Platelet-derived growth factor signaling in pericytes promotes hypothalamic inflammation and obesity.

BACKGROUND: Pericytes are a vital component of the blood-brain barrier, and their involvement in acute inflammation was recently suggested. However, it remains unclear whether pericytes contribute to hypothalamic chronic inflammation and energy metabolism in obesity. The present study investigated the impact of pericytes on the pathophysiology of obesity by focusing on platelet-derived growth factor (PDGF) signaling, which regulates pericyte functions. METHODS: Tamoxifen-inducible systemic conditional PDGF receptor ß knockout mice (Pdgfrb∆SYS-KO) and Calcium/calmodulin-dependent protein kinase type IIa (CaMKIIa)-positive neuron-specific PDGF receptor ß knockout mice (Pdgfrb∆CaMKII-KO) were fed a high-fat diet, and metabolic phenotypes before and 3 to 4 weeks after dietary loading were examined. Intracellular energy metabolism and relevant signal transduction in lipopolysaccharide- and/or platelet-derived growth factor-BB (PDGF-BB)-stimulated human brain pericytes (HBPCs) were assessed by the Seahorse XFe24 Analyzer and Western blotting. The pericyte secretome in conditioned medium from HBPCs was studied using cytokine array kit, and its impact on polarization was examined in bone marrow-derived macrophages (BMDMs), which are microglia-like cells. RESULTS: Energy consumption increased and body weight gain decreased after high-fat diet loading in Pdgfrb∆SYS-KO mice. Cellular oncogene fos (cFos) expression increased in proopiomelanocortin (POMC) neurons, whereas microglial numbers and inflammatory gene expression decreased in the hypothalamus of Pdgfrb∆SYS-KO mice. No significant changes were observed in Pdgfrb∆CaMKII-KO mice. In HBPCs, a co-stimulation with lipopolysaccharide and PDGF-BB shifted intracellular metabolism towards glycolysis, activated mitogen-activated protein kinase (MAPK), and modulated the secretome to the inflammatory phenotype. Consequently, the secretome showed an increase in various proinflammatory chemokines and growth factors including Epithelial-derived neutrophil-activating peptide 78 (C-X-C motif chemokine ligand (CXCL)5), Thymus and activation-regulated chemokine (C-C motif chemokine (CCL)17), Monocyte chemoattractant protein 1 (CCL2), and Growth-regulated oncogene α (CXCL1). Furthermore, conditioned medium from HBPCs stimulated the inflammatory priming of BMDMs, and this change was abolished by the C-X-C motif chemokine receptor (CXCR) inhibitor. Consistently, mRNA expression of CXCL5 was elevated by lipopolysaccharide and PDGF-BB treatment in HBPCs, and the expression was significantly lower in the hypothalamus of Pdgfrb∆SYS-KO mice than in control Pdgfrbflox/flox mice (FL) following 4 weeks of HFD feeding. CONCLUSIONS: PDGF receptor ß signaling in hypothalamic pericytes promotes polarization of macrophages by changing their secretome and contributes to the progression of obesity.

Oestrogen receptor α in T cells controls the T cell immune profile and glucose metabolism in mouse models of gestational diabetes mellitus.

