Brain derived neurotrophic factor in newly diagnosed diabetes and prediabetes

Long-term exposure to PM2.5 compositions and O3 and their interactive effects on DNA methylation of peripheral brain-derived neurotrophic factor promoter

This study examined the associations of long-term exposure to ambient fine particulate matter (PM2.5) compositions/ozone with methylation of peripheral brain-derived neurotrophic factor (BDNF) promoters. A total of 101 participants were recruited from a cohort in Shijiazhuang, Hebei province, China. They underwent baseline and follow-up surveys in 2011 and 2015. DNA methylation levels were detected by bisulfite-PCR amplification and pyrosequencing. Participants' three-year average levels of PM2.5 compositions and ozone were estimated. Bayesian kernel machine regression (BKMR) models were used to examine the joint effects of pollutants on methylation levels. Exposure to PM2.5 compositions and ozone mixtures at the 75th percentile was associated with increased methylation levels at CpG2 of BDNF promoter (203%, 95% CI: 89, 316) than the lowest level of exposure, and sulfate dominated the effect in the BKMR models.Our findings provide clues to the epigenetic mechanisms for the associations of PM2.5 compositions and ozone with BDNF.

Serum brain-derived neurotrophic factor levels in type 2 diabetes mellitus patients and its association with cognitive impairment: A meta-analysis

OBJECTIVE

To compare the serum levels of brain-derived neurotrophic factor (BDNF) in type 2 diabetes mellitus (T2DM) patients with healthy controls (HC) and evaluate the BDNF levels in T2DM patients with/without cognitive impairment.

METHODS

PubMed, EMBASE, and the Cochrane Library databases were searched for the published English literature on BDNF in T2DM patients from inception to December 2022. The BDNF data in the T2DM and HC groups were extracted, and the study quality was evaluated using the Agency for Healthcare Research and Quality. A meta-analysis of the pooled data was conducted using Review Manager 5.3 and Stata 12.0 software.

RESULTS

A total of 18 English articles fulfilled with inclusion criteria. The standard mean difference of the serum BDNF level was significantly lower in T2DM than that in the HC group (SMD: -2.04, z = 11.19, P <0.001). Besides, T2DM cognitive impairment group had a slightly lower serum BDNF level compared to the non-cognitive impairment group (SMD: -2.59, z = 1.87, P = 0.06).

CONCLUSION

BDNF might be involved in the neuropathophysiology of cerebral damage in T2DM, especially cognitive impairment in T2DM.

Comparative Efficacy of Metformin and Glimepiride in Modulating Pharmacological Network to Increase BDNF Levels and Benefit Type 2 Diabetes-Related Cognitive Impairment

Cognitive impairment is anotable complication of type 2 diabetes (T2DM), accompanied by reduced brain-derived neurotrophic factor (BDNF) in the brain and blood. Anti-diabetic drugs reduce hyperglycemia, yet their effect on cognitive improvement is unknown. We aimed to investigate the effect of anti-diabetic drugs regulating BDNF in T2DM through computational and case-control study design. We obtained T2DMproteins viatext-mining to construct a T2DMprotein network. From the T2DMnetwork, the metformin and glimepiride interactomes and their crucial shortest-path-stimulating BDNF were identified. Using qRTPCR, the genes encoding the shortest-path proteins were assessed in four groups (untreated-T2DM, metformin-treated, glimepiride-treated, and healthy controls). Finally, ELISA was used to assess serum BDNF levels to validate drug efficacy. As a result of this investigation, aT2DMnetwork was constructed with 3683 text-mined proteins. Then, the T2DMnetwork was explored to generate a metformin and glimepiride interactome that establishes the critical shortest-path for BDNF stimulation. Metformin stimulates BDNF via APP binding to the PRKAB1 receptor. Whereas, glimepiride increases BDNF by binding to KCNJ11 via AP2M1 and ESR1 proteins. Both drug shortest-path encoding genes differed significantly between the groups. Unlike metformin, BDNF gene and protein expression rise significantly with glimepiride. Overall, glimepiride can effectively increase BDNF, which could benefit T2DM patients with cognitive deterioration.

Pharmacological and physiological roles of adipokines and myokines in metabolic-related dementia

Dementia is a detrimental neuropathologic condition with considerable physical, mental, social, and financial impact on patients and society. Patients with metabolic syndrome (MetS), a group of diseases that occur in tandem and increase the risk of neurologic diseases, have a higher risk of dementia. The ratio between muscle and adipose tissue is crucial in MetS, as these contain many hormones, including myokines and adipokines, which are involved in crosstalk and local paracrine/autocrine interactions. Evidence suggests that abnormal adipokine and myokine synthesis and release may be implicated in various MetS, such as atherosclerosis, diabetic mellitus (DM), and dyslipidemia, but their precise role is unclear. Here we review the literature on adipokine and myokine involvement in MetS-induced dementia via glucose and insulin homeostasis regulation, neuroinflammation, vascular dysfunction, emotional changes, and cognitive function.

