Molecular Imaging of Diabetes-Associated Glutathione S-Transferase Dysregulation Using a Smart Activatable Probe.

Erectile dysfunction (ED) is a common complication of diabetes. Diabetes leads to the decrease of zinc (Zn) content, and zinc deficiency can cause sexual dysfunction, hypoplasia of sexual organs, and secondary sexual characteristics. The purpose of this study was to explore the protective effect of metformin combined with zinc on erectile function in diabetic mice induced by streptozotocin (STZ). Ten of 50 male mice were randomly selected as the control group (group C), and the remaining 40 mice were randomly divided into the diabetes treatment group (group D), diabetes + zinc group (group Z), diabetes + metformin group (group M), and diabetes + metformin + zinc group (group ZM), with 10 mice in each group. The diabetic mouse model was induced by high-fat diet (HFD) and STZ. Diabetic mice in group Z were given oral zinc (10mg/kg) once a day for 4weeks, group M diabetic mice were given metformin (200mg/kg) once a day for 4weeks, diabetic mice in group ZM were given metformin and zinc once a day for 4weeks, and group C and group D were given the same amount of sterile water. The mice that fasted overnight were killed, and blood samples and penises were collected for further experiments. The combined treatment of zinc and metformin can reduce penis weight and improve the structural damage of the cavernous body caused by diabetes. The combined treatment of zinc and metformin can improve the serum zinc content and the fluorescence intensity of free zinc ions in penis and correct the unbalanced zinc homeostasis by changing the expressions of zinc transporter (ZnT3, ZnT8, ZIP10, and ZIP14) in penis tissue. The results showed that combined treatment with zinc and metformin can increase the expression of Bcl-2, decrease the expression of Bax and caspase-3, and decrease the apoptosis index of cavernous cells caused by diabetes. In addition, the combined treatment of zinc and metformin can increase the levels of SOD, NO, and cGMP in penis tissue; decrease MDA level; inhibit TGF-β1/Smad3 pathway-related proteins; increase the expression levels of eNOS, α-SMA, and CD31 proteins; and reduce collagen deposition in the penis. In a word, we found that zinc combined with metformin can inhibit the TGF-β1/Smad3 pathway; correct the imbalance of zinc homeostasis in the cavernous body; reduce the levels of oxidative stress, fibrosis, and apoptosis; and improve the structural damage of the cavernous body in male type 2 diabetic mice.

BackgroundDiabetes mellitus is the leading cause of chronic kidney disease and end‐stage renal disease in the United States. About one‐third of patients with diabetes develop renal dysfunction, commonly referred to as diabetic nephropathy. Metformin is a widely prescribed antidiabetic medication for patients with type 2 diabetes; however, its direct effects on the renal function besides normalizing glucose levels in patients with diabetic nephropathy are poorly understood. Thus, the objective of our study was to investigate the effects of a non‐glucose lowering, low‐dose metformin treatment on the diabetic kidney using a genetic mouse model of type 2 diabetes.MethodsOur study utilized db/db mice (Leprdb), which harbor a mutation in their leptin receptors, and hence, show the signs and symptoms similar to those experienced in patients with type 2 diabetes. To accelerate the progression of nephropathy, each mouse had their left kidney removed at ten weeks of age. Heterozygous mice were used as a control group for the study. Our study had four treatment groups (n=8 per group): 1) Vehicle‐treated control (non‐diabetic), 2) Metformin‐treated control (non‐diabetic), 3) Diabetic, vehicle‐treated, and 4) Diabetic, metformin‐treated. Mice were treated with either vehicle or metformin (100 mg/kg/day) for four weeks. Fasting blood glucose and urine samples were collected at the beginning and end of the study. Plasma and kidney tissue samples were collected at the end of the study. Markers of renal dysfunction such as elevations in urine albumin‐creatinine ratio (UACR) and plasma creatinine were measured in the samples collected from the study. Alpha‐smooth muscle (α‐SMA), a marker of renal fibrosis, were measured in kidney samples via Western blotting.ResultsOur results showed that the fasting blood glucose (FBG) levels were elevated in the diabetic mice (470.29 ±73.35 mg/dL) at the beginning of the study and were gradually increased with disease progression (672.57 ±107.88 mg/dL). Our results also demonstrated that low‐dose metformin treatment did not lower FBG levels in diabetic mice (583.38 ±195.77 mg/dL). However, metformin treatment was able to prevent the increase in UACR in diabetic mice (205.3 ±112.5 vs. 117.53 ±61.56 μg albumin/mg creatinine). Results from the plasma creatinine levels show that diabetic mice had increased plasma creatinine levels (0.72 ±0.07 mg/dL) compared to the control mice (0.51 ±0.06 mg/dL). Intriguingly, low‐dose metformin treatment did not prevent the diabetes‐induced elevations in plasma creatinine levels. Western blot analysis for α‐SMA indicated that only the diabetic mice expressed α‐SMA in the kidney and low‐dose metformin treatment diminished renal expression of α‐SMA in diabetic mice.ConclusionOur findings suggest that low‐dose metformin treatment improves renal function, and ameliorates renal fibrosis observed with diabetic nephropathy. Further studies are required to investigate the mechanisms that underlie the nephroprotective effects of low‐dose metformin therapy in diabetic mice.Support or Funding InformationFundingThis study was supported by intramural funds received from Drake University through Harris Research Endowment, Kresge Endowment, and Provost fund.

