Reversal of behavioral and metabolic abnormalities, and insulin resistance syndrome, by dietary restriction in mice deficient in brain-derived neurotrophic factor

Brain-derived neurotrophic factor (BDNF) and other neurotrophic factors in type 2 diabetes mellitus and their association with neuropathy

BACKGROUND

Diabetes mellitus (DM) is associated with increased risk of morbidity and premature mortality due to its various complications. In an Indian study, the prevalence of diabetic peripheral neuropathy (DPN) in type 2 diabetic subjects was shown to be 29.2%. There is increasing evidence that a deficiency of nerve growth factor (NGF) in diabetes, as well as the calcitonin gene-related peptide (CGRP), may also contribute to the development of DPN. The aim of the current study was to evaluate nerve growth factor levels with neuropathy in type 2 DM.

MATERIALS AND METHODS

Forty healthy controls and 40 patients with type 2 DM were recruited; they were asked to report to Dept. of Physiology for initial history taking, general examination and neuropathy examination. A total of 5 mL of blood was collected for neurotrophic factor estimation as well as glycemic profile estimation.

RESULTS

The brain-derived neurotrophic factor (BDNF) values were significantly lower in the DM group whereas the insulin levels were also quite high in DM. The hot thresholds for both the upper limb and lower limb were greater in the DM group suggesting the impending neuropathy. Similarly, the Michigan scores were also greater in the DM group. The neuropathy parameters especially the Michigan A and B and the hot thresholds were positively correlated with duration of DM and glucose profile.

CONCLUSION

The neurotrophic factors especially BDNF are drastically reduced in DM patients and are negatively associated with neuropathy, and hence, BDNF can be utilized as a therapeutic target to treat and prevent neuropathy.

Effect of Glycemic Disorders and Habits on the Concentration of Selected Neurotrophic Factors in Patients with Lumbosacral Intervertebral Disc Degeneration

BACKGROUND

Unhealthy habits, such as overeating processed and high-calorie foods, alcohol abuse, and smoking, negatively impact human health. It has been suggested that the inflammatory process and the resulting growth of nerve fibers within the intervertebral disc (IVD) fissures is the main reason for the pain accompanying IVD degeneration (IVDD).

OBJECTIVES

The aim of this study was to determine whether smoking, alcohol consumption, overweight/obesity, or diabetes comorbidity contribute to the development of IVDD and how the aforementioned factors affect the levels of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and growth associated protein 43 (GAP-43) in the study and control groups (intervertebral discs, IVDs from cadavers, and serum samples from voluntary blood donors).

METHODS

The study group comprised 113 patients diagnosed with IVDD who qualified for microdiscectomy. Two control groups (I and II) were used in this study. The first included 81 IVDs obtained from Caucasian human cadavers. Control group II, on the other hand, included serum samples obtained from 113 voluntary blood donors. The expression profiles of BDNF, GDNF, and GAP-43 were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our statistical analysis confirmed that patients who were overweight/obese, smoked tobacco, consumed alcohol, or had diabetes had a higher risk of IVDD (OR > 1). Statistical analysis showed that BDNF, GAP-43, and GDNF concentrations were significantly higher in the IVDs and serum samples obtained from the study group compared to the control group (p < 0.05). In addition, higher levels of BDNF, GDNF, and GAP-43 were noted in IVDD patients who consumed alcohol, smoked tobacco, were overweight/obese, or had comorbid diabetes compared to patients without these risk factors (p < 0.05).

CONCLUSION

We showed that changes in energy metabolism, habits, and lifestyle, as well as the degenerative process of IVD in the lumbosacral spine contribute to changing the concentration profile of the analyzed neurotrophic factors.

Effect of Oleuropein on Anti-Obesity and Uncoupling Protein 1 Level in Brown Adipose Tissue in Mild Treadmill Walking Rats with Diet-Induced Obesity

Oleuropein aglycone (OA), which is the absorbed form of oleuropein, is a major phenolic compound in extra virgin olive oil. We analyzed the anti-obesity effect of OA intake combined with mild treadmill walking (MTW, 4 m/min for 20 min/d, 5-6 d/wk, without electric shocks and slope) in rats under a high-fat diet (HF). Four-week-old male Sprague-Dawley rats (n=28) were equally divided into four groups: control (HF), 0.08% oleuropein-supplemented HF (HFO), HF with MTW (HF+W), and HFO with MTW (HFO+W) groups. After 28 d, the inguinal subcutaneous fat content and weight gain were significantly lower in the HFO+W group than in the control group. The HFO+W group also had significantly higher levels of urinary noradrenaline secretion, interscapular brown adipose tissue, uncoupling protein 1, brain transient receptor potential ankyrin subtype 1 (TRPA1), vanilloid subtype 1 (TRPV1), and brain-derived neurotrophic factor (BDNF) than the control group. Especially, the HFO+W group showed a synergistic effect on noradrenaline secretion. Therefore, OA combined with MTW may accelerate the enhancement of UCP1 and BDNF levels in rats with HF-induced obesity by increasing noradrenaline secretion after TRPA1 and TRPV1 activation.

Brain-derived neurotrophic factor: Its role in energy balance and cancer cachexia

Brain-derived neurotrophic factor (BDNF) plays an important role in the development of the central and peripheral nervous system during embryogenesis. In the mature central nervous system, BDNF is required for the maintenance and enhancement of synaptic transmissions and the survival of neurons. Particularly, it is involved in the modulation of neurocircuits that control energy balance through food intake, energy expenditure, and locomotion. Regulation of BDNF in the central nervous system is complex and environmental factors affect its expression in murine models which may reflect to phenotype dramatically. Furthermore, BDNF and its high-affinity receptor tropomyosin receptor kinase B (TrkB), as well as pan-neurotrophin receptor (p75NTR) is expressed in peripheral tissues in adulthood and their signaling is associated with regulation of energy balance. BDNF/TrkB signaling is exploited by cancer cells as well and BDNF expression is increased in tumors. Intriguingly, previously demonstrated roles of BDNF in regulation of food intake, adipose tissue and muscle overlap with derangements observed in cancer cachexia. However, data about the involvement of BDNF in cachectic cancer patients and murine models are scarce and inconclusive. In the future, knock-in and/or knock-out experiments with murine cancer models could be helpful to explore potential new roles for BDNF in the development of cancer cachexia.

Mechanism and treatments of antipsychotic-induced weight gain

The long-term use of antipsychotics (APs) may cause a variety of diseases, such as metabolic syndrome, antipsychotic-induced weight gain (AIWG), and even obesity. This paper reviews the various mechanisms of AIWG and obesity in detail, involving genetics, the central nervous system, the neuroendocrine system, and the gut microbiome. The common drug and non-drug therapies used in clinical practice are also introduced, providing the basis for research on the molecular mechanisms and the future selection of treatments.

Sirtuins and redox signaling interplay in neurogenesis, neurodegenerative diseases, and neural cell reprogramming

Since the discovery of Neural Stem Cells (NSCs) there are still mechanism to be clarified, such as the role of mitochondrial metabolism in the regulation of endogenous adult neurogenesis and its implication in neurodegeneration. Although stem cells require glycolysis to maintain their stemness, they can perform oxidative phosphorylation and it is becoming more and more evident that mitochondria are central players, not only for ATP production but also for neuronal differentiation's steps regulation, through their ability to handle cellular redox state, intracellular signaling, epigenetic state of the cell, as well as the gut microbiota-brain axis, upon dietary influences. In this scenario, the 8-oxoguanine DNA glycosylase (OGG1) repair system would link mitochondrial DNA integrity to the modulation of neural differentiation. On the other side, there is an increasing interest in NSCs generation, from induced pluripotent stem cells, as a clinical model for neurodegenerative diseases (NDs), although this methodology still presents several drawbacks, mainly related to the reprogramming process. Indeed, high levels of reactive oxygen species (ROS), associated with telomere shortening, genomic instability, and defective mitochondrial dynamics, lead to pluripotency limitation and reprogramming efficiency's reduction. Moreover, while a physiological or moderate ROS increase serves as a signaling mechanism, to activate differentiation and suppress self-renewal, excessive oxidative stress is a common feature of NDs and aging. This ROS-dependent regulatory effect might be modulated by newly identified ROS suppressors, including the NAD⁺-dependent deacetylase enzymes family called Sirtuins (SIRTs). Recently, the importance of subcellular localization of NAD synthesis has been coupled to different roles for NAD in chromatin stability, DNA repair, circadian rhythms, and longevity. SIRTs have been described as involved in the control of both telomere's chromatin state and expression of nuclear gene involved in the regulation of mitochondrial gene expression, as well as in several NDs and aging. SIRTs are ubiquitously expressed in the mammalian brain, where they play important roles. In this review we summarize the current knowledge on how SIRTs-dependent modulation of mitochondrial metabolism could impact on neurogenesis and neurodegeneration, focusing mainly on ROS function and their role in SIRTs-mediated cell reprogramming and telomere protection.

