Retroperitoneal Depots Research Articles

The effect of phenotype on development of brown and white adipose tissue cellularity and nonshivering thermogenesis in the wistar fatty rat

Brown adipose tissue (BAT) has been noted in cadaveric specimens by anatomists for hundreds of years and is now known to be a primary peripheral tissue in the expression of non-shivering thermogenesis in response to perturbations in diet and environment in homeothermic species including man and animals. The Wistar Fatty Rat (WFR) is an animal model of obesity, insulin resistance (IR) and NIDDM and expresses the (-fa) obesity trait in an NIH/Wistar background. This stain has been reported to exhibit NIDDM and an impaired thermogenic response to parameters of diet and environment in the obese phenotype. Groups of lean and obese male WFR rats were maintained in hanging wire-bottomed steel cages and fed a nutritionally complete diet containing 54% CHO as equal parts cornstarch (ST) and sucrose (SUC) (50:60 w/w) plus vitamins, minerals, fiber, and essential micronutrients from 22 to 30 weeks of age. Measures of body weight were monitored and measures of resting, and norepinephrine stimulated VO2 determined. Animals were sacrificed by decapitation and the Interscapular BAT depot (IBAT) and primary white adipose tissue (WAT) depots excised in their entirety for measures of adiposity including adipocyte size and number per IBAT and WAT depots. The studies included measures of adipocyte lipid content and adipocyte number of WAT depots including the dorsal (DOR), epididymal (EPI) and visceral retroperitoneal (VRP) depots. Final Body weights, net weight gain and relative adiposity of obese were significantly greater than their lean littermates throughout the study with the greatest increase in WAT cell lipid content and adipocyte number in the VRP depot. IBAT cell number, cell lipid content of IBAT tissues and IBAT:BW ratio of obese >> lean littermates. Fasting glucose was similar in both phenotypes, but fasting insulin and the Insulin: Glucose (I: G) ratios were markedly elevated in obese+NIDDM animals. Resting VO2 and the thermic response to NE of lean >> Obese+NIDDM. A robust NE response in plasma glucose concentrations occurred in both phenotypes following NE with the greatest increase in the obese+NIDDM phenotype. The results of this study indicate that while the development of IBAT and WAT mass and cellularity became exaggerated via hyperplasia and hypertrophy in the obese-NIDDM animals, the superimposition of early hyperphagia and the NIDDM stigmata which likely includes the development of significant IR is a contributing factor. The elevations in I: G and IR of the Obese+NIDDM phenotype may further facilitate adipocyte hyperplasia and hypertrophy in both WAT and BAT depots and may further compromise the capacity of the obese diabetic animals to fully express BAT-mediated contributions to NST. Moreover, the increased BAT mass and cellularity in the Obese+NIDDM was not by itself a reliable predictor of the thermic responses to diet and environment.

198-LB: The Loss of the Lysine Acetyltransferase KAT8 in Adipocytes Confers Lipodystrophy and Metabolic Dysfunction in Male and Female Mice

KAT8, also known as MOF or MYST1, is a lysine acetyltransferase with both histone and non-histone substrates. While KAT8 is the major H4K16 acetyltransferase in Drosophila and mammals and is essential for embryonic development, its role in specific cell types is not well understood. Moreover, studies within the past decade have demonstrated lineage-, differentiation state-, or stress-dependent roles of KAT8. Our recent efforts have shown that KAT8 is necessary for in vitro adipogenesis prior to or during the proliferative phase. Notably, several, independent genetic studies reveal that single nucleotide polymorphisms (SNPs) within or near the KAT8 gene are associated with body mass index and/or waist circumference. To investigate the role of KAT8 in differentiated adipocytes and to understand the contribution of KAT8-deficient adipocytes to whole-body glucose and lipid metabolism, we generated both congenital and doxycycline-inducible adipocyte-specific knockout mice, in which Kat8 gene deletion occurs only in adiponectin-expressing cells. Adult mice lacking adipocyte KAT8 exhibited significant fat mass loss with no change in lean mass. While the size of inguinal and brown adipose tissue was significantly reduced in both sexes fed either chow or high-fat, high-sucrose (HFHS) diet, male mice also had decreased gonadal, retroperitoneal, and mesenteric depots. Histological assessments revealed substantial remodeling within adipose tissue depots, and these mice demonstrated reduced insulin sensitivity and increased lipid accumulation in the liver when fed HFHS diet. Although further investigation is necessary to identify KAT8 targets that confer lipodystrophy, these studies are the first to show the impact of the loss of adipocyte KAT8 in vivo. Disclosure A. J. Richard: n/a. T. M. Mendoza: None. J. M. Stephens: None. Funding National Institutes of Health COBRE P&F grant (P30 GM118430)

