Disruption Of Energy Homeostasis Research Articles

Bcl-2-dependent autophagy disruption during aging impairs amino acid utilization that is restored by hochuekkito

Chronic undernutrition contributes to the increase in frailty observed among elderly adults, which is a pressing issue in the sector of health care for older people worldwide. Autophagy, an intracellular recycling system, is closely associated with age-related pathologies. Therefore, decreased autophagy in aging could be involved in the disruption of energy homeostasis that occurs during undernutrition; however, the physiological mechanisms underlying this process remain unknown. Here, we showed that 70% daily food restriction (FR) induced fatal hypoglycemia in 23–26-month-old (aged) mice, which exhibited significantly lower hepatic autophagy than 9-week-old (young) mice. The liver expressions of Bcl-2, an autophagy-negative regulator, and Beclin1–Bcl-2 binding, were increased in aged mice compared with young mice. The autophagy inducer Tat-Beclin1 D11, not the mTOR inhibitor rapamycin, decreased the plasma levels of the glucogenic amino acid and restored the blood glucose levels in aged FR mice. Decreased liver gluconeogenesis, body temperature, physical activity, amino acid metabolism, and hepatic mitochondrial dynamics were observed in the aged FR mice. These changes were restored by treatment with hochuekkito that is a herbal formula containing several autophagy-activating ingredients. Our results indicate that Bcl-2 upregulation in the liver during the aging process disturbs autophagy activation, which increases the vulnerability to undernutrition. The promotion of liver autophagy may offer clinical therapeutic benefits to frail elderly patients.

Restoration of energy homeostasis by SIRT6 extends healthy lifespan

Aging leads to a gradual decline in physical activity and disrupted energy homeostasis. The NAD+-dependent SIRT6 deacylase regulates aging and metabolism through mechanisms that largely remain unknown. Here, we show that SIRT6 overexpression leads to a reduction in frailty and lifespan extension in both male and female B6 mice. A combination of physiological assays, in vivo multi-omics analyses and 13C lactate tracing identified an age-dependent decline in glucose homeostasis and hepatic glucose output in wild type mice. In contrast, aged SIRT6-transgenic mice preserve hepatic glucose output and glucose homeostasis through an improvement in the utilization of two major gluconeogenic precursors, lactate and glycerol. To mediate these changes, mechanistically, SIRT6 increases hepatic gluconeogenic gene expression, de novo NAD+ synthesis, and systemically enhances glycerol release from adipose tissue. These findings show that SIRT6 optimizes energy homeostasis in old age to delay frailty and preserve healthy aging.

Exploiting the metabolic energy demands of drug efflux pumps provides a strategy to overcome multidrug resistance in cancer

BackgroundP-glycoprotein (P-gp) is a prevalent resistance mediator and it requires considerable cellular energy to ensure ATP dependent efflux of anticancer drugs. The glycolytic pathway generates the majority of catabolic energy in cancer cells; however, the high rates of P-gp activity places added strain on its inherently limited capacity to generate ATP. This is particularly relevant for compounds such as verapamil that are believed to trap P-gp in a futile transport process that requires continuing ATP consumption. Ultimately, this leads to cell death and the hypersensitivity of resistant cells to verapamil is termed collateral sensitivity. ResultsWe show that the addition of verapamil to resistant cells produces a prominent reduction in ATP levels that supports the idea of disrupted energy homeostasis. Even in the absence of verapamil, P-gp expressing cells display near maximal rates of glycolysis and oxidative phosphorylation, which prevents an adequate response to the demand for ATP to sustain transport activity. Moreover, the near perpetually maximal rate of oxidative phosphorylation in the presence of verapamil resulted in elevated levels of reactive oxygen species that affect cell survival and underscore collateral sensitivity. ConclusionsOur results demonstrate that the strained metabolic profiles of P-gp expressing resistant cancer cells can be overwhelmed by additional ATP demands. General significanceConsequently, collateral sensitising drugs may overcome the resistant phenotype by exploiting, rather than inhibiting, the energy demanding activity of pumps such as P-gp.