Effect of abrupt and gradual calorie restriction regimens on biochemical and behavioral markers in obese mice model

Background: Although Calorie Restriction (CR) is primarily considered in obesity management, behavioral studies of CR and its methodology of implementation are not well-defined. Objective: The study aimed to determine the efficacy of the extensively researched method of CR-abrupt calorie restriction (ACR) and a newly proposed gradual calorie restriction (GCR) in terms of body weight, behavioral and biochemical parameters in the obese animal model-C57BL/6J mice. Design: Male obese mice were subjected to GCR regimen for 14 weeks which was compared and evaluated for anxiety-like behavior and stress levels with ACR. Plasma corticosterone was measured before initiation of CR and every three weeks following GCR and ACR, whereas plasma insulin was measured twice-after obesity induction and post 14 weeks of CR. The behavioral assessments were conducted before inducing CR and every three weeks following ACR and GCR. Results: A significant anxiety-like behavior and an increase in plasma corticosterone were observed in mice on GCR during the critical initial six weeks of CR (p < 0.05). Both groups showed a decrease in plasma glucose levels; however, the GCR group showed a significant reduction (p < 0.01). There was a significant decrease in social interaction in both groups with an increase in the latency period and a decrease in time spent with the stranger animal during the social interaction test (p < 0.05). Conclusion: The mice on GCR regimen demonstrated lesser anxiety-like behavior and low plasma corticosterone levels compared to those on ACR. This gives us a new avenue in CR research to evaluate the methodologies of implementing CR.

Forgetful, sad and old: Do vascular cognitive impairment and depression share a common pre-disease network and how is it impacted by ageing?

Vascular cognitive impairment (VCI) and depression frequently coexist in geriatric populations and reciprocally increase disease risks. We assert that a shared pre-disease state of the psycho-immune-neuroendocrine (PINE) network model mechanistically explains bidirectional associations between VCI and depression. Five pathophysiological sub-networks are identified that are shared by VCI and depression: neuroinflammation, kynurenine pathway imbalance, hypothalamic-pituitary-adrenal (HPA) axis overactivity, impaired neurotrophic support and cerebrovascular dysfunction. These do not act independently, and their complex interactions necessitate a systems biology approach to better define disease pathogenesis. The PINE network is already established in the context of non-communicable diseases (NCDs) such as depression, hypertension, atherosclerosis, coronary heart disease and type 2 diabetes mellitus. We build on previous literature to specifically explore mechanistic links between MDD and VCI in the context of PINE pathways and discuss key mechanistic commonalities linking these comorbid conditions and identify a common pre-disease state which precedes transition to VCI and MDD. We expand the model to incorporate bidirectional interactions with biological ageing. Diathesis factors for both VCI and depression feed into this network and the culmination of shared mechanisms (on an ageing substrate) lead to a critical network transition to one or both disease states. A common pre-disease state underlying VCI and depression can provide clinicians a unique opportunity for early risk assessment and intervention in disease development. Establishing the mechanistic elements and systems biology of this network can reveal early warning or predictive biomarkers together with novel therapeutic targets. Integrative studies are recommended to elucidate the dynamic networked biology of VCI and depression over time.

Exploring Lead loci shared between schizophrenia and Cardiometabolic traits

Individuals with schizophrenia (SCZ) have, on average, a 10- to 20-year shorter expected life span than the rest of the population, primarily due to cardiovascular disease comorbidity. Genome-wide association studies (GWAS) have previously been used to separately identify common variants in SCZ and cardiometabolic traits. However, genetic variants jointly influencing both traits remain to be fully characterised. To assess overlaps (if any) between the genetic architecture of SCZ and cardiometabolic traits, we used conditional false discovery rate (FDR) and local genetic correlation statistical framework analyses. A conjunctional FDR was used to identify shared genetic traits between SCZ and cardiometabolic risk factors. We identified 144 genetic variants which were shared between SCZ and body mass index (BMI), and 15 variants shared between SCZ and triglycerides (TG). Furthermore, we discovered four novel single nucleotide polymorphisms (SNPs) (rs3865350, rs9860913, rs13307 and rs9614186) and four proximate genes (DERL2, SNX4, LY75 and EFCAB6) which were shared by SCZ and BMI. We observed that the novel genetic variant rs13307 and the most proximate gene LY75 exerted potential effects on SCZ and BMI comorbidity. Also, we observed a mixture of concordant and opposite direction associations with shared genetic variants. We demonstrated a moderate to high genetic overlap between SCZ and cardiometabolic traits associated with a pattern of bidirectional associations. Our data suggested a complex interplay between metabolism-related gene pathways in SCZ pathophysiology.

Application of Network Analysis to Uncover Variables Contributing to Functional Recovery after Stroke

To estimate network structures to discover the interrelationships among variables and distinguish the difference between networks. Three hundred and forty-eight stroke patients were enrolled in this retrospective study. A network analysis was used to investigate the association between those variables. A Network Comparison Test was performed to compare the correlation of variables between networks. Three hundred and twenty-five connections were identified, and 22 of these differed significantly between the high- and low-Functional Independence Measurement (FIM) groups. In the high-FIM network structure, brain-derived neurotrophic factor (BDNF) and length of stay (LOS) had associations with other nodes. However, there was no association with BDNF and LOS in the low-FIM network. In addition, the use of amantadine was associated with shorter LOS and lower FIM motor subscores in the high-FIM network, but there was no such connection in the low-FIM network. Centrality indices revealed that amantadine use had high centrality with others in the high-FIM network but not the low-FIM network. Coronary artery disease (CAD) had high centrality in the low-FIM network structure but not the high-FIM network. Network analysis revealed a new correlation of variables associated with stroke recovery. This approach might be a promising method to facilitate the discovery of novel factors important for stroke recovery.

Metabolic hormones mediate cognition

Recent biochemical and behavioural evidence indicates that metabolic hormones not only regulate energy intake and nutrient content, but also modulate plasticity and cognition in the central nervous system. Disruptions in metabolic hormone signalling may provide a link between metabolic syndromes like obesity and diabetes, and cognitive impairment. For example, altered metabolic homeostasis in obesity is a strong determinant of the severity of age-related cognitive decline and neurodegenerative disease. Here we review the evidence that eating behaviours and metabolic hormones-particularly ghrelin, leptin, and insulin-are key players in the delicate regulation of neural plasticity and cognition. Caloric restriction and antidiabetic therapies, both of which affect metabolic hormone levels can restore metabolic homeostasis and enhance cognitive function. Thus, metabolic hormone pathways provide a promising target for the treatment of cognitive decline.

The Role of Intermittent Energy Restriction Diet on Metabolic Profile and Weight Loss among Obese Adults

Obesity is a disease defined by an elevated body mass index (BMI), which is the result of excessive or abnormal accumulation of fat. Dietary intervention is fundamental and essential as the first-line treatment for obese patients, and the main rule of every dietary modification is calorie restriction and consequent weight loss. Intermittent energy restriction (IER) is a special type of diet consisting of intermittent pauses in eating. There are many variations of IER diets such as alternate-day fasting (ADF) and time-restricted feeding (TRF). In the literature, the IER diet is known as an effective method for bodyweight reduction. Furthermore, IER diets have a beneficial effect on systolic or diastolic pressure, lipid profile, and glucose homeostasis. In addition, IER diets are presented as being as efficient as a continuous energy restriction diet (CER) in losing weight and improving metabolic parameters. Thus, the IER diet could present an alternative option for those who cannot accept a constant food regimen.