Perinatal Treatment with Leptin, but Not Celastrol, Protects from Metabolically Obese, Normal-Weight Phenotype in Rats

Perinatal nutrition has a well-known influence on obesity susceptibility. We previously demonstrated the protective anti-obesity effects of perinatal leptin administration. Celastrol is a natural compound acting as a leptin sensitizer with anti-obesity effects when administered in adult animals. Here, we aimed to determine if perinatal treatment with leptin, celastrol, or their combination was able to improve metabolic health in animals fed an isocaloric high-fat (HF) diet. Leptin and/or celastrol or their vehicle were administered orally to rats during the suckling period. After weaning, animals were chronically pair-fed with an HF diet provided isocaloric to the intake of a normal-fat diet by control animals to avoid obesity. Isocaloric HF feeding in vehicle-treated animals resulted in metabolic features characteristic of the metabolically obese, normal-weight (MONW) phenotype, i.e., obesity-related disturbances without increased body weight. Leptin treatment prevented liver fat deposition and insulin resistance, induced greater insulin and leptin signaling capacity, decreased gene expression of orexigenic signals at the hypothalamic level, and induced browning in retroperitoneal adipose tissue. However, celastrol treatment did not provide any protective effect and resulted in greater size of the retroperitoneal adipose depot, higher circulating glucose and insulin levels, and decreased leptin sensitivity capacity in adipose tissue. The co-administration of leptin ameliorated the negative effects of celastrol on the retroperitoneal depot, inducing browning and decreasing its size. In conclusion, the perinatal administration of leptin, but not celastrol, provided protection against the consequences of dietary unbalances leading to an MONW phenotype in adulthood.

Fish Oil Enriched in EPA, but Not in DHA, Reverses the Metabolic Syndrome and Adipocyte Dysfunction Induced by a High-Fat Diet

This study aimed to investigate the effects of two commercially available fish oils (FOs) containing different proportions of two omega-3 fatty acids (FA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on the metabolic and endocrine dysfunctions of white adipose tissue resulting from obesity. Male C57BL/6J mice, 8 weeks old, received a control or high-fat diet (CO and HF groups, with 9% and 59% energy from fat, respectively) for 8 weeks. The next 8 weeks, the HF group was subdivided into HF, HF+FO/E (HF+5:1 EPA:DHA), and HF+FO/D (HF+5:1 DHA:EPA). Supplementation was performed by gavage, three times a week. All groups that received the HF diet had lower food and caloric intake, but a higher fat intake, body weight (BW) gain, glucose intolerance, and a significant increase in inguinal (ING), retroperitoneal (RP), and epididymal (EPI) adipose tissues when compared to the CO group. Additionally, HF and HF+FO/D groups showed insulin resistance, adipocyte hypertrophy, increased lipolysis and secretion of TNF-α, resistin and IL-10 adipokines by ING and RP adipocytes, and adiponectin only by the HF+FO/D group in ING adipocytes. All of these effects were completely reversed in the HF+FO/E group, which also showed partial reversion in BW gain and glucose intolerance. Both the HF+FO/E and HF+FO/D groups showed a reduction in ING and RP adipose depots when compared to the HF group, but only HF+FO/E in the EPI depot. HF+FO/E, but not HF+FO/D, was able to prevent the changes triggered by obesity in TNF-α, Il-10, and resistin secretion in ING and RP depots. These results strongly suggest that different EPA:DHA ratios have different impacts on the adipose tissue metabolism, FO being rich in EPA, but not in DHA, and effective in reversing the changes induced by obesity.

Chemerin contributes to in vivo adipogenesis in a location-specific manner.

