Sensitive Animal Model Research Articles

An Animal Model of Trichloroethylene-Induced Skin Sensitization in BALB/c Mice.

Trichloroethylene (TCE) is a major occupational hazard and environmental contaminant that can cause multisystem disorders in the form of occupational medicamentosa-like dermatitis. Development of dermatitis involves several proinflammatory cytokines, but their role in TCE-mediated dermatitis has not been examined in a well-defined experimental model. In addition, few animal models of TCE sensitization are available, and the current guinea pig model has apparent limitations. This study aimed to establish a model of TCE-induced skin sensitization in BALB/c mice and to examine the role of several key inflammatory cytokines on TCE sensitization. The sensitization rate of dorsal painted group was 38.3%. Skin edema and erythema occurred in TCE-sensitized groups, as seen in 2,4-dinitrochlorobenzene (DNCB) positive control. Trichloroethylene sensitization-positive (dermatitis [+]) group exhibited increased thickness of epidermis, inflammatory cell infiltration, swelling, and necrosis in dermis and around hair follicle, but ear painted group did not show these histological changes. The concentrations of serum proinflammatory cytokines including tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-2 were significantly increased in 24, 48, and 72 hours dermatitis [+] groups treated with TCE and peaked at 72 hours. Deposition of TNF-α, IFN-γ, and IL-2 into the skin tissue was also revealed by immunohistochemistry. We have established a new animal model of skin sensitization induced by repeated TCE stimulations, and we provide the first evidence that key proinflammatory cytokines including TNF-α, IFN-γ, and IL-2 play an important role in the process of TCE sensitization.

Development of a High-Throughput Screening Assay to Identify Inhibitors of the Lipid Kinase PIP5K1C

Phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) regulate a variety of cellular processes, including signaling through G protein-coupled receptors (GPCRs), endocytosis, exocytosis, and cell migration. These lipid kinases synthesize phosphatidylinositol 4,5-bisphosphate (PIP2) from phosphatidylinositol 4-phosphate [PI(4)P]. Because small-molecule inhibitors of these lipid kinases did not exist, molecular and genetic approaches were predominantly used to study PIP5K1 regulation of these cellular processes. Moreover, standard radioisotope-based lipid kinase assays cannot be easily adapted for high-throughput screening. Here, we report a novel, high-throughput, microfluidic mobility shift assay to identify inhibitors of PIP5K1C. This assay uses fluorescently labeled phosphatidylinositol 4-phosphate as the substrate and recombinant human PIP5K1C. Our assay exhibited high reproducibility, had a calculated adenosine triphosphate Michaelis constant (Km) of 15 µM, performed with z’ values >0.7, and was used to screen a kinase-focused library of ~4700 compounds. From this screen, we identified several potent inhibitors of PIP5K1C, including UNC3230, a compound that we recently found can reduce nociceptive sensitization in animal models of chronic pain. This novel assay will allow continued drug discovery efforts for PIP5K1C and can be adapted easily to screen additional lipid kinases.

Medicinal properties of mangiferin, structural features, derivative synthesis, pharmacokinetics and biological activities.

The identification of biologically active and potentially therapeutically useful pharmacophores from natural products has been a long-term focus in the pharmaceutical industry. The recent emergence of a worldwide obesity and Type II diabetes epidemic has increased focus upon small molecules that can modulate energy metabolism, insulin sensitivity and fat biology. Interesting preliminary work done on mangiferin (MGF), the predominant constituent of extracts of the mango plant Mangifera indica L., portends potential for this pharmacophore as a novel parent compound for treating metabolic disorders. MGF is comprised of a C-glucosylated xanthone. Owing to the xanthone chemical structure, MGF has a redox active aromatic system and has antioxidant properties. MGF exerts varied and impressive metabolic effects in animals, improving metabolic disorders. For example we have discovered that MGF is a novel activator of the mammalian pyruvate dehydrogenase complex, leading to enhancement of carbohydrate utilization in oxidative metabolism, and leading to increased insulin sensitivity in animal models of obesity and insulin resistance. In addition, recent unbiased proteomics studies revealed that MGF upregulates proteins pivotal for mitochondrial bioenergetics and downregulates proteins controlling de novo lipogenesis in liver, helping to explain protective effects of MGF in prevention of liver steatosis. Several chemical studies have achieved synthesis of MGF, suggesting possible synthetic strategies to alter its chemical structure for development of structure-activity relationship (SAR) information. Ultimately, chemical derivatization studies could lead to the eventual development of novel therapeutics based upon the parent pharmacophore structure. Here we provide comprehensive review on chemical features of MGF, synthesis of its derivatives, its pharmacokinetics and biological activities.