Using Intermittent Fasting as a Non-pharmacological Strategy to Alleviate Obesity-Induced Hypothalamic Molecular Pathway Disruption

Intermittent fasting (IF) is a popular intervention used to fight overweight/obesity. This condition is accompanied by hypothalamic inflammation, limiting the proper signaling of molecular pathways, with consequent dysregulation of food intake and energy homeostasis. This mini-review explored the therapeutic modulation potential of IF regarding the disruption of these molecular pathways. IF seems to modulate inflammatory pathways in the brain, which may also be correlated with the brain-microbiota axis, improving hypothalamic signaling of leptin and insulin, and inducing the autophagic pathway in hypothalamic neurons, contributing to weight loss in obesity. Evidence also suggests that when an IF protocol is performed without respecting the circadian cycle, it can lead to dysregulation in the expression of circadian cycle regulatory genes, with potential health damage. In conclusion, IF may have the potential to be an adjuvant treatment to improve the reestablishment of hypothalamic responses in obesity.

Effects of Intermittent Fasting on Brain Metabolism

We are facing an obesity epidemic, and obesity itself and its close companion, type 2 diabetes, are independent risk factors for neurodegeneration. While most medical treatments fail to induce a clinically meaningful improvement in neurodegenerative disorders, lifestyle interventions have emerged in the spotlight. A recently rediscovered approach is intermittent fasting (IF), which, compared to the classic caloric restriction regimens, limits only the time of eating, rather than the number of calories allowed per day. There is already a large amount of evidence from preclinical and clinical studies showing the beneficial effects of IF. In this review, we specifically focus on the effects of IF on brain metabolism. Key molecular players modified during IF and involved in its beneficial central effects (ketone bodies, BDNF, GABA, GH/IGF-1, FGF2, sirtuin-3, mTOR, and gut microbiota) are identified and discussed. Studies suggest that IF induces several molecular and cellular adaptations in neurons, which, overall, enhance cellular stress resistance, synaptic plasticity, and neurogenesis. Still, the absence of guidelines regarding the application of IF to patients hampers its broad utilization in clinical practice, and further studies are needed to improve our knowledge on the different IF protocols and long-term effects of IF on brain metabolism before it can be widely prescribed.

Corticosterone induces discrete epigenetic signatures in the dorsal and ventral hippocampus that depend upon sex and genotype: focus on methylated Nr3c1 gene

The genomic effects of circulating glucocorticoids are particularly relevant in cortico-limbic structures, which express a high concentration of steroid hormone receptors. To date, no studies have investigated genomic differences in hippocampal subregions, namely the dorsal (dHPC) and ventral (vHPC) hippocampus, in preclinical models treated with exogenous glucocorticoids. Chronic oral corticosterone (CORT) in mouse is a pharmacological approach that disrupts the activity of the hypothalamic-pituitary-adrenal axis, increases affective behavior, and induces genomic changes after stress in the HPC of wildtype (WT) mice and mice heterozygous for the gene coding for brain-derived neurotrophic factor Val66Met (hMet), a variant associated with genetic susceptibility to stress. Using RNA-sequencing, we investigated the genomic signatures of oral CORT in the dHPC and vHPC of WT and hMet male and female mice, and examined sex and genotype differences in response to oral CORT. Males under CORT showed lower glycemia and increased anxiety- and depression-like behavior compared to females that showed instead opposite affective behavior in response to CORT. Rank-rank-hypergeometric overlap (RRHO) was used to identify genes from a continuous gradient of significancy that were concordant across groups. RRHO showed that CORT-induced differentially expressed genes (DEGs) in WT mice and hMet mice converged in the dHPC of males and females, while in the vHPC, DEGs converged in males and diverged in females. The vHPC showed a higher number of DEGs compared to the dHPC and exhibited sex differences related to glucocorticoid receptor (GR)-binding genes and epigenetic modifiers. Methyl-DNA-immunoprecipitation in the vHPC revealed differential methylation of the exons 1_C and 1_F of the GR gene (Nr3c1) in hMet females. Together, we report behavioral and endocrinological sex differences in response to CORT, as well as epigenetic signatures that i) differ in the dHPC and vHPC,ii) are distinct in males and females, and iii) implicate differential methylation of Nr3c1 selectively in hMet females.

Effect of Intermittent Fasting on Glucose Homeostasis and Bone Remodeling in Glucocorticoid-Induced Osteoporosis Rat Model

Background

The present study examined the effect of intermittent fasting (IF) on bone mineral content (BMC) and bone mineral density (BMD) and the markers of bone remodeling in a glucocorticoid-induced osteoporosis (GIO) rat model.

Methods

Forty male rats were allocated to 4 groups (N=10 per group): control group of normal rats; control+IF group (normal rats subjected to IF for 16–18 hr daily for 90 days); dexamethasone (DEX) group: (DEX [0.5 mg i.p.] for 90 days); and DEX+IF group (DEX and IF for 90 days). By the end of the experiment, BMD and BMC in the right tibia were measured. Serum levels of the following were measured: glucose; insulin; triglycerides (TGs); total cholesterol; parathyroid hormone (PTH); osteoprotegerin (OPG); receptor activator of nuclear factor-κB (RANK); bone-resorbing cytokines, including bone deoxypyridinoline (DPD), N-terminal telopeptide of collagen type I (NTX-1), and tartrate-resistant acid phosphatase 5b (TRAP-5b); and bone-forming cytokines, including alkaline phosphatase (ALP) and osteocalcin (OC).

Results

DEX administration for 90 days resulted in significantly increased serum levels of glucose, insulin, TGs, cholesterol, PTH, OPG, DPD, NTX-1, and TRAP-5b and significantly decreased BMD, BMC, and serum levels of RANK, OC, and ALP (all P<0.05). IF for 90 days significantly improved all these parameters (all P<0.05).

Conclusions

IF corrected GIO in rats by inhibiting osteoclastogenesis and PTH secretion and stimulating osteoblast activity.

Macroautophagy and normal aging of the nervous system: Lessons from animal models

Aging represents a cumulative form of cellular stress, which is thought to challenge many aspects of proteostasis. The non-dividing, long-lived neurons are particularly vulnerable to stress, and, not surprisingly, even normal aging is highly associated with a decline in brain function in humans, as well as in other animals. Macroautophagy is a fundamental arm of the proteostasis network, safeguarding proper protein turnover during different cellular states and against diverse cellular stressors. An intricate interplay between macroautophagy and aging is beginning to unravel, with the emergence of new tools, including those for monitoring autophagy in cultured neurons and in the nervous system of different organisms in vivo. Here, we review recent findings on the impact of aging on neuronal integrity and on neuronal macroautophagy, as they emerge from studies in invertebrate and mammalian models.

The association between BDNF levels and risperidone-induced weight gain is dependent on the BDNF Val66Met polymorphism in antipsychotic-naive first episode schizophrenia patients: a 12-week prospective study

A growing number of studies have shown that brain-derived neurotrophic factor (BDNF) is associated with weight gain during antipsychotic treatment in schizophrenia patients. However, there is still a lack of research results in the initial stage of antipsychotic treatment. This study aimed to evaluate the relationship between weight gain caused by risperidone monotherapy for 12 weeks and BDNF level in antipsychotic-naive and first-episode (ANFE) patients with schizophrenia, and we hypothesize that this may depend on BDNF Val66Met gene polymorphism. In a 12-week longitudinal trial, 225 ANFE patients were enrolled and treated with risperidone. Body weight was measured at baseline and during the 12-week follow-up. After treatment, the average weight of ANFE patients increased by 2.6 kg. Furthermore, we found that in patients with Val/Val genotype, the increase in serum BDNF levels was negatively correlated with risperidone-induced weight gain (r = -0.44, p = 0.008). Regression analysis showed that the baseline BDNF level was a predictor of weight gain after treatment (β = -0.45, t = -3.0, p = 0.005). Our results suggest that the BDNF signaling may be involved in weight gain caused by risperidone treatment. Furthermore, the negative association between weight gain and increased BDNF levels during risperidone treatment in ANFE schizophrenia depends on the BDNF Val66Met polymorphism.

High-Throughput Screening of Mouse Gene Knockouts Identifies Established and Novel High Body Fat Phenotypes

PURPOSE

Obesity is a major public health problem. Understanding which genes contribute to obesity may better predict individual risk and allow development of new therapies. Because obesity of a mouse gene knockout (KO) line predicts an association of the orthologous human gene with obesity, we reviewed data from the Lexicon Genome5000TM high throughput phenotypic screen (HTS) of mouse gene KOs to identify KO lines with high body fat.

MATERIALS AND METHODS

KO lines were generated using homologous recombination or gene trapping technologies. HTS body composition analyses were performed on adult wild-type and homozygous KO littermate mice from 3758 druggable mouse genes having a human ortholog. Body composition was measured by either DXA or QMR on chow-fed cohorts from all 3758 KO lines and was measured by QMR on independent high fat diet-fed cohorts from 2488 of these KO lines. Where possible, comparisons were made to HTS data from the International Mouse Phenotyping Consortium (IMPC).

RESULTS

Body fat data are presented for 75 KO lines. Of 46 KO lines where independent external published and/or IMPC KO lines are reported as obese, 43 had increased body fat. For the remaining 29 novel high body fat KO lines, Ksr2 and G2e3 are supported by data from additional independent KO cohorts, 6 (Asnsd1, Srpk2, Dpp8, Cxxc4, Tenm3 and Kiss1) are supported by data from additional internal cohorts, and the remaining 21 including Tle4, Ak5, Ntm, Tusc3, Ankk1, Mfap3l, Prok2 and Prokr2 were studied with HTS cohorts only.

CONCLUSION

These data support the finding of high body fat in 43 independent external published and/or IMPC KO lines. A novel obese phenotype was identified in 29 additional KO lines, with 27 still lacking the external confirmation now provided for Ksr2 and G2e3 KO mice. Undoubtedly, many mammalian obesity genes remain to be identified and characterized.

Effects of Intermittent Fasting on the Circulating Levels and Circadian Rhythms of Hormones

Intermittent fasting has become an increasingly popular strategy in losing weight and associated reduction in obesity-related medical complications. Overwhelming studies support metabolic improvements from intermittent fasting in blood glucose levels, cardiac and brain function, and other health benefits, in addition to weight loss. However, concerns have also been raised on side effects including muscle loss, ketosis, and electrolyte imbalance. Of particular concern, the effect of intermittent fasting on hormonal circadian rhythms has received little attention. Given the known importance of circadian hormonal changes to normal physiology, potential detrimental effects by dysregulation of hormonal changes deserve careful discussions. In this review, we describe the changes in circadian rhythms of hormones caused by intermittent fasting. We covered major hormones commonly pathophysiologically involved in clinical endocrinology, including insulin, thyroid hormones, and glucocorticoids. Given that intermittent fasting could alter both the level and frequency of hormone secretion, decisions on practicing intermittent fasting should take more considerations on potential detrimental consequences versus beneficial effects pertaining to individual health conditions.

The relationship between brain-derived neurotrophic factor and metabolic syndrome in patients with chronic schizophrenia: A systematic review

BACKGROUND & AIMS

Schizophrenia is a serious long-term disorder in which the metabolic complications and abnormalities of the brain-derived neurotrophic factor (BDNF) can be found. In this study, we conducted a systematic review of the relationship between BDNF, metabolic syndrome (MetS) and its components in schizophrenic patients.

METHODS

Data were collected mainly from PubMed, Google Scholar, Scopus, and ProQuest databases. The keywords related to the BDNF, MetS, schizophrenia were searched. Two reviewers independently screened 1061 abstracts. And eventually, a total of 7 studies (6 observational and 1 interventional) was included in the systematic reviews.

RESULTS

Four of the 7 study ascertained statistically significant inverse relationship between serum BDNF levels and MetS in schizophrenic patients. While in the other two studies, there was no inverse relationship. In the last selected study, the researchers found a weak association between the Val66Met polymorphism in BDNF Gene and clozapine-induced MetS.

CONCLUSION

Although this relationship could not be determined but BDNF levels appear to be reduced in schizophrenic patients with MetS and factors such as sex and antipsychotic class differentiation, sampling and methodology and episodes of illness could play a role in the results and outcomes.

The role and its mechanism of intermittent fasting in tumors: friend or foe?

Intermittent fasting (IF) is becoming a prevailing topic worldwide, as it can cause changes in the body’s energy metabolism processes, improve health, and affect the progression of many diseases, particularly in the circumstance of oncology. Recent research has shown that IF can alter the energy metabolism of tumor cells, thereby inhibiting tumor growth and improving antitumor immune responses. Furthermore, IF can increase cancer sensitivity to chemotherapy and radiotherapy and reduce the side effects of these traditional anticancer treatments. IF is therefore emerging as a promising approach to clinical cancer treatment. However, the balance between long-term benefits of IF compared with the harm from insufficient caloric intake is not well understood. In this article, we review the role of IF in tumorigenesis and tumor therapy, and discuss some scientific problems that remain to be clarified, which might provide some assistance in the application of IF in clinical tumor therapy.

A multidimensional functional fitness score has a stronger association with type 2 diabetes than obesity parameters in cross sectional data

Objectives

We examine here the association of multidimensional functional fitness with type 2 diabetes mellitus (T2DM) as compared to anthropometric indices of obesity such as body mass index (BMI) and waist to hip ratio (WHR) in a sample of Indian population.

Research design and method

We analysed retrospective data of 663 volunteer participants (285 males and 378 females between age 28 and 84), from an exercise clinic in which every participant was required to undergo a health related physical fitness (HRPF) assessment consisting of 15 different tasks examining 8 different aspects of functional fitness.

Results

The odds of being diabetic in the highest quartile of BMI were not significantly higher than that in the lowest quartile in either of the sexes. The odds of being a diabetic in the highest WHR quartile were significantly greater than the lowest quartile in females (OR = 4.54 (1.95, 10.61) as well as in males (OR = 3.81 (1.75, 8.3). In both sexes the odds of being a diabetic were significantly greater in the lowest quartile of HRPF score than the highest (males OR = 10.52 (4.21, 26.13); females OR = 10.50 (3.53, 31.35)). After removing confounding, the predictive power of HRPF was significantly greater than that of WHR. HRPF was negatively correlated with WHR, however for individuals that had contradicting HRPF and WHR based predictions, HRPF was the stronger predictor of T2DM.

Conclusion

The association of multidimensional functional fitness score with type 2 diabetes was significantly stronger than obesity parameters in a cross sectional self-selected sample from an Indian city.

Early life exposure to hypercaloric diet impairs eating behavior during weaning: The role of BDNF signaling and astrocyte marks

Literature shows that gestational and/or lactational exposure to hypercaloric diets induces long term effects on eating behavior and the involvement of neurochemical mechanisms. We hypothesized that the effects of hypercaloric diets in early development phases can precede an overweight or an obesity status. The aim of the present study was to evaluate the impact of gestational and lactational exposure to cafeteria diet on eating behavior and neurochemical parameters, BDNF signaling, epigenetic and astrocyte marks in the hippocampus and olfactory bulb during the weaning phase. Pregnant female rats were randomized between standard and cafeteria diet, the respective diet was maintained through the lactational period. The framework of feeding pattern, meal, and its microstructure, was observed in postnatal day 20. Exposure to cafeteria diet increased the number of meals, associated with a lower first inter-meal interval and higher consumption in both genders, without any changes in body weight. Diet exposure also reduced the number of grooming, a behavior typically found at the end of meals. Hypercaloric diet exposure reduced BDNF levels in the olfactory bulb and hippocampus from rats of both sexes and increased the content of the TrkB receptor in hippocampi. It was observed an increase in HDAC5 levels, an epigenetic mark. Still, early exposure to the hypercaloric diet reduced hippocampal GFAP and PPARγ levels, without any effect on NeuN content, indicating that alterations in astrocytes can precede those neuronal outcomes. Our results showed that changes in interrelated neurochemical signaling, BDNF, and astrocyte marks, induced by hypercaloric diet in early stages of development may be related to impairment in the temporal distribution of eating pattern and consequent amounts of consumed food during the weaning phase.

