Gonadal Fat Pad Research Articles

Adipocyte epigenetic alterations and potential therapeutic targets in transgenerationally inherited lean and obese phenotypes following ancestral exposures

ABSTRACTThe incidence of obesity has increased dramatically over the past two decades with a prevalence of approximately 40% of the adult population within the United States. The current study examines the potential for transgenerational adipocyte (fat cell) epigenetic alterations. Adipocytes were isolated from the gonadal fat pad of the great-grand offspring F3 generation 1-year old rats ancestrally exposed to DDT (dichlorodiphenyltrichloroethane), atrazine, or vehicle control in order to obtain adipocytes for DNA methylation analysis. Observations indicate that there were differential DNA methylated regions (DMRs) in the adipocytes with the lean or obese phenotypes compared to control normal (non-obese or lean) populations. The comparison of epigenetic alterations indicated that there were substantial overlaps between the different treatment lineage groups for both the lean and obese phenotypes. Novel correlated genes and gene pathways associated with DNA methylation were identified, and may aid in the discovery of potential therapeutic targets for metabolic diseases such as obesity. Observations indicate that ancestral exposures during critical windows of development can induce the epigenetic transgenerational inheritance of DNA methylation changes in adipocytes that ultimately may contribute to an altered metabolic phenotype.

Genetic knockdown of brain-derived neurotrophic factor in the nervous system attenuates angiotensin II-induced hypertension in mice.

Introduction:Brain-derived neurotropic factor (BDNF) is expressed throughout the central nervous system and peripheral organs involved in the regulation of blood pressure, but the systemic effects of BDNF in the control of blood pressure are not well elucidated.Materials and methods:We utilized loxP flanked BDNF male mice to cross with nestin-Cre female mice to generate nerve system BDNF knockdown mice, nestin-BDNF (+/–), or injected Cre adenovirus into the subfornical organ to create subfornical organ BDNF knockdown mice. Histochemistry was used to verify injection location. Radiotelemetry was employed to determine baseline blood pressure and pressor response to angiotensin II (1000 ng/kg/min). Real-time polymerase chain reaction was used to measure the expression of renin–angiotensin system components in the laminal terminalis and peripheral organs.Results:Nestin-BDNF (+/–) mice had lower renin–angiotensin system expression in the laminal terminalis and peripheral organs including the gonadal fat pad, and a lower basal blood pressure. They exhibited an attenuated hypertensive response and a weak or similar modification of renin–angiotensin system component expression to angiotensin II infusion. Subfornical organ BDNF knockdown was sufficient for the attenuation of angiotensin II-induced hypertension.Conclusion:Central BDNF, especially subfornical organ BDNF is involved in the maintenance of basal blood pressure and in augmentation of hypertensive response to angiotensin II through systemic regulation of the expression of renin–angiotensin system molecules.

Perinatal phthalate and high-fat diet exposure induce sex-specific changes in adipocyte size and DNA methylation

Environmental factors such as diet and endocrine-disrupting chemicals have individually been shown to mediate metabolic function. However, the underlying mechanism by which the combination disrupts adipocyte morphology and fat storage remains unknown. The current study evaluated early-life programming by diet and phthalate exposure. During gestation and lactation, pregnant Long–Evans hooded rat dams were fed either a control (C) or high-fat (HF) diet and were orally administered one of three phthalate dosages (0, 200 or 1000 μg/kg/day), yielding six groups of offspring: C-0, C-200, C-1000, HF-0, HF-200 and HF-1000. On postnatal day (PND) 90, gonadal fat pads were collected and analyzed for histology, gene expression and DNA methylation. Differences in body weight were observed only in males. Hematoxylin and eosin staining revealed larger adipocyte size in HF-0 vs. C-0 females. Exposure to 200 or 1000 μg/kg/day phthalates modulated diet-induced changes in adipose morphology. Compared to C-0 females, HF-0 females also had higher expression of the adipogenesis gene Wnt receptor, frizzled 1 (Fzd1) and the triglyceride cleaving enzyme lipoprotein lipase (Lpl). These increases in gene expression were accompanied by lower DNA methylation surrounding the transcription start sites of the two genes. Diet-driven effects were observed in unexposed females but not in phthalate-treated rats. Results suggest a sex-specific association between perinatal HF diet and body weight, adipocyte size and DNA methylation. Perinatal phthalate exposure appears to produce a phenotype that more closely resembles HF-fed animals.

