Biochemical efficacy of vitamin D in ameliorating endocrine and metabolic disorders in diabetic rats

Vitamin D Supplementation as a Therapeutic Strategy in Autoimmune Diabetes: Insights and Implications for LADA Management

Latent autoimmune diabetes of adults (LADA) is the most prevalent form of autoimmune diabetes (AI-D) in adulthood; however, its accurate diagnosis and optimal treatment remain challenging. Vitamin D deficiency (VDD) is commonly observed in LADA patients, while increased vitamin D exposure through supplementation and dietary intake is associated with a reduced incidence of LADA. Although limited, case reports, case-control studies, and randomized clinical trials have examined the effects of vitamin D supplementation-alone or combined with dipeptidyl peptidase-4 inhibitors (DPP4-is)-on glucose regulation, residual β-cell function, and glutamic acid decarboxylase antibody (GADA65) levels. Findings, while preliminary, indicate that vitamin D supplementation may enhance glycemic control, preserve β-cell function, and reduce autoimmune activity. Given its accessibility, affordability, and relative safety, vitamin D supplementation presents an attractive adjunct treatment option for LADA patients. This narrative review discusses current evidence on the potential therapeutic benefits of vitamin D supplementation in patients with AI-D, including LADA, who are also vitamin D deficient. Beginning with an exploration of the epidemiological patterns, clinical presentation, and diagnostic framework essential for understanding and identifying LADA, this review then examines the proposed mechanisms through which vitamin D may influence autoimmune modulation of pancreatic β-cells, integrating recent data pertinent to LADA pathology. By distilling and consolidating existing research, we aim to provide a platform for advancing targeted investigations within this distinct patient population.

Monocarbonyl analogs of curcumin C66 and B2BrBC modulate oxidative stress, JNK activity, and pancreatic gene expression in rats with streptozotocin-induced diabetes

The pathogenesis of type 1 diabetes mellitus (T1DM) involves oxidative stress and inflammation. Curcumin, a natural polyphenolic compound found in turmeric, known to exhibit antioxidative and anti-inflammatory properties, is characterized by poor chemical stability, low bioavailability, and rapid metabolism. Monocarbonyl analogs of curcumin (MACs) with a structural absence of β-diketone and enhanced stability and bioavailability present a potential solution to the challenges associated with the use of curcumin. This study aimed to evaluate the effect of two MACs, C66 and B2BrBC, on oxidative stress markers, antioxidant enzyme activity, expression of diabetes-associated genes, and signaling pathway proteins in the context of T1DM. Streptozotocin (STZ)-induced male Wistar rats or rat pancreatic RIN-m cells were used for in vivo and in vitro experiments, respectively. C66 or B2BrBC were given either before or after STZ treatment. Oxidative stress markers and antioxidant enzyme activities were determined in various tissues. Expression of diabetes-associated genes was assessed using RT-qPCR, and the activity of signaling pathway proteins in the pancreas was determined through Western blot analysis. Treatment with C66 and B2BrBC significantly reduced oxidative stress markers and positively influenced antioxidant enzyme activities. Moreover, both compounds inhibited JNK activity in the pancreas while enhancing the expression of genes crucial for β-cell survival and glucose and redox homeostasis. The findings highlight the multifaceted potential of C66 and B2BrBC in ameliorating oxidative stress, influencing gene expression patterns linked to diabetes, and modulating key signaling pathways in the pancreas. The findings suggest that these compounds can potentially address diabetes-related pathological processes.

Multifaceted Roles of Vitamin D for Diabetes: From Immunomodulatory Functions to Metabolic Regulations

Numerous studies have established associations between vitamin D and diabetes. The vitamin D receptor is widely distributed throughout the human body, including in pancreatic beta cells (β-cells), hepatocytes, and immune cells. Therefore, vitamin D's effect on the risk, progression, or complications of diabetes may be mediated through various mechanisms. These include the regulation of insulin secretion or sensitivity and modulation of β-cell function and its immunomodulatory and anti-inflammatory effects. This review extensively explores the relationship between vitamin D status and diabetes, as well as the preventive or therapeutic effects of vitamin D supplementation on diabetes from human studies. Additionally, it examines in detail the impact of vitamin D on immune and inflammatory responses in the diabetic milieux and β-cell function to better understand the underlying mechanisms through which vitamin D influences diabetes.

Vitamin D supplementation alleviates insulin resistance in prediabetic rats by modifying IRS-1 and PPARγ/NF-κB expressions

Background

Prediabetes is a condition of intermediate hyperglycemia that may progress to type 2 diabetes. Vitamin D deficiency has been frequently linked to insulin resistance and diabetes. The study aimed to investigate the role of D supplementation and its possible mechanism of action on insulin resistance in prediabetic rats.

Method

The study was conducted on 24 male Wistar rats that were randomly divided into 6 rats as healthy controls and 18 prediabetic rats. Prediabetic rats were induced with a high-fat and high-glucose diet (HFD-G) combined with a low dose of streptozotocin. Rats with the prediabetic condition were then randomized into three groups of 12-week treatment: one group that received no treatment, one that received vitamin D3 at 100 IU/kg BW, and one group that received vitamin D3 at 1000 IU/kg BW. The high-fat and high-glucose diets were continuously given throughout the twelve weeks of treatment. At the end of the supplementation period, glucose control parameters, inflammatory markers, and the expressions of IRS1, PPARγ, NF-κB, and IRS1 were measured.

Results

Vitamin D3 dose-dependently improves glucose control parameters, as shown by the reduction of fasting blood glucose (FBG), oral glucose tolerance test (OGTT), glycated albumin, insulin levels, and markers of insulin resistance (HOMA-IR). Upon histological analysis, vitamin D supplementation resulted in a reduction of the islet of Langerhans degeneration. Vitamin D also enhanced the ratio of IL-6/IL-10, reduced IRS1 phosphorylation at Ser307, increased expression of PPAR gamma, and reduced phosphorylation of NF-KB p65 at Ser536.

Conclusion

Vitamin D supplementation reduces insulin resistance in prediabetic rats. The reduction might be due to the effects of vitamin D on IRS, PPARγ, and NF-κB expression.