Protective effect of type 2 diabetes on acetaminophen-induced hepatotoxicity in male Swiss-Webster mice.

Reports have shown differences in gene expression in the skin of diabetic and normal mice both at baseline and after injury. Cluster analysis identified distinct expression patterns within intermediate filaments and extracellular proteins. This report addresses the effect of diabetes and injury on the expression of keratin-associated proteins, keratin complexes, procollagen, and collagenase (matrix metalloproteinase; MMP) genes. At baseline keratin-associated proteins and keratin complexes gene expression was increased in diabetic mice. After surgery, the level of expression for keratin-associated proteins and keratin complexes genes decreased in diabetic mice, but did not change in normal mice. If the expression of a procollagen gene differed between diabetic and normal mice, the expression was lower in diabetic mice. Procollagen gene expression was elevated after skin excision compared with noninjured skin. At baseline, the level of MMP and tissue inhibitor of metalloproteinase gene expression was comparable between mouse strains. With injury, the expression of several MMP genes was increased in both mouse strains, but to higher levels in diabetic mice. At day 7, the level of MMP-9 activity in granulation tissue was elevated. This alteration may contribute to delayed healing in diabetic mice. Therefore, differences in gene expression exist between mouse strains and can assist in understanding of physiological manifestations, including delayed healing, in diabetic mice.

ObjectiveThis study investigated the effect of crocin in methylglyoxal (MGO)-induced diabetic male mice.MethodsSeventy 1-month-old male NMRI mice weighing 20–25 g were divided into seven groups (n=10): sham, MGO (600 mg/kg/day), MGO+crocin (15, 30, and 60 mg/kg/day), MGO+metformin (150 mg/kg/day), and crocin (60 mg/kg/day). MGO was administered orally for 30 days. Starting on day 14, after confirming hyperglycemia, metformin and crocin were administered orally. On day 31, plasma and tissue samples were prepared for experimental assessments.ResultsBlood glucose and insulin levels in the MGO group were higher than those in the sham group (p<0.001), and decreased in response to metformin (p<0.001) and crocin treatment (not at all doses). Testis width and volume decreased in the MGO mice and improved in the crocin-treated mice (p<0.05), but not in the metformin group. Superoxide dismutase levels decreased in diabetic mice (p<0.05) and malondialdehyde levels increased (p<0.001). Crocin and metformin improved malondialdehyde and superoxide dismutase. Testosterone (p<0.001) and sperm count (p<0.05) decreased in the diabetic mice, and treatment with metformin and crocin recovered these variables. Luteinizing hormone levels increased in diabetic mice (p<0.001) and crocin treatment (but not metformin) attenuated this increase. Seminiferous diameter and height decreased in the diabetic mice and increased in the treatment groups. Vacuoles and ruptures were seen in diabetic testicular tissue, and crocin improved testicular morphology (p<0.01).ConclusionMGO increased oxidative stress, reduced sex hormones, and induced histological problems in male reproductive organs. Crocin and metformin improved the reproductive damage caused by MGO-induced diabetes.