Lipectomizing Mice for Applications in Metabolism.

The obesity epidemic is a critical public health problem closely associated with the development of metabolic disease. In obesity there is excess white adipose tissue, a dynamic tissue that has many biological functions. Specifically visceral adipose tissue (VAT) is an active endocrine organ producing hormones that control systemic metabolism. VAT accumulates immune cells that produce cytokines that drive chronic inflammation and promote insulin resistance. VAT can be surgically removed in experimental animals (lipectomy) to explore mechanisms by which VAT participates in metabolic, endocrine, and immunological functions. This chapter describes the technical protocol for efficient and successful removal of the gonadal fat pads in mice.

Resistance to Diet-Induced Obesity in Mice Lacking OPA1 in Adipose Tissue Occurs Independently of Fat-Derived FGF-21 and BAT Function

Optic Atrophy 1 (OPA1) is a mitochondrial protein that regulates mitochondrial dynamics and function. The role of OPA1 in adipose tissue physiology and systemic metabolism is incompletely understood. We generated mice lacking OPA1 in adipose tissue (OPA1 Ad-KO) and demonstrated that OPA1 deletion in adipose tissue completely prevents diet-induced obesity (DIO). This metabolic protection occurs concomitantly with increased levels of FGF-21 in adipose tissue and the circulation and higher energy expenditure. In the present study, we sought to determine the contribution of fat-derived FGF-21 and brown adipocyte function to the phenotype observed in OPA1 Ad-KO mice. To test whether changes in BAT function are responsible for the resistance to DIO, soon after weaning, OPA1 Ad-KO mice were fed either 60% high-fat diet (HFD) or 10% fat diet (control diet) for 8 weeks at thermoneutral conditions (30oC), when BAT function is dampened. To test whether fat-derived FGF-21 is required for the resistance to DIO in OPA1 Ad-KO mice, we generated mice lacking both OPA1 and FGF-21 in adipose tissue, by using the cre recombinase under the control of the adiponectin promoter (DKO). We, then, fed 4-week old DKO mice either 60% HFD or 10% control diet for 4 weeks. OPA1 Ad-KO mice fed a HFD under thermoneutral conditions failed to gain weight. Diet-induced increases in total fat mass was completely prevented. Although BAT mass was equally increased in WT and Ad-KO mice, gonadal and inguinal fat pads were significantly reduced in OPA1 Ad-KO mice fed HFD. Likewise, after 4 weeks of high-fat feeding, DKO mice had significantly reduced body weight and total fat mass compared to WT mice. In conclusion, our data suggest that reducing BAT function is not sufficient to induce fat expansion in OPA1 Ad-KO mice in response to HFD. Additionally, here we show that adipose tissue-derived FGF-21 is dispensable for the resistance to DIO observed in OPA1 Ad-KO mice. Disclosure R. Pereira: None. A.C. Olvera: None. A.A. Marti: None. R. Hewezi: None. W.A. Bui Tran: None. M.J. Potthoff: None. E. Abel: None.

Lectin-like oxidized low-density lipoprotein receptor-1 promotes endothelial dysfunction in LDL receptor knockout background

ObjectiveLectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for oxidized LDL in endothelial cells. LOX-1 is highly expressed in atherosclerotic plaques. The impact of LOX-1 on development of endothelial dysfunction in large vessels in absence or presence of atherosclerosis-prone conditions has not been studied to date. MethodsMice with endothelial cell-specific LOX-1 overexpression (bLOX-1tg) were analyzed. Wild-type (WT) mice served as controls. In addition, bLOX-1tg mice were crossed with LDL receptor knockout (Ldlr−/−) mice. All mice were fed a western-type diet (WD) or control diet (CD) for 20 weeks. Afterwards, endothelial function was analyzed ex vivo in thoracic aortas using a Mulvany myograph. ResultsWD induced hypertriglyceridemia (bLOX-1tg: 1.6-fold; WT: 1.4-fold) and hypercholesterolemia (P < 0.0001) in bLOX-1tg and WT mice without HDL-elevation in bLOX-1tg mice. Gonadal fat pad weight was 1.7 and 1.2-fold increased on CD and WD in bLOX-1tg mice compared to WT. LOX-1 overexpression impaired endothelial function by 15–16% (P < 0.05) on CD and WD. Crossing bLOX-1tg mice into Ldlr−/− background strongly elevated total (∼6-fold) and LDL-cholesterol (∼9-fold) compared to WT and bLOX-1tg mice on WD. Endothelial function in response to WD was impaired in bLOX-1tg/Ldlr−/− mice (Effmax: 56.7 ± 23.0%) compared to WT (Effmax: 88.2 ± 15.8%, P < 0.001), bLOX-1tg (Effmax: 76.7 ± 12.9%, P < 0.05) and Ldlr−/− mice (Effmax: 70.1 ± 13.1%, P < 0.05). No differences between WT, bLOX-1tg and Ldlr−/− mice were detectable when comparing all genotypes. ConclusionEndothelial LOX-1 overexpression in an atherosclerosis-prone background impairs endothelial function, proving its importance in the development of atherosclerosis.

IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice.

Insulin-like growth factors (IGFs) and myostatin have opposing roles in regulating the growth and size of skeletal muscle, with IGF1 stimulating, and myostatin inhibiting, growth. However, it remains unclear whether these proteins have mutually dependent, or independent, roles. To clarify this issue, we crossed myostatin null (Mstn-/-) mice with mice overexpressing Igf1 in skeletal muscle (Igf1+) to generate six genotypes of male mice; wild type (Mstn+/+ ), Mstn+/-, Mstn-/-, Mstn+/+:Igf1+, Mstn+/-:Igf1+ and Mstn-/-:Igf1+ Overexpression of Igf1 increased the mass of mixed fibre type muscles (e.g. Quadriceps femoris) by 19% over Mstn+/+ , 33% over Mstn+/- and 49% over Mstn-/- (P < 0.001). By contrast, the mass of the gonadal fat pad was correspondingly reduced with the removal of Mstn and addition of Igf1 Myostatin regulated the number, while IGF1 regulated the size of myofibres, and the deletion of Mstn and Igf1+ independently increased the proportion of fast type IIB myosin heavy chain isoforms in T. anterior (up to 10% each, P < 0.001). The abundance of AKT and rpS6 was increased in muscles of Mstn-/-mice, while phosphorylation of AKTS473 was increased in Igf1+mice (Mstn+/+:Igf1+, Mstn+/-:Igf1+ and Mstn-/-:Igf1+). Our results demonstrate that a greater than additive effect is observed on the growth of skeletal muscle and in the reduction of body fat when myostatin is absent and IGF1 is in excess. Finally, we show that myostatin and IGF1 regulate skeletal muscle size, myofibre type and gonadal fat through distinct mechanisms that involve increasing the total abundance and phosphorylation status of AKT and rpS6.

In utero exposure to di-(2-ethylhexyl) phthalate induces metabolic disorder and increases fat accumulation in visceral depots of C57BL/6J mice offspring.

Excessive visceral fat accumulation is associated with metabolic disorders. Di-(2-ethylhexyl) phthalate (DEHP), a candidate environmental obesogen, affects lipid metabolism and adipogenesis. Perinatal exposure to DEHP may be associated with metabolic disorders of dams and offspring. The aim of the present study was to explore the effects of exposure of pregnant dams to DEHP on the metabolism and fat distribution of their offspring, and to determine the mechanisms for these effects. Pregnant C57BL/6J mice were administered DEHP via gavage (0.05 or 500 mg/kg/day) from gestational days 1-19. Pups were sacrificed at nine weeks of age. Serum leptin, insulin, lipid and fasting glucose levels, and the weights of the inguinal (subcutaneous) and gonadal (visceral) fat pads were determined. mRNA expression levels of two developmental genes, T-box 15 (Tbx15) and glypican 4 (Gpc4) were detected in fat tissues. A 100% abortion rate was exhibited in 500 mg/kg DEHP-treated dams, whereas exposure to 0.05 mg/kg DEHP did not affect reproductive outcomes. Pups from the 0.05 mg/kg exposure group were used for subsequent experimentation. Serum leptin, insulin, lipid and fasting glucose concentrations in these pups were significantly higher than those of control pups (P<0.05). Although no significant change in body weight was detected, the visceral fat weights of DEHP-exposed pups were significantly higher than those of control pups (P<0.05). Compared with controls, mRNA expression levels of Tbx15 in subcutaneous fat and Gpc4 in visceral fat were significantly increased among DEHP-exposed pups (P<0.01). The present results suggest that in utero exposure to an environmentally safe dose of DEHP may lead to excessive visceral fat accumulation and metabolic disorders in offspring and that aberrant expression of Tbx15 and Gpc4 may have an important role in these effects.