Beta Cell Dysfunction in Youth- and Adult-Onset Type 2 Diabetes: An Extensive Narrative Review with a Special Focus on the Role of Nutrients

Traditionally a disease of adults, type 2 diabetes (T2D) has been increasingly diagnosed in youth, particularly among adolescents and young adults of minority ethnic groups. Especially, during the recent COVID-19 pandemic, obesity and prediabetes have surged not only in minority ethnic groups but also in the general population, further raising T2D risk. Regarding its pathogenesis, a gradually increasing insulin resistance due to central adiposity combined with a progressively defective β-cell function are the main culprits. Especially in youth-onset T2D, a rapid β-cell activity decline has been observed, leading to higher treatment failure rates, and early complications. In addition, it is well established that both the quantity and quality of food ingested by individuals play a key role in T2D pathogenesis. A chronic imbalance between caloric intake and expenditure together with impaired micronutrient intake can lead to obesity and insulin resistance on one hand, and β-cell failure and defective insulin production on the other. This review summarizes our evolving understanding of the pathophysiological mechanisms involved in defective insulin secretion by the pancreatic islets in youth- and adult-onset T2D and, further, of the role various micronutrients play in these pathomechanisms. This knowledge is essential if we are to curtail the serious long-term complications of T2D both in pediatric and adult populations.

Vitamin D regulates insulin and ameliorates apoptosis and oxidative stress in pancreatic tissues of rats with streptozotocin-induced diabetes

This study was designed to evaluate the potential therapeutic efficacy of vitamin D (Vit D) in averting the harmful effects of type 2 diabetes mellitus (T2D). Forty male Wistar rats were allotted into four groups: (1) the control, (2) Vit D, (3) streptozotocin (STZ), and (4) STZ + Vit D groups. Rats co-treated with Vit D had significantly (p < 0.05) decreased levels of cortisol; proinflammatory cytokines, including interleukin-6 (IL-6); and malondialdehyde (MDA). Meanwhile, the levels of insulin significantly (p < 0.05) increased, whereas the activity of the antioxidant system, including glutathione (GSH), superoxide dismutase (SOD), catalase, and total antioxidant capacity (TAC), significantly (p < 0.05) decreased. Histopathological examination revealed the destruction of beta cells in the islets of Langerhans in rats with diabetes. Meanwhile, immunoexpression revealed an increase in the immunoreactivity of caspase-3 and endothelial nitric oxide synthase and a reduction in the immunoreactivity of insulin in rats with diabetes. In conclusion, Vit D ameliorated the harmful biochemical impact of diabetes mellitus, probably by increasing insulin secretion and sensitivity, ameliorating β-cell function, and decreasing cortisol levels; also, the anti-inflammatory effect of Vit D reduces the number of proinflammatory cytokines (e.g., IL-6) and increases the activity of the antioxidant system, such as GSH, SOD, TAC, and catalase while reducing lipid peroxidation enzymes (e.g., MDA).

Vitamin D and Beta Cells in Type 1 Diabetes: A Systematic Review

The prevalence of type 1 diabetes (T1D) is rising steadily. A potential contributor to the rise is vitamin D. In this systematic review, we examined the literature around vitamin D and T1D. We identified 22 papers examining the role of vitamin D in cultured β-cell lines, islets, or perfused pancreas, and 28 papers examining vitamin D in humans or human islets. The literature reports strong associations between T1D and low circulating vitamin D. There is also high-level (systematic reviews, meta-analyses) evidence that adequate vitamin D status in early life reduces T1D risk. Several animal studies, particularly in NOD mice, show harm from D-deficiency and benefit in most studies from vitamin D treatment/supplementation. Short-term streptozotocin studies show a β-cell survival effect with supplementation. Human studies report associations between VDR polymorphisms and T1D risk and β-cell function, as assessed by C-peptide. In view of those outcomes, the variable results in human trials are generally disappointing. Most studies using 1,25D, the active form of vitamin D were ineffective. Similarly, studies using other forms of vitamin D were predominantly ineffective. However, it is interesting to note that all but one of the studies testing 25D reported benefit. Together, this suggests that maintenance of optimal circulating 25D levels may reduce the risk of T1D and that it may have potential for benefits in delaying the development of absolute or near-absolute C-peptide deficiency. Given the near-complete loss of β-cells by the time of clinical diagnosis, vitamin D is much less likely to be useful after disease-onset. However, given the very low toxicity of 25D, and the known benefits of preservation of C-peptide positivity for long-term complications risk, we recommend considering daily cholecalciferol supplementation in people with T1D and people at high risk of T1D, especially if they have vitamin D insufficiency.

Characterization of the structural, oxidative, and immunological features of testis tissue from Zucker diabetic fatty rats

The purpose of this study was to characterize the testicular profile of Zucker diabetic fatty (ZDF) rats presenting with type 2 diabetes mellitus (DM2) in the absence or presence of obesity. To achieve this, testes were collected from 270-day-old male Wistar (n = 15), ZDF nonobese (n = 15), and ZDF obese rats (n = 16). Changes to the testicular structure were quantified morphometrically, while immunocytochemistry was employed to assess caspase-3 activity. Reactive oxygen species (ROS) production, fluctuations of major antioxidant molecules, and the extent of damage to the proteins and lipids were assessed in tissue lysates. Levels of selected interleukins (ILs) were determined by enzyme-linked immunosorbent assay. The results reveal significant alterations to the testicular structure accompanied by caspase-3 overexpression, particularly in ZDF obese rats. The most notable disruption of the oxidative balance, characterized by ROS overproduction, antioxidant deficiency, protein, and lipid deterioration was recorded in ZDF rats suffering from both DM2 and obesity. Accordingly, the highest concentrations of pro-inflammatory IL-1, IL-6, and IL-18 accompanied by reduced levels of the anti-inflammatory IL-10 were found in testicular tissue collected from ZDF obese rats. This study highlights the vulnerability of male gonads to pathophysiological changes caused by hyperglycemia, which are further exacerbated by excessive adipose tissue.