Brain-derived neurotrophic factor in diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor expressed in several tissues, including the brain, gut, and pancreas. Activation of the BDNF/TrkB/CREB reduces hepatic gluconeogenesis, induces hepatic insulin signal transduction, and protects against pancreatic beta-cell loss in diabetes mellitus (DM). Several studies have investigated the possible association between BDNF and DM and its complications, but the results have been conflicting.

AIM

In the present study, we aimed at systematically reviewing the literature on the serum and plasma levels of BDNF in DM and its subgroups such as T2DM, DM patients with depression, and patients with retinopathy.

METHODS

A comprehensive search was conducted in PubMed, Scopus, and Web of Science. We identified 28 eligible studies and calculated the standardized mean difference (SMD) of outcomes as an effect measure.

RESULTS

The meta-analysis included 2734 patients with DM and 6004 controls. Serum BDNF levels were significantly lower in patients with DM vs. controls (SMD = -1.00, P<0.001). Plasma BDNF levels were not different in patients with DM compared with controls. When conducting subgroup analysis, serum BDNF levels were lower among patients with T2DM (SMD = -1.26, P<0.001), DM and depression (SMD = -1.69, P<0.001), and patients with diabetic retinopathy (DR) vs. controls (SMD = -1.03, P = 0.01).

CONCLUSIONS

Serum BDNF levels were lower in patients with DM, T2DM, DM with depression, and DM and DR than the controls. Our findings are in line with the hypothesis that decreased BDNF levels might impair glucose metabolism and contribute to the pathogenesis of DM and its complications.

Cognition and BDNF levels in prediabetes and diabetes: A mediation analysis of a cross-sectional study

AIM

Clinical and epidemiological studies suggest links between dementias and Type 2 diabetes (T2DM). The underlying mechanisms of diabetes-related cognitive impairment are largely unknown. This study aims to investigate the role of BDNF in cognitive impairment in prediabetes and T2DM.

METHODS

The study included 68 patients with prediabetes (preDM), 96 patients with T2DM, and 65 healthy controls. The cognitive function of the patients was evaluated with the Montreal Cognitive Assessment (MoCA) test and serum BDNF levels were measured by Elisa. The MoCA scores and BDNF levels were compared between diabetes groups after adjusting for age, gender, and education using ANCOVA. The role of BDNF in the diabetes-related cognitive impairment was investigated through mediation analysis.

RESULTS

Patients with T2DM had significantly lower cognitive performance, particularly in memory. Diabetes was found to be a predictor of both cognitive impairment and BDNF levels. A significant increase in serum BDNF levels was observed in patients with T2DM. However, the mediator role of BDNF in the pathology of cognitive impairment in diabetes was not determined.

CONCLUSION

Cognitive impairment is prevalent in patients with T2DM and should be included in routine screening for complications. The results of the mediation analysis suggest that although BDNF is a biomarker affected by T2DM and cognition, it does not play a mediator role between cognitive impairment and diabetes.

Increased brain-derived neurotrophic factor in the serum of persons with nonalcoholic fatty liver disease

The increasing prevalence of nonalcoholic fatty liver disease (NAFLD) is a global health problem. In recent years, the inhibitory effect of brain-derived neurotrophic factor (BDNF) on diabetes mellitus and fatty liver has been clarified. The purpose of this study was to analyze the relationship between serum BDNF and NAFLD which caused by abnormal metabolism of glucose and lipids. This cross-sectional study involved 429 participants (mean age, 63.5 years: men, 38.5%) with low alcohol intake. Of the participants, those who had an increase in echogenicity of the liver parenchyma and hepato-renal contrast on ultrasonography were classified as the NAFLD group (n = 88), and the others were classified as the normal (n = 341) group. The NAFLD group was further classified into a mild group (n = 60) and a severe group (n = 28) based on the intensity of echogenicity and visualization of the hepatic vessels and diaphragm. Median BDNF levels were higher in the NAFLD group than the normal group (35.5 vs. 42.3 ng/mL, p < 0.01). Furthermore, BDNF levels tended to be associated with the severity of NAFLD (p < 0.01). In addition to the univariate analysis, in the sex- and age-adjusted model, there was a significant association between the BDNF levels and NAFLD severity (p < 0.01). The fully adjusted regression analysis also showed a positive association between the serum BDNF level and NAFLD (p < 0.01). These results suggest that NAFLD patients have a compensatory increase in circulating BDNF levels.