Contributions of white and brown adipose tissues to the circadian regulation of energy metabolism.

The term energy metabolism comprises the entirety of chemical processes associated with uptake, conversion, storage, and breakdown of nutrients. All these must be tightly regulated in time and space to ensure metabolic homeostasis in an environment characterized by cycles such as the succession of day and night. Most organisms evolved endogenous circadian clocks to achieve this goal. In mammals, a ubiquitous network of cellular clocks is coordinated by a pacemaker residing in the hypothalamic suprachiasmatic nucleus. Adipocytes harbor their own circadian clocks, and large aspects of adipose physiology are regulated in a circadian manner through transcriptional regulation of clock-controlled genes. White adipose tissue (WAT) stores energy in the form of triglycerides at times of high energy levels that then serve as fuel in times of need. It also functions as an endocrine organ, releasing factors in a circadian manner to regulate food intake and energy turnover in other tissues. Brown adipose tissue (BAT) produces heat through nonshivering thermogenesis, a process also controlled by the circadian clock. We here review how WAT and BAT contribute to the circadian regulation of energy metabolism. We describe how adipose rhythms are regulated by the interplay of systemic signals and local clocks and summarize how adipose-originating circadian factors feed-back on metabolic homeostasis. The role of adipose tissue in the circadian control of metabolism becomes increasingly clear as circadian disruption leads to alterations in adipose tissue regulation, promoting obesity and its sequelae. Stabilizing adipose tissue rhythms, in turn, may help to combat disrupted energy homeostasis and obesity.

Nicotinamide ameliorates energy deficiency and improves retinal function in Cav-1-/- mice.

Caveolin-1(Cav-1) is involved in lipid metabolism and energy homeostasis, which is important for the energetically demanding retina. Although retinal function deficits were noted in Cav-1 knockout (Cav-1-/- ) mice, the underlying causes remain largely unknown. Here, we investigate if the disruption in energy homeostasis presents a potential mechanism for retinal function deficits in Cav-1-/- retina and if it can be ameliorated by nicotinamide (NAM).In this study, NAM was administrated orally for 2weeks in Cav-1-/- mice before experiments. Oxidative lipidomics was conducted to detect the oxylipin changes, the retinal energy flux was measured by seahorse assay, and the retinal function was assessed by electroretinogram (ERG). Cav-1 deficiency induced the dysregulation of oxidative lipidomics and reduction in energy consumption/production in the retina by decreasing Na+ /K+ -ATPase, oxidative phosphorylation CII, cytochrome c, and oxygen consumption rate (OCR). A decrease in Sirt1 was also detected. Therapeutic administration of NAM significantly increased Sirt1 expression and improved energy deficiency by increasing Na+ /K+ -ATPase, cytochrome c, and OCR. The dysregulation of oxidative lipidomics was partially recovered, and the retinal function was improved as assessed by ERG compared to Cav-1-/- mice. Our study demonstrated the dysregulation of oxidative lipidomicsin Cav-1-/- retina and established a link between energy deficiency and retinal function deficits in Cav-1-/- mice. Administration of NAM ameliorated energy deficiency, increased the expression of Sirt1, and improved retinal function, which presents a potential therapeutic strategy for Cav-1 deficiency-induced retinal function deficits.

Chronic exposure to methylmercury enhances the anorexigenic effects of leptin in C57BL/6J male mice

Several studies have demonstrated that heavy metals disrupt energy homeostasis. Leptin inhibits food intake and decreases body weight through activation of its receptor in the hypothalamus. The impact of heavy metals on leptin signaling in the hypothalamus is unclear. Here, we show that the environmental pollutant, methylmercury (MeHg), favors an anorexigenic profile in wild-type males. C57BL/6J mice were exposed to MeHg via drinking water (5 ppm) up to 30 days. Our data shows that MeHg exposure was associated with changes in leptin induced activation of Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in the hypothalamus. In males, the activation of JAK2/STAT3 signaling pathway was sustained by an increase in SOCS3 protein levels. In females, MeHg-activated STAT3 was inhibited by a concomitant increase in PTP1B. Taken together, our data suggest that MeHg enhanced leptin effects in males, favoring an anorexigenic profile in males, which notably, have been shown to be more sensitive to the neurological effects of this organometal than females. A better understanding of MeHg-induced molecular mechanism alterations in the hypothalamus advances the understanding of its neurotoxicity and provides molecular sites for novel therapies.