Marrow Adipose Tissue Expansion Coincides with Insulin Resistance in MAGP1-Deficient Mice.

Marrow adipose tissue (MAT) is an endocrine organ with the potential to influence skeletal remodeling and hematopoiesis. Pathologic MAT expansion has been studied in the context of severe metabolic challenge, including caloric restriction, high fat diet feeding, and leptin deficiency. However, the rapid change in peripheral fat and glucose metabolism associated with these models impedes our ability to examine which metabolic parameters precede or coincide with MAT expansion. Microfibril-associated glycoprotein-1 (MAGP1) is a matricellular protein that influences cellular processes by tethering signaling molecules to extracellular matrix structures. MAGP1-deficient (Mfap2−/−) mice display a progressive excess adiposity phenotype, which precedes insulin resistance and occurs without changes in caloric intake or ambulation. Mfap2−/− mice were, therefore, used as a model to associate parameters of metabolic disease, bone remodeling, and hematopoiesis with MAT expansion. Marrow adiposity was normal in Mfap2−/− mice until 6 months of age; however, by 10 months, marrow fat volume had increased fivefold relative to wild-type control at the same age. Increased gonadal fat pad mass and hyperglycemia were detectable in Mfap2−/− mice by 2 months, but peaked by 6 months. The development of insulin resistance coincided with MAT expansion. Longitudinal characterization of bone mass demonstrated a disconnection in MAT volume and bone volume. Specifically, Mfap2−/− mice had reduced trabecular bone volume by 2 months, but this phenotype did not progress with age or MAT expansion. Interestingly, MAT expansion in the 10-month-old Mfap2−/− mice was associated with modest alterations in basal hematopoiesis, including a shift from granulopoiesis to B lymphopoiesis. Together, these findings indicate MAT expansion is coincident with insulin resistance, but not excess peripheral adiposity or hyperglycemia in Mfap2−/− mice; and substantial MAT accumulation does not necessitate a proportional decrease in either bone mass or bone marrow cellularity.

Abstract A08: A patient-derived xenograft model to study the effects of postmenopausal obesity on endocrine therapy resistance