AIMS/HYPOTHESIS: The imbalance between maternal insulin resistance and a relative lack of insulin secretion underlies the pathogenesis of gestational diabetes mellitus (GDM). Alterations in T cell subtypes and increased levels of circulating proinflammatory cytokines have been proposed as potential mechanisms underlying the pathophysiology of insulin resistance in GDM. Since oestrogen modulates T cell immunity, we hypothesised that oestrogen plays a homeostatic role in visceral adipose tissue by coordinating T cell immunity through oestrogen receptor α (ERα) in T cells to prevent GDM. METHODS: Female CD4-cre ERαfl/fl (KO) mice on a C57BL/6 background with ERα ablation specifically in T cells, and ERαfl/fl (ERα-floxed [FL]) mice were fed 60 kJ% high-fat diet (HFD) for 4 weeks. Female mice mated with male BALB/c mice to achieve allogenic pregnancy and were maintained on an HFD to generate the GDM model. Mice were divided into four experimental groups: non-pregnant FL, non-pregnant KO, pregnant FL (FL-GDM) and pregnant KO (KO-GDM). GTTs and ITTs were performed on day 12.5 or 13.5 and 16.5 after breeding, respectively. On day 18.5 after breeding, mice were killed and T cell subsets in the gonadal white adipose tissue (gWAT) and spleen were analysed using flow cytometry. Histological examination was also conducted and proinflammatory gene expression in gWAT and the liver was evaluated. RESULTS: KO mice that mated with BALB/c mice showed normal fertility rates and fetal weights as compared with FL mice. Body and tissue weights were similar between FL and KO mice. When compared with FL-GDM mice, KO-GDM mice showed decreased insulin secretion (serum insulin concentration 15 min after glucose loading: 137.3 ± 18.3 pmol/l and 40.1 ± 36.5 pmol/l, respectively; p < 0.05), impaired glucose tolerance (glucose AUC in GTT: 2308.3 ± 54.0 mmol/l × min and 2620.9 ± 122.1 mmol/l × min, respectively; p < 0.05) and increased numbers of T helper (Th)17 cells in gWAT (0.4 ± 0.0% vs 0.8 ± 0.1%; p < 0.05). However, the contents of Th1 and regulatory T cells (Tregs) in gWAT remained similar between FL-GDM and KO-GDM. Glucose-stimulated insulin secretion was similar between isolated islets derived from FL and KO mice, but was reduced by IL-17A treatment. Moreover, the levels of proinflammatory gene expression, including expression of Emr1 and Tnfa in gWAT, were significantly higher in KO-GDM mice than in FL-GDM mice (5.1-fold and 2.7-fold, respectively; p < 0.01 for both). Furthermore, KO-GDM mice showed increased expression of genes encoding hepatokines, Ahsg and Fgf21 (both were 2.4-fold higher vs FL-GDM mice; p < 0.05 and p = 0.09, respectively), with no changes in inflammatory gene expression (e.g., Tnfa and Ifng) in the liver compared with FL-GDM mice. CONCLUSIONS/INTERPRETATION: Deletion of ERα in T cells caused impaired maternal adaptation of insulin secretion, changes in hepatokine profiles, and enhanced chronic inflammation in gWAT alongside an abnormal increase in Th17 cells. These results suggest that the ERα-mediated oestrogen signalling effects in T cells regulate T cell immunity and contribute to glucose homeostasis in pregnancy.

Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A.

The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama.

Stromal cell-derived factor 1 (SDF1) attenuates platelet-derived growth factor-B (PDGF-B)-induced vascular remodeling for adipose tissue expansion in obesity.

Platelet-derived growth factor-B (PDGF-B) is a main factor to promote adipose tissue angiogenesis, which is responsible for the tissue expansion in obesity. In this process, PDGF-B induces the dissociation of pericytes from blood vessels; however, its regulatory mechanism remains unclear. In the present study, we found that stromal cell-derived factor 1 (SDF1) plays an essential role in this regulatory mechanism. SDF1 mRNA was increased in epididymal white adipose tissue (eWAT) of obese mice. Ex vivo pharmacological analyses using cultured adipose tissue demonstrated that physiological concentrations (1-100 pg/mL) of SDF1 inhibited the PDGF-B-induced pericyte dissociation from vessels via two cognate SDF1 receptors, CXCR4 and CXCR7. In contrast, higher concentrations (> 1 ng/mL) of SDF1 alone caused the dissociation of pericytes via CXCR4, and this effect disappeared in the cultured tissues from PDGF receptor ß (PDGFRß) knockout mice. To investigate the role of SDF1 in angiogenesis in vivo, the effects of anagliptin, an inhibitor of dipeptidyl peptidase 4 (DPP4) that degrades SDF1, were examined in mice fed a high-fat diet. Anagliptin increased the SDF1 levels in the serum and eWAT. These changes were associated with a reduction of pericyte dissociation and fat accumulation in eWAT. AMD3100, a CXCR4 antagonist, cancelled these anagliptin effects. In flow-cytometry analysis, anagliptin increased and decreased the PDGF-B expression in endothelial cells and macrophages, respectively, whereas anagliptin reduced the PDGFRß expression in pericytes of eWAT. These results suggest that SDF1 negatively regulates the adipose tissue angiogenesis in obesity by altering the reactivity of pericytes to PDGF-B.