Vitamin D attenuates endothelial dysfunction in streptozotocin induced diabetic rats by reducing oxidative stress

Diabetes mellitus (DM) is associated with micro- and macrovascular complications and increased cardiovascular risk. Vitamin D deficiency is the most common nutrient deficiency in the world. This study aimed to examine the effects of diabetes on the endothelial function and the role of vitamin D supplementation. Male Wistar rats (n = 30) were randomly assigned to three groups; control untreated, diabetic untreated, and diabetic groups treated with vitamin D at a dose of 12.5 μg/kg body weight, dissolved in 0.3 ml olive oil orally for 10 weeks. Compared to the control group, the serum glucose, serum asymmetric dimethylarginine (ADMA), aortic malondialdehyde (MDA) levels, endothelin-1 (ET-1) level, inducible nitric oxide synthase (iNOS) activity in diabetic rats were increased, whereas aortic superoxide dismutase (SOD) activity, nitric oxide (NO) levels, and constitutive NOS (cNOS) activity were decreased. Administration of vitamin D to diabetic rats resulted in a decrease of serum glucose, serum ADMA, a decrease of aortic MDA levels, ET-1 and iNOS activity, an increase of aortic SOD activity, NO levels, and cNOS activity. Vitamin D administration attenuated diabetic induced endothelial dysfunction by reducing oxidative stress. These results indicate that chronic vitamin D treatment might be useful in preventing diabetic vascular complications associated with endothelial dysfunction.

Role and mechanism(s) of incretin-dependent therapies for treating diabetes mellitus

Diabetes mellitus (DM) is a worldwide ailment which leads to chronic complications like cardiac disorders, renal perturbations, limb amputation and blindness. Type one diabetes (T1DM), Type two diabetes (T2DM), Another types of diabetes, such as genetic errors in function of β-cell and action of insulin, cystic fibrosis, chemical-instigated diabetes or following tissue transplantation), and pregnancy DM (GDM). In response to nutritional ingestion, the gut may release a pancreatic stimulant that affects carbohydrate metabolism. The duodenum produces a 'chemical excitant' that stimulates pancreatic output, and researchers have sought to cure diabetes using gut extract injections, coining the word 'incretin' to describe the phenomena. Incretins include GIP and GLP-1. The 'enteroinsular axis' is the link between pancreas and intestine. Nutrient, neuronal and hormonal impulses from intestine to cells secreting insulin were thought to be part of this axis. In addition, the hormonal component, incretin, must meet two requirements: (1) it secreted by foods, mainly carbohydrates, and (2) it must induce an insulinotropic effect which is glucose-dependent. In this review, we clarify the ability of using incretin-dependent treatments for treating DM.

Association Between Serum Vitamin D Levels and Ketosis Episodes in Hospitalized Patients with Newly Diagnosed Ketosis-Prone Type 2 Diabetes

PURPOSE

This study aimed to investigate the relationship between 25-hydroxyvitamin D (25OHD) and the onset of ketosis in newly diagnosed patients with ketosis-prone type 2 diabetes (KPT2D).

PATIENTS AND METHODS

A total of 162 patients with non-autoimmune newly diagnosed diabetes mellitus were included in this cross-sectional study. Patients were classified into KPT2D (n = 71) or non-ketotic type 2 diabetes (NKT2D, n = 91). Anthropometric parameters, islet functions, biochemical parameters, and body composition were determined in both KPT2D and NKT2D groups. Correlation analysis was performed to determine the associations between 25OHD and plasma ketones. The risk factors associated with ketosis episodes in patients with new-onset KPT2D were evaluated using binary logistic regression analysis.

RESULTS

Vitamin D deficiency was observed in both patients with KPT2D and NKT2D. Compared with the NKT2D group, serum 25OHD values were lower in the participants of the KPT2D group [14.20 (10.68, 19.52) vs 16.98 (13.54,2.96) ng/mL, P = 0.011]. Serum 25OHD was associated with plasma ketones (R = -0.387). Serum 25OHD is an independent protective factor for ketosis or ketoacidosis episodes in patients with new onset of KPT2D (P = 0.037, OR = 0.921).

CONCLUSION

Vitamin D levels are associated with ketosis episodes in patients with KPT2D. Serum 25OHD is an independent protective factor for ketosis episodes in patients with KPT2D.

Serum 25(OH)D Levels Modify the Association between Triglyceride and IR: A Cross-Sectional Study

BACKGROUND

Triglycerides and 25(OH)D had been reported as correlates of IR, but the results suggest substantial heterogeneity across races. In addition, little research reported on whether different 25(OH)D levels affect triglycerides and IR. Therefore, a similar study on the US population would be a great addition to the current one. This study investigated the association between triglycerides and IR at different 25(OH)D levels.

METHODS

A total of 19,926 participants were included, each containing specific indicators for the study project. IR was estimated as a HOMA-IR index ≥2.73. Four multivariate logistic regression models were developed to analyze the association between TG and IR and whether different 25(OH)D levels influenced this association. Smoothed fitting curves were plotted.

RESULTS

Triglyceride was significantly associated with IR (OR: 1.3, 95 CI %), while this association received different 25(OH)D levels (P for interaction <0.001). The effect value OR was 1.33 with the high levels, and its effect value OR was 1.28 with the low levels.

CONCLUSION

This study demonstrates that triglyceride levels are significantly associated with insulin in the US adult population and can be used as a predictor of IR. This correlation was compromised at different 25 (OH)D levels, so future studies need to be explored in more ethnically diverse contexts.

Conundrum of vitamin D on glucose and fuel homeostasis

As an endocrine hormone, vitamin D plays an important role in bone health and calcium homeostasis. Over the past two decades, the non-calcemic effects of vitamin D were extensively examined. Although the effect of vitamin D on beta cell function were known for some time, the effect of vitamin D on glucose and fuel homeostasis has attracted new interest among researchers. Yet, to date, studies remain inconclusive and controversial, in part, due to a lack of understanding of the threshold effects of vitamin D. In this review, a critical examination of interventional trials of vitamin D in prevention of diabetes is provided. Like use of vitamin D for bone loss, the benefits of vitamin D supplementation in diabetes prevention were observed in vitamin D-deficient subjects with serum 25-hydroxyvitamin D < 50 nmol/L (20 ng/mL). The beneficial effect from vitamin D supplementation was not apparent in subjects with serum 25-hydroxyvitamin D > 75 nmol/L (30 ng/mL). Furthermore, no benefit was noted in subjects that achieved serum 25-hydroxyvitamin D > 100 nmol/L (40 ng/mL). Further studies are required to confirm these observations.