Cognitive Impact of Calorie Restriction: A Narrative Review

The impairment of cognitive function can cause substantial emotional and financial burdens. A recent global increasing trend in cognitive impairment and associated disorders has been observed, which will continue to grow as the population ages rapidly. As a nonpharmaceutical approach, calorie restriction (CR) has received extensive research interests due to its health benefits, including maintaining cognitive function. In this narrative review, we first briefly introduce the role of cognitive function in activities of daily living and CR as a part of healthy lifestyle behaviors to protect against cognitive decline. Second, we present results from human studies demonstrating that CR might be beneficial for improving age-related cognitive decline and cognitive impairment in the clinical population such as obesity and type 2 diabetes. Third, the potential mechanisms regarding the protective effects of CR on cognition are discussed. Fourth, specific suggestions are highlighted to be considered in future human studies. Overall, although there are few data available from human studies, CR appears to be beneficial for cognitive protection for both healthy and clinical populations. Further scientific investigations are needed before a firm conclusion can be made.

Brain-Derived Neurotrophic Factor and Diabetes

Diabetes and its chronic complications still represent a great clinical problem, despite improvements made in the diagnosis and treatment of the disease. People with diabetes have a much higher risk of impaired brain function and psychiatric disorders. Neurotrophins are factors that protect neuronal tissue and improve the function of the central nervous system, and among them is brain-derived neurotrophic factor (BDNF). The level and function of BDNF in diabetes seems to be disturbed by and connected with the presence of insulin resistance. On the other hand, there is evidence for the highly beneficial impact of physical activity on brain function and BDNF level. However, it is not clear if this protective phenomenon works in the presence of diabetes. In this review, we summarize the current available research on this topic and find that the results of published studies are ambiguous.

Pathophysiological Features of Obesity and its Impact on Cognition: Exercise Training as a Non-Pharmacological Approach

BACKGROUND

The number of individuals with obesity is growing worldwide and this is a worrying trend, as obesity has shown to cause pathophysiological changes, which result in the emergence of comorbidities such as cardiovascular disease, diabetes mellitus type 2 and cancer. In addition, cognitive performance may be compromised by immunometabolic deregulation of obesity. Although in more critical cases, the use of medications is recommended, a physically active lifestyle is one of the main foundations for health maintenance, making physical training an important tool to reduce the harmful effects of excessive fat accumulation.

AIM

The purpose of this review of the literature is to present the impact of immunometabolic alterations on cognitive function in individuals with obesity, and the role of exercise training as a non-pharmacological approach to improve the inflammatory profile, energy metabolism and neuroplasticity in obesity.

METHOD

An overview of the etiology and pathophysiology of obesity to establish a possible link with cognitive performance in obese individuals, with the executive function being one of the most affected cognitive components. In addition, the brain-derived neurotrophic factor (BDNF) profile and its impact on cognition in obese individuals are discussed. Lastly, studies showing regular resistance and/or aerobic training, which may be able to improve the pathophysiological condition and cognitive performance through the improvement of the inflammatory profile, decreased insulin resistance and higher BDNF production are discussed.

CONCLUSION

Exercise training is essential for reestablishment and maintenance of health by increasing energy expenditure, insulin resistance reduction, anti-inflammatory proteins and neurotrophin production corroborating to upregulation of body function.

Endoplasmic reticulum stress in the livers of BDNF heterozygous knockout mice

Context: Involvement of endoplasmic reticulum (ER) stress and brain-derived neurotrophic factor (BDNF) in hepatic lipid metabolism has been reported previously. Objective: The effects of chronic BDNF deficiency on ER stress response in the livers were examined in this study. Methods: BDNF^(+/-) mice, characterised by BDNF deficiency, and their wild-type (WT) littermates were used. The ER stress was induced by tunicamycin (Tm) (0.5 mg/kg, intraperitoneal). Animals were divided into four groups; WT, WT + Tm, BDNF^(+/-), and BDNF^(+/-)+Tm. Results: At the basal conditions, BDNF deficiency did not affect hepatic cell death or lipid accumulation. However, during ER stress, BDNF^(+/-)+Tm group showed increased apoptosis, GADD153 immunostaining, sterol regulatory element-binding protein-1c (SREBP-1c) level, and steatosis compared to the WT + Tm group. Conclusion: Endogenous BDNF might be protective against apoptosis through GADD153 suppression and steatosis via SREBP-1c suppression during ER stress. This effect of BDNF might be clinically important for type 2 diabetes and obesity, which are related with both ER stress and BDNF deficiency.

Converging evidence points towards a role of insulin signaling in regulating compulsive behavior

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder with childhood onset, and is characterized by intrusive thoughts and fears (obsessions) that lead to repetitive behaviors (compulsions). Previously, we identified insulin signaling being associated with OCD and here, we aim to further investigate this link in vivo. We studied TALLYHO/JngJ (TH) mice, a model of type 2 diabetes mellitus, to (1) assess compulsive and anxious behaviors, (2) determine neuro-metabolite levels by 1 H magnetic resonance spectroscopy (MRS) and brain structural connectivity by diffusion tensor imaging (DTI), and (3) investigate plasma and brain protein levels for molecules previously associated with OCD (insulin, Igf1, Kcnq1, and Bdnf) in these subjects. TH mice showed increased compulsivity-like behavior (reduced spontaneous alternation in the Y-maze) and more anxiety (less time spent in the open arms of the elevated plus maze). In parallel, their brains differed in the white matter microstructure measures fractional anisotropy (FA) and mean diffusivity (MD) in the midline corpus callosum (increased FA and decreased MD), in myelinated fibers of the dorsomedial striatum (decreased FA and MD), and superior cerebellar peduncles (decreased FA and MD). MRS revealed increased glucose levels in the dorsomedial striatum and increased glutathione levels in the anterior cingulate cortex in the TH mice relative to their controls. Igf1 expression was reduced in the cerebellum of TH mice but increased in the plasma. In conclusion, our data indicates a role of (abnormal) insulin signaling in compulsivity-like behavior.

Alternate-day feeding leads to improved glucose regulation on fasting days without significant weight loss in genetically obese mice

Alternate-day fasting (ADF) is effective for weight loss and increases insulin sensitivity in diet-induced obese rodents. However, the efficacy of ADF in genetic models of obesity has not been comprehensively studied. Mice that are deficient in leptin ( ob/ob mice) are obese, diabetic, and prone to deep bouts of torpor when fasted. We tested the hypotheses that an ADF protocol in ob/ob mice would result in 1) induction of torpor on fasted days, 2) minimal body weight loss if the mice experienced torpor, and 3) no improvement in glucose control in the absence of weight loss. Female ob/ob mice and littermate controls were assigned to 1) an ad libitum regimen or 2) an ADF regimen, consisting of fasting every other day with ad libitum feeding between fasts. Over a 19-day period, littermate control mice on the ADF regimen consumed the same amount of food as littermate control mice on the ad libitum regimen, whereas the ADF ob/ob mice consumed 37% less food than ad libitum ob/ob mice. Fasting days, but not fed days, led to torpor in both genotypes. Fasting days, but not fed days, led to weight loss in both genotypes relative to ad libitum controls. Fasting days, but not fed days, produced enhanced insulin sensitivity in both genotypes and normalized circulating glucose in ob/ob mice. These data demonstrate improved glucose control on fasting days with the use of ADF in a genetic model of obesity in the face of minimal weight loss.

Ketogenic diet prevents impaired prepulse inhibition of startle in an acute NMDA receptor hypofunction model of schizophrenia

Recent transcriptomic, proteomic and metabolomics studies have highlighted an abnormal cerebral glucose and energy metabolism as one of the potential pathophysiological mechanisms of schizophrenia. This raises the possibility that a metabolically-based intervention might have therapeutic value in the management of schizophrenia, a notion supported by our recent results that a low carbohydrate/high-fat therapeutic ketogenic diet (KD) prevented a variety of behavioural abnormalities induced by pharmacological inhibition of NMDA glutamate receptors. Here we asked if the beneficial effects of KD can be generalised to impaired prepulse inhibition of startle (PPI), a translationally validated endophenotype of schizophrenia, in a pharmacological model in mice. Furthermore, we addressed the issue of whether the effect of KD is linked to the calorie-restricted state typical of the initial phase of KD. We fed male C57BL/6 mice a KD for 7 weeks and tested PPI at 3 and 7 weeks, in the presence and absence of a significant digestible energy deficit, respectively. We used an NMDA receptor hypo-function model of schizophrenia induced by acute injection of dizocilpine (MK-801). We found that KD effectively prevented MK-801-induced PPI impairments at both 3 and 7 weeks, irrespective of the presence or absence of digestible energy deficit. Furthermore, there was a lack of correlation between PPI and body weight changes. These results support the efficacy of the therapeutic KD in a translational model of schizophrenia and furthermore provide evidence against the role of calorie restriction in its mechanism of action.