N-acetylaspartate availability is essential for juvenile survival on fat-free diet and determines metabolic health.

N-acetylaspartate (NAA) is synthesized by aspartate N-acetyltransferase (gene: Nat8l) from acetyl-coenzyme A and aspartate. In the brain, NAA is considered an important energy metabolite for lipid synthesis. However, the role of NAA in peripheral tissues remained elusive. Therefore, we characterized the metabolic phenotype of knockout (ko) and adipose tissue-specific (ako) Nat8l-ko mice as well as NAA-supplemented mice on various diets. We identified an important role of NAA availability in the brain during adolescence, as 75% of Nat8l-ko mice died on fat-free diet (FFD) after weaning but could be rescued by NAA supplementation. In adult life, NAA deficiency promotes a beneficial metabolic phenotype, as Nat8l-ko and Nat8l-ako mice showed reduced body weight, increased energy expenditure, and improved glucose tolerance on chow, high-fat, and FFDs. Furthermore, Nat8l-deficient adipocytes exhibited increased mitochondrial respiration, ATP synthesis, and an induction of browning. Conversely, NAA-treated wild-type mice showed reduced adipocyte respiration and lipolysis and increased de novo lipogenesis, culminating in reduced energy expenditure, glucose tolerance, and insulin sensitivity. Mechanistically, our data point to a possible role of NAA as modulator of pancreatic insulin secretion and suggest NAA as a critical energy metabolite for adipocyte and whole-body energy homeostasis.-Hofer, D. C., Zirkovits, G., Pelzmann, H. J., Huber, K., Pessentheiner, A. R., Xia, W., Uno, K., Miyazaki, T., Kon, K., Tsuneki, H., Pendl, T., Al Zoughbi, W., Madreiter-Sokolowski, C. T., Trausinger, G., Abdellatif, M., Schoiswohl, G., Schreiber, R., Eisenberg, T., Magnes, C., Sedej, S., Eckhardt, M., Sasahara, M., Sasaoka, T., Nitta, A., Hoefler, G., Graier, W. F., Kratky, D., Auwerx, J., Bogner-Strauss, J. G. N-acetylaspartate availability is essential for juvenile survival on fat-free diet and determines metabolic health.

[Insulin resistance and cognitive function].

Risk of Alzheimer disease is increased in patients with diabetes. Insulin resistance is identified as a pathogenic mechanism of impaired cognitive dysfunction. Amyloid beta oligomers cause impaired insulin signaling at IRS-1 via mechanisms of TNFalpha and JNK activation. Attenuation of PI-3 kinase pathway is also involved in the hyper-phosphorylation of Tau. Impairment of orexin function is connected to the age related insulin resistance and shortening of life expectancy. Synapse deterioration and loss via these mechanisms underlying defective brain insulin signaling result in cognitive dysfunction. Stimulation of insulin signaling is a developing therapeutic approach in Alzheimer disease. Nasal insulin administration, thiazolidinedione, and GLP-1 receptor agonist possess neuronal protective effects in the treatment of mild cognitive dysfunction. Further identification of the pathogenic mechanism connecting between Alzheimer disease and insulin resistance contributes to development of novel therapeutics in Alzheimer disease.

C-terminal peptide of preproorexin enhances brain-derived neurotrophic factor expression in rat cerebrocortical cells and recognition memory in mice.

During the production of orexin A and B from preproorexin, a common precursor protein, in hypothalamic orexin neurons, C-terminal peptide (herein called preproorexin C-peptide) is concomitantly produced via post-translational processing. The predicted three-dimensional structure of preproorexin C-peptide is similar among mammalian species, suggestive of a conserved function in the mammalian brain. However, C-peptide has long been regarded as a non-functional peptide. We herein examined the effects of rat and/or mouse preproorexin C-peptide on gene expression and cell viability in cultured rat cerebrocortical cells and on memory behavior in C57BL/6J mice. Rat and mouse C-peptides both increased brain-derived neurotrophic factor (Bdnf) mRNA levels. Moreover, C-peptide enhanced high K+-, glutamate-, and BDNF-induced increases in Bdnf mRNA levels without affecting forskolin-induced Bdnf expression. H-89, a protein kinase A inhibitor, blocked C-peptide-induced Bdnf expression, whereas rolipram, a phosphodiesterase inhibitor, enhanced this effect. Intracellular cyclic AMP concentrations were elevated by C-peptide. These results demonstrate that preproorexin C-peptide promoted Bdnf mRNA expression by a cyclic AMP-dependent mechanism. Eleven amino acids at the N terminus of rat preproorexin C-peptide exerted similar effects on Bdnf expression as full-length preproorexin C-peptide. Preproorexin C-peptide also exerted protective effects against CoCl2-induced neuronal cell death. An intracerebroventricular injection of mouse preproorexin C-peptide induced c-fos and Bdnf expression in the cerebral cortex and hippocampus and enhanced novel object recognition memory in mice. Collectively, the present results show that preproorexin C-peptide is a functional substance, at least in some pharmacological and neuronal settings.