Lessons learned from the porcine CARPA model: constant and variable responses to different nanomedicines and administration protocols

AbstractPigs provide a sensitive and quantitative animal model of complement (C) activation-related pseudoallergy (CARPA) caused by liposomes and a wide range of nanoparticulate drugs or drug nanocarriers (nanomedicines). The tetrad of symptoms (hemodynamic, hematological, laboratory and skin changes) that arise within minutes after i.v. injection of reactogenic nanomedicines (RNMs) are highly reproducible among different pigs but the presence, direction and relative severity of symptoms are very different with different RNMs and their administration schedule. Bolus administration of RNMs usually trigger pulmonary hypertension with or without various degrees of systemic hyper- or hypotension, tachy-or bradycardia, arrhythmia, blood cell and inflammatory mediator changes and skin rash. These reactions can be rapid or protracted, and fully tachyphylactic, semi-tachyphylactic or non-tachyphylactic. Slow infusion usually diminishes the reactions and/or entail delayed, protracted and less severe hemodynamic and other changes. The goal of this review is to present some technical details of the porcine CARPA model, point out its constant and variable parameters, show examples of different reactions, highlight the unique features and capabilities of the model and evaluate its utility in preclinical safety assessment. The information obtained in this model enables the understanding of the complex pathomechanism of CARPA involving simultaneous anaphylatoxin and inflammatory mediator actions at multiple sites in different organs.

Successful Transplantation of Kidney Allografts in Sensitized Rats After Syngeneic Hematopoietic Stem Cell Transplantation and Fludarabine

Current methods to remove donor-specific HLA antibody (DSA) from sensitized patients remain imperfect. We tested novel approaches to desensitization using an animal model of allogeneic sensitization with skin grafts from dark agouti (DA) to Lewis rats. At the peak IgG alloantibody response we transplanted DA kidneys into nephrectomized Lewis recipients (n = 6) and all died within 10 days from antibody-mediated rejection (AMR). Allogeneic hematopoietic stem cell transplants (HSCT) from DA donors failed to engraft after lethal or sub-lethal irradiation. Sensitized rats given lethal irradiation plus syngeneic green fluorescent protein (GFP) + HSCT had repopulation of blood, spleen, thymus and lymph nodes by GFP+ cells. At 2 months after HSCT, serum DSA levels were reduced 60-70% and DSA (IgG) production in cultured splenocytes was also significantly decreased. However, there was only a modest improvement in graft survival from an average of 6.5 to 13.9 (n = 9) days. Adding seven daily doses of fludarabine to the preconditioning regimen resulted in long-term survival (>90 days) in 7 out of 10 rat kidney allografts. We conclude that syngeneic HSCT performed after preconditioning with irradiation and fludarabine can reduce DSA, prevent DSA rebound and AMR, enabling successful transplantation in animals with strong antibody reactivity to the donor MHC.

173: Probiotics in a gnotobiotic piglet model of preterm infants

Mucosal surfaces of newborns are colonized by microbes in dependence on their delivery and nutrition. Are probiotics safety to Caesarean section derived immunocompromised preterm infants? Hysterectomy derived preterm germ-free piglets, either treated or non-treated with serum, were colonized with Lactobacillus rhamnosus (LGG) four hours after hysterectomy. Bacterial translocation of LGG, its protection against subsequent infection of the piglets with Salmonella Typhimurium, and induction of plasma and intestinal levels of inflammatory cytokines IL-1 beta, IL-6, IL-8, IL-10, IFN-gamma, TNF-alpha (xMAP), and HMGB1 (ELISA) were estimated. LGG did not translocate in one week old preterm piglets. It was found in mesenteric lymph nodes in piglets subsequently infected with S. Typhimurium only but it did not translocate to other organs (blood, liver, spleen, and lungs). Inflammatory cytokine values were not induced by LGG alone but they were dramatically increased in piglets infected with Salmonella . The piglets treated with mixed serum of adult sows showed reduced levels of inflammatory cytokines as in the intestine so in plasma. It is necessary to develop highly sensitive animal models to evaluate a safety of different probiotics for immunocompromised preterm infants. A high attention should be paid to a selection of suitable markers to evaluate possible risk of these probiotics. Inflammatory cytokines in the intestine/feces of preterm newborns should be a suitable candidates of such markers. This work was supported by Grants 13-14736S of the Czech Science Foundation , FR-TI4/504 of the Ministry of Industry and Trade of the Czech Republic and the Institutional Research Concept RVO: 61388971 of the Institute of Microbiology .