Effect of a high sucrose and high fat diet in BDNF (+/-) mice on oxidative stress markers in adipose tissues

The purpose of this study was to investigate the effects of a high fat and a high sucrosediet in wild type and BDNF (+/-) mice on oxidative stress in epididymal and subcutaneousadipose tissues by measuring different markers of oxidative stress and antioxidant enzymes. Wild type (WT) and BDNF (+/-) male mice were divided into six groups receiving fed control diet (CD), high sucrose diet (HSD), or high fat diet (HFD) for four months. Levels of 3-nitrotyrosine (3-NT) increased in the HFD-fed BDNF (+/-) mice, while 4-hydroxynonenal (4-HNE) levels increased in the CD and HFD-fed BDNF (+/-) groups. Malondialdehyde (MDA) levels decreased in subcutaneous tissue compared to epididymal adipose tissue, independently of diet type. Superoxide dismutase (SOD) activity was reduced by HFD (p < 0.05), butglutathione peroxidase (GSH-Px) activity was increased by HSD in epididymal adipose tissuein BDNF (+/-) mice (p < 0.05). GSH-Px activities was increased by CD and HFD in subcutaneous adipose tissue of BDNF (+/-) (p < 0.05). SOD2 and GSH-Px3 expressions were only decreased by HSD in epididymal and subcutaneous adipose tissues of BDNF (+/-) mice (p < 0.05). In conclusion, reduced BDNF may increase OS in epididymal adipose tissue, but not in subcutaneous adipose tissue following HSD and HFD.

Sex difference in the association of body mass index and BDNF levels in Chinese patients with chronic schizophrenia

RATIONALE AND OBJECTIVE

Schizophrenia displays sex differences in many aspects. Decreased brain-derived neurotrophic factor (BDNF) levels have been reported to be associated with high body weight or obesity as well as other psychopathological aspects in schizophrenia patients. This study aimed to explore sex differences in the relationship between serum BDNF levels and obesity in patients with chronic schizophrenia.

METHODS

We recruited 132 Chinese patients with chronic schizophrenia (98 males and 34 females) and compared sex differences in the body mass index (BMI), obesity, serum BDNF levels, and their associations. Psychopathology symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). A regression model with various demographic and clinical variables was applied to predict the serum levels of BDNF.

RESULTS

Female patients had a higher rate of obesity and higher BMI, but lower BDNF levels than male schizophrenia patients. A significantly negative correlation was observed between BMI and BDNF levels only in female patients but not in male patients. The multiple regression model with demographic and clinical variables significantly predicted BDNF levels only in female patients, with a medium size effect. And only in female patients, BMI made a significant contribution to this prediction.

CONCLUSION

Our results indicate significant sex differences in the obesity, BMI, BDNF levels, and their association in chronic patients with schizophrenia, showing a significant inverse correlation between BMI and BDNF levels only in female patients. Thus, sex needs to be considered when assessing the relationship between BDNF and metabolic syndromes in schizophrenia.

Intermittent administration of a fasting-mimicking diet intervenes in diabetes progression, restores β cells and reconstructs gut microbiota in mice

Fasting and especially intermittent fasting have been shown to be an effective intervention in many diseases, such as obesity and diabetes. The fasting-mimicking diet (FMD) has recently been found to ameliorate metabolic disorders. To investigate the effect of a new type of low-protein low-carbohydrate FMD on diabetes, we tested an FMD in db/db mice, a genetic model of type 2 diabetes. The diet was administered every other week for a total of 8 weeks. The intermittent FMD normalized blood glucose levels in db/db mice, with significant improvements in insulin sensitivity and β cell function. The FMD also reduced hepatic steatosis in the mice. Deterioration of pancreatic islets and the loss of β cells in the diabetic mice were prevented by the FMD. The expression of β cell progenitor marker Ngn3 was increased by the FMD. In addition, the FMD led to the reconstruction of gut microbiota. Intermittent application of the FMD increased the genera of Parabacteroides and Blautia while reducing Prevotellaceae, Alistipes and Ruminococcaceae. The changes in these bacteria were also correlated with the fasting blood glucose levels of the mice. Furthermore, intermittent FMD was able to reduce fasting blood glucose level and increase β cells in STZ-induced type 1 diabetic mouse model. In conclusion, our study provides evidence that the intermittent application of an FMD is able to effectively intervene in the progression of diabetes in mice.

A high-fat diet induced NMRI mouse model of metabolic syndrome: focus on brain-derived neurotrophic factor (BDNF)

The association of brain-derived neurotrophic factor (BDNF) as a member of neurotrophin family and metabolic syndrome (MetS) has been proposed, however basic evidence necessary to prove (or disprove) this association in non-genetic animal model is rare. Therefore, we investigated the alteration of encephalic BDNF gene expression in a mouse model of high-fat diet (HFD) induced MetS. To translate MetS, male NMRI mice (9 weeks old; N = 13) fed on a HFD including suet powder (37.50%) and granulated sugar (19.85%) while control mice were fed a diet contained suet powder (6.25%) and granulated sugar (49.09%). We monitored the development of MetS by measuring fasting blood sugar (FBS) and lipid (total cholesterol (TC) and triacylglycerol (TGs)) and lipoprotein (high-density lipoprotein cholesterol (HDL-C), very low-density lipoprotein cholesterol (VLDL-C)) profiles, atherogenic index (AI), and somatic indices after 1 and 3 months of dietary interventions. The HFD intake led to increased body weight, liver weight, FBS, TC, and decreased HDL-C as compared to chow diet in mice after first month of dietary intervention. The increased FBS, body weight, abdominal fat mass, TGs, TC, and VLDL-C and decreased HDL-C were observed in HFD-fed mice as compared to those of chow-fed mice at 3th month. The statistical comparison of two HFD groups in two time intervals of 1st and 3th month confirmed that our HFD-induced MetS model was reliable because FBS, TGs and VLDL-C, TC, and AI have been increased significantly during selected time intervals. The AI increased significantly in HFD-fed mice compared to chow-fed mice after 3 months. The AI in HFD-fed mice treated with HFD for 3 months was increased significantly as compared to mice fed HFD for 1 month. Our diet-induced model more closely mimics the changes observed in human MetS and showed that encephalic BDNF gene in mice fed HFD was under-expressed by 0.30 fold with respect to chow-fed mice after 3 months of dietary intervention.

Brain-derived neurotrophic factor (BDNF) serum level in women with first-episode depression, correlation with clinical and metabolic parameters

BACKGROUND

Brain-derived neurotrophic factor (BDNF) influences neuron differentiation during development, as well as the synaptic plasticity and neuron survival in adulthood. BDNF has been implicated in the pathogenesis of psychiatric disorders and its serum level is a potential biomarker for depression. The aim of this study was to examine serum levels of BDNF in first-episode depression and its correlation with clinical and metabolic parameters.

MATERIALS AND METHODS

The study was performed on a group of 60 women: 30 diagnosed with a first-episode of depression and 30 healthy controls. 17-Item Hamilton Depression Rating Scale (HDRS-17) was used to assess the severity of depression. Patients were randomly chosen for treatment with sertraline or venlafaxine. BDNF serum levels and metabolic parameters: fasting serum glucose, cholesterol, triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) were measured at baseline and week 8 of treatment.

RESULTS

There were no differences between BDNF level in depressed patients compared with the healthy controls. Lack of differences in medication effect of sertraline or venlafaxine on HDRS-17 scores during 8 weeks of treatment was observed. Correlation of BDNF at baseline and fasting serum glucose at baseline and week 8 was detected.

CONCLUSIONS

Correlations of BDNF serum levels with metabolic parameters were observed.