The Good, the Bad and the Unknown Aspects of Ghrelin in Stress Coping and Stress-Related Psychiatric Disorders.

Ghrelin is a peptide hormone released by specialized X/A cells in the stomach and activated by acylation. Following its secretion, it binds to ghrelin receptors in the periphery to regulate energy balance, but it also acts on the central nervous system where it induces a potent orexigenic effect. Several types of stressors have been shown to stimulate ghrelin release in rodents, including nutritional stressors like food deprivation, but also physical and psychological stressors such as foot shocks, social defeat, forced immobilization or chronic unpredictable mild stress. The mechanism through which these stressors drive ghrelin release from the stomach lining remains unknown and, to date, the resulting consequences of ghrelin release for stress coping remain poorly understood. Indeed, ghrelin has been proposed to act as a stress hormone that reduces fear, anxiety- and depression-like behaviors in rodents but some studies suggest that ghrelin may - in contrast - promote such behaviors. In this review, we aim to provide a comprehensive overview of the literature on the role of the ghrelin system in stress coping. We discuss whether ghrelin release is more than a byproduct of disrupted energy homeostasis following stress exposure. Furthermore, we explore the notion that ghrelin receptor signaling in the brain may have effects independent of circulating ghrelin and in what way this might influence stress coping in rodents. Finally, we examine how the ghrelin system could be utilized as a therapeutic avenue in stress-related psychiatric disorders (with a focus on anxiety- and trauma-related disorders), for example to develop novel biomarkers for a better diagnosis or new interventions to tackle relapse or treatment resistance in patients.

Obesity induced by estrogen deficiency is associated with hypothalamic inflammation

Occurrence of obesity during the postmenopausal period is closely associated with inflammatory processes in multiple peripheral organs that are metabolically active. Hypothalamic inflammation has been recognized as one of the major underlying causes of various metabolic disorders, including obesity. The association between menopause-related obesity and hypothalamic inflammation remains poorly understood. We observed an elevation in hypothalamic inflammation in the ovariectomized mice, which displayed altered metabolic phenotypes and visceral obesity. Furthermore, we confirmed that ovariectomized mice displayed microglial activation accompanied by the upregulation of multiple genes involved in the inflammatory responses in hypothalamic microglia. Collectively, the current findings suggest that hypothalamic inflammation associated with microglial functioning could be a major pathogenic element in disruption of energy homeostasis during the postmenopausal period.

Disruption of energy homeostasis by food restriction or high ambient temperature exposure affects gonadal function in male house finches (Haemorhous mexicanus).

Reproductive success requires that individuals acquire sufficient energy resources. Restricting food availability or increasing energy expenditure (e.g., thermoregulation) inhibits reproductive development in multiple avian species, but the nature of the energy-related signal mediating this effect is unclear. To investigate this question, we examined reproductive and metabolic physiology in male house finches that either underwent moderate food restriction (FR) or were exposed to high temperature (HT), in which birds were held at a high, but not locally atypical, ambient temperature cycle (37.8°C day, 29.4°C night) compared to a control group (CT; 29.4°C day, 21.1°C night). We hypothesized that FR and HT inhibit reproductive development by lowering available metabolic fuel, in particular plasma glucose (GLU) and free fatty acids (FFA). Following FR for 4weeks, finches lost body mass, had marginally higher plasma FFA, and experienced a 90% reduction in testis mass compared to CT birds. Four weeks of HT exposure resulted in reduced voluntary food consumption and muscle mass, as well as an 80% reduction in testis mass relative to CT birds. Both FR and HT birds expressed less testicular 17β-hydroxysteroid dehydrogenase (17β-HSD) mRNA than controls but the expression of other testicular genes measured was unaffected by either treatment. Neither treatment significantly influenced plasma GLU. This study is among the first to demonstrate a negative effect of HT on reproductive development in a wild bird. Further studies are needed to clarify the role of metabolic mediators and their involvement under various conditions of energy availability and demand.