Since chemerin’s identification as an adipokine, it has been associated with a number of human diseases including diabetes and obesity. However, the basic scientific foundation for these clinical determinations is still lacking. Fibroblastic mouse 3T3 cells are unable to develop lipid droplets if chemerin is not present. Thus, we hypothesized that an in vivo rat model chemerin knockout (KO; an advancement from the previously mentioned in vitro cultures) would have limited accumulation of lipid in adipocytes compared to their wild-type (WT) counterparts. Female WT/KO rats (Sprague Dawley background) were fed a low-fat diet starting at 8 weeks of age with weekly body weight and food consumption monitoring. At 25 weeks of age, adipose tissue depots were dissected and flash frozen for PCR analysis or fixed with paraformaldehyde for histology. Over the 17 weeks of experimentation, WT and KO animals did not have differences in total body weight or food consumption but KO animals had a significantly reduced amount of visceral fat compared to WT animals (via microCT at 8 and 25 weeks). Histology of retroperitoneal and mesenteric depots demonstrated a significant leftward shift in adipocyte size in the mesenteric but not the retroperitoneal depot of the KO compared to WT animals. Similarly, in the mesenteric fat of the KO rat, gene expression of adiponectin, fatty acid synthase, perilipin, and leptin were significantly reduced compared to mesenteric fat of WT animals and retroperitoneal fat of both WT and KO animals. Adiponectin was highlighted by a protein-protein interaction network as being important for the physiological effects of chemerin removal. These data are the first, to our knowledge, to demonstrate chemerin’s adipokine potential in vivo and identify it as fat depot location-specific.

Impaired glucose transport in inguinal adipocytes after short-term high-sucrose feeding in mice

Diets enriched in sucrose severely impair metabolic regulation and are associated with obesity, insulin resistance and glucose intolerance. In the current study, we investigated the effect of 4 weeks high-sucrose diet (HSD) feeding in C57BL6/J mice, with specific focus on adipocyte function. Mice fed HSD had slightly increased adipose tissue mass but displayed similar hepatic triglycerides, glucose and insulin levels, and glucose clearance capacity as chow-fed mice. Interestingly, we found adipose depot-specific differences, where both the non- and insulin-stimulated glucose transports were markedly impaired in primary adipocytes isolated from the inguinal fat depot from HSD-fed mice. This was accompanied by decreased protein levels of both GLUT4 and AS160. A similar but much less pronounced trend was observed in the retroperitoneal depot. In contrast, both GLUT4 expression and insulin-stimulated glucose uptake were preserved in adipocytes isolated from epididymal adipose tissue with HSD. Further, we found a slight shift in cell size distribution towards larger cells with HSD and a significant decrease of ACC and PGC-1α expression in the inguinal adipose tissue depot. Moreover, fructose alone was sufficient to decrease GLUT4 expression in cultured, mature adipocytes.Altogether, we demonstrate that short-term HSD feeding has deleterious impact on insulin response and glucose transport in the inguinal adipose tissue depot, specifically. These changes occur before the onset of systemic glucose dysmetabolism and therefore could provide a mechanistic link to overall impaired energy metabolism reported after prolonged HSD feeding, alone or in combination with HFD.

Depot-specific inflammation with decreased expression of ATM2 in white adipose tissues induced by high-margarine/lard intake.

A high-fat diet has been recognized as an important risk factor of obesity, with variable impacts of different fatty acid compositions on the physiological process. To understand the effects of a high-margarine/lard diet, which is a major source of trans fatty acids (TFAs)/ saturated fatty acids (SFAs), elaidic acid as a biomarker of margarine intake was used to screen affected adipokines on mature human adipocytes in vitro. Weaned male Wistar rats were fed a high-fat diet enriched with margarine/lard to generate obesity-prone (OP) and obesity-resistant (OR) models, which were then used to explore the inflammatory responses of depot-specific white adipose tissue. Adiposity, glucose and lipid metabolism parameters and macrophage cell markers were also compared in vivo. In the subcutaneous depot, a high-margarine diet induced elevated IL-6, MCP-1 and XCL1 expression levels in both M-OP and M-OR groups. High-lard diet-fed rats displayed higher protein expression levels of MCP-1 and XCL1 compared with the control group. In the epididymal depot, significantly elevated IL-6 production was observed in M-OP rats, and high-lard diet-fed rats displayed elevated IL-6 and decreased XCL1 expression. In the retroperitoneal depot, a high-margarine diet caused higher IL-6 and MCP-1 expression levels, a high-lard diet caused elevated IL-6 expression in L-OP/L-OR rats, and elevated XCL1 expression was observed only in L-OP rats. In general, CD206 mRNA levels were notably down-regulated by high-fat diet feeding in the above-mentioned depots. CD11c mRNA levels were slightly upregulated in the subcutaneous depot of OP rats fed a high-margarine/lard diet. In the epidydimal depot, higher expression levels of F4/80 and CD206 mRNA were observed only in high-margarine diet-fed OP rats. These results suggest that depot-specific inflammation with decreased expression of adipose tissue anti-inflammatory M2-type (ATM2) macrophages could be induced by high-margarine/lard intake.

