Accelerated biological aging as potential mediator mediates the relationship between pro-inflammatory diets and the risk of depression and anxiety: A prospective analysis from the UK biobank.

BACKGROUND: The relationship between inflammatory dietary patterns and the risk of depression/anxiety has not been clearly established due to differences in study populations, geographic regions, sex, and methods of calculating the inflammatory index. METHODS: We drew upon a prospective cohort in the UK Biobank and calculated the energy-adjusted dietary inflammatory index (E-DII). The follow-up time was defined from the date of completing the last dietary survey questionnaire to the date of diagnosis of depression, anxiety, phobic anxiety, other types of anxiety, death, loss to follow-up, or the respective censoring dates for England (September 30, 2021), Scotland (July 31, 2021), and Wales (February 28, 2018). The final follow-up times end on September 30, 2021, July 31, 2021, and February 28, 2018, for England, Scotland, and Wales, respectively. During the follow-up process, if a participant develops the condition, dies, or is lost to follow-up, the follow-up is terminated. We used Cox regression to evaluate the connection between E-DII and depression/anxiety. We employed restricted cubic spline curves for nonlinear relationships. We also conducted mediation analyses to explore whether biological age mediated the relationship between E-DII and depression. Additionally, we investigated whether genetic susceptibility modified the relationship between E-DII and depression through interaction modeling. RESULTS: In the final analysis, we included a total of 151,295, 159,695, 165,649, and 160,097 participants for the analysis of depression, all types of anxiety, specific phobia anxiety, and other types of anxiety, respectively. For every one-unit increase in E-DII, the risk of experiencing depression and anxiety increased by 5 % and 4 %, respectively. We identified a "J"-shaped nonlinear relationship (P for nonlinear = 0.003) for both depression and anxiety. A significant association with an elevated risk of depression was observed when E-DII exceeded 0.440, and an increased risk of anxiety was noted when E-DII was more than -0.196. Mediation analysis demonstrated that PhenoAge age acceleration (AA) (For depression, proportion of mediation = 9.6 %; For anxiety, proportion of mediation = 10.1 %) and Klemera-Doubal method Biological Age (KDM AA) (For depression, proportion of mediation = 2.9 %; For anxiety, proportion of mediation = 5.1 %) acted as mediators between E-DII and the development of depression and anxiety (P < 0.05). CONCLUSIONS: Diets with pro-inflammatory characteristics are associated with a heightened risk of depression and anxiety. Furthermore, the association of pro-inflammatory diets and depression is mediated by biological age.

Natural compounds as obesity pharmacotherapies.

Obesity has become a serious global public health problem, affecting over 988 million people worldwide. Nevertheless, current pharmacotherapies have proven inadequate. Natural compounds have garnered significant attention due to their potential antiobesity effects. Over the past three decades, ca. 50 natural compounds have been evaluated for the preventive and/or therapeutic effects on obesity in animals and humans. However, variations in the antiobesity efficacies among these natural compounds have been substantial, owing to differences in experimental designs, including variations in animal models, dosages, treatment durations, and administration methods. The feasibility of employing these natural compounds as pharmacotherapies for obesity remained uncertain. In this review, we systematically summarized the antiobesity efficacy and mechanisms of action of each natural compound in animal models. This comprehensive review furnishes valuable insights for the development of antiobesity medications based on natural compounds.

Independent activation of CREB3L2 by glucose fills a regulatory gap in mouse ß-cells by co-ordinating insulin biosynthesis with secretory granule formation.