0139 Associations of Actigraphic Sleep Parameters with Maximal Oxygen Consumption and Resting Metabolism in Well-Functioning Older Adults

Abstract Introduction Both poor sleep and poor cardiorespiratory fitness are common in older age and associated with negative health outcomes. Additionally, among older adults, higher resting metabolic rate (RMR) has been associated with increased morbidity and mortality risk. To evaluate whether, and in what ways, sleep may affect these relationships, we investigated the association of actigraphic sleep indices with cardiorespiratory fitness and RMR in older adults. Methods We studied 393 community-dwelling participants in the Baltimore Longitudinal Study of Aging (mean age 73.5±10.3 years, 52% women) who completed 6.7±0.9 nights of wrist actigraphy, RMR testing, and a maximal graded exercise test. Primary predictors included mean actigraphic total sleep time (TST, minutes), sleep efficiency (SE, %), wake after sleep onset (WASO, minutes), and average wake bout length (WBL, minutes). Cardiorespiratory fitness, as measured by maximal oxygen consumption (V O2MAX; ml/kg/min), and RMR (kcal/day) were the primary outcomes. Results After adjustment for age, sex, race, body mass index, comorbidity index, and depressive symptoms, longer WBL was associated with lower V O2MAX (β=-0.12, 95% confidence interval (CI)=-0.20, -0.04), greater WASO was associated with lower V O2MAX (β=-0.09, 95% CI=-0.17, -0.01), and greater SE was associated with higher V O2MAX (β=0.12, 95% CI=0.03, 0.20). In addition, longer TST was associated with lower RMR (β=-0.10, 95% CI=-0.19, -0.01) and longer WBL was linked to higher RMR (β=0.12, 95% CI=0.04, 0.21). Conclusion In well-functioning older adults, indices of greater wakefulness after sleep onset are linked with poorer cardiorespiratory fitness and higher resting metabolism, while longer and more efficient sleep are associated with better fitness and lower resting metabolic rate. Our findings suggest that sleep disturbance may be linked to disrupted energy homeostasis, evidenced by excessive energy expenditure at rest and inefficient energy utilization in response to maximal demands. Prospective analyses are necessary to determine the nature of these associations. Support This study was supported in part by National Institute on Aging (NIA) grants R01AG050507 and T32-AG027668, the NIA Intramural Research Program (IRP), and Research and Development Contract HHSN-260-2004-00012C.

Neurotrophic effects of GM1 ganglioside, NGF, and FGF2 on canine dorsal root ganglia neurons in vitro

Dogs share many chronic morbidities with humans and thus represent a powerful model for translational research. In comparison to rodents, the canine ganglioside metabolism more closely resembles the human one. Gangliosides are components of the cell plasma membrane playing a role in neuronal development, intercellular communication and cellular differentiation. The present in vitro study aimed to characterize structural and functional changes induced by GM1 ganglioside (GM1) in canine dorsal root ganglia (DRG) neurons and interactions of GM1 with nerve growth factor (NGF) and fibroblast growth factor (FGF2) using immunofluorescence for several cellular proteins including neurofilaments, synaptophysin, and cleaved caspase 3, transmission electron microscopy, and electrophysiology. GM1 supplementation resulted in increased neurite outgrowth and neuronal survival. This was also observed in DRG neurons challenged with hypoxia mimicking neurodegenerative conditions due to disruptions of energy homeostasis. Immunofluorescence indicated an impact of GM1 on neurofilament phosphorylation, axonal transport, and synaptogenesis. An increased number of multivesicular bodies in GM1 treated neurons suggested metabolic changes. Electrophysiological changes induced by GM1 indicated an increased neuronal excitability. Summarized, GM1 has neurotrophic and neuroprotective effects on canine DRG neurons and induces functional changes. However, further studies are needed to clarify the therapeutic value of gangliosides in neurodegenerative diseases.