Bet v 1 – a Trojan horse for small ligands boosting allergic sensitization?

Birch pollen allergy represents the main cause of winter and spring pollinosis in the temperate climate zone of the northern hemisphere and sensitization towards Bet v 1, the major birch pollen allergen, affects over 100 million allergic patients. The major birch pollen allergen Bet v 1 has been described as promiscuous acceptor for a wide variety of hydrophobic ligands. In search of intrinsic properties of Bet v 1, which account responsible for the high allergenic potential of the protein, we thought to investigate the effects of ligand-binding on immunogenic as well as allergenic properties. As surrogate ligand of Bet v 1 sodium deoxycholate (DOC) was selected. Recombinant and natural Bet v 1 were characterised physico-chemically as well as immunologically in the presence or absence of DOC, and an animal model of allergic sensitization was established. Moreover, human IgE binding to Bet v 1 was analysed by nuclear magnetic resonance (NMR) spectroscopy. Ligand-binding had an overall stabilizing effect on Bet v 1. This translated in a Th2 skewing of the immune response in a mouse model. Analyses of human IgE binding on Bet v 1 in mediator release assays revealed that ligand-bound allergen-induced degranulation at lower concentrations; however, in basophil activation tests with human basophils ligand-binding did not show this effect. For the first time, human IgE epitopes on Bet v 1 were determined using antibodies isolated from patients' sera. The IgE epitope mapping of Bet v 1 demonstrated the presence of multiple binding regions. Deoxycholate binding stabilizes conformational IgE epitopes on Bet v 1; however, the epitopes themselves remain unaltered. Therefore, we speculate that humans are exposed to both ligand-bound and free Bet v 1 during sensitization, disclosing the ligand-binding cavity of the allergen as key structural element.

Serum bilirubin levels and risk of prediabetes in young and healthy adults

Inflammation and oxidative stress have been implicated in the development of diabetes mellitus, which is one of the leading risk factors for cardiovascular diseases [ 1 Nolan C.J. Damm P. Prentki M. Type 2 diabetes across generations: from pathophysiology to prevention and management. Lancet. Jul 9 2011; 378: 169-181 Abstract Full Text Full Text PDF PubMed Scopus (643) Google Scholar , 2 Shoelson S.E. Lee J. Goldfine A.B.. Inflammation and insulin resistance. J Clin Invest. Jul 2006; 116: 1793-1801 Crossref PubMed Scopus (84) Google Scholar , 3 Houstis N. Rosen E.D. Lander E.S. Reactive oxygen species have a causal role in multiple forms of insulin resistance. Nature. Apr 13 2006; 440: 944-948 Crossref PubMed Scopus (1927) Google Scholar , 4 Meigs J.B. Larson M.G. Fox C.S. Keaney Jr., J.F. Vasan R.S. Benjamin E.J. Association of oxidative stress, insulin resistance, and diabetes risk phenotypes: the Framingham Offspring Study. Diabetes Care. Oct 2007; 30: 2529-2535 Crossref PubMed Scopus (176) Google Scholar ]. In this context, the antioxidant and anti-inflammatory effects of bilirubin, a breakdown product of the hemoglobin catabolism, have been increasingly recognized in recent years [ 5 Stocker R. Yamamoto Y. Mcdonagh A.F. Glazer A.N. Ames B.N. Bilirubin is an antioxidant of possible physiological importance. Science. Feb 27 1987; 235: 1043-1046 Crossref PubMed Scopus (2890) Google Scholar , 6 Tomaro M.L. Batlle A.M. Bilirubin: its role in cytoprotection against oxidative stress. Int J Biochem Cell Biol. Mar 2002; 34: 216-220 Crossref PubMed Scopus (119) Google Scholar ]. Serum bilirubin concentrations appear to be inversely related to cardiovascular risk factors [ 7 Oda E. Bilirubin is negatively associated with A1C independently of fasting plasma glucose, age, obesity, inflammation, hemoglobin, and iron in apparently healthy Japanese men and women. Diabetes Care. Oct 2010; 33: e131 Crossref PubMed Scopus (11) Google Scholar , 8 Choi S.H. Yun K.E. Choi H.J. Relationships between serum total bilirubin levels and metabolic syndrome in Korean adults. Nutr Metab Cardiovasc Dis. Jan 2013; 23: 31-37 Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar ], and have been associated with improved insulin sensitivity in animal models [ [8] Choi S.H. Yun K.E. Choi H.J. Relationships between serum total bilirubin levels and metabolic syndrome in Korean adults. Nutr Metab Cardiovasc Dis. Jan 2013; 23: 31-37 Abstract Full Text Full Text PDF PubMed Scopus (72) Google Scholar ].