Metabolic and molecular framework for the enhancement of endurance by intermittent food deprivation

Evolutionary considerations suggest that the body has been optimized to perform at a high level in the food-deprived state when fatty acids and their ketone metabolites are a major fuel source for muscle cells. Because controlled food deprivation in laboratory animals and intermittent energy restriction in humans is a potent physiologic stimulus for ketosis, we designed a study to determine the impact of intermittent food deprivation during endurance training on performance and to elucidate the underlying cellular and molecular mechanisms. Male mice were randomly assigned to either ad libitum feeding or alternate-day food deprivation (ADF) groups, and half of the mice in each diet group were trained daily on a treadmill for 1 mo. A run to exhaustion endurance test performed at the end of the training period revealed superior performance in the mice maintained on ADF during training compared to mice fed ad libitum during training. Maximal O₂ consumption was increased similarly by treadmill training in mice on ADF or ad libitum diets, whereas respiratory exchange ratio was reduced in ADF mice on food-deprivation days and during running. Analyses of gene expression in liver and soleus tissues, and metabolomics analysis of blood suggest that the metabolic switch invoked by ADF and potentiated by exercise strongly modulates molecular pathways involved in mitochondrial biogenesis, metabolism, and cellular plasticity. Our findings demonstrate that ADF engages metabolic and cellular signaling pathways that result in increased metabolic efficiency and endurance capacity.-Marosi, K., Moehl, K., Navas-Enamorado, I., Mitchell, S. J., Zhang, Y., Lehrmann, E., Aon, M. A., Cortassa, S., Becker, K. G., Mattson, M. P. Metabolic and molecular framework for the enhancement of endurance by intermittent food deprivation.

Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting

OBJECTIVE

Intermittent fasting (IF) is a term used to describe a variety of eating patterns in which no or few calories are consumed for time periods that can range from 12 hours to several days, on a recurring basis. This review is focused on the physiological responses of major organ systems, including the musculoskeletal system, to the onset of the metabolic switch: the point of negative energy balance at which liver glycogen stores are depleted and fatty acids are mobilized (typically beyond 12 hours after cessation of food intake).

RESULTS AND CONCLUSIONS

Emerging findings suggest that the metabolic switch from glucose to fatty acid-derived ketones represents an evolutionarily conserved trigger point that shifts metabolism from lipid/cholesterol synthesis and fat storage to mobilization of fat through fatty acid oxidation and fatty acid-derived ketones, which serve to preserve muscle mass and function. Thus, IF regimens that induce the metabolic switch have the potential to improve body composition in overweight individuals. Moreover, IF regimens also induce the coordinated activation of signaling pathways that optimize physiological function, enhance performance, and slow aging and disease processes. Future randomized controlled IF trials should use biomarkers of the metabolic switch (e.g., plasma ketone levels) as a measure of compliance and of the magnitude of negative energy balance during the fasting period.

Sugars, exercise and health

BACKGROUND

There is a direct link between a variety of addictions and mood states to which exercise could be relieving. Sugar addiction has been recently counted as another binge/compulsive/addictive eating behavior, differently induced, leading to a high-significant health problem. Regularly exercising at moderate intensity has been shown to efficiently and positively impact upon physiological imbalances caused by several morbid conditions, including affective disorders. Even in a wider set of physchiatric diseases, physical exercise has been prescribed as a complementary therapeutic strategy.

METHOD

A comprehensive literature search was carried out in the Cochrane Library and MEDLINE databases (search terms: sugar addiction, food craving, exercise therapy, training, physical fitness, physical activity, rehabilitation and aerobic).

RESULTS

Seeking high-sugar diets, also in a reward- or craving-addiction fashion, can generate drastic metabolic derangements, often interpolated with affective disorders, for which exercise may represent a valuable, universal, non-pharmachological barrier.

LIMITATIONS

More research in humans is needed to confirm potential exercise-mechanisms that may break the bond between sugar over-consumption and affective disorders.

CONCLUSIONS

The purpose of this review is to address the importance of physical exercise in reversing the gloomy scenario of unhealthy diets and sedentary lifestyles in our modern society.

Long-term caloric restriction in ApoE-deficient mice results in neuroprotection via Fgf21-induced AMPK/mTOR pathway

Caloric restriction (CR) decelerates the aging process, extends lifespan and exerts neuroprotective effects in diverse species by so far unknown mechanisms. Based on known neuroprotective effects of fibroblastic growth factor 21 (Fgf21) we speculate that CR upregulates Fgf21, which phosphorylates neuronal AMP-activated protein kinase (AMPK), leading to a decrease of mammalian target of rapamycin (mTOR) signaling activity and an inhibition of tau-hyperphosphorylation. This in turn reduces the formation of neurofibrillary tangles, a neuropathological hallmark of Alzheimer's disease. ApoE-deficient mice (ApoE−/−), serving as a model of neurodegeneration, showed upon CR vs. ad libitum feeding increased Fgf21 levels in both, plasma and brain as well as higher phosphorylation of fibroblastic growth factor receptor 1c (Fgfr1c), extracellular signal-regulated kinases 1/2 (ERK1/2) and AMPK in brain, lower activity of mTOR and decreased Tau-phosphorylation. Finally, CR in ApoE−/− mice caused neuroprotection as indicated by a higher synaptic plasticity shown by immunohistochemical analysis with increased numbers of PSD95-positive neurons and a better cognitive performance as analyzed with Morris water maze test. These data provide substantial evidence that neuroprotection upon CR seems to be Fgf21-dependent. Further experiments are necessary to evaluate Fgf21 as a therapeutic tool to treat tauopathy for improvement of cognitive performance.

Impact of intermittent fasting on health and disease processes

Humans in modern societies typically consume food at least three times daily, while laboratory animals are fed ad libitum. Overconsumption of food with such eating patterns often leads to metabolic morbidities (insulin resistance, excessive accumulation of visceral fat, etc.), particularly when associated with a sedentary lifestyle. Because animals, including humans, evolved in environments where food was relatively scarce, they developed numerous adaptations that enabled them to function at a high level, both physically and cognitively, when in a food-deprived/fasted state. Intermittent fasting (IF) encompasses eating patterns in which individuals go extended time periods (e.g., 16-48h) with little or no energy intake, with intervening periods of normal food intake, on a recurring basis. We use the term periodic fasting (PF) to refer to IF with periods of fasting or fasting mimicking diets lasting from 2 to as many as 21 or more days. In laboratory rats and mice IF and PF have profound beneficial effects on many different indices of health and, importantly, can counteract disease processes and improve functional outcome in experimental models of a wide range of age-related disorders including diabetes, cardiovascular disease, cancers and neurological disorders such as Alzheimer's disease Parkinson's disease and stroke. Studies of IF (e.g., 60% energy restriction on 2days per week or every other day), PF (e.g., a 5day diet providing 750-1100kcal) and time-restricted feeding (TRF; limiting the daily period of food intake to 8h or less) in normal and overweight human subjects have demonstrated efficacy for weight loss and improvements in multiple health indicators including insulin resistance and reductions in risk factors for cardiovascular disease. The cellular and molecular mechanisms by which IF improves health and counteracts disease processes involve activation of adaptive cellular stress response signaling pathways that enhance mitochondrial health, DNA repair and autophagy. PF also promotes stem cell-based regeneration as well as long-lasting metabolic effects. Randomized controlled clinical trials of IF versus PF and isoenergetic continuous energy restriction in human subjects will be required to establish the efficacy of IF in improving general health, and preventing and managing major diseases of aging.

The mechanism of acute fasting-induced antidepressant-like effects in mice

Acute fasting induced antidepressant‐like effects. However, the exact brain region and mechanism of these actions are still largely unknown. Therefore, in this study the antidepressant‐like effects of acute fasting on c‐Fos expression and BDNF levels were investigated. Consistent with our previous findings, immobility time was remarkably shortened by 9 hrs fasting in the forced swimming test. Furthermore, these antidepressant‐like effects of 9 fasting were inhibited by a 5‐HT_2A/2C receptor agonist (±)‐1‐(2, 5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane hydrochloride (DOI), and the effect of DOI was blocked by pretreatment with a selective 5‐HT_2A receptor antagonist ketanserin. Immunohistochemical study has shown that c‐Fos level was significantly increased by 9 hrs fasting in prefrontal cortex but not hippocampus and habenular. Fasting‐induced c‐Fos expression was further enhanced by DOI in prefrontal cortex, and these enhancements were inhibited by ketanserin. The increased BDNF levels by fasting were markedly inhibited by DOI in frontal cortex and hippocampus, and these effects of DOI on BDNF levels were also blocked by ketanserin. These findings suggest that the antidepressant‐like effects of acute fasting may be exerted via 5‐HT_2A receptor and particularly sensitive to neural activity in the prefrontal cortex. Furthermore, these antidepressant‐like effects are also mediated by CREB and BDNF pathway in hippocampus and frontal cortex. Therefore, fasting may be potentially helpful against depression.