PCB126 blocks the thermogenic beiging response of adipocytes.

Subcutaneous white adipose tissue is capable of becoming thermogenic in a process that is referred to as "beiging." Beiging is associated with activation of the uncoupling protein, UCP1, and is known to be important for preventing adipose hypertrophy and development of insulin resistance. Polychlorinated biphenyls (PCBs) accumulate in fat, and it is hypothesized that disruption of adipogenesis and adipocyte function by PCBs may be causative in the development of obesity and diabetes. We developed immortal human subcutaneous preadipocytes that, when differentiated, are capable of beiging. Preadipocytes that were treated with polychlorinated biphenyl congener 126 (PCB126), followed by differentiation, were suppressed for their ability to activate UCP1 upon β-adrenergic stimulation with norepinephrine (NE), demonstrating a block in the beiging response. Treatment of preadipocytes with another known endogenous AhR agonist, indoxyl sulfate (IS), followed by differentiation also blocked the NE-stimulated upregulation of UCP1. Knockdown of the aryl hydrocarbon receptor (AhR) caused the preadipocytes to be refractory to PCB126 and IS effects. The chemical AhR antagonist, CH223191, was effective at preventing the effects of PCB126 but not IS, indicating AhR ligand specificity of CH223191. Repression of NE-induced UCP1 upregulation was also observed when already-differentiated mature adipocytes were treated with PCB126 but not IS. These results indicate that exposure of preadipocytes to endogenous (IS) or exogenous (PCB126) AhR agonists is effective at blocking them from becoming functional adipocytes that are capable of the beiging response. Mature adipocytes may have differential responses. This finding suggests a mechanism by which dioxin-like PCBs such as PCB126 could lead to disruption in energy homeostasis, potentially leading to obesity and diabetes.

Caulis Spatholobi Ameliorates Obesity through Activating Brown Adipose Tissue and Modulating the Composition of Gut Microbiota.

Obesity is associated with disrupted energy homeostasis and intestinal dysbiosis. Caulis Spatholobi, traditional Chinese medicine for herbal therapy, contains a wide range of bioactive compounds and has a specific pharmacological function. However, its effects on obesity and related metabolic disorder have remained largely unexplored. In this study, we showed that the water extract of Caulis Spatholobi (WECS) has a significant effect in inhibiting body weight gain, decreasing adiposity, maintaining glucose homeostasis, reducing insulin resistance and improving hepatic steatosis in diet-introduced obesity (DIO) mice. Besides, the administration of WECS significantly increased the expression levels of genes involved in the brown adipose tissue (BAT) activation and thermogenesis in DIO mice. Also, the activation of BAT treated with WECS was also confirmed in BAT primary cells. Mechanisms, the improvement of glucose homeostasis and insulin resistance may be related to the upregulated MAPK and AMPK pathways in white adipose tissue (WAT) and BAT. Notably, WECS also improved the obesity-induced gut microbiota dysbiosis, which induced an increase of anti-obesity and anti-diabetes related bacteria genus. In conclusion, Caulis Spatholobi can ameliorate obesity through activating brown adipose tissue and modulating the composition of gut microbiota. Our findings provide a novel perspective on Chinese medicine applications and provide a promising therapeutic approach for the treatment of obesity and metabolic disorders.

The energetic brain - A review from students to students.

The past 20years have resulted in unprecedented progress in understanding brain energy metabolism and its role in health and disease. In this review, which was initiated at the 14th International Society for Neurochemistry Advanced School, we address the basic concepts of brain energy metabolism and approach the question of why the brain has high energy expenditure. Our review illustrates that the vertebrate brain has a high need for energy because of the high number of neurons and the need to maintain a delicate interplay between energy metabolism, neurotransmission, and plasticity. Disturbances to the energetic balance, to mitochondria quality control or to glia-neuron metabolic interaction may lead to brain circuit malfunction or even severe disorders of the CNS. We cover neuronal energy consumption in neural transmission and basic ('housekeeping') cellular processes. Additionally, we describe the most common (glucose) and alternative sources of energy namely glutamate, lactate, ketone bodies, and medium chain fatty acids. We discuss the multifaceted role of non-neuronal cells in the transport of energy substrates from circulation (pericytes and astrocytes) and in the supply (astrocytes and microglia) and usage of different energy fuels. Finally, we address pathological consequences of disrupted energy homeostasis in the CNS.