Adjunctive vitamin A and D for the glycaemic control in patients with concurrent type 2 diabetes and tuberculosis: a randomised controlled trial

The objective of this study is to investigate the effects of vitamin A, D and their interaction on the glycaemic control in patients with both diabetes and tuberculosis. Tuberculosis infection and its treatment induce hyperglycaemia and complicate the glycaemic control in patients with diabetes. A randomised controlled trial with a 2 × 2 factorial design was conducted in a tuberculosis-specialised hospital in Qingdao, China. A total of 279 patients who have both diabetes and tuberculosis were included in this analysis. The patients received standard anti-tuberculosis treatment alone (control group), or together with a dose of vitamin A (600 μg RAE/d) or vitamin D (10 μg/d) or a combination of vitamin A (600 μg RAE/d) and vitamin D (10 μg/d) for 2 months. The effects of the intervention on fasting plasma glucose and 2-h postprandial blood glucose were investigated by ANCOVA. The analysis was adjusted for baseline values, age, sex, smoking, drinking and antidiabetic treatment as covariates. No significant effect was observed for vitamin A and D supplementation on fasting plasma glucose, 2-h postprandial blood glucose, BMI and related blood parameters. No interaction was observed between vitamin A and D supplementation for these endpoints. Vitamin A and D supplementation showed a null effect on the glycaemic control for patients with concurrent diabetes and tuberculosis. Future work should evaluate the effect of vitamin A and D supplementation on insulin-related indices for these patients and investigate the effect of vitamin D receptor genotypes.

Role of Oxidative Stress and Reduced Endogenous Hydrogen Sulfide in Diabetic Nephropathy

Purpose

Persistent hyperglycemia lead towards depletion of hydrogen sulfide (H₂S) resulting in generation of oxidative stress and diabetic nephropathy. The aim of the current study was to explore the antioxidant potential of H₂S and captopril, a -SH containing compound in streptozotocin (STZ)-induced diabetic nephropathy.

Methods

Fifty four Wistar-Kyoto (WKY) rats male (200-250g) were divided into nine groups (n=6) with each group injected once with STZ (60mg/kg i.p) except normal control. After 3 weeks of induction of diabetes, groups were assigned as normal control, diabetic control, diabetic-captopril, diabetic-NaHS, diabetic-captopril-NaHS, diabetic-spironolactone, diabetic-metformin, diabetic-metformin-NaHS and diabetic-vitamin-c. All the animals were served with normal saline (N/S 4mL/kg p.o), captopril (50mg/kg/day p.o), sodium hydrosulfide (NaHS) (56µmol/kg i.p), spironolactone (50mg/kg/day s.c), metformin (500mg/kg/day p.o) and vitamin-c (50mg/kg p.o) on daily basis for next 4 weeks, respectively. Metabolic studies, H₂S levels, renal hemodynamics and oxidative stress markers were analyzed at 0, 14 and 28 days followed by histopathological analysis of renal tissues.

Results

The results showed decreased H₂S levels, body weight, sodium to potassium ratio, glutathione (GSH), superoxide dismutase (SOD), total antioxidant assay (T-AOC) with malondialdehyde (MDA) and blood glucose levels significantly increased among diabetic rats. Treatment with captopril, NaHS, metformin, spironolactone and vitamin C showed significant improvement among renal hemodynamics and oxidative stress markers, respectively. But treatment groups like NaHS in combination with captopril and metformin showed more pronounced effects.

Conclusion

The observations suggest that H₂S mediated protective effects on STZ-induced diabetic nephropathy may be associated with reduced oxidative stress via augmenting the antioxidant effect.

Effects of redox interference on the pancreatic mitochondria and the abnormal blood glucose

Reactive oxygen species (ROS) has been implicated as a contributor to both the onset and the progression of diabetes, however how does redox state affect diabetes has not been fully understood. Here we study the role of redox interference on pancreatic mitochondria and the progression of diabetes. We applied streptozotocin (STZ) to establish diabetes mellitus (DM) model in rats, applied FeSO₄ to produce oxidative stress (OS) and Ganoderma lucidum polysaccharides as antioxidant intervention (AO). Our results showed that in OS and DM group, oxidative stress caused the imbalance of redox state, resulting in higher lipid peroxidation level and lower antioxidant level, while AO treatment group reduced blood glucose by repairing the redox balance. The insulin level has the order of Normal Control (NC)<AO < DM < OS, suggesting oxidative stress promoted insulin secretion in a compensatory mechanism. The Mn-SOD expression in OS groups of pancreas were significantly lower than other groups, while the p53 expression was significantly higher. The mitochondrial ultrastructure of pancreatic β cells were impaired in DM group, and the damage was more severe in OS group, paralleled with significantly reduced secretory granules, both of which were repaired in the AO group. Our results demonstrated that the redox state can affect the blood glucose of diabetic rats, and oxidative stress can aggravate diabetes, while the early antioxidant treatment can alleviate the process of diabetes through reversing the imbalance of redox state and repairing the pancreatic mitochondria. These results suggest that redox balance plays an important role in the treatment of diabetes.

Licochalcone B Ameliorates Liver Cancer via Targeting of Apoptotic Genes, DNA Repair Systems, and Cell Cycle Control

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a ubiquitous multifunctional protein required in the DNA base excision repair pathway and a noteworthy reducing-oxidizing factor that regulates the activity of various transcription factors. Cyclin-dependent kinases (CDKs) assume a key role in directing the progression of the cell- cycle. The present study evaluated the synergistic efficacy of using licochalcone B (LCB) and fullerene C60 (FnC60) nanoparticles against diethylnitrosamine (DEN)-induced hepatocarcinoma in rats and relevant signaling pathways, with APE1/Ref-1 and CDK-4, as novel anti-cancer- targeting. LCB alone and in combination with FnC60 significantly decreased DNA fragmentation, oxidative DNA damage (8-hydroxy-2'-deoxyguanosine levels), APE1/Ref-1, CDK-4, retinoblastoma, B- cell lymphoma-2 (Bcl-2), B-cell lymphoma-xL (Bcl-xL), and β-arrestin-2 mRNA expression, and APE1/Ref-1 and CDK-4 protein expression. In contrast, these treatments significantly increased the expression of protein 53 (p53), Bcl-2-associated X protein (Bax), and caspase-3. These data suggest that LCB either alone or in combination with FnC60 elicited significant protective effects against DEN-induced hepatocarcinogenesis, which may have occurred because of the regulation of enzymes involved in DNA repair and cell-cycle control at S phase progression as well as the induction of apoptosis at the gene and protein expression levels. Furthermore, FnC60 potentiated the effect of LCB at the molecular level, possibly through targeting of cancerous cells.