OBJECTIVE: Although individual steps have been characterized, there is little understanding of the overall process whereby glucose co-ordinates the biosynthesis of insulin with its export out of the endoplasmic reticulum (ER) and incorporation into insulin secretory granules (ISGs). Here we investigate a role for the transcription factor CREB3L2 in this context. METHODS: MIN6 cells and mouse islets were analysed by immunoblotting after treatment with glucose, fatty acids, thapsigargin and various inhibitors. Knockdown of CREB3L2 was achieved using si or sh constructs by transfection, or viral delivery. In vivo metabolic phenotyping was conducted after deletion of CREB3L2 in ß-cells of adult mice using Ins1-CreER+. Islets were isolated for RNAseq and assays of glucose-stimulated insulin secretion (GSIS). Trafficking was monitored in islet monolayers using a GFP-tagged proinsulin construct that allows for synchronised release from the ER. RESULTS: With a Km ≈3.5 mM, glucose rapidly (T1/2 0.9 h) increased full length (FL) CREB3L2 followed by a slower rise (T1/2 2.5 h) in its transcriptionally-active cleavage product, P60 CREB3L2. Glucose stimulation repressed the ER stress marker, CHOP, and this was partially reverted by knockdown of CREB3L2. Activation of CREB3L2 by glucose was not due to ER stress, however, but a combination of O-GlcNAcylation, which impaired proteasomal degradation of FL-CREB3L2, and mTORC1 stimulation, which enhanced its conversion to P60. cAMP generation also activated CREB3L2, but independently of glucose. Deletion of CREB3L2 inhibited GSIS ex vivo and, following a high-fat diet (HFD), impaired glucose tolerance and insulin secretion in vivo. RNAseq revealed that CREB3L2 regulated genes controlling trafficking to-and-from the Golgi, as well as a broader cohort associated with ß-cell compensation during a HFD. Although post-Golgi trafficking appeared intact, knockdown of CREB3L2 impaired the generation of both nascent ISGs and proinsulin condensates in the Golgi, implying a defect in ER export of proinsulin and/or its processing in the Golgi. CONCLUSION: The stimulation of CREB3L2 by glucose defines a novel, rapid and direct mechanism for co-ordinating the synthesis, packaging and storage of insulin, thereby minimizing ER overload and optimizing ß-cell function under conditions of high secretory demand. Upregulation of CREB3L2 also potentially contributes to the benefits of GLP1 agonism and might in itself constitute a novel means of treating ß-cell failure.

The evaluation of cognitive-behavioral therapy-based intervention on type 2 diabetes patients with comorbid metabolic syndrome: a randomized controlled trial.

BACKGROUND: Cognitive behavior therapy (CBT) has been applied in intervention research in diabetes patients with satisfying results. However, there was no research on type 2 diabetes (T2DM) patients with comorbidities. This study aimed to investigate the effectiveness of CBT on psychological variables, behavior variables, quality of life, sleep quality, and physical variables among adult T2DM patients with comorbid metabolic syndrome (MS). METHODS: 281 patients aged 18-75 years were recruited from Ningbo First Hospital in China from October 2021 to March 2022. Patients were randomized to the intervention group (IG, N = 148) or control group (CG, N = 133). Patients in the IG received 12 CBT-based sessions during a six-month intervention time. Patients in the CG received the usual care only. Univariate General Linear Model was used to analyze the effect of CBT-based interventions. The analysis was conducted by SPSS Version 28. RESULTS: Results indicated that CBT-based intervention was superior in the following aspects: relieving depression symptoms: IG (4.11 ± 4.35 vs. 1.99 ± 2.12), CG (3.40 ± 3.26 vs. 2.32 ± 1.88), interaction effect (F = 4.074, P = 0.044); enhancing diabetes self-care behaviors: IG (26.79 ± 12.18 vs. 37.49 ± 10.83), CG (25.82 ± 13.71 vs. 31.96 ± 11.72), interaction effect (F = 5.242, P = 0.022); promoting the efficacy of CBT: IG (47.45 ± 6.83 vs. 50.76 ± 4.98), CG (46.74 ± 6.94 vs. 47.87 ± 5.11), interaction effect (F = 5.198, P = 0.023); improving subjective sleep quality: IG (0.93 ± 0.68 vs. 0.69 ± 0.63), CG (1.03 ± 0.72 vs. 1.01 ± 0.68), interaction effect (F = 3.927, P = 0.048). CONCLUSIONS: The CBT-based intervention was beneficial in improving depression symptoms, diabetes self-care behaviors, the efficacy of CBT, and sleep quality in T2DM patients with comorbid MS. The downtrend of body mass index, systolic blood pressure, diastolic pressure, and glycated hemoglobin was larger in the intervention group but not to a significant level. TRIAL REGISTRATION: This study has been prospectively registered at Australia New Zealand Clinical Trials Registry (Registration ID: ACTRN12621001348842 website: https://www.anzctr.org.au/trial/MyTrial.aspx ).