Flaxseed and quercetin improve anti-inflammatory cytokine level and insulin sensitivity in animal model of metabolic syndrome, the fructose-fed rats

The purpose of this study is to assess the beneficial effect of quercetin, flaxseed and/or in combination as synergetic in an animal model of metabolic syndrome (MtS), high fructose (HF)-fed rats. Fifty male Sprague–Dawley rats, 3-month old and weighing between 110 and 120g were randomly divided into 2 groups. Rats were given drinking water (−ve control rats) or 10% fructose in drinking water (HF; fructose-fed rats) with standard chow for 8weeks. After 4weeks of fructose feeding, HF-fed rats were further divided into matched 4 subgroups. Different groups of animals (n−10, each group) were administered; 10% HF (5mg/kg, +ve control), flaxseed (F; 50mg/kg), quercetin (Q; 50mg/kg), flaxseed+quercetin, (FQ; 25mg/kg of each), respectively. All ingredients were given orally once daily and subsequent 4weeks. Serum glucose, insulin, lipids profile, leptin, and adiponectin were estimated. After 4weeks of feeding, a significant increase in blood glucose level was observed in HF fed rats compared to normal rats, but this increase was significantly decreased after administration of F, Q and FQ. The raised serum insulin level in HF fed rats was significantly decreased after administration of F and FQ groups. Significantly higher concentrations of triacylglycerols (TG), total cholesterol and low density lipoprotein cholesterol (LDL-C) were observed in HF fed rats and these increases were lower after administration of F, Q and FQ. There was a significant increase in serum high density lipoprotein cholesterol (HDL-C) in the FQ group. The increased serum leptin level was decreased significantly in F, Q and FQ groups. Whereas the reduction of serum adiponectin level in HF fed rats was increased in F, Q and FQ groups. These data suggested that protective effect of flaxseed and quercetin consumption as functional foods could reduce risk for people with decreased insulin sensitivity and increased oxidative stress, such as those with the metabolic syndrome or type 2 diabetes.

Abstract 523: Differences in Sodium and Potassium Regulation during Mental Stress in Normotensive Youths

Background: In Dahl salt sensitive rats, the “air puff stress” increases blood pressure (BP) and is associated with acute renal sodium (Na) retention. This study revealed increased dietary potassium (K) may abolish stress induced Na retention. Our human studies have shown the mental stress (MS) of playing a video game increases BP in youths, but the effect on Na excretion is bimodal. Retainers (NaR), retain Na with MS while excreters (NaE), excrete Na during MS. A greater increase in BP with a prolonged effect is seen in NaR. This stress induced NaR phenomena can be abolished by Ang II blockage. Because BP effects of Na intake are closely related to K intake, this study sought to compare U Na V and U K V before and after MS between NaE and NaR. Methods: We compared parallel changes in U Na V, U K V, aldosterone (aldo), and Ang II in response to 1 hour of MS in 90 healthy youths (16-19 years) after a 3 day Na/K controlled diet. We compared NaE (n=64) to NaR (n=26). Results: The change in U Na V (5.5mEq±0.6SEM vs. -3.4mEq±0.7SEM; p=<0.001), U K V (2.1mEq±0.3SEM vs. 0.4mEq±0.2SEM; p=0.002), aldo (-15.4 pg/mL ±5.3SEM vs. 3.7 pg/mL ±7.9SEM; p=0.055) and Ang II (0.4 pg/mL ±0.7SEM vs. 4.9pg/mL±3.6SEM; p=0.085) was greater in NaE vs NaR, as seen in the figure. Similarly, both groups had a baseline U Na V/U K V ratio of 4:1, which changed during stress to 2:1 in NaR and 3:1 in NaE. Conclusion: MS in normotensive youths has remarkably different effects on U Na V and U K V. Salt sensitive animal models have shown K supplementation may reverse Na retention in response to MS. This study suggests K supplementation may reverse the Na/K ratio to pre-stress conditions. Figure: Delta value comparison between NaE & NaR in UNaV, UKV, aldo, & Ang II.