The protective effect of Satureja bachtiarica hydroalcoholic extract on streptozotocin-induced diabetes through modulating glucose transporter 2 and 4 expression and inhibiting oxidative stress

CONTEXT

Oxidative stress plays an important role in development of diabetes mellitus. Satureja bachtiarica Bunge (Lamiaceae) is a rich source of bioactive compounds with antioxidant properties.

OBJECTIVE

This study investigates the antidiabetic effect of hydroalcoholic extract of aerial parts of S. bachtiarica.

METHODS AND MATERIALS

Male Wistar rats were randomly divided into six groups (n = 8) including control (normal saline), diabetic [Streptozotocin (STZ)], intervention (STZ plus hydroalcoholic extract of S. bachtiarica at doses of 75, 150 and 250 mg/kg/d) and positive control (STZ plus captopril 50 mg/kg/d) groups. A single intraperitoneal (IP) injection of STZ (60 mg/kg) was used to induce diabetes and IP therapy with drugs was performed for four weeks.

RESULTS

In diabetic rats, serum total antioxidant capacity (TAC) decreased significantly, but glucose, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT) and malondialdehyde (MDA) increased significantly as compared to the control (p < 0.05). Treatment with extract (250 mg/kg) caused a significant decline in serum glucose, GGT, ALT, AST and MDA as well as a significant increase in serum TAC (p < 0.05). During the intervention period, diabetic rats showed significant weight loss, but extract (250 mg/kg) treated rats did not show any weight loss. Extract (250 mg/kg) up-regulated GLUT2 expression and down-regulated GLUT4 expression in the liver (p < 0.05). S. bachtiarica extract at all dosage levels prevented STZ-induced histological damage of liver, kidney and pancreas.

DISCUSSION AND CONCLUSIONS

S. bachtiarica extract exhibits antidiabetic effects through modulation of oxidative stress and expression of GLUT2 and GLUT4.

Exercise and Vitamin D Supplementation Modify Spleen Morphology in Lean, but not, in Monosodium-Glutamate-Obese Rats

We evaluated the effect of exercise and vitamin D supplementation on histological aspects of the spleens of lean and obese rats. Male Wistar rats received neonatal administration of monosodium glutamate (MSG; 4g/Kg), while Control (CON) rats received an equimolar solution. At 30 days of age, CON and MSG rats were subdivided into Exercised (E) or Sedentary (S) groups and Vitamin D (VD; 12µg/Kg) supplemented or non-supplemented (NS) groups. At the 86th day of life, rats were euthanized, and their body weights and adiposity were evaluated. Spleens were submitted to histomorphometric analysis of the white pulp (WP), germinal center (GC) and lymphatic nodule (LN). Data are presented as mean ± SEM (p<0.05). MSG treatment promoted a reduction in spleen weight, increased LN thickness and WP area, but reduced GC occupation, compared to spleens of CON-lean rats (p<0.05). Exercise and VD did not provoke changes in the spleens of MSG-obese rats. In CON-lean rats, E and VD induced augmentation of LN thickness. VD supplementation increased the WP area, while E reduced GC area occupation in spleens of CON-lean rats (p<0.05). In conclusion, exercise and VD supplementation increased LN thickness and WP area, but had the opposite effect on the GC in spleens of CON-lean rats. However, neither exercise nor VD supplementation prevented the development of morphological abnormalities in the spleens of MSG-obese rats.

Changes of serum 25(OH) D3 and IGF-1 levels in patients with thyroid nodules

BACKGROUND

The present study aimed to study the relationship between serum 25 hydroxyvitamin D3(25(OH)D3) and insulin-like growth factor-1 (IGF-1) and thyroid nodules.

METHODS

Two hundred eighty-nine cases with thyroid nodules and 109 health subjects (control group) who admitted to the Hebei General Hospital during June 2016 to December 2016 were included in the study. Basic clinical information (age, sex, thyroid function, liver and kidney function, hypertension history, etc.) of patients were collected. Serum 25(OH) D3 and Serum IGF-1 were detected by electrochemiluminescence and radioimmunoassay methods, respectively. The relationship between the above-mentioned factors and thyroid nodules was statistically analyzed.

RESULTS

Serum 25(OH)D3, IGF-1, fasting blood glucose (FBG), total cholesterol (TC), waist circumference (WC), total triiodothyronine (TT3), total thyroxine (TT4), hypertension history, and drinking history were significantly different between the nodules group and the control group (P < 0.05). Logistic regression analysis showed that there was a negative correlation between thyroid nodules and levels of 25(OH)D3, IGF-1, TT3, as well as a positive correlation with FBG, TC, TT4, and hypertension. There was a positive correlation between IGF-1 and serum 25(OH)D3 in thyroid nodules (P < 0.05). After correcting the aforementioned factors, high-level of serum 25(OH)D3 was significantly correlated with the decreased incidence of thyroid nodules.

CONCLUSIONS

The incidence of thyroid nodules is relatively lower in a high-level of serum 25(OH)D3, and serum 25(OH)D3 may be a direct protective factor for thyroid nodules. Serum IGF-1 can be one of the indirect protective factors for thyroid nodules as well.