Targeting reduced mitochondrial DNA quantity as a therapeutic approach in pediatric high-grade gliomas.

BackgroundDespite increased understanding of the genetic events underlying pediatric high-grade gliomas (pHGGs), therapeutic progress is static, with poor understanding of nongenomic drivers. We therefore investigated the role of alterations in mitochondrial function and developed an effective combination therapy against pHGGs.MethodsMitochondrial DNA (mtDNA) copy number was measured in a cohort of 60 pHGGs. The implication of mtDNA alteration in pHGG tumorigenesis was studied and followed by an efficacy investigation using patient-derived cultures and orthotopic xenografts.ResultsAverage mtDNA content was significantly lower in tumors versus normal brains. Decreasing mtDNA copy number in normal human astrocytes led to a markedly increased tumorigenicity in vivo. Depletion of mtDNA in pHGG cells promoted cell migration and invasion and therapeutic resistance. Shifting glucose metabolism from glycolysis to mitochondrial oxidation with the adenosine monophosphate–activated protein kinase activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) or the pyruvate dehydrogenase kinase inhibitor dichloroacetate (DCA) significantly inhibited pHGG viability. Using DCA to shift glucose metabolism to mitochondrial oxidation and then metformin to simultaneously target mitochondrial function disrupted energy homeostasis of tumor cells, increasing DNA damage and apoptosis. The triple combination with radiation therapy, DCA and metformin led to a more potent therapeutic effect in vitro and in vivo.ConclusionsOur results suggest metabolic alterations as an onco-requisite factor of pHGG tumorigenesis. Targeting reduced mtDNA quantity represents a promising therapeutic strategy for pHGG.

The melanocortin pathway and control of appetite-progress and therapeutic implications.

The initial discovery that ob/ob mice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the 'starved state' activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.

Repeated clodronate-liposome treatment results in neutrophilia and is not effective in limiting obesity-linked metabolic impairments.

Depletion of macrophages is thought to be a therapeutic option for obesity-induced inflammation and metabolic dysfunction. However, whether the therapeutic effect is a direct result of reduced macrophage-derived inflammation or secondary to decreases in fat mass is controversial, as macrophage depletion has been shown to disrupt energy homeostasis. This study was designed to determine if macrophage depletion via clodronate-liposome (CLD) treatment could serve as an effective intervention to reduce obesity-driven inflammatory and metabolic impairments independent of changes in energy intake. After 16 wk on a high-fat diet (HFD) or the AIN-76A control (low-fat) diet (LFD) ( n = 30/diet treatment), male C57BL/6J mice were assigned to a CLD- or PBS-liposome treatment ( n = 15/group) for 4 wk. Liposomes were administered biweekly via intraperitoneal injections (8 administrations in total). PBS-liposome-treated groups were pair-fed to their CLD-treated dietary counterparts. Metabolic function was assessed before and after liposome treatment. Adipose tissue, as well as the liver, was investigated for macrophage infiltration and the presence of inflammatory mediators. Additionally, a complete blood count was performed. CLD treatment reduced energy intake. When controlling for energy intake, CLD treatment was unable to regress metabolic dysfunction or nonalcoholic fatty liver disease and impaired adipose tissue insulin action. Moreover, repeated CLD treatment induced neutrophilia and anemia, increased adipose tissue mRNA expression of the proinflammatory cytokines IL-6 and IL-1β, and augmented circulating IL-6 and monocyte chemoattractant protein-1 concentrations ( P < 0.05). This study suggests that repeated intraperitoneal administration of CLD to deplete macrophages attenuates obesity by limiting energy intake. Moreover, after controlling for the benefits of weight loss, the accompanying detrimental side effects limit regular CLD treatment as an effective therapeutic strategy.