Potential for NPY receptor-related therapies for polycystic ovary syndrome: an updated review.

Polycystic ovary syndrome (PCOS) is a complex endocrine disease that can cause female infertility and bring economic burden to families and to society. The clinical and/or biochemical manifestations include hyperandrogenism, persistent anovulation, and polycystic ovarian changes, often accompanied by insulin resistance and obesity. Although its pathogenesis is unclear, PCOS involves the abnormal regulation of the hypothalamic-pituitary-ovarian axis and the abnormal activation of GnRH neurons. Neuropeptide Y (NPY) is widely distributed in the arcuate nucleus of the hypothalamus and functions as the physiological integrator of two neuroendocrine systems, one governing feeding and the other controlling reproduction. In recent years, an increasing number of studies have focused on the improvement of the reproductive and metabolic status of PCOS through the therapeutic application of NPY and its receptors. In this review, we summarize the central and peripheral regulation of NPY and its receptors in the development of PCOS and discuss the potential for NPY receptor-related therapies for PCOS.

The effect of Parkin gene S/N 167 polymorphism on resting spontaneous brain functional activity in Parkinson's Disease.

BACKGROUND: Genetic susceptibility plays a significant role in Parkinson's disease (PD) development. Carriers of the Parkin S/N167 mutation may have an increased risk of PD and altered spontaneous brain activity. OBJECTIVE: This study aims to investigate the potential pathogenesis of PD through a comparative analysis of the amplitude of low-frequency fluctuations (ALFF) in resting-state functional magnetic resonance imaging (rs-fMRI) of subjects with Parkin gene S/N 167 polymorphisms, and to examine the association between spontaneous brain activity and clinical scale scores of PD. METHODS: A total of 69 PD patients and 84 healthy controls (HC) were included in the study. Each subject was genotyped for the Parkin gene S/N 167 polymorphism and underwent rs-fMRI scans. ALFF analysis was employed to evaluate the relationship among genotypes, interactive brain regions, and clinical symptoms in PD. RESULTS: PD patients exhibited decreased ALFF values in the right anterior lobe and vermis of the cerebellum compared to HC. No significant interaction was found between the gene's main effect and the "group × genotype" effect on brain ALFF values. One-factor ANOVA revealed no significant difference in ALFF values between PD subgroups; however, the ALFF values in the right anterior lobe and vermis of the cerebellum were lower in the PD-G and PD-GA groups compared to the HC-G and HC-GA groups. Spearman correlation analysis demonstrated that ALFF values in the PD-GG and PD-GA groups were negatively associated with UPDRS-III scores in the bilateral lingual gyrus (Lingual R/L). CONCLUSION: Parkin gene S/N 167 polymorphisms may influence brain functional activity in specific brain regions, and ALFF values are associated with motor symptoms in PD patients.

Critical role of lateral habenula circuits in the control of stress-induced palatable food consumption.

Chronic stress fuels the consumption of palatable food and can enhance obesity development. While stress- and feeding-controlling pathways have been identified, how stress-induced feeding is orchestrated remains unknown. Here, we identify lateral habenula (LHb) Npy1r-expressing neurons as the critical node for promoting hedonic feeding under stress, since lack of Npy1r in these neurons alleviates the obesifying effects caused by combined stress and high fat feeding (HFDS) in mice. Mechanistically, this is due to a circuit originating from central amygdala NPY neurons, with the upregulation of NPY induced by HFDS initiating a dual inhibitory effect via Npy1r signaling onto LHb and lateral hypothalamus neurons, thereby reducing the homeostatic satiety effect through action on the downstream ventral tegmental area. Together, these results identify LHb-Npy1r neurons as a critical node to adapt the response to chronic stress by driving palatable food intake in an attempt to overcome the negative valence of stress.

Deficiency of neuropeptide Y attenuates neointima formation after vascular injury in mice.