Abstract Introduction: Obesity affects more than one-third of adults in the U.S. and increases the risk for and worsens outcomes of individuals with cancer. Obese women have a greater risk of postmenopausal hormone-receptor positive breast cancer and are more likely to relapse after endocrine therapy. The prevailing dogma is that elevated circulating estrogen, produced by aromatase in abundant adipose tissue, drives breast cancer formation and progression. While estrogen is clearly an important factor in the obesity-breast cancer relationship, increasing the dose of aromatase inhibitors provides no added benefit to obese women with breast cancer. A switch from hormone- to growth factor-dependence has been implicated in the development of endocrine therapy resistance. Hypothesis and Study Objective: We hypothesized that obese, postmenopausal women have elevated growth factor production in adipose tissue, which supports the progression of breast tumors that were previously dependent on estrogen. The purpose of our study was to develop a transplant-competent mouse model of obesity and postmenopausal breast cancer using estrogen receptor (ER) positive breast cancer patient-derived xenografts (PDX) from peri- and postmenopausal women (ages 45-71). Methods: Rag1-null mice on the C57Bl/6 background were fed either a low fat (LFD) or high fat (HFD) diet for 10 weeks. Thermoneutral housing was used to facilitate development of the obese phenotype. Animal weights and percent body fat were monitored. After weight separation (approximately 10 weeks), mice were ovariectomized and implanted with an ER+ estrogen-dependent PDX derived from a 54 year old woman bilaterally into the orthotopic site (inguinal mammary fat pad). Mice were given slow release estrogen pellets and tumor growth was monitored. After 8 weeks of tumor growth, a subset of animals received estrogen withdrawal (EWD) to mimic the menopausal transition. Results: HFD-fed mice weighed more, and had significantly increased body fat percentages, as well as subcutaneous, and gonadal fat pad weights, compared to LFD-fed mice. After EWD, tumors regressed in LFD-fed mice; however, the HFD prevented tumor regression in the absence of estrogen. Circulating estrogen levels in both LFD and HFD EWD groups were not significantly different. Tumor cellularity and Ki67 were greater in HFD- compared to LFD-fed mice in the absence of estrogen. Phospho-protein analysis of tumors suggested increased human epidermal growth factor receptor 2 (HER2) and fibroblast growth factor receptor (FGFR) signaling in HFD-EWD versus LFD-EWD mice. Conclusions: We have developed a novel, transplant-competent mouse model of obesity and menopause using a specialized HFD and thermoneutral housing. Using this model, we determined that HFD supports the growth of a previously estrogen-dependent breast cancer PDX after EWD, potentially through increased signaling through HER2 and FGFR pathways. Our mouse model, in combination with PDX breast tumors, will offer novel insights into the relationships between obesity, menopause, and ER+ breast cancer progression. Citation Format: Elizabeth Wellberg, Britta Jacobsen, Peter Kabos, Paul MacLean, Carol Sartorius. A patient-derived xenograft model to study the effects of postmenopausal obesity on endocrine therapy resistance. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr A08.

Cathepsin S controls adipocytic and osteoblastic differentiation, bone turnover, and bone microarchitecture

Cathepsin S is a cysteine protease that controls adipocyte differentiation and has been implicated in vascular and metabolic complications of obesity. Considering the inverse relation of osteoblasts and adipocytes and their mutual precursor cell, we hypothesized that cathepsin S may also affect osteoblast differentiation and bone remodeling. Thus, the fat and bone phenotypes of young (3months old) and aged (12 or 18months old) cathepsin S knock-out (KO) and wild-type (WT) mice were determined.Cathepsin S KO mice had a normal body weight at both ages investigated, even though the amount of subscapular and gonadal fat pads was reduced by 20%. Further, cathepsin S deficiency impaired adipocyte formation (−38%, p<0.001), which was accompanied by a lower expression of adipocyte-related genes and a reduction in serum leptin, IL-6 and CCL2 (p<0.001). Micro-CT analysis revealed an unchanged trabecular bone volume fraction and density, while tissue mineral density was significantly lower in cathepsin S KO mice at both ages. Aged KO mice further had a lower cortical bone mass (−2.3%, p<0.05). At the microarchitectural level, cathepsin S KO mice had thinner trabeculae (−8.3%), but a better connected trabecular network (+24%). Serum levels of the bone formation marker type 1 procollagen amino-terminal-propeptide and osteocalcin were both 2–3-fold higher in cathepsin S KO mice as was the mineralized surface. Consistently, osteogenic differentiation was increased 2-fold along with an increased expression of osteoblast-specific genes. Interestingly, serum levels of C-terminal telopeptide of type I collagen were also higher (+43%) in cathepsin S KO mice as were histological osteoclast parameters and ex vivo osteoclast differentiation.Thus, cathepsin S deficiency alters the balance between adipocyte and osteoblast differentiation, increases bone turnover, and changes bone microarchitecture. Therefore, bone and fat metabolisms should be monitored when using cathepsin S inhibitors clinically.