Ontogeny and Thermogenic Role for Sternal Fat in Female Sheep.

Brown adipose tissue acting through a unique uncoupling protein (UCP1) has a critical role in preventing hypothermia in newborn sheep but is then thought to rapidly disappear during postnatal life. The extent to which the anatomical location of fat influences postnatal development and thermogenic function in adulthood, particularly following feeding, is unknown, and we examined both in our study. Changes in gene expression of functionally important pathways (i.e., thermogenesis, development, adipogenesis, and metabolism) were compared between sternal and retroperitoneal fat depots together with a representative skeletal muscle over the first month of postnatal life, coincident with the loss of brown fat and the accumulation of white fat. In adult sheep, implanted temperature probes were used to characterize the thermogenic response of fat and muscle to feeding and the effects of reduced or increased adiposity. UCP1 was more abundant in sternal fat than in retroperitoneal fat and was retained only in the sternal depot of adults. Distinct differences in the abundance of gene pathway markers were apparent between tissues, with sternal fat exhibiting some similarities with muscle that were not apparent in the retroperitoneal depot. In adults, the postprandial rise in temperature was greater and more prolonged in sternal fat than in retroperitoneal fat and muscle, a difference that was maintained with altered adiposity. In conclusion, sternal adipose tissue retains UCP1 into adulthood, when it shows a greater thermogenic response to feeding than do muscle and retroperitoneal fat. Sternal fat may be more amenable to targeted interventions that promote thermogenesis in large mammals.

Insulin, IGF-1, and GH Receptors Are Altered in an Adipose Tissue Depot-Specific Manner in Male Mice With Modified GH Action.

Growth hormone (GH) is a determinant of glucose homeostasis and adipose tissue (AT) function. Using 7-month-old transgenic mice expressing the bovine growth hormone (bGH) gene and growth hormone receptor knockout (GHR-/-) mice, we examined whether changes in GH action affect glucose, insulin, and pyruvate tolerance and AT expression of proteins involved in the interrelated signaling pathways of GH, insulinlike growth factor 1 (IGF-1), and insulin. Furthermore, we searched for AT depot-specific differences in control mice. Glycated hemoglobin levels were reduced in bGH and GHR-/- mice, and bGH mice displayed impaired gluconeogenesis as judged by pyruvate tolerance testing. Serum IGF-1 was elevated by 90% in bGH mice, whereas IGF-1 and insulin were reduced by 97% and 61% in GHR-/- mice, respectively. Igf1 RNA was increased in subcutaneous, epididymal, retroperitoneal, and brown adipose tissue (BAT) depots in bGH mice (mean increase ± standard error of the mean in all five depots, 153% ± 27%) and decreased in all depots in GHR-/- mice (mean decrease, 62% ± 4%). IGF-1 receptor expression was decreased in all AT depots of bGH mice (mean decrease, 49% ± 6%) and increased in all AT depots of GHR-/- mice (mean increase, 94% ± 8%). Insulin receptor expression was reduced in retroperitoneal, mesenteric, and BAT depots in bGH mice (mean decrease in all depots, 56% ± 4%) and augmented in subcutaneous, retroperitoneal, mesenteric, and BAT depots in GHR-/- mice (mean increase: 51% ± 1%). Collectively, our findings indicate a role for GH in influencing hormone signaling in AT in a depot-dependent manner.