BACKGROUND: Restenosis after percutaneous coronary intervention (PCI) limits therapeutic revascularization. Neuropeptide Y (NPY), co-stored and co-released with the sympathetic nervous system, is involved in this process, but its exact role and underlying mechanisms remain to be fully understood. This study aimed to investigate the role of NPY in neointima formation after vascular injury. METHODS: Using the left carotid arteries of wild-type (WT, NPY-intact) and NPY-deficient (NPY-/-) mice, ferric chloride-mediated carotid artery injury induced neointima formation. Three weeks after injury, the left injured carotid artery and contralateral uninjured carotid artery were collected for histological analysis and immunohistochemical staining. RT-qPCR was used to detect the mRNA expression of several key inflammatory markers and cell adhesion molecules in vascular samples. Raw264.7 cells were treated with NPY, lipopolysaccharide (LPS), and lipopolysaccharide-free, respectively, and RT-qPCR was used to detect the expression of these inflammatory mediators. RESULTS: Compared with WT mice, NPY-/- mice had significantly reduced neointimal formation three weeks after injury. Mechanistically, immunohistochemical analysis showed there were fewer macrophages and more vascular smooth muscle cells in the neointima of NPY-/- mice. Moreover, the mRNA expression of key inflammatory markers such as interleukin-6 (IL-6), transforming growth factor-ß1 (TGF-ß1), and intercellular adhesion molecule-1 (ICAM-1) was significantly lower in the injured carotid arteries of NPY-/- mice, compared to that in the injured carotid arteries of WT mice. In RAW264.7 macrophages, NPY significantly promoted TGF-ß1 mRNA expression under unactivated but not LPS-stimulated condition. CONCLUSIONS: Deletion of NPY attenuated neointima formation after artery injury, at least partly, through reducing the local inflammatory response, suggesting that NPY pathway may provide new insights into the mechanism of restenosis.

Monitoring AKT activity and targeting in live tissue and disease contexts using a real-time Akt-FRET biosensor mouse.

Aberrant AKT activation occurs in a number of cancers, metabolic syndrome, and immune disorders, making it an important target for the treatment of many diseases. To monitor spatial and temporal AKT activity in a live setting, we generated an Akt-FRET biosensor mouse that allows longitudinal assessment of AKT activity using intravital imaging in conjunction with image stabilization and optical window technology. We demonstrate the sensitivity of the Akt-FRET biosensor mouse using various cancer models and verify its suitability to monitor response to drug targeting in spheroid and organotypic models. We also show that the dynamics of AKT activation can be monitored in real time in diverse tissues, including in individual islets of the pancreas, in the brown and white adipose tissue, and in the skeletal muscle. Thus, the Akt-FRET biosensor mouse provides an important tool to study AKT dynamics in live tissue contexts and has broad preclinical applications.

Identification of indocyanine green as a STT3B inhibitor against mushroom α-amanitin cytotoxicity.

The "death cap", Amanita phalloides, is the world's most poisonous mushroom, responsible for 90% of mushroom-related fatalities. The most fatal component of the death cap is α-amanitin. Despite its lethal effect, the exact mechanisms of how α-amanitin poisons humans remain unclear, leading to no specific antidote available for treatment. Here we show that STT3B is required for α-amanitin toxicity and its inhibitor, indocyanine green (ICG), can be used as a specific antidote. By combining a genome-wide CRISPR screen with an in silico drug screening and in vivo functional validation, we discover that N-glycan biosynthesis pathway and its key component, STT3B, play a crucial role in α-amanitin toxicity and that ICG is a STT3B inhibitor. Furthermore, we demonstrate that ICG is effective in blocking the toxic effect of α-amanitin in cells, liver organoids, and male mice, resulting in an overall increase in animal survival. Together, by combining a genome-wide CRISPR screen for α-amanitin toxicity with an in silico drug screen and functional validation in vivo, our study highlights ICG as a STT3B inhibitor against the mushroom toxin.

ß-cell function is regulated by metabolic and epigenetic programming of islet-associated macrophages, involving Axl, Mertk, and TGFß receptor signaling.