Mice lacking G0S2 are lean and cold-tolerant

G0/G1 switch gene 2 (G0S2) is a protein that was first identified in a search for lymphocyte G0/G1 switch genes. A direct role for G0S2 in cell cycle regulation has proven elusive. Yet, there is prior evidence for G0S2 functioning in tumor suppression, immune regulation and lipolysis. To explore definitively G0S2 functions, mice lacking G0S2 were generated and characterized. G0S2−/− mice were born at a Mendelian ratio and were phenotypically normal, with the exception of a possible lactation defect. G0S2−/− female mice carried viable pups to term, but could not typically sustain them beyond 48 h. G0S2 is shown here to be most highly expressed in adipose tissue. It is also expressed in liver, skeletal muscle, lung, ventricles of the heart, and components of the kidney. G0S2 loss significantly decreased relative body weight gain as compared with wild-type (WT) (G0S2+/+) mice, with a significant decrease in gonadal fat pad weight and a significant increase in serum glycerol levels. This decreased relative body weight gain is not associated with a significant decrease in food intake or increase in activity of G0S2−/− mice. In fact, G0S2−/− mice were significantly less active at night than G0S2+/+ mice. When fed with a high fat diet (45% fat diet), G0S2 loss did not prevent diet-induced obesity in mice. Intriguingly, G0S2 loss improved acute cold tolerance, augmenting expression of genes involved in thermogenesis. In summary, in vivo roles for G0S2 were found in lactation, energy balance, and thermogenesis. This study provides a basis for tumor suppressive effects of G0S2 by regulating lipolysis.

The Sex Chromosome Trisomy mouse model of XXY and XYY: metabolism and motor performance

BackgroundKlinefelter syndrome (KS), caused by XXY karyotype, is characterized by low testosterone, infertility, cognitive deficits, and increased prevalence of health problems including obesity and diabetes. It has been difficult to separate direct genetic effects from hormonal effects in human studies or in mouse models of KS because low testosterone levels are confounded with sex chromosome complement.MethodsIn this study, we present the Sex Chromosome Trisomy (SCT) mouse model that produces XXY, XYY, XY, and XX mice in the same litters, each genotype with either testes or ovaries. The independence of sex chromosome complement and gonadal type allows for improved recognition of sex chromosome effects that are not dependent on levels of gonadal hormones. All mice were gonadectomized and treated with testosterone for 3 weeks. Body weight, body composition, and motor function were measured.ResultsBefore hormonal manipulation, XXY mice of both sexes had significantly greater body weight and relative fat mass compared to XY mice. After gonadectomy and testosterone replacement, XXY mice (both sexes) still had significantly greater body weight and relative fat mass, but less relative lean mass compared to XY mice. Liver, gonadal fat pad, and inguinal fat pad weights were also higher in XXY mice, independent of gonadal sex. In several of these measures, XX mice also differed from XY mice, and gonadal males and females differed significantly on almost every metabolic measure. The sex chromosome effects (except for testis size) were also seen in gonadally female mice before and after ovariectomy and testosterone treatment, indicating that they do not reflect group differences in levels of testicular secretions. XYY mice were similar to XY mice on body weight and metabolic variables but performed worse on motor tasks compared to other groups.ConclusionsWe find that the new SCT mouse model for XXY and XYY recapitulates features found in humans with these aneuploidies. We illustrate that this model has significant promise for unveiling the role of genetic effects compared to hormonal effects in these syndromes, because many phenotypes are different in XXY vs. XY gonadal female mice which have never been exposed to testicular secretions.

C5a Receptor Deficiency Alters Energy Utilization and Fat Storage

ObjectiveTo investigate the impact of whole body C5a receptor (C5aR) deficiency on energy metabolism and fat storage.DesignMale wildtype (WT) and C5aR knockout (C5aRKO) mice were fed a low fat (CHOW) or a high fat high sucrose diet-induced obesity (DIO) diet for 14 weeks. Body weight and food intake were measured weekly. Indirect calorimetry, dietary fatload clearance, insulin and glucose tolerance tests were also evaluated. Liver, muscle and adipose tissue mRNA gene expression were measured by RT-PCR.ResultsAt week one and 12, C5aRKO mice on DIO had increased oxygen consumption. After 12 weeks, although food intake was comparable, C5aRKO mice had lower body weight (−7% CHOW, −12% DIO) as well as smaller gonadal (−38% CHOW, −36% DIO) and inguinal (−29% CHOW, −30% DIO) fat pads than their WT counterparts. Conversely, in WT mice, C5aR was upregulated in DIO vs CHOW diets in gonadal adipose tissue, muscle and liver, while C5L2 mRNA expression was lower in C5aRKO on both diet. Furthermore, blood analysis showed lower plasma triglyceride and non-esterified fatty acid levels in both C5aRKO groups, with faster postprandial triglyceride clearance after a fatload. Additionally, C5aRKO mice showed lower CD36 expression in gonadal and muscle on both diets, while DGAT1 expression was higher in gonadal (CHOW) and liver (CHOW and DIO) and PPARγ was increased in muscle and liver.ConclusionThese observations point towards a role (either direct or indirect) for C5aR in energy expenditure and fat storage, suggesting a dual role for C5aR in metabolism as well as in immunity.