White adipose tissue IFN-γ expression and signalling along the progression of rodent cancer cachexia

Cachexia is associated with increased morbidity and mortality in cancer. The White adipose tissue (WAT) synthesizes and releases several pro-inflammatory cytokines that play a role in cancer cachexia-related systemic inflammation. IFN-γ is a pleiotropic cytokine that regulates several immune and metabolic functions. To assess whether IFN-γ signalling in different WAT pads is modified along cancer-cachexia progression, we evaluated IFN-γ receptors expression (IFNGR1 and IFNGR2) and IFN-γ protein expression in a rodent model of cachexia (7, 10, and 14days after tumour implantation). IFN-γ protein expression was heterogeneously modulated in WAT, with increases in the mesenteric pad and decreased levels in the retroperitoneal depot along cachexia progression. Ifngr1 was up-regulated 7days after tumour cell injection in mesenteric and epididymal WAT, but the retroperitoneal depot showed reduced Ifngr1 gene expression. Ifngr2 gene expression was increased 7 and 14days after tumour inoculation in mesenteric WAT. The results provide evidence that changes in IFN-γ expression and signalling may be perceived at stages preceding refractory cachexia, and therefore, might be employed as a means to assess the early stage of the syndrome.

Age-Related Changes in Sirtuin 7 Expression in Calorie-Restricted and Refed Rats

Background: Sirtuins (SIRT1-7) have been implicated to mediate the beneficial effects of calorie restriction for healthy aging. While the physiological functions of SIRT7 are still poorly understood, SIRT7 has recently been shown to affect ribosome biogenesis, mitochondrial gene expression, and hepatic lipid metabolism. Objective: To analyze the effects of age and short-term calorie restriction (SCR) and subsequent refeeding on SIRT7 expression in key metabolic tissues. Methods: Four- and 24-month-old male Wistar rats were subjected to 40% SCR for 30 days, followed by ad libitum feeding for 2 or 4 days. Liver, white adipose tissue (WAT), heart and skeletal muscle samples were analyzed by real-time PCR and Western blotting for SIRT7 mRNA and protein expression, respectively. Results: Aging had diverse effects on SIRT7 levels in lipogenic tissues: both the mRNA and protein levels increased in the retroperitoneal depot (rWAT), did not change in the epididymal depot (eWAT), and decreased in the subcutaneous depot (sWAT) and the liver of old as compared to young animals. In the heart, extensor digitorum longus muscle (EDL) and soleus muscle (SOL), Sirt7 gene but not protein expression was lower in old than in young control rats. SCR did not affect SIRT7 expression in WAT and the liver in both age groups. In the heart of young animals, SCR did not affect SIRT7 mRNA or protein level. In EDL, SIRT7 protein but not mRNA levels decreased after SCR and remained reduced upon refeeding. In SOL, both SIRT7 mRNA and protein expression were inhibited by refeeding. In old rats, cardiac Sirt7 expression increased after SCR and refeeding. In old rats' EDL and SOL muscles, SIRT7 protein expression was inhibited by refeeding. Conclusion: Age-related changes of SIRT7 gene expression in key organs of energy homeostasis are tissue dependent.

Development of indices to estimate fat reserves in the wild American mink (Neovison vison)

Insight into body fat dynamics of wild mustelids could help to monitor changes in their nutritional status. Adipose tissue depots of wild American mink (Neovison vison, n = 50) were dissected to determine how fat was distributed throughout the body and to develop practical and reliable indices to estimate percent body fat in harvested mink. The average percent body fat of mink caught between July and April was 6.2 %, which is very low compared to previously studied farm-bred mink (adult females in summer = 20 %, subadult males in winter = 38 %). Most of the dissected adipose tissue was located in the subcutaneous (SC) fat layer (≈81 %) confirming earlier data on farmed mink. The total fat masses were higher in the subadults/adults than in the juveniles and in the male mink compared to the females. The mass of the SC fat layer was the best predictor for total fat mass (R 2 = 0.98) and percent body fat (R 2 = 0.89) when using simple regressions. As this depot can be laborious and difficult to remove with consistency, the omental fat mass could be also used as a predictor for total fat mass (R 2 = 0.70) and percent body fat (R 2 = 0.42) in juveniles and the retroperitoneal fat mass in subadults/adults (R 2 = 0.80 and 0.79, respectively). We also evaluated the different fat depots using the part-whole methodology by removing the mass of the fat depot of interest from the dependent variable. According to the part-whole regressions, the masses of the omental (R 2 = 0.66) and mesenteric depots (R 2 = 0.56) were the best predictors for total fat mass in the juveniles and the masses of the retroperitoneal (R 2 = 0.78) and diaphragmatic depots (R 2 = 0.77) in the subadults/adults. Based on both simple and part-whole regressions, omental fat can be suggested as a predictor for total fat mass in juvenile mink and retroperitoneal fat in subadult/adult mink due to their relatively good predictive power and ease of dissection.