Carnosine improves cognitive impairment through promoting SIRT6 expression and inhibiting ER stress in a diabetic encephalopathy model

Diabetic encephalopathy is one of complications of diabetes mellitus. Carnosine is a dipeptide composed of β-alanine and L-histidine. Study has shown that carnosine could ameliorate cognitive impairment in animal model with diabetes mellitus. However, the mechanism remains unclear. An animal model of type 2 diabetes (db/db mice) was used in this study. The animals were treated with 0.9 % saline or carnosine (100 mg/kg) for 8 weeks. Morris water maze was tested after drug administration. Oxidative stress-related factors malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), and pro-inflammatory factors inducible nitric oxide synthase (iNOS) were measured. Synapse-related protein postsynapticdensity 95 (PSD95) and brain-derived neurotrophic factor (BDNF) were detected by western blot. Besides, the expressions of sirtuin 6 (SIRT6), binding immunoglobulin protein (BIP), protein kinase R-like endoplasmic reticulum kinase (PERK), phospho-protein kinase R-like endoplasmic reticulum kinase (P-PERK), inositol-requiring enzyme-1α (IRE1α), phospho-inositol-requiring enzyme-1α (P-IRE1α), activating transcription factor 6 (ATF6), C/EBP-homologous protein (CHOP) in the hippocampus of the brain were detected. The results showed that treatment with carnosine ameliorated cognitive impairment in db/db mice. Carnosine reduced neuronal oxidative stress damage and iNOS expression in db/db mice. Meanwhile, carnosine relieved neurodegeneration in the hippocampus of db/db mice. Furthermore, carnosine promoted the expression of SIRT6 and reduced the expressions of endoplasmic reticulum (ER) related factors (BIP, P-PERK, P-IRE1α, ATF6, CHOP). In conclusion, these data suggested that the protective effect of carnosine against diabetic encephalopathy might be related to SIRT6/ER stress pathway.

Methylation Status of Exon IV of the Brain-Derived Neurotrophic Factor (BDNF)-Encoding Gene in Patients with Non-Diabetic Hyperglycaemia (NDH) before and after a Lifestyle Intervention

BDNF signalling in hypothalamic neuronal circuits is thought to regulate mammalian food intake. In light of this, we investigated how a lifestyle intervention influenced serum levels and DNA methylation of BDNF gene in fat tissue and buffy coat of NDH individuals. In total, 20 participants underwent anthropometric measurements/fasting blood tests and adipose tissue biopsy pre-/post-lifestyle (6 months) intervention. DNA was extracted from adipose tissue and buffy coat, bisulphite converted, and pyrosequencing was used to determine methylation levels in exon IV of the BDNF gene. RNA was extracted from buffy coat for gene expression analysis and serum BDNF levels were measured by ELISA. No differences were found in BDNF serum levels, but buffy coat mean BDNF gene methylation decreased post-intervention. There were correlations between BDNF serum levels and/or methylation and cardiometabolic markers. (i) Pre-intervention: for BDNF methylation, we found positive correlations between mean methylation in fat tissue and waist-hip ratio, and negative correlations between mean methylation in buffy coat and weight. (ii) Post-intervention: we found correlations between BDNF mean methylation in buffy coat and HbA1c, BDNF methylation in buffy coat and circulating IGFBP-2, and BDNF serum and insulin. Higher BDNF % methylation levels are known to reduce BNDF expression. The fall in buffy coat mean BDNF methylation plus the association between lower BDNF methylation (so potentially higher BDNF) and higher HbA1c and serum IGFBP-2 (as a marker of insulin sensitivity) and between lower serum BDNF and higher circulating insulin are evidence for the degree of BDNF gene methylation being implicated in insulinisation and glucose homeostasis, particularly after lifestyle change in NDH individuals.

Dietary Macronutrients Do Not Differently Influence Postprandial Serum and Plasma Brain-Derived Neurotrophic Factor Concentrations: A Randomized, Double-Blind, Controlled Cross-Over Trial

Objectives: Brain-derived neurotrophic factor (BDNF) plays a role in cognition and metabolism. Specific nutrients can affect fasting BDNF concentrations, which are potentially mediated by insulin and/or glucose. Since macronutrients trigger each a different insulin and glucose response, we examined postprandial effects of meals rich in fat, carbohydrates, or protein on BDNF concentrations. BDNF was analyzed in serum and plasma, since concentration differences can be found between matrices.

Methods: Healthy overweight/obese male participants (n = 18) participated in this randomized, double-blind, cross-over trial consisting of three test days with 1 week wash-out periods. Either a high-fat (En% fat, carbohydrates, protein: 52.3, 39.2, 8.0), high-carbohydrate (En% 9.6, 81.5, 8.6) or high-protein meal (En% 10.6, 51.5, 36.9) was consumed on each test day. BDNF concentrations were measured after 0, 60, and 240 min. Glucose and insulin concentrations were measured after 0, 15, 30, 45, 60, 90, 120, and 240 min.