The objective of this study was to characterise the fulminant type 1 diabetes mellitus (DM) accompanying abrupt hyperglycaemia and ketonuria observed in insulin receptor substrate 2 (IRS2)-deficient mice. IRS2-deficient mice backcrossed onto the original C57BL/6J:Jc1 background (B6J-IRS2(-/-) mice) for more than 10 generations were used. Eight male IRS2-deficient mice with ketonuria and abrupt increase in plasma glucose concentrations over 25 mmol/l were used as the fulminant type 1 diabetic mice (diabetic mice) and 8 male IRS2-deficient mice (8 weeks old) without glycosuria were used as the control mice. Plasma metabolite, immunoreactive insulin (IRI) and C-peptide concentrations, hepatic energy metabolism related enzyme activities and histopathological change in pancreatic islets were investigated. The diabetic mice showed significantly higher plasma glucose and cholesterol concentrations and lower plasma IRI and C-peptide concentrations than the control mice. In livers of the diabetic mice, glycolytic and malate-aspartate shuttle enzyme activities decreased significantly and gluconeogenic, lipogenic and ketone body synthesis enzyme activities increased significantly compared to those in the control mice. The pancreatic islets of the diabetic mice decreased significantly in size and number of beta cells. The diabetic IRS2-deficient mice did not show the islet-related antibodies observed in the diabetic NOD mice in their sera. The characteristics of the diabetic IRS2-deficient mice resembled those of the human nonautoimmune fulminant type 1 DM. IRS2-deficient mice may be a useful animal model for studying the degradation mechanism of pancreatic beta cells in the process of development of fulminant type 1 DM.

Our objective was to investigate the potential of lutein in enhancing the efficacy of metformin in diabetes treatment and the underlying mechanisms involved. Here, the study was conducted with type 2 diabetic mice, which was induced by a high-fat diet with streptozotocin. Twenty-four diabetic model mice were divided into four groups: model control group, metformin group, lutein group, and lutein combined with metformin (Lut_Met) group. Six C57BL/6 mice were assigned to the normal control group and provided a normal chow diet. First, we found that the blood glucose concentration, area of the curve of the oral glucose tolerance test, and homeostasis model assessment for insulin resistance and imidazole propionate (ImP) levels of the Lut_Met group were significantly lower than those of the metformin group at the 8th week. Additionally, a significant positive correlation was observed between the reduction in blood glucose and the ImP levels in the Lut_Met group. The Firmicutes/Bacteroidota ratio in the Lut_Met group was significantly lower than that in the model control and metformin groups. In addition, the abundance of Eggerthella lenta in the Lut_Met group was significantly lower than that in the metformin group and showed a positive relationship with ImP levels. Moreover, compared with the metformin treatment, Lut_Met intervention had a significant impact on the AMPK signaling pathway. Further western blot analyses revealed that the ratio of phosphorylated AMPK/β-Actin to AMPK/β-Actin in the Lut_Met group was significantly greater than that in the metformin group. In conclusion, lutein has the potential to enhance the favorable effects of metformin on blood glucose metabolism and insulin resistance in a mouse model of diabetes. The underlying mechanisms are likely associated with the modulation of the gut microbiota-ImP axis and AMPK phosphorylation.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-16133-y.

Background: The aim of the study was to investigate the hypoglycemic effects of Phloridzin.Methods and Materials: High fat diet induced diabetic KKAy mice were administered with phloridzin at an oral dose (60 mg/kg/day, ig.) for 10 weeks. A range of parameters, including blood glucose and lipid, serum insulin, glucose tolerance, were tested to evaluate its anti-hyperglycemic effects.Results: Phloridzin decreased water-intake, body weight, FBG, FINS, HOME-IR, Serum leptin, and CRP levels, increased serum adiponectin level in diabetic mice. Phloridzin also improved the oral glucose tolerance test (OGTT) to a certain degree. In addition, phloridzin decreased liver index, and epididymal, perirenal white adipose tissue indexs, increased pancreas index in diabetic mice. At last, phloridzin increased hepatic GK activity and hepatic glycogen level, decreased hepatic PEPCK, G-6-Pase activities in diabetic mice.Conclusions: Phloridzin possessed anti-hyperglycemic activities.Keywords: Diabetes, Phloridzin, FBG, Insulin resistance, Area under curve