Eplerenone ameliorates the phenotypes of metabolic syndrome with NASH in liver-specific SREBP-1c Tg mice fed high-fat and high-fructose diet.

Because the renin-angiotensin-aldosterone system has been implicated in the development of insulin resistance and promotion of fibrosis in some tissues, such as the vasculature, we examined the effect of eplerenone, a selective mineralocorticoid receptor (MR) antagonist, on nonalcoholic steatohepatitis (NASH) and metabolic phenotypes in a mouse model reflecting metabolic syndrome in humans. We adopted liver-specific transgenic (Tg) mice overexpressing the active form of sterol response element binding protein-1c (SREBP-1c) fed a high-fat and fructose diet (HFFD) as the animal model in the present study. When wild-type (WT) C57BL/6 and liver-specific SREBP-1c Tg mice grew while being fed HFFD for 12 wk, body weight and epididymal fat weight increased in both groups with an elevation in blood pressure and dyslipidemia. Glucose intolerance and insulin resistance were also observed. Adipose tissue hypertrophy and macrophage infiltration with crown-like structure formation were also noted in mice fed HFFD. Interestingly, the changes noted in both genotypes fed HFFD were significantly ameliorated with eplerenone. HFFD-fed Tg mice exhibited the histological features of NASH in the liver, including macrovesicular steatosis and fibrosis, whereas HFFD-fed WT mice had hepatic steatosis without apparent fibrotic changes. Eplerenone effectively ameliorated these histological abnormalities. Moreover, the direct suppressive effects of eplerenone on lipopolysaccharide-induced TNFα production in the presence and absence of aldosterone were observed in primary-cultured Kupffer cells and bone marrow-derived macrophages. These results indicated that eplerenone prevented the development of NASH and metabolic abnormalities in mice by inhibiting inflammatory responses in both Kupffer cells and macrophages.

A transdermal treatment with MC903 ameliorates diet-induced obesity by reducing visceral fat and increasing myofiber thickness and energy consumption in mice.

AIM: MC903 is a synthetic derivative of vitamin D3 that has been designed to diminish its impact on calcium metabolism and is clinically used as a transdermal reagent for psoriasis. Animal studies showed that an oral or intraperitoneal vitamin D3 treatment prevented the development of obesity. In contrast, the bioavailability of orally administered vitamin D3 is reported to be low in obese patients. In the current study, we aimed to investigate the impact of a transdermal treatment with MC903 in established obese mice. We further studied the underlying mechanisms of MC903-mediated metabolic improvement. MATERIALS AND METHODS: Male C57BL/6 J mice were fed standard chow or a 60% high-fat diet (HFD) for 7 weeks, and a transdermal treatment with MC903 on the ear auricle was initiated thereafter. The metabolic profiles of mice were analyzed during 4 weeks of treatment, and mice were dissected for histological and gene expression analyses. The direct impacts of MC903 and vitamin D3 were investigated using 3T3-L1 adipocytes and C2C12 myotubes in vitro. RESULTS: HFD-fed mice showed significant increases in body and epididymal white adipose tissue (eWAT) weights with enlarged adipocytes. They exhibited glucose intolerance, decreased oxygen consumption, and chronic inflammation in eWAT. The transdermal treatment with MC903 significantly ameliorated these metabolic abnormalities in HFD-fed mice without affecting food consumption. In accordance with enhanced energy metabolism, myofiber diameters and the expression of uncoupling protein 3 (UCP3) in the gastrocnemius and soleus muscle were significantly increased in MC903-treated HFD mice. In addition, vitamin D3 and MC903 both suppressed adipogenic differentiation and enhanced lipolysis in 3T3-L1 adipocytes, and increased UCP3 expression in cultured C2C12 myotubes. Furthermore, MC903 increased oxygen consumption and UCP3 knockdown significantly decreased them in C2C12 myotubes. CONCLUSIONS: A transdermal treatment with MC903 increased myofiber diameter and energy metabolism and decreased visceral fat accumulation, thereby improving obesity and glucose intolerance in mice.