Results: BDNF concentrations were higher in serum compared with plasma (P < 0.001). Postprandial BDNF concentrations in serum decreased significantly after the high-fat (P = 0.013) and high-carbohydrate meals (P = 0.040), and showed a trend after the high-protein meal (P = 0.076). No differences were found between meals (P = 0.66). Postprandial BDNF concentrations measured in plasma did not significantly change after the different meals (P = 0.47). As total area under the curve (AUC) for glucose was significantly higher after the high-carbohydrate meal compared with the high-fat (P = 0.003) and high-protein meals (P < 0.001), and the total AUC for insulin was higher after the high-carbohydrate (P < 0.001) and high-protein meals (P < 0.001) compared with the high-fat meal, it seems that acute changes in glucose and insulin do not affect postprandial BDNF concentrations. However, after the high-protein meal, the higher total AUC for glucose correlated with lower serum BDNF concentrations, and a higher maximal increase in glucose correlated with a lower maximal increase in plasma BDNF concentrations. There were no correlations with insulin concentrations after either meal.

Conclusion: Serum BDNF concentrations were higher than plasma concentrations. Since postprandial BDNF responses were not different between the meals, we conclude that there is no role for insulin or glucose in regulating postprandial BDNF concentrations.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT03139890].

Multifactorial Mechanism of Sarcopenia and Sarcopenic Obesity. Role of Physical Exercise, Microbiota and Myokines

Obesity and ageing place a tremendous strain on the global healthcare system. Age-related sarcopenia is characterized by decreased muscular strength, decreased muscle quantity, quality, and decreased functional performance. Sarcopenic obesity (SO) is a condition that combines sarcopenia and obesity and has a substantial influence on the older adults’ health. Because of the complicated pathophysiology, there are disagreements and challenges in identifying and diagnosing SO. Recently, it has become clear that dysbiosis may play a role in the onset and progression of sarcopenia and SO. Skeletal muscle secretes myokines during contraction, which play an important role in controlling muscle growth, function, and metabolic balance. Myokine dysfunction can cause and aggravate obesity, sarcopenia, and SO. The only ways to prevent and slow the progression of sarcopenia, particularly sarcopenic obesity, are physical activity and correct nutritional support. While exercise cannot completely prevent sarcopenia and age-related loss in muscular function, it can certainly delay development and slow down the rate of sarcopenia. The purpose of this review was to discuss potential pathways to muscle deterioration in obese individuals. We also want to present the current understanding of the role of various factors, including microbiota and myokines, in the process of sarcopenia and SO.

Low-Frequency Genetic Variant in the Hepatic Glucokinase Gene Is Associated With Type 2 Diabetes and Insulin Resistance in Chinese Population

Glucokinase (GCK) regulates insulin secretion and hepatic glucose metabolism, and its inactivating variants could cause diabetes. We aimed to evaluate the association of a low-frequency variant of GCK (rs13306393) with type 2 diabetes (T2D), prediabetes, or both (impaired glucose regulation [IGR]) in a Chinese population. An association study was first conducted in a random cluster sampling population (sample 1: 537 T2D, 768 prediabetes, and 1,912 control), and then another independent population (sample 2: 3,896 T2D, 2,301 prediabetes, and 868 control) was used to confirm the findings in sample 1. The A allele of rs13306393 was associated with T2D (odds ratio 3.08 [95% CI 1.77-5.36], P = 0.00007) in sample 1; rs13306393 was also associated with prediabetes (1.67 [1.05-2.65], P = 0.03) in sample 2. In a pooled analysis of the two samples, the A allele increased the risk of T2D (1.57 [1.15-2.15], P = 0.005), prediabetes (1.83 [1.33-2.54], P = 0.0003) or IGR (1.68 [1.26-2.25], P = 0.0004), insulin resistance estimated by HOMA (β = 0.043, P = 0.001), HbA_1c (β = 0.029, P = 0.029), and urinary albumin excretion (β = 0.033, P = 0.025), irrespective of age, sex, and BMI. Thus, the Chinese-specific low-frequency variant increased the risk of T2D through reducing insulin sensitivity rather than islet β-cell function, which should be considered in the clinical use of GCK activators in the future.

Genetics and Clinical Characteristics of PPARγ Variant-Induced Diabetes in a Chinese Han Population

OBJECTIVES

PPARγ variants cause lipodystrophy, insulin resistance, and diabetes. This study aimed to determine the relationship between PPARγ genotypes and phenotypes and to explore the pathogenesis of diabetes beyond this relationship.

METHODS

PPARγ2 exons in 1,002 Chinese patients with early-onset type 2 diabetes (diagnosed before 40 years of age) were sequenced. The functions of variants were evaluated by in vitro assays. Additionally, a review of the literature was performed to obtain all reported cases with rare PPARγ2 variants to evaluate the characteristics of variants in different functional domains.

RESULTS

Six (0.6%) patients had PPARγ2 variant-induced diabetes (PPARG-DM) in the early-onset type 2 diabetes group, including three with the p.Tyr95Cys variant in activation function 1 domain (AF1), of which five patients (83%) had diabetic kidney disease (DKD). Functional experiments showed that p.Tyr95Cys suppresses 3T3-L1 preadipocyte differentiation. A total of 64 cases with damaging rare variants were reported previously. Patients with rare PPARγ2 variants in AF1 of PPARγ2 had a lower risk of lipodystrophy and a higher rate of obesity than those with variants in other domains, as confirmed in patients identified in this study.