Chronic low-dose exposure of nonylphenol alters energy homeostasis in the reproductive system of female rats

Nonylphenol (NP) as a confirmed endocrine disrupt chemical that causes reproductive and developmental toxicity. Previous studies focused only on short-term, high-dose exposure in vivo, or in vitro on female reproductive toxicity, which cannot accurately simulate the real human exposure scenario. The present study aims to explore NP toxicity and the underlying mechanisms of chronic low-dose NP exposure (500 μg/kg·bw/day, for 8 weeks) in the reproductive system of female rats. The results indicated that NP exposure caused female reproductive toxicity, including alterations in serum 17β-estradiol (E2) levels, endometria hyperplasia, altered oogenesis and significant changes in the metabolic profile observed in urine, serum, uterus and ovary. Furthermore, expression of the energy-sensitive proteins carnitine palmitoyltransferase I (CPTI), adenosine 5′-monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor gamma (PPAR-γ) were found to be down-regulated in uterus under NP exposure, which suggested the impaired fatty acid oxidation. Accordingly, a comprehensive metabolomics study in key reproductive tissues and body fluids revealed that 12 metabolites were associated with energy metabolism as potential biomarkers for the evaluation of low toxicity at early stages, with L-carnitines being the most representative ones. The present findings provide evidence that chronic low-dose NP exposure can significantly disrupt energy homeostasis in females, thus offering further insights into NP reproductive toxicity.

IDH2 Deficiency Disrupts Energy Homeostasis and Skeletal Muscle Development by Upregulating UCP1 Expression in Mice

Isocitrate dehydrogenase 2 (IDH2) is a mitochondrial specific enzyme that catalyses the oxidative decarboxylation of isocitrate into α‐ketoglutarate with concurrent reduction of NADP+ to NADPH. We previous reported that IDH2 knock‐out (KO) increased obesity resistance via UCP1‐mediated enhanced energy expenditure in adipose and liver tissues. Since skeletal muscle is the most mitochondria abundant tissue and is a major site for energy expenditure, we here examined the effects of IDH2 KO on skeletal muscle energy homeostasis and its growth. Calf skeletal muscle samples (i.e., mixed part of soleus, gastrocnemius, and plantaris muscles) were harvested from 11‐week‐old male IDH2 KO (n=4) and wild type (WT; C57BL/6; n=4) mice, and a ratio of skeletal muscle weight to body weight was measured. Subsequently, marker of mitochondrial DNA to nucleic DNA ratio was measured by PCR analysis. In addition, mRNA expression levels involved in fatty acid β‐oxidation (CPT1 and FAT), adipogenesis (PPARγ, C/EBPα, C/EBPβ, aP2, and ZFP423), thermogenesis (UCP1, BMP7, and PRDM16), myogenesis (MRF4 and MyoD), and mitochondria biogenesis (PGC‐1α, TFAM, ERRα, and MFN2) were compared. Interestingly, a ratio of skeletal muscle weight to body weight was significantly lower in IDH2 KO mice compared to that of WT mice (P=0.0004). Further, mitochondrial content was relatively lower in skeletal muscle of IDH2 KO mice than the WT mice albeit it was not statistically significant (P=0.09). In consistent with the muscle mass, there were trends of decrease in the expressions of myogenesis (MyoD, P=0.07) as well as mitochondrial biogenesis genes in IDH2 KO mice (PGC‐1α, P&lt;0.05; TFAM, P=0.07). Last, the expression level of UCP1, a hallmark of thermogenesis, was remarkably increased in skeletal muscle whereas adipogenesis pathway (PPARγ, P&lt;0.005; C/EBPβ, P=0.06; ZFP423, P&lt;0.05) was down‐regulated in skeletal muscle of IDH2 KO mice. However, UCP1 seems not directly regulated by the expression of BMP7 or PRDM16 as the expression of BMP7 and PRDM16 was also down‐regulated in IDH2 KO mice. Taken together, our study suggests that IDH2 deficiency may upregulate UCP1‐mediated thermogenesis possibly to adopt limited NADPH supply. In turn, the thermogenesis‐induced energy imbalance may cause suppression of myogenesis, mitochondria biogenesis, adipogenic signaling pathway, and skeletal muscle growth. Our study will provide scientific background to further studies on the mechanistic functions of IDH2 in skeletal muscle development.Support or Funding InformationThis work was supported by the University of Arkansas, VPRED Start‐up fund (KJK, and PJH). Support has been provided in part by the Arkansas Biosciences Institute, a partnership of scientists from Arkansas Children's Hospital, Arkansas State University, the University of Arkansas‐Division of Agriculture, the University of Arkansas, Fayetteville, and the University of Arkansas for Medical Sciences. The Arkansas Biosciences Institute is the major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000 (JKK, JHP, KEB, and BCK).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