Detection of 11 beta-hydroxysteroid dehydrogenase type 1, the glucocorticoid and mineralocorticoid receptor in various adipose tissue depots of dairy cows supplemented with conjugated linoleic acids.

Early lactating cows mobilize adipose tissue (AT) to provide energy for milk yield and maintenance and are susceptible to metabolic disorders and impaired immune response. Conjugated linoleic acids (CLA), mainly the trans-10, cis-12 isomer, reduce milk fat synthesis and may attenuate negative energy balance. Circulating glucocorticoids (GC) are increased during parturition in dairy cows and mediate differentiating and anti-inflammatory effects via glucocorticoid (GR) and mineralocorticoid receptors (MR) in the presence of the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1). Activated GC are the main ligands for both receptors in AT; therefore, we hypothesized that tissue-specific GC metabolism is effected by varying amounts of GR, MR and 11βHSD1 and/or their localization within AT depots. Furthermore, the lipolytic and antilipogenic effects of CLA might influence the GC/GR/MR system in AT. Therefore, we aimed to localize GR and MR as well as the expression pattern and activity of 11βHSD1 in different AT depots during early lactation in dairy cows and to identify potential effects of CLA. Primiparous German Holstein cows were divided into a control (CON) and a CLA group. From day 1 post-partum (p.p.) until sample collection, the CLA group was fed with 100 g/d CLA (contains 10 g each of the cis-9, trans-11 and the trans-10, cis-12-CLA isomers). CON cows (n = 5 each) were slaughtered on day 1, 42 and 105 p.p., while CLA cows (n = 5 each) were slaughtered on day 42 and 105 p.p. Subcutaneous fat from tailhead, withers and sternum, and visceral fat from omental, mesenteric and retroperitoneal depots were sampled. The localization of GR and 11βHSD1 in mature adipocytes - being already differentiated - indicates that GC promote other effects via GR than differentiation. Moreover, MR were observed in the stromal vascular cell fraction and positively related to the pre-adipocyte marker Pref-1. However, only marginal CLA effects were observed in this study.

Influence of regular physical activity and caloric restriction on β‐adrenergic and natriuretic peptide receptor expression in retroperitoneal adipose tissue of OLETF rats

The mechanisms underlying exercise-induced increases in adipose tissue blood flow and lipolysis involve both β-adrenergic receptor (βAR)- and natriuretic peptide receptor (NPR)-dependent processes. We hypothesized that daily wheel running (RUN) would increase the expression of NPR1, NPR2, βAR2 and βAR3 in retroperitoneal (RP) and epididymal (EPI) adipose tissues of obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Four-week-old OLETF rats were assigned to sedentary (SED, n = 6), calorie-restricted (CR, n = 8; fed 70% of SED) or RUN groups (n = 8). Rats were killed at 40 weeks of age. By design, body weight and adiposity were similar between RUN and CR animals, but each was lower than SED (P < 0.01). Compared with SED, RP depots of RUN rats exhibited 1.7- to 3.2-fold greater NPR1, NPR2, βAR2 and βAR3 mRNA levels (all P < 0.05). There were no differences between CR and SED in the expression of these genes in RP adipose tissues, and there were no differences in gene expression among groups in EPI adipose tissues. At the protein level, βAR2 and βAR3 were elevated in RUN and CR groups relative to the SED group in RP adipose tissues. In order to gain insight into the mechanisms underlying the activity-induced increases in NPR and βAR mRNAs, RP adipose tissue explants from Wistar rats were treated with atrial natriuretic peptide (ANP), adrenaline and/or S-nitroso-N-acetyl-dl-penicillamine (SNAP; a nitric oxide donor) in organ culture experiments. SNAP synergistically enhanced adrenaline- and ANP-stimulated increases in NPR2 and βAR2 mRNA levels. Our data suggest that physical activity-induced increases in nitric oxide interact with adrenaline and ANP to trigger the induction of NPR and βAR mRNAs in the RP adipose tissue depot of the OLETF rat.