CONCLUSION

The prevalence of PPARG-DM is similar in Caucasian and Chinese populations, and DKD was often observed in these patients. Patients with variants in the AF1 of PPARγ2 had milder clinical phenotypes and lack typical lipodystrophy features than those with variants in other domains. Our findings emphasize the importance of screening such patients via genetic testing and suggest that thiazolidinediones might be a good choice for these patients.

Influence of BDNF Genetic Polymorphisms in the Pathophysiology of Aging-related Diseases

For the first time in history, most of the population has a life expectancy equal or greater than 60 years. By the year 2050, it is expected that the world population in that age range will reach 2000 million, an increase of 900 million with respect to 2015, which poses new challenges for health systems. In this way, it is relevant to analyze the most common diseases associated with the aging process, namely Alzheimer´s disease, Parkinson Disease and Type II Diabetes, some of which may have a common genetic component that can be detected before manifesting, in order to delay their progress. Genetic inheritance and epigenetics are factors that could be linked in the development of these pathologies. Some researchers indicate that the BDNF gene is a common factor of these diseases, and apparently some of its polymorphisms favor the progression of them. In this regard, alterations in the level of BDNF expression and secretion, due to polymorphisms, could be linked to the development and/or progression of neurodegenerative and metabolic disorders. In this review we will deepen on the different polymorphisms in the BDNF gene and their possible association with age-related pathologies, to open the possibilities of potential therapeutic targets.

Sarcopenic obesity: Myokines as potential diagnostic biomarkers and therapeutic targets?

Sarcopenic obesity (SO) is a condition characterized by the occurrence of both sarcopenia and obesity and imposes a heavy burden on the health of the elderly. Controversies and challenges regarding the definition, diagnosis and treatment of SO still remain because of its complex pathogenesis and limitations. Over the past few decades, numerous studies have revealed that myokines secreted from skeletal muscle play significant roles in the regulation of muscle mass and function as well as metabolic homeostasis. Abnormalities in myokines may trigger and promote the pathogenesis underlying age-related and metabolic diseases, including obesity, sarcopenia, type 2 diabetes (T2D), and SO. This review mainly focuses on the role of myokines as potential biomarkers for the early diagnosis and therapeutic targets in SO.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

Association of Brain-Derived Neurotrophic Factor With Cognitive Function: An Investigation of Sex Differences in Patients With Type 2 Diabetes

OBJECTIVE

Although a reduction in brain-derived neurotrophic factor (BDNF) has been implicated as a cause of cognitive impairment in type 2 diabetes mellitus (T2DM), the role of sex in moderating this effect has not been explored.

METHODS

We compared the difference in serum BDNF and performance on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) between 96 men and 134 women with T2DM. We compared this with the difference in serum BDNF and performance in the control group (104 men, 144 women).

RESULTS

Patients with T2DM performed worse on most RBANS indices (η = 0.372, all p < .05); within T2DM patients, men performed worse than women on the delayed memory score (74.1 (12.1) versus 79.9 (11.5), p = .002) and on the total score (71.4 (11.5) versus 76.5 (10.8), p = .025). Serum BDNF was lower in patients with T2DM versus controls (7.5 (2.7) ng/ml versus 11.5 (2.7) ng/ml, p < .001), and in men compared with women (6.9 (2.4) versus 7.9 (2.8), p = .024). Serum BDNF levels positively correlated with delayed memory score in patients with T2DM (β = 0.19, p = .007). However, this association was only observed in women, not in men (pinteraction = 0.04). Among healthy controls, no sex differences were noted in either RBANS or BDNF levels (η = 0.04, Cohen's d < 0.163, all p > .05).

CONCLUSIONS

Our results show sex differences in poorer cognitive performance, lower BDNF concentration, and their relationship in T2DM patients, suggesting that female sex may be a protective factor for cognitive decline in T2DM patients. However, the findings should be regarded as preliminary because of the cross-sectional design and chronicity of the diabetes.

Developing Insulin and BDNF Mimetics for Diabetes Therapy

Diabetes is a global public health concern nowadays. The majority of diabetes mellitus (DM) patients belong to type 2 diabetes mellitus (T2DM), which is highly associated with obesity. The general principle of current therapeutic strategies for patients with T2DM mainly focuses on restoring cellular insulin response by potentiating the insulin-induced signaling pathway. In late-stage T2DM, impaired insulin production requires the patients to receive insulin replacement therapy for maintaining their glucose homeostasis. T2DM patients also demonstrate a drop of brain-derived neurotrophic factor (BDNF) in their circulation, which suggests that replenishing BDNF or enhancing its downstream signaling pathway may be beneficial. Because of their protein nature, recombinant insulin or BDNF possess several limitations that hinder their clinical application in T2DM treatment. Thus, developing orally active "insulin pill" or "BDNF pill" is essential to provide a more convenient and effective therapy. This article reviews the current development of non-peptidyl chemicals that mimic insulin or BDNF and their potential as anti-diabetic agents.