Effect of vascular endothelial growth factor receptor 2 antagonism on adiposity in obese mice

Development and maintenance of fat depots require angiogenesis, in which vascular endothelial growth factor (VEGF) and its receptors play a crucial role. We have evaluated the effect of blocking VEGF receptor 2 (VEGF-R2) with a MAB (DC101) on adipose tissue of mice with established obesity. Therefore, obese male wild-type C57B1/6 mice were treated with i.p. injection of DC101 (40 mg/kg body weight, twice weekly during 13 weeks) or of the control antibody 1C8. Treatment with DC101 resulted in a slightly lower body weight but had no effect on subcutaneous (SC) or gonadal (GON) white adipose tissue mass, as monitored by MRI. Histochemical analysis of isolated SC and GON fat pads did not reveal significant effects of DC101 treatment on adipocyte or blood vessel size or density. Plasma levels of the liver enzymes aspartate aminotransferase and alanine aminotransferase as well as liver triglyceride levels were significantly decreased following DC101 treatment. Plasma glucose levels were markedly lower upon DC101 treatment, whereas insulin and adiponectin levels were not affected. Furthermore, Akt phosphorylation in adipose tissues was not affected. Thus, in vivo VEGF-R2 blockade in mice with established nutritionally induced obesity did not significantly affect insulin signaling in adipose tissue or adiposity.

The Sex-Dependent Impact of Chronic Clozapine and Haloperidol Treatment on Characteristics of the Metabolic Syndrome in a Rat Model

An increased risk for metabolic syndrome has been described for patients with psychotic disorders. Antipsychotic drugs possibly contribute to metabolic changes. Haloperidol or clozapine was orally fed to male and female Sprague Dawley rats for 12 weeks, and body weight gain, food and water intake were measured. The serum levels of fasting glucose, HbA1c, triglycerides, cholesterol, HDL and LDL, insulin, leptin, adiponectin and ghrelin were determined. Gonadal and perirenal fat pads were removed and weighed. We found increased body weight in the male clozapine group, but decreased ones in the male haloperidol group. Clozapine-treated male and female animals had higher fasting glucose, adiponectin, leptin, ghrelin, cholesterol, HDL and LDL levels, whereas haloperidol caused increased levels of insulin and decreased values of HbA1c, cholesterol, HDL and LDL. Both antipsychotic drugs cause sex-dependent metabolic changes, which are risk factors for the metabolic syndrome, be it hyperinsulinemia under haloperidol treatment or hyperglycemia, hyperleptinemia and hyperlipidemia under clozapine.

Metabolic comparison of weight matched obese male and female mice

Estrogen is a known regulator of body composition and insulin sensitivity. However, a reduction in body weight (BW) is commonly associated with the reported benefits of estrogen. The purpose of this study was to compare the metabolic health of obese male and female mice matched for BW. Male and female mice were fed a high fat diet until they achieved a BW where insulin resistance is typically observed (45 g). BW gain was much more rapid in male mice as it took 3.5 months to achieve this target BW (44 g) while it took 6 months for females to achieve a similar BW (46 g). Plasma estrogen concentrations were not different between obese (92.7 pg/mL) and age matched lean (92.5 pg/mL) female mice. Despite a similar final BW, obese females had significantly larger gonadal (3.7 vs 2.2 g) and subcutaneous (3.3 vs 2.3 g) fat pads as compared to obese males. Glucose area under the curve following a glucose tolerance test was significantly improved in obese female mice as compared to obese male mice. Improved glucose tolerance was associated with reduced gonadal fat gene expression of CD11c, MCP‐1 and IL‐6 with a trend for decreased IL‐1β. Overall, our data demonstrate that circulating concentrations of estrogen were not altered in obese female mice and when matched for BW, female mice displayed increased adipose tissue mass, reduced adipose tissue inflammation and improved glucose tolerance as compared to obese male mice.

