Caloric intake increased over a long period of time may induce the development of obesity, causing so-called low-grade inflammation. The organism responses to the inflammation by the activation and production of cellular components of the immune system, such as macrophages or proinflammatory cytokines. The adipose tissue itself is involved in the production of bioactive molecules, including leptin and adiponectin. Increased concentration of proinflammatory cytokines can lead to a dysfunction of important metabolic pathways and impair organ's function. For the purpose of closer knowledge of the etiology of obesity and its metabolic complications, inbred strains of mice with different genetic backround are most commonly used. We aimed to define the impact of high-fat diet (HFD) on adipose and liver tissue of C57BL/6J and A/J murine strains with a different susceptibility to diet-induced obesity. We focused on description of morphological and functional changes of adipose tissue and on the evaluation of plasma leptin and adiponectin levels of mice in the early postnatal development. Next, we measured the expression of leptin mRNA in four tissues. In this study we described how the increased caloric intake leads to increased triacylglycerides (TAG) storage in the liver and to a higher inflammatory...

Development of the sympathetic nervous system (SNS) tone onto peripheral organs has been shown to be susceptible to a wide range of external factors, such as temperature. Although it was initially postulated that the sympathetic signal is uniform across the body, there is growing evidence that there can be target-specific sympathetic signals. To date, evidence for a relationship between developmental influences on SNS tone and organ function is purely correlational. An obstacle to investigating the programming of SNS permanently altering physiology is that experimental manipulations of SNS activity during development would impact multiple organ functions simultaneously, which could affect the overall health of the animal and therefore confound interpretation of the results. Here we used brown adipose tissue (BAT) as a platform to define a critical period and identify molecules that contribute to the development of SNS outflow to peripheral organs. In addition, we explored the molecular target-specificity of sympathetic neurons by performing a single-cell RNA sequencing transcriptomic analysis of adult mouse stellate ganglion (SG) in conjunction with retrograde tracing from two of its targets, brown adipose tissue and forelimb. We discovered four molecularly distinct populations of SG neurons that express unique combinations of neuropeptides and receptors, but we did not find evidence of target specificity. The four distinct SG neuronal populations had marker genes that showed unique expression in each population, including genes encoding secreted peptides and receptors of circulating factors. Also, we found that the expression of some of the marker genes differs across the sympathetic chain, which could provide a means for coordinated regulation of SNS responses to specific types of homeostatic challenges.

Historical experiments regarding the influence of low ambient temperatures were often accompanied with the development of detrimental effects. Our laboratory recently published a protocol of mild cold acclimation (5 weeks in 8 ± 1 řC) which induces cardioprotective phenotype in rats (Rattus norvegicus). An important mechanism of cold acclimation is the activation and increase of brown adipose tissue. Besides the nonshivering thermogenesis brown adipose tissue can produce a multitude of autocrine, paracrine, and endocrine factors which might positively influence whole-body metabolism and function of other important organs. The effect of cold acclimation on brown adipose tissue is not however explored very well. The aim of this work was to asses selected parameters of respiration of isolated brown adipose tissue mitochondria of control rats living in 24 ± 1 řC and compare it with that of rats exposed to 8 ± 1 řC for 1 day, 3 days, 10 days, and 5 weeks. Results of this works were 1) the increase in respiration occurs after the 1-day cold exposure and 2) the highest respiration per 1 mg of mitochondrial protein appears to be after the 10 days of cold exposure. Key-words: Brown adipose tissue, mitochondria, respiration, cold acclimation

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20968号 / 医博第4314号 / 新制||医||1026(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 長船 健二, 教授 上杉 志成, 教授 岩田 想 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

Obesity is a growing problem that impacts both adults and children. Obesity is linked to the development of unfavorable health outcomes like excess fat accumulation in the liver, a problem known as non-alcoholic fatty liver disease (NAFLD). Brown adipose tissue (BAT), a thermogenic body fat that can be turned on by cold, produces heat by consuming circulating lipids and glucose in a futile cycle. Less active cold-stimulated BAT is linked to obesity and type 2 diabetes in adults but whether this relationship exists in children is unknown. In rodents, increases in BAT activity are associated with reductions in NAFLD, effects that may be mediated through changes in the gut microbiome and reductions in peripheral serotonin. Whether the gut microbiome and serotonin play a role in regulating BAT activity in adults and children is not known. In this thesis, we have utilized magnetic resonance imaging (MRI) proton density fat fraction (PDFF) to assess BAT in the supraclavicular (SCV) region after three hours and one hour of whole-body cold exposure in adults and children, respectively. In 60 adults (aged 18-57 years), we examined whether there is a relationship between cold-stimulated BAT activity and liver fat (assessed via MRI) and whether gut microbiota plays a role in connecting these two tissues. In children, we investigated, BAT activity after whole-body cold exposure in 26 boys (aged 8-10 years). We also explored if BAT activity was different between boys with and without overweight/obesity. Finally, in young boys, we measured the levels of serotonin in platelet-poor plasma and its metabolic end product 5-hydroxyindole acetic acid (5-HIAA) in the urine. We explored if these measures of circulating serotonin were related to cold-stimulated BAT activity and if they were different between boys with and without overweight/obesity. The findings from this research indicate that higher cold-stimulated BAT activity is associated with lower liver fat in adults, but that this relationship is unlikely mediated through changes in the gut microbiota. Additionally, boys with overweight/obesity have lower cold-stimulated BAT activity and lower 5-HIAA in their urine compared to those with normal weight. Moreover, circulatory serotonin is negatively related to total adiposity. However, circulating serotonin is not related to cold-stimulated BAT activity in this cohort. These findings are important as they indicate for the first time that increasing BAT activity in adults and children could potentially be a new avenue for the treatment of NAFLD and obesity. / Thesis / Doctor of Philosophy (PhD) / Obesity is a risk factor for the accumulation of extra liver fat, a problem known as non-alcoholic fatty liver disease (NAFLD). Brown adipose tissue (BAT) is a kind of body fat that rather than storing calories like white fat burns calories when switched on by cold. Studies in adults have shown that people with obesity and type 2 diabetes have less active BAT suggesting switching it on may be helpful to promote weight loss and lower glucose. However, whether this relationship exists in children is not known. In rodents, increased BAT activity has also been linked to reductions in NAFLD, effects that might involve a hormone called serotonin, or changes in the gut microbiome but whether this is important in children and adults is also not understood. In this thesis, we utilized magnetic resonance imaging (MRI) to examine BAT activity after whole-body cold exposure in adults (3 hours) and children (1 hour). In 60 adults (aged 18-57 years), we report that higher cold-stimulated BAT activity is linked to NAFLD, but gut microbiota does not seem to play a role in this relationship. In 26 boys (aged 8-10 years), BAT is less responsive to cold in boys with overweight/obesity compared to boys with normal weight. Additionally, serotonin is lower in boys with overweight/obesity compared to boys with normal weight. These findings suggest that increasing BAT activity in adults and children could potentially be a new avenue for the treatment of NAFLD and obesity.