Heterogeneous time-dependent response of adipose tissue during the development of cancer cachexia

Cancer cachexia induces loss of fat mass that accounts for a large part of the dramatic weight loss observed both in humans and in animal models; however, the literature does not provide consistent information regarding the set point of weight loss and how the different visceral adipose tissue depots contribute to this symptom. To evaluate that, 8-week-old male Wistar rats were subcutaneously inoculated with 1 ml (2×10(7)) of tumour cells (Walker 256). Samples of different visceral white adipose tissue (WAT) depots were collected at days 0, 4, 7 and 14 and stored at -80 °C (seven to ten animals/each day per group). Mesenteric and retroperitoneal depot mass was decreased to the greatest extent on day 14 compared with day 0. Gene and protein expression of PPARγ2 (PPARG) fell significantly following tumour implantation in all three adipose tissue depots while C/EBPα (CEBPA) and SREBP-1c (SREBF1) expression decreased over time only in epididymal and retroperitoneal depots. Decreased adipogenic gene expression and morphological disruption of visceral WAT are further supported by the dramatic reduction in mRNA and protein levels of perilipin. Classical markers of inflammation and macrophage infiltration (f4/80, CD68 and MIF-1α) in WAT were significantly increased in the later stage of cachexia (although showing a incremental pattern along the course of cachexia) and presented a depot-specific regulation. These results indicate that impairment in the lipid-storing function of adipose tissue occurs at different times and that the mesenteric adipose tissue is more resistant to the 'fat-reducing effect' than the other visceral depots during cancer cachexia progression.

OR05-4 Positive association of serum prolactin concentrations with all-cause and cardiovascular mortality: Results from a 10-year follow-up of the Study of Health Pomerania (SHIP)

of ECM deposition in bGH mice. ECM deposition in adipose tissue was assessed in WAT collected from bGH versus littermate control mice at 10, 26, and 62 weeks of age, in both males and females. Adipose tissue samples from subcutaneous, perigonadal, retroperitoneal, and mesenteric depots were fixed and embedded in paraffin blocks and stained with pico-sirius red. When assessing overall collagen content, the bGH mice showed dramatic increases in ECM deposition when compared to the WT controls at most ages and in both sexes. When comparing different depots, collagen staining appeared most prevalent in the subcutaneous depot as compared to intra-abdominal depots in both male and female mice. Based on these results, analysis of collagen gene expression levels will be conducted. Specifically, collagens I, III, IV, V and VI in the subcutaneous, epididymal, mesenteric, and retroperitoneal adipose tissue depots of 6 month-old male mice will be examined through quantitative PCR analysis and results will be reported. Our histological results demonstrate a novel role of GH in adipose tissue function and suggest that ECM deposition likely contributes to the WAT depot specific differences previously reported in mice with modified GH action. Additional studies will be conducted in other GH transgenic mouse models to further establish the connection between GH and the collagen content of WAT and to deepen our understanding of the role of the ECM in WAT dysfunction.

Gene expression analysis of the liver and skeletal muscle of psyllium-treated mice