Expression of the human apoE2 isoform in adipocytes: altered cellular processing and impaired adipocyte lipogenesis

Expression of apoE in adipocytes has been shown to have an important role in modulating adipocyte triglyceride (TG) metabolism and gene expression that is independent of circulating and extracellular apoE. The impact of adipocyte expression of common human apoE isoforms was evaluated using adipocytes harvested from human apoE2, -3, and -4 knock-in mice. Expression of the apoE2 isoform was associated with an increase in adipocyte apoE gene expression and apoE synthesis. Newly synthesized apoE2 was unstable in adipocytes and demonstrated increased degradation and decreased secretion. ApoE2-expressing mice were hyperlipidemic, and had increased size of gonadal fat pads and of adipocytes, compared with apoE3 mice. In isolated cells, however, expression of the apoE2 isoform produced defective lipogenesis and increased TG hydrolysis. Incubation of adipose tissue with apoE3-containing TG-rich lipoproteins resulted in a significant increase in TG in adipose tissue from apoE3 and -E4 mice, but not apoE2 mice. Reduced capacity to internalize FFA as lipogenic substrate contributed to defective lipogenesis. Newly synthesized apoE2 is unstable in adipocytes and results in decreased adipocyte TG synthesis and defective FA uptake. These changes recapitulate those observed in apoE knockout adipocytes and have implications for understanding metabolic disturbances in humans expressing the E2 isoform.

Glucose and lipid homeostasis in adult rat is impaired by early-life exposure to perfluorooctane sulfonate

Perfluorooctane sulfonate (PFOS), which belongs to the degradation product of many perfluorinated compounds, is on the list of persistent organic pollutants (POPs) and is currently detected in both wildlife and humans. The consequence of gestational and lactational exposure to PFOS on prediabetes effect in offspring was investigated in rats in the present study. Maternal rats were treated with vehicle, 0.5 mg/kg/day or 1.5 mg/kg/day PFOS respectively from gestation day 0 to postnatal day 21. The glucose and lipid metabolism effects were investigated on the offspring in adulthood. The gestational and lactational exposure to PFOS led to low body weight from birth to weaning, and evoked signs of a prediabetic state, with elevated fasting serum insulin and leptin level, impaired glucose tolerance, though the fasting serum glucose and glycosylated serum protein level were normal. Abnormal lipid homeostasis was also observed by the phenomenon of hepatic steatosis and increased gonadal fat pad weight. However, the circulating serum level of fasting triglyceride and cholesterol level were no different from controls. Our results suggested that developmental exposure to PFOS may contribute to glucose and lipid metabolic disorder in adulthood.

β-Arrestin-1 Protein Represses Diet-induced Obesity

Diet-related obesity is a major metabolic disorder. Excessive fat mass is associated with type 2 diabetes, hepatic steatosis, and arteriosclerosis. Dysregulation of lipid metabolism and adipose tissue function contributes to diet-induced obesity. Here, we report that β-arrestin-1 knock-out mice are susceptible to diet-induced obesity. Knock-out of the gene encoding β-arrestin-1 caused increased fat mass accumulation and decreased whole-body insulin sensitivity in mice fed a high-fat diet. In β-arrestin-1 knock-out mice, we observed disrupted food intake and energy expenditure and increased macrophage infiltration in white adipose tissue. At the molecular level, β-arrestin-1 deficiency affected the expression of many lipid metabolic genes and inflammatory genes in adipose tissue. Consistently, transgenic overexpression of β-arrestin-1 repressed diet-induced obesity and improved glucose tolerance and systemic insulin sensitivity. Thus, our findings reveal that β-arrestin-1 plays a role in metabolism regulation.