We have exploited islet-associated macrophages (IAMs) as a model of resident macrophage function, focusing on more physiological conditions than the commonly used extremes of M1 (inflammation) versus M2 (tissue remodeling) polarization. Under steady state, murine IAMs are metabolically poised between aerobic glycolysis and oxidative phosphorylation, and thereby exert a brake on glucose-stimulated insulin secretion (GSIS). This is underpinned by epigenetic remodeling via the metabolically regulated histone demethylase Kdm5a. Conversely, GSIS is enhanced by engaging Axl receptors on IAMs, or by augmenting their oxidation of glucose. Following high-fat feeding, efferocytosis is stimulated in IAMs in conjunction with Mertk and TGFß receptor signaling. This impairs GSIS and potentially contributes to ß-cell failure in pre-diabetes. Thus, IAMs serve as relays in many more settings than currently appreciated, fine-tuning insulin secretion in response to dynamic changes in the external environment. Intervening in this nexus might represent a means of preserving ß-cell function during metabolic disease.

The combined effect of metformin and mirabegron on diet-induced obesity.

Anti-obesity medications act by suppressing energy intake (EI), promoting energy expenditure (EE), or both. Metformin (Met) and mirabegron (Mir) cause weight loss by targeting EI and EE, respectively. However, anti-obesity effects during concurrent use of both have yet to be explored. In this study, we investigated the anti-obesity effects, metabolic benefits, and underlying mechanisms of Met/Mir combination therapy in two clinically relevant contexts: the prevention model and the treatment model. In the prevention model, Met/Mir caused further 12% and 14% reductions in body weight (BW) gain induced by a high-fat diet compared to Met or Mir alone, respectively. In the treatment model, Met/Mir additively promoted 17% BW loss in diet-induced obese mice, which was 13% and 6% greater than Met and Mir alone, respectively. Additionally, Met/Mir improved glucose tolerance and insulin sensitivity. These benefits of Met/Mir were associated with increased EE, activated brown adipose tissue thermogenesis, and white adipose tissue browning. Significantly, Met/Mir did not cause cardiovascular dysfunction in either model. Together, the combination of Met and Mir could be a promising approach for the prevention and treatment of obesity by targeting both EI and EE simultaneously.

The role of dietary salt in metabolism and energy balance: Insights beyond cardiovascular disease.

Dietary salt (NaCl) is essential to an organism's survival. However, today's diets are dominated by excessive salt intake, which significantly impacts individual and population health. High salt intake is closely linked to cardiovascular disease (CVD), especially hypertension, through a number of well-studied mechanisms. Emerging evidence indicates that salt overconsumption may also be associated with metabolic disorders. In this review, we first summarize recent updates on the mechanisms of salt-induced CVD, the effects of salt reduction and the use of salt substitution as a therapy. Next, we focus on how high salt intake can impact metabolism and energy balance, describing the mechanisms through which this occurs, including leptin resistance, the overproduction of fructose and ghrelin, insulin resistance and altered hormonal factors. A further influence on metabolism worth noting is the reported role of salt in inducing thermogenesis and increasing body temperature, leading to an increase in energy expenditure. While this result could be viewed as a positive metabolic effect because it promotes a negative energy balance to combat obesity, caution must be taken with this frame of thinking given the deleterious consequences of chronic high salt intake on cardiovascular health. Nevertheless, this review highlights the importance of salt as a noncaloric nutrient in regulating whole-body energy homeostasis. Through this review, we hope to provide a scientific framework for future studies to systematically address the metabolic impacts of dietary salt and salt replacement treatments. In addition, we hope to form a foundation for future clinical trials to explore how these salt-induced metabolic changes impact obesity development and progression, and to elucidate the regulatory mechanisms that drive these changes, with the aim of developing novel therapeutics for obesity and CVD.

Recent progress on the role of non-coding RNA in postoperative cognitive dysfunction.

Postoperative cognitive dysfunction (POCD), especially in elderly patients, is a serious complication characterized by impairment of cognitive and sensory modalities after surgery. The pathogenesis of POCD mainly includes neuroinflammation, neuronal apoptosis, oxidative stress, accumulation of Aß, and tau hyperphosphorylation; however, the exact mechanism remains unclear. Non-coding RNA (ncRNA) may play an important role in POCD. Some evidence suggests that microRNA, long ncRNA, and circular RNA can regulate POCD-related processes, making them promising biomarkers in POCD diagnosis, treatment, and prognosis. This article reviews the crosstalk between ncRNAs and POCD, and systematically discusses the role of ncRNAs in the pathogenesis and diagnosis of POCD. Additionally, we explored the possible mechanisms of ncRNA-associated POCD, providing new knowledge for developing ncRNA-based treatments for POCD.