Resting phase-administration of lemborexant ameliorates sleep and glucose tolerance in type 2 diabetic mice.

Sleep disorders are associated with increased risk of obesity and type 2 diabetes. Lemborexant, a dual orexin receptor antagonist (DORA), is clinically used to treat insomnia. However, the influence of lemborexant on sleep and glucose metabolism in type 2 diabetic state has remained unknown. In the present study, we investigated the effect of lemborexant in type 2 diabetic db/db mice exhibiting both sleep disruption and glucose intolerance. Single administration of lemborexant at the beginning of the light phase (i.e., resting phase) acutely increased total time spent in non-rapid eye movement (NREM) and REM sleep in db/db mice. Durations of NREM sleep-, REM sleep-, and wake-episodes were also increased by this administration. Daily resting-phase administration of lemborexant for 3-6 weeks improved glucose tolerance without changing body weight and glucose-stimulated insulin secretion in db/db mice. Similar improvement of glucose tolerance was caused by daily resting-phase administration of lemborexant in obese C57BL/6J mice fed high fat diet, whereas no such effect was observed in non-diabetic db/m+ mice. Diabetic db/db mice treated daily with lemborexant exhibited increased locomotor activity in the dark phase (i.e., awake phase), although they did not show any behavioral abnormality in the Y-maze, elevated plus maze, and forced swim tests. These results suggest that timely promotion of sleep by lemborexant improved the quality of wakefulness in association with increased physical activity during the awake phase, and these changes may underlie the amelioration of glucose metabolism under type 2 diabetic conditions.

Hachimijiogan, a traditional herbal medicine, modulates adipose cell function and ameliorates diet-induced obesity and insulin resistance in mice.

Hachimijiogan (HJG) has originally been used to ameliorate a variety of symptoms associated with low ambient temperatures. However, its pharmacological action in metabolic organs remains unclear. We hypothesized that HJG may modulate metabolic function and have a potential therapeutic application to metabolic diseases. To test this hypothesis, we investigated metabolic action of HJG in mice. Male C57BL/6J mice chronically administered with HJG showed a reduction in adipocyte size with increased transcription of beige adipocyte-related genes in subcutaneous white adipose tissue. HJG-mixed high-fat diet (HFD)-fed mice showed alleviation of HFD-induced weight gain, adipocyte hypertrophy, liver steatosis with a significant reduction in circulating leptin and Fibroblast growth factor 21 despite no changes in food intake or oxygen consumption. Feeding an HJG-mixed HFD following 4-weeks of HFD feeding, while a limited effect on body weight, improved insulin sensitivity with a reversal of decreased circulating adiponectin. In addition, HJG improved insulin sensitivity in the leptin-deficient mice without significant effects on body weight. Treatment with n-butanol soluble extracts of HJG potentiated transcription of Uncoupling protein 1 mediated by ß3-adrenergic agonism in 3T3L1 adipocytes. These findings provide evidence that HJG modulates adipocyte function and may exert preventive or therapeutic effects against obesity and insulin resistance.

Central versus peripheral impact of estradiol on the impaired glucose metabolism in ovariectomized mice on a high-fat diet.