F235. DIFFERENTIAL EFFECTS OF ANTIPSYCHOTICS ON NEUROINFLAMMATION AND ENERGY SENSING IN A HYPOTHALAMIC CELL LINE

BackgroundAntipsychotics (AP)s are the cornerstone of treatment for schizophrenia but cause serious metabolic side-effects. The hypothalamus is the primary brain region responsible for whole body energy regulation and disruptions in energy sensing (e.g. insulin signaling) and inflammation in this brain region have been implicated in the development of peripheral insulin resistance and obesity. Thus, it is possible that hypothalamic inflammation and disturbed energy sensing could be involved in AP-induced metabolic disturbances. Data in relation to AP-associated changes in inflammatory markers in schizophrenia has been inconsistent, owing in part to confounds of illness-related factors (e.g. diet, smoking) and secondary effects of weight gain. To our knowledge, direct effects of APs on hypothalamic cells in relation to insulin signaling and inflammation have not been examined.MethodsTo examine direct, molecular effects of APs in the hypothalamus, an immortalized rat hypothalamic cell line, rHypoE-19, was treated with olanzapine (dose range between 0.25–100 uM), clozapine (2.5–100 uM) or aripiprazole (5–20 uM). Western blotting was used to detect changes in the energy sensing protein AMPK, components of the insulin signaling pathway (AKT, GSK3B), and components of the mitogen activated-protein kinase (MAPK) pathway (ERK1/2, JNK, p38), the latter which are linked to inflammation. Quantitative real-time PCR was performed to determine changes in the mRNA expression of interleukin (IL)-6, IL-10 and brain derived neurotrophic factor (BDNF).ResultsBoth olanzapine (100 uM) and clozapine (100 uM) significantly increased pERK1/2 and pJNK protein expression, while aripiprazole (20 uM) only increased pJNK. Clozapine (100 uM) and aripiprazole (5 and 20 uM) significantly increased AMPK phosphorylation and inhibited insulin-induced phosphorylation of AKT. Olanzapine (100 uM) treatment caused a significant increase in IL-6 while aripiprazole (20 uM) significantly decreased IL-10. Olanzapine (100 uM) and aripiprazole (20 uM) increased BDNF expression.DiscussionAll the APs studied upregulated pJNK, along with olanzapine-associated increases in IL-6, and aripiprazole-associated decreases in IL-10, together suggesting AP-mediated upregulation of pro-inflammatory pathways in rHypoE-19 neurons. Aripiprazole and clozapine (but not olanzapine) inhibited insulin-stimulated AKT, suggesting impaired hypothalamic insulin action by some, but not all, APs. Clozapine additionally increased AMPK phosphorylation (activation), an orexigenic energy sensor, which would also be expected to disrupt energy homeostasis. Conversely, olanzapine and aripiprazole increased BDNF, a factor linked to the underlying etiology of schizophrenia, suggesting BDNF upregulation may be a mechanism of therapeutic action. Taken together, our findings suggest differential and pleotropic effects of APs on neuroinflammation and energy sensing in the hypothalamus, which do not necessarily align consistently with known metabolic liability of these agents (i.e. clozapine = olanzapine > aripiprazole). Our data warrants further exploration into the mechanism of these effects, including replication of these effects in an in vivo model.