Genotrophic effect of neurotrophins - Restart of β-cell regeneration in diabetes mellitus

Type 2 diabetes mellitus is an epidemic worldwide and a proved risk factor for cardiovascular complications. In 89% of the cases, it deals, in fact, with metabolic syndrome of multifactorial etiopathogenesis. This paradigm has been generalized by the neurotrophic theory emphasizing the role of hyponeurotrophinemia of key factor. Both type 2 diabetes mellitus and metabolic syndrome are characterized by insulin resistance and pancreatic β-cell damage. Cyclic keeping the fast enhances plasma neurotrophin levels. Fasting induces prenatal-development gene expression in adult pancreas and promotes neurogenin (Ngn)-3 gene expression to generate insulin producing β-cells. Probably, the increased plasma and tissue levels of the nerve growth factor and brain-derived neurotrophic factor after fasting reprogramme Ngn-3 gene expression as this genotrophic action enhances Ngn-3 protein synthesis. This results in regeneration of damaged pancreatic β-cells and restores insulin secretion in type 1 and type 2 diabetes mellitus.

How much variance in insulin resistance is explained by obesity?

Background: Obesity is believed to be the major cause of insulin resistance, although many other obesity-independent signals are shown to affect insulin sensitivity.Aim: We address the degree to which variation in insulin resistance is explained by morphometric and biochemical measures of obesity.Methods: PubMed and Google Scholar were searched for epidemiological studies published between 1994 and 2015 that report correlations between at least one measure of obesity and that of insulin resistance.Results: A total of 63 studies satisfied inclusion criteria. Frequency distribution of coefficients of determination between morphometric measures of obesity and insulin resistance was skewed with the mode being less than 10%, class and median being 17.3%. Plasma leptin concentration, but not plasma non-esterified fatty acid level, was better correlated with insulin resistance, the median variance explained being 33.29%. Morphometric measures alone had a median variance explained of 16%. Ethnicity explained part of the variance across studies with the correlation being significantly poorer in Asians.Conclusion: The extremely limited predictive power of morphometric and biochemical measures of obesity suggests that more research needs to focus on the obesity-independent signals that affect insulin sensitivity as well as leptin expression.

The interrelationship of metabolic syndrome and neurodegenerative diseases with focus on brain-derived neurotrophic factor (BDNF): Kill two birds with one stone

The brain-derived neurotrophic factor (BDNF) is involved in metabolic syndrome (MetS) and neurodegenerative diseases (NDD) like Alzheimer's disease, Huntington's disease, Parkinson's disease and depression. If one factor plays an essential role in the pathogenesis of two diseases, it can be concluded that there might be a common root in these two diseases, as well. This review was aimed to highlight the crucial roles of BDNF in the pathogenesis of MetS and NDD and to introduce sole prophylactic or therapeutic applications, BDNF gene therapy and BDFN administration, in controlling MetS and NDD.

Potential unfavorable impacts of BDNF Val66Met polymorphisms on metabolic risks in average population in a longevous area

Background

Brain-derived neurotrophic factor (BDNF) has been implicated in cognitive performance and the modulation of several metabolic parameters in some disease models, but its potential roles in successful aging remain unclear. We herein sought to define the putative correlation between BDNF Val66Met and several metabolic risk factors including BMI, blood pressure, fasting plasma glucose (FPG) and lipid levels in a long-lived population inhabiting Hongshui River Basin in Guangxi.

Methods

BDNF Val66Met was typed by ARMS-PCR for 487 Zhuang long-lived individuals (age ≥ 90, long-lived group, LG), 593 of their offspring (age 60–77, offspring group, OG) and 582 ethnic-matched healthy controls (aged 60–75, control group, CG) from Hongshui River Basin. The correlations of genotypes with metabolic risks were then determined.

Results

As a result, no statistical difference was observed on the distribution of allelic and genotypic frequencies of BDNF Val66Met among the three groups (all P > 0.05) except that AA genotype was dramatically higher in females than in males of CG. The HDL-C level of A allele (GA/AA genotype) carriers was profoundly lower than was non-A (GG genotype) carriers in the total population and the CG (P = 0.009 and 0.006, respectively), which maintained in females, hyperglycemic and normolipidemic subgroup of CG after stratification by gender, BMI, glucose and lipid status. Furthermore, allele A carriers, with a higher systolic blood pressure, exhibited 1.63 folds higher risk than non-A carriers to be overweight in CG (OR = 1.63, 95% CI: 1.05 - 2.55, P = 0.012). Multiple regression analysis displayed that the TC level of LG reversely associated with BDNF Val66Met genotype.

Conclusions

These data suggested that BDNF 66Met may play unfavorable roles in blood pressure and lipid profiles in the general population in Hongshui River area which might in part underscore their poorer survivorship versus the successful aging individuals and their offspring.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0393-0) contains supplementary material, which is available to authorized users.

Activity-Based Anorexia Alters the Expression of BDNF Transcripts in the Mesocorticolimbic Reward Circuit

Anorexia nervosa (AN) is a complex eating disorder with severe dysregulation of appetitive behavior. The activity-based anorexia (ABA) paradigm is an animal model in which rodents exposed to both running wheels and scheduled feeding develop aspects of AN including paradoxical hypophagia, dramatic weight loss, and hyperactivity, while animals exposed to only one condition maintain normal body weight. Brain-derived neurotrophic factor (BDNF), an activity-dependent modulator of neuronal plasticity, is reduced in the serum of AN patients, and is a known regulator of feeding and weight maintenance. We assessed the effects of scheduled feeding, running wheel access, or both on the expression of BDNF transcripts within the mesocorticolimbic pathway. We also assessed the expression of neuronal cell adhesion molecule 1 (NCAM1) to explore the specificity of effects on BDNF within the mesocorticolimbic pathway. Scheduled feeding increased the levels of both transcripts in the hippocampus (HPC), increased NCAM1 mRNA expression in the ventral tegmental area (VTA), and decreased BDNF mRNA levels in the medial prefrontal cortex (mPFC). In addition, wheel running increased BDNF mRNA expression in the VTA. No changes in either transcript were observed in the nucleus accumbens (NAc). Furthermore, no changes in either transcript were induced by the combined scheduled feeding and wheel access condition. These data indicate that scheduled feeding or wheel running alter BDNF and NCAM1 expression levels in specific regions of the mesocorticolimbic pathway. These findings contribute to our current knowledge of the molecular alterations induced by ABA and may help elucidate possible mechanisms of AN pathology.

Identification of mutations through dominant screening for obesity using C57BL/6 substrains

The discovery of leptin substantiated the usefulness of a forward genetic approach in elucidating the molecular network regulating energy metabolism. However, no successful dominant screening for obesity has been reported, which may be due to the influence of quantitative trait loci between the screening and counter strains and the low fertility of obese mice. Here, we performed a dominant screening for obesity using C57BL/6 substrains, C57BL/6J and C57BL/6N, with the routine use of in vitro fertilization. The screening of more than 5000 mutagenized mice established two obese pedigrees in which single nucleotide substitutions in Mc4r and Sim1 genes were identified through whole-exome sequencing. The mutation in the Mc4r gene produces a premature stop codon, and the mutant SIM1 protein lacks transcriptional activity, showing that the haploinsufficiency of SIM1 and MC4R results in obesity. We further examined the hypothalamic neuropeptide expressions in the mutant pedigrees and mice with diet-induced obesity, which showed that each obesity mouse model has distinct neuropeptide expression profiles. This forward genetic screening scheme is useful and applicable to any research field in which mouse models work.