Age-related loss of ovarian function promotes adiposity and insulin resistance in women. Estrogen (E(2)) directly enhances insulin sensitivity and suppresses lipogenesis in peripheral tissues. Recently, the central actions of E(2) in the regulation of energy homeostasis are becoming clearer; however, the functional relevance and degree of contribution of the central vs. peripheral actions of E(2) are currently unknown. Therefore, we prepared and analyzed four groups of mice. 1) CONTROL: sham-operated mice fed a regular diet, 2) OVX-HF: ovariectomized (OVX) mice fed a 60% high-fat diet (HF), 3) E2-SC: OVX-HF mice subcutaneously treated with E(2), and 4) E2-ICV: OVX-HF mice treated with E(2) intracerebroventricularly. OVX-HF mice showed increased body weight with both visceral and subcutaneous fat volume enlargement, glucose intolerance, and insulin resistance. Both E2-SC and E2-ICV equally ameliorated these abnormalities. Although the size of adipocytes and number of CD11c-positive macrophages in perigonadal fat in OVX-HF were reduced by both E(2) treatments, peripherally administered E(2) decreased the expression of TNFα, lipoprotein lipase, and fatty acid synthase in the white adipose tissue (WAT) of OVX-HF. In contrast, centrally administered E(2) increased hormone-sensitive lipase in WAT, decreased the hepatic expression of gluconeogenic enzymes, and elevated core body temperature and energy expenditure with marked upregulation of uncoupling proteins in the brown adipose tissue. These results suggest that central and peripheral actions of E(2) regulate insulin sensitivity and glucose metabolism via different mechanisms, and their coordinated effects may be important to prevent the development of obesity and insulin resistance in postmenopausal women.

Role of orexin in the central regulation of glucose and energy homeostasis.

Hypothalamic orexin neurons are known to regulate sleep/wake stability, feeding behavior, emotions, autonomic nerve activity, and whole-body energy metabolism. In addition, emerging evidence indicates that orexin contributes to central regulation of glucose homeostasis. Intriguingly, central administration of orexin is reported to cause blood glucose-elevating effect or blood glucose-lowering effect in rodents, depending on the experimental conditions. Here we reviewed the recent reports regarding the mode and mechanism of actions of orexin on these two opposing effects, and discuss the functional significance for the maintenance of glucose homeostasis. The fact that orexin exhibits biphasic effects on autonomic nerve activity and lipolysis suggests that orexin dually regulates the glucose appearance. In fact, orexin neurons are activated not only depending on the demand for glucose but also according to a circadian rhythm in the suprachiasmatic nucleus. The excited orexin neurons appear to alter the sympathetic or parasympathetic outflow to the periphery, and modulate the glucose production and utilization. Furthermore, deficiency of orexin action, particularly reduction of orexin 2 receptor-signaling, disrupts the mechanism for protection against insulin resistance associated with aging or induced by chronic high fat feeding in mice. Taken together, hypothalamic orexin system may manage multiple tasks to coordinate the interconnection among the arousal, feeding, circadian, and glucose homeostasis pathways.

Multitasking bamboo leaf-derived compounds in prevention of infectious, inflammatory, atherosclerotic, metabolic, and neuropsychiatric diseases.

Bamboo is a medicinal plant, and has long been used as a traditional/folk medicine and a food preservative in Japan. Bamboo leaf contains many active ingredients with medicinal benefits. In particular, recent studies demonstrated that bamboo leaf extract and its constituents have great potential to prevent infectious, inflammatory, cardiovascular, metabolic, and neurological/neuropsychiatric diseases. In this review, we summarize the prophylactic and possible therapeutic effects of bamboo leaf extract and its constituent compounds against these disorders. The effects of the extract are explainable in part by the effects of some constituent compounds: p-coumaric acid, myricetin, orientin, stachyose, and vitexin. Moreover, coenzyme Q10, an anti-oxidative constituent, alleviates oxidative stress which underlies the common pathogenic mechanisms of the development of diabetic complications, atherosclerosis and periodontal disease. Some flavonoids contained in bamboo leaf, such as orientin and vitexin, have been reported to regulate gut microbiota responsible for maintaining whole-body functions, suggesting a possible interaction between bamboo leaf extract and probiotics. Thus, bamboo leaf is a valuable natural resource for the development of multiple pharmacotherapies.

Suvorexant and mirtazapine improve chronic pain-related changes in parameters of sleep and voluntary physical performance in mice with sciatic nerve ligation.