No description available.

Effect of Sepsis on Circulating CTRP3 Levels Adam Musick, Madison Shipley, Fei Tu, Chuanfu Li, Valentin Yakubenko, and Jonathan M. Peterson. Adipose tissue is an active endocrine organ which secrets several pro- and anti- inflammatory mediators, collectively called adipokines. Our previous work has identified a novel anti-inflammatory adipokine called C1q TNF Related Protein 3 (CTRP3). Others have previously demonstrated that localized overexpression of CTRP3 protects myocardial tissue from lipopolysaccharide (LPS)-induced sepsis, further supporting the potential protective role of CTRP3. However, endogenous regulation of CTRP3 in response to a sepsis event has not been explored. Further, other adipokines have been identified as diagnostic/prognostic biomarkers for critically ill patients. Therefore, the purpose of this project was to determine the effects of a sepsis event on the circulating CTRP3 levels. METHODS: Gonadal adipose tissue and serum were collected 8 hours after induction of the cecal-puncture and ligation (CLP) model of sepsis or sham control mice. The circulating levels of CTRP3 were quantified by immunoblot analysis. The transcription levels of CTRP3 in adipose tissue were measured by Real-Time PCR. In addition, to explore a potential mechanism for a protective role of CTRP3, thioglycollate-induced peritoneal macrophages were isolated and binding of recombinant CTRP3 was determined by imaging flow cytometry. RESULTS: Circulating CTRP3 levels decreased by approximately 90% compared to sham mice. However, adipose tissue transcription levels of CTRP3 was not difference between CLP and sham mice. Further, imaging flow cytometry demonstrated that CTRP3 binds directly to isolated macrophages. CONCLUSION: The overserved reduction in circulating CTRP3 protein levels and the absence of changes to the CTRP3 transcription, indicate that during sepsis CTRP3 is actively removed from the blood. As CTRP3 binds directly to macrophages and has been previously shown to attenuate LPS-induced macrophage activation these data could indicate that under normal conditions CTRP3 combines with active macrophages to help suppress cytokine overexpression. However, it appears that during sepsis the endogenous CTRP3 levels are quickly depleted. Combine these data support future research to determine if circulating CTRP3 levels are a biomarker indicative of sepsis prognosis and to determine if increasing the circulating levels of CTRP3 could reduce the cytokine storm associated to a sepsis event. Further, as we have demonstrated CTRP3 binds directly to macrophages, future studies are also needed to explore the potential anti-inflammatory mechanism of CTRP3 action on macrophages.

Ames dwarf (df/df) mice are homozygous for a spontaneous mutation in the prop1 gene due to which there is no development of anterior pituitary cells – somatotrophs, lactotrophs and thyrotrophs, leading to a deficiency of growth hormone (GH), prolactin (PRL) and thyrotropin (TSH). They tend to become obese as they age, but still live longer and healthier lives compared to their wild-type littermates, being very insulin sensitive, showing no signs of diabetes and cancer. These mutant mice also have high circulating levels of anti-inflammatory and antidiabetic adiponectin. Plasma levels of this adipokine usually decrease with an increase in accumulation of visceral fat (VF). We thus believe that VF in df/df mice, developed in the absence of GH signaling, may be functionally different from the same fat depots in normal (N) mice and may be beneficial, rather than detrimental, to the overall health of the animal. We performed surgeries involving removal of VF depots (epididymal and perirenal fat) in both groups of mice and hypothesize that the beneficial effects of visceral fat removal (VFR) will be present exclusively in N mice as VF in df/df mice contributes to enhanced insulin sensitivity by producing decreased levels of pro-inflammatory adipokines like TNF and IL-6. We found that VFR improved insulin sensitivity only in N mice but not in the df/df mice. This intervention led to an upregulation of certain players of the insulin signaling pathway in the skeletal muscle of N mice only, with no alteration in df/df mice. The subcutaneous fat of df/df mice showed a downregulation of these insulin signaling genes upon VFR. Compared to N mice, epididymal fat of df/df mice (sham-operated) had increased gene expression of some of the players involved in insulin signaling and a decrease in transcript levels of TNFa. Ames dwarf mice had decreased levels of IL-6 protein in EF and in circulation. High circulating levels of adiponectin and iv decreased levels of IL-6 in circulation could contribute to the high insulin sensitivity observed in the Ames dwarf mice. Understanding the mechanisms responsible for VF having positive effects on insulin signaling in df/df mice would be important for future treatment of obese diabetic patients.

No description available.