HESI Cardic Safety Committee: Prospective studies to evaluate the sensitivity of animal models to predict effects of human drugs on cardiac contractility

HESI Cardic Safety Committee: Prospective studies to evaluate the sensitivity of animal models to predict effects of human drugs on cardiac contractility

Effects of exposure to 50 Hz electromagnetic fields on Morris water-maze performance of prenatal and neonatal mice

Extremely low-frequency magnetic fields (ELF-MF), such as those originating from residential and occupational power lines, household appliances and medical devices, have been reported repeatedly to produce a variety of biological effects, which may induce a number of changes in behavioral differences of different living species, like insects and rodents. The purpose of the present study is to investigate the possible effect of an extremely low-frequency magnetic field ELF-MF (50Hz, 1mT) on spatial learning and memory functions in mice (prenatal and neonatal exposed mice) following a continuous 7-day exposure, using Morris water-maze. Immature mice have been chosen for this study since; the immature rodent brain still has the capacity to undergo proliferation, differentiation and re-organization and more closely resembles the developing brain of a human child. Thus, the immature rodent brain may provide a sensitive and useful animal model to study the possible biological effects of ELF-MF. Our results provide convincing evidence that long time MF exposure to immature mice; causes appreciable long term deficit in learning abilities.

Abstract 2460: Discovery of potent androgen receptor antagonists for treating CRPC and AR+ breast cancer.

Abstract Androgen Receptor (AR) antagonists have been used in clinic to treat prostate cancer. One example is bicalutamide (Casodex®), which is used along with castration to treat advanced prostate cancer. Unfortunately, the patients developed resistance to bicalutamide (alone or in combination therapy) after only 0.5-2 years of treatment, resulting in castration-resistant prostate cancer (CRPC). Elevated AR expression in tumor cells correlates with a change in the functional activity of bicalutamide from antagonist to agonist, suggesting that prostate tumors may adapt to survive on any residual agonism. MDV3100, a more potent AR antagonist (∼5x vs bicalutamide) without residual agonism, has demonstrated excellent efficacy in CRPC patients and has been approved by FDA for treating CRPC in clinic. Recently, AR antagonists demonstrated anti-tumor activities in preclinical AR+ breast cancer models. Approximately 75% of invasive breast cancers were founded to be AR+. Although MDV3100 is generally well-tolerated, there is a need to eliminate the clinically observed CNS adverse side effects (∼1% incidences of seizure). Suzhou Kintor launched a research effort looking for more potent full AR antagonists with reduced CNS drug distribution. Lead series was rapidly generated by computer-aided drug design. Designed molecules based on clinically proven thiohydantoin core were docked into AR LBD binding site and filtered with criteria of binding and ability to induce antagonism conformation. Initial optimization mainly focused on improving AR antagonism potency. Additional substitutions were introduced in the left hand side to increase binding affinity to AR whereas more extended fragment was used in the AR helix 12 region to prevent AR to adopt agonism conformation hence ensure full antagonism (which may help overcome resistance arise from residual AR agonism). Further optimization for ADME properties with focus to reduce CNS drug exposure led to discovery of several candidate compounds, after overcoming the challenge of increase polarity while maintaining/improving AR antagonism potency. GT0918 and GT0903 emerged as two of top candidates for further preclinical clinical development. Both compounds have excellent affinity with AR (4-10x tighter than MDV3100), as well as potent AR antagonism (2-5x more potent than MDV3100). They also demonstrated good anti-tumor efficacy in both hormone sensitive and CRPC animal models. In addition, both candidate compounds demonstrated anti-proliferation effects in AR positive breast cancer cell lines (MCF-7 and MDA-MB-453). With higher polar surface area (PSA), GT0918 demonstrated low CNS drug distribution and no seizure was observed in animal toxicity studies (up to 1g/kg, rat/dog). With improved ADME profile (better solubility and predicted to have less drug accumulation in patients), GT0918 is being developed for Phase I trial start. Citation Format: Youzhi Tong, Chunyun Chen, Juan Wu, Huihui Zhang, Xiaojun Wu, Yanmei Duan, Wei Gao, Xiaoxia Niu, Linglan Ma, Chuangxing Guo. Discovery of potent androgen receptor antagonists for treating CRPC and AR+ breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2460. doi:10.1158/1538-7445.AM2013-2460