OBJECTIVEAutophagy is a critical cellular system for removal of aggregated proteins and damaged organelles. Although dysregulated autophagy is implicated in the development of heart failure, the role of autophagy in the development of diabetic cardiomyopathy has not been studied. We investigated whether chronic activation of the AMP-activated protein kinase (AMPK) by metformin restores cardiac function and cardiomyocyte autophagy in OVE26 diabetic mice.RESEARCH DESIGN AND METHODSOVE26 mice and cardiac-specific AMPK dominant negative transgenic (DN)-AMPK diabetic mice were treated with metformin or vehicle for 4 months, and cardiac autophagy, cardiac functions, and cardiomyocyte apoptosis were monitored.RESULTSCompared with control mice, diabetic OVE26 mice exhibited a significant reduction of AMPK activity in parallel with reduced cardiomyocyte autophagy and cardiac dysfunction in vivo and in isolated hearts. Furthermore, diabetic OVE26 mouse hearts exhibited aggregation of chaotically distributed mitochondria between poorly organized myofibrils and increased polyubiquitinated protein and apoptosis. Inhibition of AMPK by overexpression of a cardiac-specific DN-AMPK gene reduced cardiomyocyte autophagy, exacerbated cardiac dysfunctions, and increased mortality in diabetic mice. Finally, chronic metformin therapy significantly enhanced autophagic activity and preserved cardiac functions in diabetic OVE26 mice but not in DN-AMPK diabetic mice.CONCLUSIONSDecreased AMPK activity and subsequent reduction in cardiac autophagy are important events in the development of diabetic cardiomyopathy. Chronic AMPK activation by metformin prevents cardiomyopathy by upregulating autophagy activity in diabetic OVE26 mice. Thus, stimulation of AMPK may represent a novel approach to treat diabetic cardiomyopathy.

Reactive oxygen species (ROS) may play key roles in vascular inflammation and atherogenesis in patients with diabetes. In this study, xanthine oxidase (XO) system was examined as a potential source of superoxide in mice with streptozotocin (STZ)-induced experimental diabetes. Plasma XO activity increased 3-fold in diabetic mice (50±33 μU/ml) 2 weeks after the onset of diabetes, as compared with non-diabetic control mice (15±6 μU/ml). In vivo superoxide generation in diabetic mice was evaluated by an in vivo electron spin resonance (ESR)/spin probe method. Superoxide generation was significantly enhanced in diabetic mice, and the enhancement was restored by the administration of superoxide dismutase (SOD) and 4,5-dihydroxy-1,3-benzene disulfonic acid (Tiron), which was reported to scavenge superoxide. Pretreatment of diabetic mice with XO inhibitors, allopurinol and its active metabolite oxipurinol, normalized the increased superoxide generation. In addition, there was a correlation (r=0.78) between the level of plasma XO activity and the relative degree of superoxide generation in diabetic and non-diabetic mice. Hence, the results of this study strongly suggest that superoxide should be generated through the increased XO seen in the diabetic model mice, which may be involved in the pathogenesis of diabetic vascular complications.

Exercise precision medicine for type 2 diabetes: Targeted benefit or risk?

Background: The aim of the study was to investigate the hypoglycemic effects of Phloridzin.&#x0D; Methods and Materials: High fat diet induced diabetic KKAy mice were administered with phloridzin at an oral dose (60&#x0D; mg/kg/day, ig.) for 10 weeks. A range of parameters, including blood glucose and lipid, serum insulin, glucose tolerance, were tested&#x0D; to evaluate its anti-hyperglycemic effects.&#x0D; Results: Phloridzin decreased water-intake, body weight, FBG, FINS, HOME-IR, Serum leptin, and CRP levels, increased serum&#x0D; adiponectin level in diabetic mice. Phloridzin also improved the oral glucose tolerance test (OGTT) to a certain degree. In addition,&#x0D; phloridzin decreased liver index, and epididymal, perirenal white adipose tissue indexs, increased pancreas index in diabetic mice. At&#x0D; last, phloridzin increased hepatic GK activity and hepatic glycogen level, decreased hepatic PEPCK, G-6-Pase activities in diabetic&#x0D; mice.&#x0D; Conclusions: Phloridzin possessed anti-hyperglycemic activities.