Research progress on the role of exosomes in obstructive sleep apnea-hypopnea syndrome-related atherosclerosis.

Cardiovascular disease (CVD) is a leading cause of mortality worldwide. Atherosclerosis, a multifactorial disease with complicated pathogenesis, is the main cause of CVD, underlying several major adverse cardiovascular events. Obesity is the main cause of obstructive sleep apnea (OSA) and a significant risk for atherosclerosis. OSA is an independent risk factor for CVD. Recent research has focused on understanding the underlying molecular mechanisms by which OSA influences atherosclerosis pathogenesis. The role of exosomes in this process has attracted considerable attention. Exosomes are a type of extracellular vesicles (EV) that are released from many cells (both healthy and diseased) and mediate cell-to-cell communication by transporting microRNAs (miRNAs), proteins, mRNAs, DNA, or lipids to target cells, thereby modulating the functions of target cells and tissues. Intermittent hypoxia in OSA alters the exosomal carrier in circulation and promotes the permeability and dysfunction of endothelial cells, which have been associated with the pathogenesis of atherosclerosis. This review discusses the potential roles of exosomes and exosome-derived molecules in the development and progression of OSA-related atherosclerosis. Additionally, we explore the possible mechanisms underlying OSA-related atherosclerosis and provide new insights for the development of novel exosome-based therapeutics for OSA-related atherosclerosis and CVD.

Osteoporosis pathogenesis and treatment: existing and emerging avenues.

Osteoporotic fractures lead to increased disability and mortality in the elderly population. With the rapid increase in the aging population around the globe, more effective treatments for osteoporosis and osteoporotic fractures are urgently required. The underlying molecular mechanisms of osteoporosis are believed to be due to the increased activity of osteoclasts, decreased activity of osteoblasts, or both, which leads to an imbalance in the bone remodeling process with accelerated bone resorption and attenuated bone formation. Currently, the available clinical treatments for osteoporosis have mostly focused on factors influencing bone remodeling; however, they have their own limitations and side effects. Recently, cytokine immunotherapy, gene therapy, and stem cell therapy have become new approaches for the treatment of various diseases. This article reviews the latest research on bone remodeling mechanisms, as well as how this underpins current and potential novel treatments for osteoporosis.

Metabolic disorders on cognitive dysfunction after traumatic brain injury.

Cognitive dysfunction is a common adverse consequence of traumatic brain injury (TBI). After brain injury, the brain and other organs trigger a series of complex metabolic changes, including reduced glucose metabolism, enhanced lipid peroxidation, disordered neurotransmitter secretion, and imbalanced trace element synthesis. In recent years, several research and clinical studies have demonstrated that brain metabolism directly or indirectly affects cognitive dysfunction after TBI, but the mechanisms remain unclear. Drugs that improve the symptoms of cognitive dysfunction caused by TBI are under investigation and treatments that target metabolic processes are expected to improve cognitive function in the future. This review explores the impact of metabolic disorders on cognitive dysfunction after TBI and provides new strategies for the treatment of metabolic disorders.

TNFAIP3 Reduction-of-Function Drives Female Infertility and CNS Inflammation.

Women with autoimmune and inflammatory aetiologies can exhibit reduced fecundity. TNFAIP3 is a master negative regulator of inflammation, and has been linked to many inflammatory conditions by genome wide associations studies, however its role in fertility remains unknown. Here we show that mice harbouring a mild Tnfaip3 reduction-of-function coding variant (Tnfaip3I325N) that reduces the threshold for inflammatory NF-κB activation, exhibit reduced fecundity. Sub-fertility in Tnfaip3I325N mice is associated with irregular estrous cycling, low numbers of ovarian secondary follicles, impaired mammary gland development and insulin resistance. These pathological features are associated with infertility in human subjects. Transplantation of Tnfaip3I325N ovaries, mammary glands or pancreatic islets into wild-type recipients rescued estrous cycling, mammary branching and hyperinsulinemia respectively, pointing towards a cell-extrinsic hormonal mechanism. Examination of hypothalamic brain sections revealed increased levels of microglial activation with reduced levels of luteinizing hormone. TNFAIP3 coding variants may offer one contributing mechanism for the cause of sub-fertility observed across otherwise healthy populations as well as for the wide variety of auto-inflammatory conditions to which TNFAIP3 is associated. Further, TNFAIP3 represents a molecular mechanism that links heightened immunity with neuronal inflammatory homeostasis. These data also highlight that tuning-up immunity with TNFAIP3 comes with the potentially evolutionary significant trade-off of reduced fertility.