HOMA-IR increase after antidepressant treatment in depressed patients with the Met allele of the Val66Met BDNF genetic polymorphism

BACKGROUND

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with response to antidepressant drugs in depressed patients and with metabolic side effects after antipsychotic treatment. This study aims to assess the association between this polymorphism and insulin resistance after antidepressant treatment in depressed patients.

METHODS

One hundred forty-eight Caucasian patients with a current unipolar major depressive episode (DSM IV-TR) were genotyped for the BDNF Val66Met polymorphism and assessed at baseline and after 3 and 6 months of antidepressant treatment for the 'Homoeostasis model assessment of insulin resistance' (HOMA-IR) index, a valid measure of insulin resistance based on fasting plasma insulinaemia and glycaemia. Because validity assumptions were fulfilled, data were analysed using analysis of variance for repeated measures.

RESULTS

The 52 (35%) Met carriers and 96 (65%) Val/Val patients were not different at baseline for clinical characteristics and HOMA-IR. A significant Val66Met × time interaction (p = 0.02), a significant time effect (p = 0.03) and a significant Val66Met effect (p = 0.0497) were shown for HOMA-IR. A significant Val66Met × time interaction (p = 0.01) and a significant time effect (p = 0.003) were shown for fasting glycaemia. HOMA-IR and fasting glycaemia changes after antidepressant treatment were significantly higher in Met carrier than in Val/Val patients (HOMA-IR changes: Met: 0.71 ± 3.29 v. Val/Val: -0.16 ± 1.34, t = 2.3, df = 146, p = 0.02, glycaemia changes: Met: 0.09 ± 0.30 v. Val/Val: 0.02 ± 0.16, t = -2.0, df = 146, p = 0.045).

CONCLUSIONS

The Met allele of the Val66Met BDNF polymorphism confers to depressed patients a higher risk of insulin-resistance after antidepressant treatment. These patients could benefit from specific monitoring of metabolism and preventive measures.

Abnormal expressions of AGEs, TGF-β1, BDNF and their receptors in diabetic rat colon-Associations with colonic morphometric and biomechanical remodeling

Present study aims to investigate the role of AGEs, TGF-β1, BDNF and their receptors on diabetes-induced colon remodeling. Diabetes was induced by a single tail vein injection 40 mg/kg of STZ. The parameters of morphometric and biomechanical properties of colonic segments were obtained from diabetic and normal rats. The expressions of AGE, RAGE, TGF- β1, TGF- β1 receptor, BDNF and TrkB were immunohistochemically detected in different layers of the colon. The expressions of AGE, RAGE, TGF-β1 and TGF- β1 receptor were increased whereas BDNF and TrkB were decreased in the diabetic colon (P < 0.05, P < 0.01). AGE, RAGE and TGF-β1 receptor expressions were positively correlated whereas the BDNF expression was negatively correlated with most of the morphometry and biomechanical parameters (P < 0.05, P < 0.01, P < 0.001). AGE, TGF- β1 and BDNF in different layers correlated with their receptors RAGE, TGF- β1 receptor and TrkB respectively. STZ-induced diabetes up-regulated the expression of AGE, RAGE, TGF- β1 and TGF- β1 receptors and down-regulated BDNF and TrkB in different layers of diabetic colon mainly due to hyperglycemia. Such changes maybe important for diabetes-induced colon remodeling, however it is needed to further perform mechanistic experiments in order to study causality or approaches that explain the relevance of the molecular pathways.

Lower Circulating miR-122 Level in Patients with HNF1A Variant-Induced Diabetes Compared with Type 2 Diabetes

miR-122, the expression of which is regulated by several transcription factors, such as HNF1A, was recently reported to be associated with type 2 diabetes (T2DM) and hepatocellular carcinoma. HNF1A variants can cause diabetes and might be involved in the development of primary liver neoplasm. Differences in miR-122 expression among different types of diabetes have not been studied. This study aimed to investigate differences in serum miR-122 levels in Chinese patients with different forms of diabetes, including T2DM, type 1 diabetes (T1DM), HNF1A variant-induced diabetes (HNF1A-DM), glucokinase variant-induced diabetes (GCK-DM), and mitochondrial A3243G mutation-induced diabetes (MDM). In total, 12 HNF1A-DM patients, 24 gender-, age-, and body mass index-matched (1 : 2) T2DM patients and 24 healthy subjects were included in this study. In addition, 30 monogenic diabetes (11 GCK-DM and 19 MDM) and 17 T1DM patients were included. Fasted blood biochemistry and miR-122 were measured. The results showed that the HNF1A-DM patients had lower miR-122 levels [0.046 (0.023, 0.121)] than T2DM patients [0.165 (0.036, 0.939), P = 0.02] and healthy controls [0.249 (0.049, 1.234), P = 0.019]. The area under the curve of the receiver operating characteristic curve for miR-122 to discriminate HNF1A-DM and T2DM was 0.687 (95% CI: 0.52-0.86, P = 0.07). There was no difference in serum miR-122 among HNF1A-DM, GCK-DM, MDM, and T1DM patients. Lower serum miR-122 is a unique feature of HNF1A-DM patients and might partially explain the increased risk for liver neoplasm and abnormal lipid metabolism in HNF1A-DM patients.