To investigate the protective effects of metformin on the diabetic mice with cognitive impairment induced by the combination of streptozotocin (STZ) and isoflurane anesthesia. The isoflurane-anesthetized cognitive impairment model mice were established and then observed via behavioral tests and histopathological examination. Then these model mice were randomly assigned to three groups, which received the PBS, low and high doses of metformin, respectively. The body weight, food and water consumption of model mice were measured every other day. The mechanisms of metformin on ameliorating the cognitive dysfunction were further investigated by histomorphological, biochemical and Western blot analysis. After 14-days treatment of metformin, the diabetic symptoms in STZ-induced diabetic mice were significantly alleviated. Metformin could restore the isoflurane- and STZ-induced hippocampal tissue damage, cognitive and memory impairment in exposed space via improving the oxidative stress, upregulating the contents of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in the hippocampus tissues of diabetic mice. Furthermore, chronic treatment of metformin significantly down-regulated the expression of AGEs, RAGE, pNF-κB, iNOS, and COX-2. In conclusion, metformin can improve the isoflurane- and STZ-induced cognitive impairment in diabetic mice via improving oxidative stress and inhibiting the AGEs/RAGE/NF-κB signaling pathway.

(+)-1,1’-Bislunatin (Bsl) is a bisanthraquinone isolated from the endophytic fungus Diaporthe sp. GNBP-10 derived from the gambier plant (Uncaria gambier Roxb.). This study aims to evaluate the hypoglycemic effect of Bsl in experimental diabetic male mice. DDY Male mice were induced with streptozotocin (STZ) at a dose of 40 mg/kg BW intraperitoneal for 5 consecutive days to obtain experimental diabetic mice. The treatments in this study included: (1) normal control group (without STZ induction), (2) negative control group (STZ induction), (3) positive control group (STZ induction and metformin administration), (4) Bsl treatment 20 mg/kg BW, (5) Bsl treatment 100 mg/kg BW, (6) Bsl treatment 500 mg/kg BW. The results showed that Bsl treatment with various doses could reduce blood glucose levels as well as a positive control (the group with metformin treatment) (p <0.05). There was no significant difference between the normal control, all Bsl test groups, and positive control. This fact indicates that Bsl could return blood glucose levels to a normal level for STZ-induced diabetic mice and the positive control. The results of Bsl treatment in STZ-induced diabetic mice can reduce blood glucose levels, and this compound is expected to be a safer candidate for type 2 diabetes drugs. Further research related to in-vivo tests using other experimental animals is still needed to prove the efficacy of the Bsl compound.

Reductions in central catecholamines produced by intraventricular injections of 6-hydroxydopamine (6-OHDA) cause weight loss and decreased plasma glucose in diabetes (db/db) mice. The effects of this treatment were examined in short-term (64-day) and long-term (120-day) survival groups. Diabetes mice treated with 6-OHDA decreased food intake, lost weight, and maintained a lower weight than vehicle-treated controls until vehicle-treated animals began to enter the terminal stages of the syndrome, indicated by a loss of body weight. Diabetes mice given 6-OHDA lost weight despite reduced body temperatures and activity levels. Blood glucose levels were always lower in 6-OHDA than in ad lib fed vehicle-treated db/db mice. The 6-OHDA treatment also improved pancreatic islet granulation. Pair feeding vehicle-treated with 6-OHDA-treated db/db mice did not halt weight gain in the vehicle-treated group. However, measurement of carcass fat indicated similar losses in db/db-6-OHDA mice and vehicle-treated mice when the vehicle group was pair-fed with lean controls. Treatment with 6-OHDA produced long-term improvement in the diabetes syndrome, but the decreased body weight of the 6-OHDA-treated diabetes mice could not be completely accounted for by changes in food intake or measured indices of energy expenditure.