The effect of chronic oral vitamin D supplementation on adiposity and insulin secretion in hypothalamic obese rats

Reduced plasma vitamin D (VD) levels may contribute to excessive white adipose tissue, insulin resistance (IR) and dyslipidaemia. We evaluated the effect of chronic oral VD supplementation on adiposity and insulin secretion in monosodium glutamate (MSG)-treated rats. During their first 5 d of life, male neonate rats received subcutaneous injections of MSG (4 g/kg), while the control (CON) group received saline solution. After weaning, groups were randomly distributed into VD supplemented (12 µg/kg; three times/week) and non-supplemented (NS) rats, forming four experimental groups (n 15 rats/group): CON-NS, CON-VD, MSG-NS and MSG-VD. At 76 d of life, rats were submitted to an oral glucose tolerance test (OGTT; 2 g/kg), and at 86 d, obesity, IR and plasma metabolic parameters were evaluated. Pancreatic islets were isolated for glucose-induced insulin secretion (GIIS), cholinergic insulinotropic response and muscarinic 3 receptor (M3R), protein kinase C (PKC) and protein kinase A (PKA) expressions. Pancreas was submitted to histological analyses. VD supplementation decreased hyperinsulinaemia (86 %), hypertriacylglycerolaemia (50 %) and restored insulin sensibility (89 %) in MSG-VD rats, without modifying adiposity, OGTT or GIIS, compared with the MSG-NS group. The cholinergic action was reduced (57 %) in islets from MSG-VD rats, without any change in M3R, PKA or PKC expression. In conclusion, chronic oral VD supplementation of MSG-obese rats was able to prevent hyperinsulinaemia and IR, improving triacylglycerolaemia without modifying adiposity. A reduced cholinergic pancreatic effect, in response to VD, could be involved in the normalisation of plasma insulin levels, an event that appears to be independent of M3R and its downstream pathways.

The possible neuroprotective effects of melatonin in aluminum chloride-induced neurotoxicity via antioxidant pathway and Nrf2 signaling apart from metal chelation

Aluminum (Al) had well-identified adverse influences on the nervous system mainly through the creation of reactive oxygen species (ROS). Melatonin works as an antioxidant through the inhibition of ROS and attenuating peroxidation of lipids. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a pivotal transcription factor which controls the transcription of antioxidant enzymes. This study was conducted to determine the potential neuroprophylactic impacts of melatonin in aluminum chloride (AlCl₃)-initiated neurotoxicity including potential mechanism(s) of action and relevant signaling in rats. Thirty-six male rats were distributed into 4 groups: Control; AlCl₃ (50 mg/kg bwt, i.p, 3 times weekly for 3 months); melatonin (5 mg/kg bwt, i.p daily for 2 weeks before AlCl₃ and sustained for the next 3 months); and melatonin with AlCl₃. Neuronal alterations were histopathologically and biochemically evaluated. The neuronal antioxidant-related genes and relevant Nrf2 protein expression were determined by real-time PCR and Western blotting, respectively. The current data showed a substantial increase in brain damage biomarkers, acetylecholinesterase (AchE) activity, and malondialdehyde (MDA) content while the enzymatic antioxidant expression as glutathione-s-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were substantially attenuated in the aluminum-treated group, with cleared histopathological changes as inflammatory cell infiltration with neuronal degeneration. Supplementation of melatonin resulted in an obvious amelioration in all previous abnormal alteration observed in AlCl₃-treated rats rather than increased Al burden and/or altered Fe and Cu homeostasis with upregulating both total and phosphorylated Nrf2 expression. Therefore, the study concluded that melatonin has a potential ability to be neuroprophylactic against Al-induced neurotoxic effect and oxidative damage in the rat brain through upregulating and instigating Nrf2 signaling apart from metal chelation.

The molecular and biochemical insight view of lycopene in ameliorating tramadol-induced liver toxicity in a rat model: implication of oxidative stress, apoptosis, and MAPK signaling pathways

The influence of tramadol (TD) on hepatic tissue and the potential efficiency of lycopene to mitigate TD-induced hepatotoxic impacts were determined. Forty male albino rats were allocated into four groups: group I, untreated (placebo); group II, injected with TD (15 mg kg^-1) intraperitoneally (i.p.); group III, gastrogavaged with lycopene (10 mg kg^-1) per os (p.o.); and group IV received TD with lycopene with the same mentioned doses for 15 days. The results demonstrated that TD induced augmentation in tissue lipid peroxidation biomarker and disturbance in the antioxidant homeostasis and elevated the activity of serum liver injury biomarkers and decreased serum protein, globulin, and albumin. Hepatic glutathione S-transferase (GST), superoxide dismutase (SOD), thioredoxin-1 (Txn-1), and catalase (CAT) activities and gene expression were decreased and glutathione content was reduced in the TD-challenged rats, and these effects were alleviated by lycopene. Furthermore, TD induced apoptosis in liver tissues as shown by DNA fragmentation and upregulation of proapoptotic Bax and Casp-3 while lycopene upregulated the antiapoptotic Bcl-2. The results of Western blot showed that lycopene initiated low expression of mitogen activated protein kinase pathway (MAPK) protein expression in liver tissues of TD-challenged rats. In addition, lycopene reduced fatty degeneration and necrosis of the liver in TD-challenged group. Our data demonstrate that lycopene appears to be highly efficient in mitigating the hepatotoxic impacts of TD by preventing lipid peroxidation and initiating modifications in the expression and activity of antioxidant pathways. Surprisingly, lycopene fortified liver tissue by inhibiting DNA fragmentation and apoptosis signaling induced by TD. MAPK activation may be dependent from ROS generation; due to lycopene which possessed antioxidant potential did have a substantial effect on MAPK activity.

Role of lncRNAs as prognostic markers of hepatic cancer and potential therapeutic targeting by S-adenosylmethionine via inhibiting PI3K/Akt signaling pathways

Hepatic cancer (HCC) is a well-identified dilemma throughout the world, and hence, the molecular mechanisms and strategy for preventive protection against this malignancy are critical. S-adenosylmethionine (SAM) is a unique methyl granter in vast reactions, including DNA methylation, and secures the genome against hypomethylation, which is a hallmark of tumors. Consequently, SAM may control the rate of gene expression. The objective of this investigation was to evaluate the expression of long noncoding RNAs (lncRNAs) transcript involved in hepatic tumorigenesis, including additional coding CEBPA (ecCEBPA) and urothelial carcinoma related 1 (UCA1), antioxidant enzymes transcripts, and relevant signaling pathway in diethylnitrosamine (DEN)-prompted HCC along with their conceivable targeting by SAM at different stages of HCC in rats. Our outcomes revealed that SAM particularly when given at the starting phase downregulates ecCEBPA and UCA1 gene transcripts and ameliorate histopathological alterations in DEN-initiated HCC. Interestingly, SAM attenuates DEN-induced upregulation of PI3K/Akt protein expression. However, SAM upregulates the antioxidant enzymes mRNA transcripts and effectively diminishing DNA oxidation. The results of a DNA fragmentation assay further support the capacity of SAM to ameliorate DEN-induced hepatic malignancy. These results revealed the role of ecCEBPA and UCA1 in HCC and suggest that these lncRNAs may be helpful as prognostic and analytical biomarkers of HCC. Curiously, SAM readily targets the studied genes via inhibiting PI3K/Akt signaling pathway, which should make SAM an appealing agent for both chemoprevention and treatment of HCC.

