal growth. The chronic inflammatory state and oxidative stress associated with GD exacerbate these complications, creating a hostile intrauterine environment. GD's complex pathophysiology involves multiple disruptions in insulin signaling, mitochondrial function, inflammation, and oxidative stress. Effective management requires early detection, preventive strategies, and international collaboration to standardize care and improve outcomes for mothers and babies.

Anti-Type II Diabetic Effects of Coix Seed Prolamin Hydrolysates: Physiological and Transcriptomic Analyses

Previous studies have demonstrated that enzymatically prepared coix seed prolamin hydrolysates (CHPs) contain several bioactive peptides that efficiently inhibit the activity of target enzymes (α-glucosidase and dipeptidyl kinase-IV) in type 2 diabetes mellitus (T2DM). However, the anti-T2DM effects and potential mechanisms of CHPs as a whole in vivo have not yet been systematically explored. Therefore, we evaluated the preventive, therapeutic, and modifying effects of CHPs on T2DM by combining physiological and liver transcriptomics with a T2DM mouse model. The results showed that sustained high-fructose intake led to prediabetic symptoms in mice, with abnormal fluctuations in blood glucose and blood lipid levels. Intervention with CPHs effectively prevented weight loss; regulated abnormal changes in blood glucose; improved impaired glucose tolerance; inhibited the abnormal expression of total cholesterol, triglycerides, and low-density lipoproteins; alleviated insulin resistance; and restored pancreatic islet tissue function in mice fed a high-fructose diet. In addition, we found that CHPs also play a palliative role in the loss of liver function and protect various organ tissues (including the liver, kidneys, pancreas, and heart), and are effective in preventing damage to the liver and pancreatic islet cells. We also found that the intake of CHPs reversed the abnormally altered hepatic gene profile in model mice and identified 381 differentially expressed genes that could serve as key genes for preventing the development of T2DM, which are highly correlated with multiple glycolipid metabolic pathways. We demonstrated that CHPs play a positive role in the normal functioning of the insulin signalling pathway dominated by the IRS-1/PI3K/AKT (insulin receptor substrates-1/phosphoinositide 3-kinase/protein kinase B) pathway. In summary, CHPs can be used as effective food-borne glucose-modifying components of healthy foods.