Cognition, serum BDNF levels, and BDNF Val66Met polymorphism in type 2 diabetes patients and healthy controls

Background and aims

Type 2 diabetes (T2DM) is associated with cognitive deficits. However, their pathophysiological mechanisms are still unknown. Recent study suggests that brain-derived neurotrophic factor (BDNF) is correlated with cognitive deficits in T2DM patients. This study was to determine whether altered serum BDNF levels and cognitive deficits depended on the BDNF Val66Met polymorphism in T2DM.

Results

The BDNF Val66Met polymorphism may not contribute directly to the susceptibility to T2DM. The total and nearly all index scores (all p < 0.01) except for the attention and visuospatial/constructional indexes (both p > 0.05) of RBANS were markedly decreased in T2DM compared with healthy controls. Serum BDNF levels were significantly lower in patients than that in controls (p < 0.001), and BDNF was positively associated with delayed memory in patients (p < 0.05). The Met variant was associated with worse delayed memory performance among T2DM patients but not among normal controls. Moreover, serum BDNF was positively associated with delayed memory among Met homozygote patients (β = 0.29, t = 2.21, p = 0.033), while serum BDNF was negatively associated the RBANS total score (β = –0.92, t = –3.40, p = 0.002) and language index (β = −1.17, t = –3.54, p = 0.001) among Val homozygote T2DM patients.

Conclusions

BDNF gene Val66Met variation may be associated with cognitive deficits in T2DM, especially with delayed memory. The association between lower BDNF serum levels and cognitive impairment in T2DM is dependent on the BDNF Val66Met polymorphism.

Methods

We recruited 311 T2DM patients and 346 healthy controls and compared them on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), serum BDNF levels, and the BDNF Val66Met polymorphism.

Mice lacking PKC-θ in skeletal muscle have reduced intramyocellular lipid accumulation and increased insulin responsiveness in skeletal muscle

Protein kinase C-θ (PKC-θ) is a lipid-sensitive molecule associated with lipid-induced insulin resistance in skeletal muscle. Rodent models have not cohesively supported that PKC-θ impairs insulin responsiveness in skeletal muscle. The purpose of this study was to generate mice that lack PKC-θ in skeletal muscle and determine how lipid accumulation and insulin responsiveness are affected in that tissue. Mice lacking PKC-θ in skeletal muscle (SkM^PKCθKO) and controls (SkM^PKCθWT) were placed on a regular diet (RD) or high-fat diet (HFD) for 15 wk, followed by determination of food intake, fasting glucose levels, lipid accumulation, and insulin responsiveness. There were no differences between SkM^PKCθWT and SkM^PKCθKO mice on a RD. SkM^PKCθKO mice on a HFD gained less weight from 10 through 15 wk of dietary intervention ( P < 0.05). This was likely due to less caloric consumption ( P = 0.0183) and fewer calories from fat ( P < 0.001) compared with SkM^PKCθWT mice on a HFD. Intramyocellular lipid accumulation ( P < 0.0001), fatty acid binding protein 4, and TNF-α mRNA levels ( P < 0.05) were markedly reduced in SkM^PKCθKO compared with SkM^PKCθWT mice on a HFD. As a result, fasting hyperglycemia was mitigated and insulin responsiveness, as indicated by Akt phosphorylation, was maintained in SkM^PKCθKO on a HFD. Liver lipid accumulation was not affected by genotype, suggesting the deletion of PKC-θ from skeletal muscle has a tissue-specific effect. PKC-θ is a regulator of lipid-induced insulin resistance in skeletal muscle. However, the effects of this mutation may be tissue specific. Further work is warranted to comprehensively evaluated whole body metabolic responses in this model.