Evidence of antidiabetic activity of Spirulina fusiformis against streptozotocin-induced diabetic Wistar albino rats

The aim of our study is to investigate the protective effect of Spirulina fusiformis against streptozotocin-induced diabetes in Wistar albino rats. Rats were divided into five groups: group I was normal control, group II was diabetic control (50 mg/kg b.w. of streptozotocin, i.p.), group III was Spirulina fusiformis (400 mg/kg b.w., p.o.) treated diabetic rats; group IV was Glibenclamide (0. 6 mg/kg b.w., p.o.) treated diabetic rats and group V was treated with Spirulina fusiformis (400 mg/kg b.w., p.o.) alone. There was significant elevation in the levels of blood glucose, serum lipid profile and serum renal markers (total protein, urea, creatinine and uric acid) in the diabetic rats. Also, diabetic rats showed significantly (P < 0.05) reduced antioxidant status (reduced levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione; increased levels of TBARS), impaired oral glucose tolerance and elevated HbA1C. Spirulina fusiformis was able to normalize the above mentioned parameters. Significant histopathological changes were found in the pancreas, liver and kidney sections of the diabetic control group while treatment with Spirulina fusiformis was able to minimize the extent of tissue damage. Current study shows that Spirulina fusiformis possesses significant antidiabetic and antihyperlipidemic effects in streptozotocin-induced diabetic rats by effectively reducing the rise in blood glucose levels and lipid profile.

Vitamin D3 intake as regulator of insulin degrading enzyme and insulin receptor phosphorylation in diabetic rats

Insulin-degrading enzyme (IDE, insulysin) is a rate-limiting enzyme in the insulin degradation process. It is an intracellular 110-kDa thiol zinc-metalloendopeptidase located in the cytosol, peroxisomes, endosomes and cell surface. IDE catalyzes degradation of several small proteins including insulin, amylin and β-amyloid protein. In addition, insulin clearance was expressed as a target in the treatment of type 2 diabetes given the role of hyperinsulinemia in the pathogenesis of insulin resistance. In this study, fourtyadult male Wistar albino rats were used, thirty rats received 20% fructose in drinking water (HFW) for six weeks to induce diabetes. Subsequently, these rats developed significantly higher body weights, dyslipidemia, hyperglycemia and insulin resistance compared to their controls. Significant increase in the levels of serum glucagon, IDE in liver tissue along with an inhibition of insulin receptor phosphorylation were also observed. Concurrent oral administration of vitamin D3 along with HFW resulted in significant decrease of serum glucose, total cholesterol, triacylglycerol and LDL-C levels. Vitamin D alleviated also insulin resistance, where both IDE, glucagon levels showed significant decrease along with activation of insulin receptor phosphorylation. Normal rats, received vitamin D3 only demonstrated non significant changes of the studied biomarkers. We concluded that vitamin D3 ameliorated insulin resistance and hyperinsulinemia in diabetic rat model received HFW through reduction of IDE and activation of insulin receptor phosphorylation.

Pleiotropic protective effects of Vitamin D against high fat diet-induced metabolic syndrome in rats: One for all

Several lines of evidence point to the association of vitamin D deficiency with the different components of metabolic syndrome. Yet, the effect of vitamin D supplementation on metabolic syndrome is not clearly elucidated. Herein, we tested the hypothesis that administration of vitamin D, either alone or in combination of metformin can improve metabolic and structural derangements associated with metabolic syndrome. Fifty wistar rats were randomly assigned to serve either as normal control (10 rats) or metabolic syndrome rats, by feeding them with a standard or a high fat diet (HFD), respectively. Metabolic syndrome rats were further assigned to receive either vehicle, Metformin (100mg/Kg orally), vitamin D (6ng/Kg SC.) or both, daily for 8 weeks. Body weight, blood pressure, serum glucose, insulin, insulin resistance, lipid profile, oxidative stress, serum uric acid and Ca⁺² were assessed at the end of the study. Histopathological examination of hepatic, renal and cardiac tissues were also performed. Treatment with vitamin D was associated with a significant improvement of the key features of metabolic syndrome namely obesity, hypertension and dyslipidaemia with a neutral effect on Ca⁺² level. When combined with metformin, most of the other metabolic abnormalities were ameliorated. Furthermore, a significant attenuation of the associated hepatic steatosis was observed with vitamin D as well as vitamin D/metformin combination. In conclusion, vitamin D can improve hypertension, metabolic and structural abnormalities induced by HFD, and it provides additional benefits when combined with metformin. Therefore, vitamin D could represent a feasible therapeutic option for prevention of metabolic syndrome.

Protective effects of Egyptian cloudy apple juice and apple peel extract on lipid peroxidation, antioxidant enzymes and inflammatory status in diabetic rat pancreas

Background

Apples possess rich content of varied polyphenolic compounds showing a variety of biological activities that may ascribe to worthy effects against some chronic diseases. The present study was designed to assess the protective effects of the cloudy apple juice (CAJ) and apple peel extract (APE) of Egyptian Anna apple on the complications in experimental diabetes.

Materials and methods

Four groups were studied. Diabetes was induced by a single dose of streptozotocin (STZ) to only three groups of albino Wistar rats. Two of the diabetic groups received either CAJ or APE for 21 days. At the end of the study, lipid profile parameters were measured in serum while lipid peroxidation (LPO) level, antioxidant enzyme activities and inflammatory markers were evaluated in pancreas tissue samples. The gas chromatography–mass spectrometry (GC-MS) analysis of phenolic compounds found in CAJ and APE was carried out. Moreover, total phenolic content of CAJ and APE were measured.