Both chronic pain and sleep disorders are associated with a reduction in the quality of life. They can be both a cause and a consequence of each other, and should therefore be simultaneously treated. However, optimal treatments for chronic pain-related sleep disorders are not well established. Here, we aimed to investigate the effects of suvorexant, a novel sleep drug, and mirtazapine, a noradrenergic and specific serotonergic antidepressant, on pain-related changes in sleep parameters in a preclinical chronic pain mice model, by partial sciatic nerve ligation. We evaluated the quantity, duration, and depth of sleep by analyzing the electroencephalogram and voluntary activity by counting the number of wheel rotations to determine various symptoms of sleep disorders, including reduced total sleep time, fragmentation, low quality, and impaired activity in the daytime. Suvorexant and mirtazapine normalized the reduction in sleep time and fragmented sleep, further regaining the sleep depth at sleep onset in the chronic pain state in nerve-ligated mice. Mirtazapine also increased the percentage of rapid eye movement sleep in mice. Suvorexant decreased voluntary activity, which was prolonged after administration; however, mirtazapine did not decrease it. Although the effects of suvorexant and mirtazapine on sleep and activity are different, both suvorexant and mirtazapine could be potential therapeutic agents for chronic pain-related sleep disorders.

Ebselen enhances insulin sensitivity and decreases oxidative stress by inhibiting SHIP2 and protects from inflammation in diabetic mice.

Ebselen, a multifunctional organoselenium compound, has been recognized as a potential treatment for diabetes-related disorders. However, the underlying mechanisms whereby ebselen regulates metabolic pathways remain elusive. We discovered that ebselen inhibits lipid phosphatase SHIP2 (Src homology 2 domain-containing inositol-5-phosphatase 2), an emerging drug target to ameliorate insulin resistance in diabetes. We found that ebselen directly binds to and inhibits the catalytic activity of the recombinant SHIP2 phosphatase domain and SHIP2 in cultured cells, the skeletal muscle and liver of the diabetic db/db mice, and the liver of the SHIP2 overexpressing (SHIP2-Tg) mice. Ebselen increased insulin-induced Akt phosphorylation in cultured myotubes, enhanced insulin sensitivity and protected liver tissue from lipid peroxidation and inflammation in the db/db mice, and improved glucose tolerance more efficiently than metformin in the SHIP2-Tg mice. SHIP2 overexpression abrogated the ability of ebselen to induce glucose uptake and reduce ROS production in myotubes and blunted the effect of ebselen to inhibit SHIP2 in the skeletal muscle of the SHIP2-Tg mice. Our data reveal ebselen as a potent SHIP2 inhibitor and demonstrate that the ability of ebselen to ameliorate insulin resistance and act as an antioxidant is at least in part mediated by the reduction of SHIP2 activity.

Hypothalamic orexin prevents non-alcoholic steatohepatitis and hepatocellular carcinoma in obesity.

Non-alcoholic steatohepatitis (NASH) occasionally occurs under obesity; however, factors modulating the natural history of fatty liver disease remain unknown. Since hypothalamic orexin that regulates physical activity and autonomic balance prevents obesity, we investigate its role in NASH development. Male orexin-deficient mice fed a high-fat diet (HFD) show severe obesity and progression of NASH with fibrosis in the liver. Hepatic fibrosis also develops in ovariectomized orexin-deficient females fed an HFD but not ovariectomized wild-type controls. Moreover, long-term HFD feeding causes hepatocellular carcinoma (HCC) in orexin-deficient mice. Intracerebroventricular injection of orexin A or pharmacogenetic activation of orexin neurons acutely activates hepatic mTOR-sXbp1 pathway to prevent endoplasmic reticulum (ER) stress, a NASH-causing factor. Daily supplementation of orexin A attenuates hepatic ER stress and inflammation in orexin-deficient mice fed an HFD, and autonomic ganglionic blocker suppresses the orexin actions. These results suggest that hypothalamic orexin is an essential factor for preventing NASH and associated HCC under obesity.

Food odor perception promotes systemic lipid utilization.

Food cues during fasting elicit Pavlovian conditioning to adapt for anticipated food intake. However, whether the olfactory system is involved in metabolic adaptations remains elusive. Here we show that food-odor perception promotes lipid metabolism in male mice. During fasting, food-odor stimulation is sufficient to increase serum free fatty acids via adipose tissue lipolysis in an olfactory-memory-dependent manner, which is mediated by the central melanocortin and sympathetic nervous systems. Additionally, stimulation with a food odor prior to refeeding leads to enhanced whole-body lipid utilization, which is associated with increased sensitivity of the central agouti-related peptide system, reduced sympathetic activity and peripheral tissue-specific metabolic alterations, such as an increase in gastrointestinal lipid absorption and hepatic cholesterol turnover. Finally, we show that intermittent fasting coupled with food-odor stimulation improves glycemic control and prevents insulin resistance in diet-induced obese mice. Thus, olfactory regulation is required for maintaining metabolic homeostasis in environments with either an energy deficit or energy surplus, which could be considered as part of dietary interventions against metabolic disorders.