Biochemical and metabolomic effects of perinatal choline deficiency in the piglet

Choline plays an essential role in tissue development during gestation and early postnatal life, and the piglet (Sus scrofa) may serve as a translational animal model to study perinatal effects of choline deficiency. Our objective was to determine developmental changes in piglets exposed to differing levels of choline both prenatally and postnatally. A factorial arrangement of choline sufficient (CS; 50% above requirement) and choline deficient (CD; 50% below requirement) diets were provided during the prenatal (last 65 d of gestation) and postnatal (48 h after birth through 28 d of age) periods. An interactive effect of choline level and perinatal period was observed for body weight gain (P < 0.001), and prenatal CD piglets had smaller (P = 0.014) brains than prenatal CS piglets. Blood chemistry panels revealed generalized impairments in liver function in postnatal CD piglets. Overall, metabolomic analysis identified 276 biochemicals and revealed that choline deficiency in the pre‐ and postnatal periods altered plasma levels of metabolites related to choline biosynthesis, glycolysis, and lipid metabolism. Additionally, interactive effects were noted for glycolytic intermediates, carnitine‐related metabolites, and many choline‐containing lysolipids. We conclude that the piglet is a sensitive animal model for studying developmental aspects of perinatal choline deficiency.U.S. Department of Agriculture Hatch Project ILLU‐538–319

Estrogen effects in allergy and asthma.

Asthma prevalence and severity are greater in women than in men, and mounting evidence suggests this is in part related to female steroid sex hormones. Of these, estrogen has been the subject of much study. This review highlights recent research exploring the effects of estrogen in allergic disease. Estrogen receptors are found on numerous immunoregulatory cells and estrogen's actions skew immune responses toward allergy. It may act directly to create deleterious effects in asthma, or indirectly via modulation of various pathways including secretory leukoprotease inhibitor, transient receptor potential vanilloid type 1 ion channel and nitric oxide production to exert effects on lung mechanics and inflammation. Not only do endogenous estrogens appear to play a role, but environmental estrogens have also been implicated. Environmental estrogens (xenoestrogens) including bisphenol A and phthalates enhance allergic sensitization in animal models and may enhance development of atopic disorders like asthma in humans. Estrogen's role in allergic disease remains complex. As allergic diseases continue to increase in prevalence and affect women disproportionately, gaining a fuller understanding of its effects in these disorders will be essential. Of particular importance may be effects of xenoestrogens on allergic disease.

SIRT1 in Type 2 Diabetes: Mechanisms and Therapeutic Potential

The prevalence of type 2 diabetes mellitus (T2DM) has been increasing worldwide. Therefore, a novel therapeutic strategy by which to prevent T2DM is urgently required. Calorie restriction (CR) can retard the aging processes, and delay the onset of numerous age-related diseases including diabetes. Metabolic CR mimetics may be therefore included as novel therapeutic targets for T2DM. Sirtuin 1 (SIRT1), a NAD+-dependent histone deacetylase that is induced by CR, is closely associated with lifespan elongation under CR. SIRT1 regulates glucose/lipid metabolism through its deacetylase activity on many substrates. SIRT1 in pancreatic β-cells positively regulates insulin secretion and protects cells from oxidative stress and inflammation, and has positive roles in the metabolic pathway via the modulation in insulin signaling. SIRT1 also regulates adiponectin secretion, inflammation, glucose production, oxidative stress, mitochondrial function, and circadian rhythms. Several SIRT1 activators, including resveratrol have been demonstrated to have beneficial effects on glucose homeostasis and insulin sensitivity in animal models of insulin resistance. Therefore, SIRT1 may be a novel therapeutic target for the prevention of T2DM, implicating with CR. In this review, we summarize current understanding of the biological functions of SIRT1 and discuss its potential as a promising therapeutic target for T2DM.