Computerized cognitive training and brain derived neurotrophic factor during bed rest: mechanisms to protect individual during acute stress

Acute stress, as bed rest, was shown to increase plasma level of the neurotrophin brain-derived neurotrophic factor (BDNF) in older, but not in young adults. This increase might represent a protective mechanism towards acute insults in aging subjects. Since computerized cognitive training (CCT) is known to protect brain, herein we evaluated the effect of CCT during bed rest on BDNF, muscle mass, neuromuscular function and metabolic parameters. The subjects that underwent CCT did not show an increase of BDNF after bed rest, and showed an anti-insular modification pattern in metabolism. Neuromuscular function parameters, already shown to beneficiate from CCT, negatively correlated with BDNF in research participants undergoing CCT, while positively correlated in the control group. In conclusion, BDNF increase can be interpreted as a standardized protective mechanism taking place whenever an insult occurs; it gives low, but consistent preservation of neuromuscular function. CCT, acting as an external protective mechanism, seems to modify this standardized response, avoiding BDNF increase or possibly modifying its time course. Our results suggest the possibility of differential neuroprotective mechanisms among ill and healthy individuals, and the importance of timing in determining the effects of protective mechanisms.

Biological predictors of insulin resistance associated with posttraumatic stress disorder in young military veterans

Posttraumatic stress disorder (PTSD) is associated with increased risk for Type 2 diabetes and cardiovascular disease (cardiometabolic disease), warranting research into targeted prevention strategies. In the present case-control study of 160 young (mean age 32.7 years) male military veterans, we aimed to assess whether PTSD status predicted increased markers of cardiometabolic risk in otherwise healthy individuals, and further, to explore biological pathways between PTSD and these increased markers of cardiometabolic risk. Toward these aims, we compared measures of cardiometabolic risk, namely insulin resistance (IR) (HOMA-IR), metabolic syndrome (MetS) and prediabetes, between 80 PTSD cases and 80 controls without PTSD. We then determined whether PTSD-associated increases in HOMA-IR were correlated with select biological variables from pathways previously hypothesized to link PTSD with cardiometabolic risk, including systemic inflammation (increased C-reactive protein, interleukin-6, and tumor necrosis factor α), sympathetic over-activity (increased resting heart rate), and neuroendocrine dysregulation (increased plasma cortisol or serum brain-derived neurotrophic factor (BDNF)). We found PTSD diagnosis was associated with substantially higher HOMA-IR (cases 4.3±4.3 vs controls 2.4±2.0; p<0.001), and a higher frequency of MetS (cases 21.3% vs controls 2.5%; p<0.001), but not prediabetes (cases 20.0% vs controls 18.8%; p>0.05). Cases also had increased pro-inflammatory cytokines (p<0.01), heart rate (p<0.001), and BDNF (p<0.001), which together predicted increased HOMA-IR (adjusted R²=0.68, p<0.001). Results show PTSD diagnosis in young male military veterans without cardiometabolic disease is associated with increased IR, predicted by biological alterations previously hypothesized to link PTSD to increased cardiometabolic risk. Findings support further research into early, targeted prevention of cardiometabolic disease in individuals with PTSD.

Posttraumatic stress disorder eliminates association of TrkB rs1187327 with HDL-C in Chinese Han adolescents

Tropomyosin-related kinase receptor B (TrkB) has been observed to be a common player in posttraumatic stress disorder (PTSD) and the regulation of serum lipids levels. However, interplays of PTSD with TrkB on serum lipids levels have not been explored yet. This study was to investigate the interplays of PTSD and TrkB rs1187327 on serum lipid profiles. Variants of TrkB rs1187327 of 709 high school students were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses and verified by DNA sequencing. The PTSD Checklist Civilian Version (PCL-C) was used to assess PTSD. Colorimetric methods were used to determine the serum levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and glucose. The results show that the GG homozygotes had a significantly higher level of HDL-C than the A allele carriers of TrkB rs1187327 after the adjustment for gender, age and body mass index (BMI) (1.44 ± 0.299 mmol/L vs. 1.39 ± 0.266 mmol/L, p = 0.036). When PTSD was taken into account, the higher than the A allele carriers level of HDL-C of the GG homozygotes was observed significant after the adjustment for gender, age and BMI only in the subjects without PTSD (1.44 ± 0.293 mmol/ L vs. 1.39 ± 0.267 mmol/L, p = 0.030), but not in the subjects with PTSD. These results suggest that the A allele of TrkB rs1187327 may be associated with decreased levels of serum HDL-C in general healthy adolescents, but not in adolescents with PTSD.

Epigenetic regulation of glucose metabolism

PURPOSE OF REVIEW

Glucose metabolism is a central process in mammalian energy homeostasis. Its deregulation is a key factor in development of metabolic disease like diabetes and cancer. In recent decades, our understanding of gene regulation at the signaling, chromatin and posttranscriptional levels has seen dramatic developments.

RECENT FINDINGS

A number of epigenetic mechanisms that do not affect the genetic code can be assessed with new technologies. However, increasing complexity becomes a major challenge for translation into clinical application.

SUMMARY

The current review provides an update of transcriptional control of glucose metabolism, focusing on epigenetic regulators, DNA-methylation, histone modifications and noncoding RNAs. Recent studies heavily support the importance of those mechanisms for future therapeutics and preventive efforts for metabolic diseases.