Both type I and II IFN induce insulin resistance by inducing different isoforms of SOCS expression in 3T3-L1 adipocytes.

Although elevation of the blood glucose level is a causal adverse effect of treatment with interferon (IFN), the precise underlying molecular mechanism is largely unknown. We examined the effects of type I and type II IFN (IFN-ß and IFN-γ) on insulin-induced metabolic signaling leading to glucose uptake in 3T3-L1 adipocytes. IFN-ß suppressed insulin-induced tyrosine phosphorylation of IRS-1 without affecting its expression, whereas IFN-γ reduced both the protein level and tyrosine phosphorylation. Although both IFNs stimulated phosphorylation of STAT1 (at Tyr(701)) and STAT3 (at Tyr(705)) after treatment for 30 min, subsequent properties of induction of the SOCS isoform were different. IFN-ß preferentially induced SOCS1 rather than SOCS3, whereas IFN-γ strongly induced SOCS3 expression alone. In addition, adenovirus-mediated overexpression of either SOCS1 or SOCS3 inhibited insulin-induced tyrosine phosphorylation of IRS-1, whereas the reduction of IRS-1 protein was observed only in SOCS3-expressed cells. Notably, IFN-ß-induced SOCS1 expression and suppression of insulin-induced tyrosine phosphorylation of IRS-1 were attenuated by siRNA-mediated knockdown of STAT1. In contrast, adenovirus-mediated expression of a dominant-negative STAT3 (F-STAT3) attenuated IFN-γ-induced SOCS3 expression, reduction of IRS-1 protein, and suppression of insulin-induced glucose uptake but did not have any effect on the IFN-ß-mediated SOCS1 expression and inhibition of insulin-induced glucose uptake. Interestingly, pretreatment of IFN-γ with IL-6 synergistically suppressed insulin signaling, even when IL-6 alone had no significant effect. These results indicate that type I and type II IFN induce insulin resistance by inducing distinct SOCS isoforms, and IL-6 synergistically augments IFN-γ-induced insulin resistance by potentiating STAT3-mediated SOCS3 induction in 3T3-L1 adipocytes.

Human adipose tissue is a putative direct target of daytime orexin with favorable metabolic effects: A cross-sectional study.

OBJECTIVE: Orexin/hypocretin (Ox) and its receptors (OxR), a neuroendocrine system centrally regulating sleep/wakefulness, were implicated in the regulation of peripheral metabolism. It was hypothesized that human adipose tissue constitutes a direct target of the OxA/OxR system that associates with distinct metabolic profile(s). METHODS: Serum Ox levels and abdominal subcutaneous and visceral adipose tissue expression of Ox/HCRT, OxR1/HCRTR1, and OxR2/HCRTR2 were measured in n = 81 patients. RESULTS: Higher morning circulating Ox levels were associated with improved lipid profile and insulin sensitivity, independently of BMI (ß = -0.363, p = 0.018 for BMI-adjusted homeostatic model of insulin resistance). Adipose HCRT mRNA was detectable in <20% of patients. Visceral HCRT expressers were mostly (80%) males and, compared with nonexpressers, had lower total and LDL cholesterol. HCRTR1 was readily detectable, and HCRTR2 was undetectable. HCRTR1 mRNA and OxR1 protein expression were higher in subcutaneous than visceral adipose tissue, and among nonobese patients, patients with obesity, and patients with obesity and T2DM were 3.4 (1.0), 0.7 (0.1), 0.6 (0.1) (AU) (p < 0.001) and 1.0 (0.2), 0.5 (0.1), 0.4 (0.1) (AU) (p = NS), respectively. Higher visceral HCRTR1 expression was associated with lower fasting insulin and homeostatic model of insulin resistance, also after adjusting for BMI. In human adipocytes, HCRTR1 expression did not exhibit significant oscillation. CONCLUSIONS: Human adipose tissue is a putative direct target of the OxA-OxR1 system, with higher morning input being associated with improved metabolic profile.