XBP1 maintains beta cell identity, represses beta-to-alpha cell transdifferentiation and protects against diabetic beta cell failure during metabolic stress in mice.

AIMS/HYPOTHESIS: Pancreatic beta cell dedifferentiation, transdifferentiation into other islet cells and apoptosis have been implicated in beta cell failure in type 2 diabetes, although the mechanisms are poorly defined. The endoplasmic reticulum stress response factor X-box binding protein 1 (XBP1) is a major regulator of the unfolded protein response. XBP1 expression is reduced in islets of people with type 2 diabetes, but its role in adult differentiated beta cells is unclear. Here, we assessed the effects of Xbp1 deletion in adult beta cells and tested whether XBP1-mediated unfolded protein response makes a necessary contribution to beta cell compensation in insulin resistance states. METHODS: Mice with inducible beta cell-specific Xbp1 deletion were studied under normal (chow diet) or metabolic stress (high-fat diet or obesity) conditions. Glucose tolerance, insulin secretion, islet gene expression, alpha cell mass, beta cell mass and apoptosis were assessed. Lineage tracing was used to determine beta cell fate. RESULTS: Deletion of Xbp1 in adult mouse beta cells led to beta cell dedifferentiation, beta-to-alpha cell transdifferentiation and increased alpha cell mass. Cell lineage-specific analyses revealed that Xbp1 deletion deactivated beta cell identity genes (insulin, Pdx1, Nkx6.1, Beta2, Foxo1) and derepressed beta cell dedifferentiation (Aldh1a3) and alpha cell (glucagon, Arx, Irx2) genes. Xbp1 deletion in beta cells of obese ob/ob or high-fat diet-fed mice triggered diabetes and worsened glucose intolerance by disrupting insulin secretory capacity. Furthermore, Xbp1 deletion increased beta cell apoptosis under metabolic stress conditions by attenuating the antioxidant response. CONCLUSIONS/INTERPRETATION: These findings indicate that XBP1 maintains beta cell identity, represses beta-to-alpha cell transdifferentiation and is required for beta cell compensation and prevention of diabetes in insulin resistance states.

Arcuate NPY is involved in salt-induced hypertension via modulation of paraventricular vasopressin and brain-derived neurotrophic factor.

Chronic high salt intake is one of the leading causes of hypertension. Salt activates the release of the key neurotransmitters in the hypothalamus such as vasopressin to increase blood pressure, and neuropepetide Y (NPY) has been implicated in the modulation of vasopressin levels. NPY in the hypothalamic arcuate nucleus (Arc) is best known for its control in appetite and energy homeostasis, but it is unclear whether it is also involved in the development of salt-induced hypertension. Here, we demonstrate that wild-type mice given 2% NaCl salt water for 8 weeks developed hypertension which was associated with marked downregulation of NPY expression in the hypothalamic Arc as demonstrated in NPY-GFP reporter mice as well as by in situ hybridization analysis. Furthermore, salt intake activates neurons in the hypothalamic paraventricular nucleus (PVN) where mRNA expression of brain-derived neurotrophic factor (BDNF) and vasopressin was found to be upregulated, leading to elevated serum vasopressin levels. This finding suggests an inverse correlation between the Arc NPY level and expression of vasopressin and BDNF in the PVN. Specific restoration of NPY by injecting AAV-Cre recombinase into the Arc only of the NPY-targeted mutant mice carrying a loxP-flanked STOP cassette reversed effects of salt intake on vasopressin and BDNF expression, leading to a normalization of salt-dependent blood pressure. In summary, our study uncovers an important Arc NPY-originated neuronal circuitry that could sense and respond to peripheral electrolyte signals and thereby regulate hypertension via vasopressin and BDNF in the PVN.