Psyllium, a dietary fibre rich in soluble components, has both cholesterol- and TAG-lowering effects. Many studies have verified these actions using liver samples, whereas little information is available on the effects of psyllium treatment on other organs. The purpose of the present study was to evaluate the possible beneficial effects of psyllium. We investigated the gene expression profiles of both liver and skeletal muscle using DNA microarrays. C57BL/6J mice were fed a low-fat diet (LFD; 7 % fat), a high-fat diet (HFD; 40 % fat) or a HFD with psyllium (40 % fat+5 % psyllium; HFD+Psy) for 10 weeks. Body weights and food intake were measured weekly. After 10 weeks, the mice were killed and tissues were collected. Adipose tissues were weighed, and plasma total cholesterol and TAG blood glucose levels were measured. The expression levels of genes involved in glycolysis, gluconeogenesis, glucose transport and fatty acid metabolism were measured by DNA microarray in the liver and skeletal muscle. In the HFD+Psy group, plasma total cholesterol, TAG and blood glucose levels significantly decreased. There was a significant reduction in the relative weight of the epididymal and retroperitoneal fat tissue depots in mice fed the HFD+Psy. The expression levels of genes involved in fatty acid oxidation and lipid transport were significantly up-regulated in the skeletal muscle of the HFD+Psy group. This result suggests that psyllium stimulates lipid transport and fatty acid oxidation in the muscle. In conclusion, the present study demonstrates that psyllium can promote lipid consumption in the skeletal muscle; and this effect would create a slightly insufficient glucose state in the liver.

Maternal fructose consumption during gestation increases body weight and fat mass in young adult offspring

Increased fructose (FR) consumption is a potential cause of adult obesity and the metabolic syndrome but the extent to which enhanced exposure to FR through pregnancy influences later body mass and composition of offspring has received little attention. Our study examined the effect of FR consumption during gestation body mass and composition in young adulthood. Female rats received 10% FR solution (n=8) or tap water (C) (n=8) throughout gestation and lactation in addition to standard chow. Offspring were weaned at 21 days; 1 male and 1 female/litter were fed standard chow plus tap water to 90 days of age. Retroperitoneal and epididymal (males) and uterine (females) fat was dissected and weighed. Body weight was offspring born and reared to FR dams compared to C (Females ‐ C: 251.9±6.7; FR: 278.6±5.67 g (p&lt;0.01); Males – C: 469.3±7.44; FR: 506.7±13.49 g (p= 0.05). Fat mass was greater in all depots (absolute and relative) regardless of gender (e.g. retroperitoneal depot: Females – C: 2.1±0.11; FR: 3.2±0.27g (p&lt;0.01); Males – C: 6.4±0.74; FR: 10.9±1.57 g (p&lt;0.05)). Exposure to FR through pregnancy and lactation promotes postnatal growth and fat deposition in the offspring irrespective of gender. FR consumption during pregnancy deserves further attention given its potential contribution to obesity in offspring. Funding: NSERC (Canada); British Heart Foundation.

Heterogeneity Among White Adipose Tissue Depots in Male C57BL/6J Mice

The widespread prevalence of obesity has lead to extensive research on white adipose tissue (WAT), which frequently uses the C57BL/6J mouse strain as a model. In many studies, results obtained in one WAT depot are often extrapolated to all WAT. However, functional differences among WAT depots are now becoming apparent. Thus, to identify the molecular mechanisms responsible for WAT depot-specific differences under "normal" conditions, four C57BL/6J mouse WAT depots (inguinal, mesenteric, epididymal, and retroperitoneal) were analyzed. Depot proteomic profiles, along with weights, protein contents, adipocyte sizes and oxidative stress were determined. Mesenteric WAT had almost twice the protein content of the other depots analyzed. Mean adipocyte size was highest in epididymal and lowest in mesenteric and inguinal depots. The proteome of inguinal WAT displayed low levels of enzymes involved in ATP generation, glucose and lipid metabolism, and antioxidant proteins. Higher levels of these proteins were observed in mesenteric and epididymal WAT, with variable levels in the retroperitoneal depot. Some of these proteins showed depot-specific correlations with plasma levels of insulin, leptin, and adiponectin. In agreement with the proteomic data, levels of the antioxidant protein heat shock protein β1 (HSPβ1) also were lower in inguinal WAT when analyzed by western blotting and immunohistochemistry. Also, lipid peroxidation products showed similar trends. Our results are consistent with lower triglyceride turnover and lower oxidative stress in inguinal than mesenteric and epididymal WAT. The observed WAT depot-specific differences provide clues as to the mechanisms leading to these depots' respective diverse functions.

Distribution and Development of Brown Adipocytes in the Murine and Human Adipose Organ

Murine white and brown adipocytes are found together in dissectible visceral and subcutaneous fat depots supplied by specific vessels and nerves, forming a multi-depot organ with plastic properties. Many of the anatomo-physiological features of murine fat depots apply to humans.