Results

The significant increase of blood glucose level, serum total cholesterol (TC), triglycerides (TG), low- density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein (VLDL) levels, in addition to tissue malondialdehyde (MDA), nuclear factor kappa B (NF-kB), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8) levels, but a significant decrease in high-density lipoprotein cholesterol (HDL-C), and the activity of pancreatic antioxidant enzymes were the remarkably parameters observed in diabetic control rats. Dissimilarly, oral supplementation of 15 ml/kg CAJ and 1 g/kg APE for 21 days resulted in a significant decrease in fasting blood glucose, serum TC, TG, LDL-C, VLDL-C and tissue MDA, NF-kB, TNF-α, IL-6, IL-8 levels coupled with a significant elevation of HDL-C and antioxidant enzymes’ activity when compared with diabetic control animals.

Conclusions

The results indicate that Egyptian CAJ and APE supplementation may have protective effects against deleterious complications of diabetes mellitus.

Beta Cell Function and the Nutritional State: Dietary Factors that Influence Insulin Secretion

Approximately 366 million people worldwide have been diagnosed with type-2 diabetes (T2D). Chronic insulin resistance, decreased functional β-cell mass, and elevated blood glucose are defining characteristics of T2D. Great advances have been made in understanding the pathogenesis of T2D with respect to the effects of dietary macronutrient composition and energy intake on β-cell physiology and glucose homeostasis. It has been further established that obesity is a leading pathogenic factor for developing insulin resistance. However, insulin resistance may not progress to T2D unless β-cells are unable to secret an adequate amount of insulin to compensate for decreased insulin sensitivity. Therefore, pancreatic β-cell dysfunction plays an important role in the development of overt diabetes. This paper reviews recent research findings on the effects of several micronutrients (zinc, vitamin D, iron, vitamin A), leucine, and the phytochemical, genistein on pancreatic β-cell physiology with emphasis on their effects on insulin secretion, specifically in the context of T2D.

Vitamin D deficiency impairs glucose-stimulated insulin secretion and increases insulin resistance by reducing PPAR-γ expression in nonobese Type 2 diabetic rats

Human studies have provided relatively strong associations of poor vitamin D status with Type 2 diabetes but do not explain the nature of the association. Here, we explored the physiological pathways that may explain how vitamin D status modulates energy, lipid and glucose metabolisms in nonobese Type 2 diabetic rats. Goto-Kakizaki (GK) rats were fed high-fat diets containing 25 (VD-low), 1000 (VD-normal) or 10,000 (VD-high) cholecalciferol-IU/kg diet for 8 weeks. Energy expenditure, insulin resistance, insulin secretory capacity and lipid metabolism were measured. Serum 25-OH-D levels, an index of vitamin D status, increased dose dependently with dietary vitamin D. VD-low resulted in less fat oxidation without a significant difference in energy expenditure and less lean body mass in the abdomen and legs comparison to the VD-normal group. In comparison to VD-low, VD-normal had lower serum triglycerides and intracellular fat accumulation in the liver and skeletal muscles which was associated with down-regulation of the mRNA expressions of sterol regulatory element binding protein-1c and fatty acid synthase and up-regulation of gene expressions of peroxisome proliferator-activated receptors (PPAR)-α and carnitine palmitoyltransferase-1. In euglycemic hyperinsulinemic clamp, whole-body and hepatic insulin resistance was exacerbated in the VD-low group but not in the VD-normal group, possibly through decreasing hepatic insulin signaling and PPAR-γ expression in the adipocytes. In 3T3-L1 adipocytes 1,25-(OH)2-D (10 nM) increased triglyceride accumulation by elevating PPAR-γ expression and treatment with a PPAR-γ antagonist blocked the triglyceride deposition induced by 1,25-(OH)2-D treatment. VD-low impaired glucose-stimulated insulin secretion in hyperglycemic clamp and decreased β-cell mass by decreasing β-cell proliferation. In conclusion, vitamin D deficiency resulted in the dysregulation of glucose metabolism in GK rats by simultaneously increasing insulin resistance by decreasing adipose PPAR-γ expression and deteriorating β-cell function and mass.

Clinical implications of vitamin D deficiency

Vitamin D deficiency is a common medical problem worldwide and its prevalence rises along with latitude, obesity, sedentary lifestyle, limited sunlight exposure and aging. A great body of evidence has shown that patients with vitamin D deficiency have increased cardiovascular risks and total mortality. Conversely, the presence of comorbidities progressive with age such as abdominal obesity, insulin resistance, type 2 diabetes and hypertension places the patients at an increased risk of vitamin D deficiency. The multidirectional effect of vitamin D deficiency is present in different phases of the aging process. Based on the literature review, the risk factors for vitamin D insufficiency most often found in post-menopausal women include limited sun exposure and time spent outdoors, inadequate dietary vitamin D intake, winter season and increased age. Vitamin D supplementation in this group might offer prevention of falls and fractures and may be beneficial for cardiovascular health, what may be especially important in osteoporotic and elderly populations. Prevention and treatment processes involve education regarding sunlight exposure and pharmacological cholecalciferol supplementation according to the recommendations for Central Europe. This manuscript reviews the role of vitamin D and its deficiency and considers their clinical implications, with particular regard to peri- and postmenopausal women.

Efficacy of supplementary vitamin D on improvement of glycemic parameters in patients with type 2 diabetes mellitus; a randomized double blind clinical trial

Introduction: Studies have revealed the association between vitamin D deficiency and changes in blood glucose and insulin levels as well as sensitivity of the target tissues to insulin.

Objective: In this study, we examined the effect of adding vitamin D (cholecalciferol ; 50,000 units) to therapeutic regimen of T2DM patients compared to placebo on regulating the blood glucose and glycemic parameters.

Patients and Methods: This study was a double blind clinical trial conducted on 60 type 2 diabetes mellitus (T2DM) patients. Exclusion criteria were taking calcium, vitamin D supplements or any drugs effecting calcium and vitamin D metabolism in the past 6 months. Serum 25-Hydroxy vitamin D [25(OH)D] level was measured with ELISA method. Patients were administered weekly vitamin D supplementation (50000 units) for 12 weeks.

Results: There was no significant relation between HbA1c and 25(OH)D level prior the study (p> 0.05). After intervention, 25(OH)D level in interventional group was significantly higher compared to that of control group. HbA1c in male interventional group was significantly less than that of control group (p= 0.0068).

Conclusion: Weekly vitamin D supplementation had beneficial effect on glycemic parameters in male type 2 diabetic patients.