Telmisartan ameliorates insulin sensitivity by activating the AMPK/SIRT1 pathway in skeletal muscle of obese db/db mice

BackgroundTelmisartan is a well-established angiotensin II type 1 receptor blocker that improves insulin sensitivity in animal models of obesity and insulin resistance, as well as in humans. Telmisartan has been reported to function as a partial agonist of the peroxisome proliferator-activated receptor (PPAR) γ, which is also targeted by the nicotinamide adenine dinucleotide (NAD)-dependent deacetylase (SIRT1). Here, we investigated the pathways through which telmisartan acts on skeletal muscle, in vitro as well as in vivo.MethodsNine-week-old male db/db mice were fed a 60% high-fat diet, with orally administrated either vehicle (carboxymethyl-cellulose, CMC), 5 mg/kg telmisartan, or 5 mg/kg telmisartan and 1 mg/kg GW9662, a selective irreversible antagonist of PPARγ, for 5 weeks. Effects of telmisartan on Sirt1 mRNA, AMPK phosphorylation, and NAD+/NADH ratio were determined in C2C12 cultured myocytes.Results and discussionTelmisartan treatment improved insulin sensitivity in obese db/db mice fed a high-fat diet and led to reduction in the size of hypertrophic pancreatic islets in these mice. Moreover, in vitro treatment with telmisartan led to increased expression of Sirt1 mRNA in C2C12 skeletal muscle cells; the increase in Sirt1 mRNA in telmisartan-treated C2C12 myoblasts occurred concomitantly with an increase in AMPK phosphorylation, an increase in NAD+/NADH ratio, and increases in the mRNA levels of PGC1α, FATP1, ACO, and GLUT4.ConclusionsOur results indicate that telmisartan acts through a PPARγ-independent pathway, but at least partially exerts its effects by acting directly on skeletal muscle AMPK/SIRT1 pathways.

Characterization of Eosinophils, Class II Receptor, and B Cells in Laryngeal Mucosa From an Animal Model of Sensitization and Inhalatory Challenge With Ovalbumin

Characterization of Eosinophils, Class II Receptor, and B Cells in Laryngeal Mucosa From an Animal Model of Sensitization and Inhalatory Challenge With Ovalbumin

Sirtuin biology and relevance to diabetes treatment

Sirtuins are a group of NAD(+)-dependent enzymes that post-translationally modify histones and other proteins. Among seven mammalian sirtuins, SIRT1 has been the most extensively studied and has been demonstrated to play a critical role in all major metabolic organs and tissues. SIRT1 regulates glucose and lipid homeostasis in the liver, modulates insulin secretion in pancreatic islets, controls insulin sensitivity and glucose uptake in skeletal muscle, increases adiponectin expression in white adipose tissue and controls food intake and energy expenditure in the brain. Recently, SIRT3 has been demonstrated to modulate insulin sensitivity in skeletal muscle and systemic metabolism, and Sirt3-null mice manifest characteristics of metabolic syndrome on a high-fat diet. Thus, it is reasonable to believe that enhancing the activities of SIRT1 and SIRT3 may be beneficial for Type 2 diabetes. Although it is controversial, the SIRT1 activator SRT1720 has been reported to be effective in improving glucose metabolism and insulin sensitivity in animal models. More research needs to be conducted so that we can better understand the physiological functions and molecular mechanisms of sirtuins in order to therapeutically target these enzymes for diabetes treatment.

Estimating Efficacy and Drug ED50's Using von Frey Thresholds: Impact of Weber's Law and Log Transformation

The use of von Frey filaments, originally developed by Maximilian von Frey, has become the cornerstone for assaying mechanical sensitivity in animal models and is widely used for human assessment. While there are certain limitations associated with their use that make comparisons between studies not straightforward at times, such as stimulus duration and testing frequency, von Frey filaments provide a good measurement of mechanosensation. Here we describe the application of von Frey filaments to testing in animal models, specifically with respect to determining changes in sensory thresholds in a pain state using the Dixon up-down method. In a literature survey, we found that up to 75% of reports using this method analyze the data with parametric statistical analysis and of those that used nonparametric analysis, none took into account that mechanical sensation is perceived on a logarithmic scale (Weber's Law) when calculating efficacy. Here we outline a more rigorous analysis for calculating efficacy and ED50's from von Frey data that incorporates Weber's Law. We show that this analysis makes statistical and biological sense and provide a specific example of how this change affects data analysis that brings results from animal models more in line with clinical observations. PerspectiveThis focus article argues that analyzing von Frey paw withdrawal threshold data obtained by using the Dixon up-down method without considering Weber's Law is inappropriate. An analysis method that incorporates how mechanical sensation is perceived and how its application brings results from animal models more in line with clinical data is presented.