Browsing by Subject "Brown adipose tissue"

Now showing 1 - 4 of 4
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    Exploring the relationship of brown adipose tissue to bone microarchitecture using 7T MRI and micro-CT
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Zhang, Ping; Yu, Baohai; Shao, Shuying; Zhang, Ranxu; Zeng, Yan; Li, Jujia; Ren, Congcong; Zhou, Xiaoyue; Zhao, Jian
    Background. Brown adipose tissue (BAT) is involved both in energy production and bone metabolism. The purpose of this study was to analyze the relationship between BAT and microarchitecture at cancellous and cortical bone using Kunming mice and the methods of 7T magnetic resonance imaging (MRI) combined with micro-CT. Methods. Twenty-four female Kunming mice were examined by 7T MRI and measured T2* relaxation time on the deep and superficial interscapular BAT (iBAT) and subcutaneous white adipose tissue (sWAT). Cancellous bone microarchitecture of the distal femur and cortical bone of the middle femur were examined by micro-CT. A paired t-test was used to analyze the differences in T2* values between iBAT and sWAT. The correlation between BAT T2* values and bone microstructure parameters were analyzed using Pearson’s correlation. Results. T2* values of the deep and superficial iBAT (6.36±3.31 ms and 6.23±2.61 ms) were significantly shorter than those of sWAT (16.30±3.05 ms, tdeep iBAT=- 10.816), tsuperficial iBAT=-12.276, p<0.01). Deep iBAT T2* values were significantly and negatively correlated with bone volume, cancellous thickness, and bone thickness (Th) and trabecular thickness (Tb.Th) of the cancellous bone of femur. Deep iBAT T2* values were significantly and positively correlated with the structural model index of cancellous bone of femur. Deep iBAT T2* values were significantly and negatively correlated with bone mineral density of the cortical bone of femur. Conclusions. MRI can distinguish the two adipose tissues from each other. T2* values of BAT were lower than WAT on MRI. BAT related bone remodeling was more correlated with the microstructure of cancellous bone than that of cortical bone.
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    Possible role of brown adipose tissue as a mediator during cyclosporine-A treatment
    (Murcia : F. Hernández, 1994) Buján, J.; Jurado, F.; Gianonatti, M.C.; Contreras, L.A.
    Cyclosporine-A (CsA) is a potent immunosuppressor used successfully to control rejection in organ transplantation. According to the most recent evidence, this drug modifies the lipid metabolism of the patient, provoking a rise in the blood lipids, constituting an important risk factor for acceleration of the atherogenic process. Taking into account that brown adipose tissue (BAT) constitutes the major storage site for cholesterol and triglycerides in the rat, and given the apparent lack of references about the implications of CsA on this tissue in the literature, we proposed to study the possible morphological changes occurring in BAT following the administration of this drug. Two groups of female Sprague-Dawley rats were set up, the control group and a treated group in which each animal received subcutaneous injection of 5 mglkg body weightlday of CsA. After 4, l l , 25 and 34 days of treatment, subgroups of animals were sacrificed and the brown adipose tissue removed was apportioned for subsequent microscopic assessment. The greatest degree of atypia and activity in the BAT was observed after administration of 11 doses of the drug, at which point there was a marked reduction in the cell size with loss of lipidic coalescence. With subsequent doses, the tissue slowly initiated a process of recovery. CsA also induced morphological changes in the BAT that. in the early stages of the study, appeared to be correlated with a lipolytic response of the tissue to the drug; thus, the BAT may be acting as a system to eliminate the excess of lipids in the blood provoked by CsA administration, while toward the end of treatment, there was a certain stability between the drug and the activity of the brown adipose tissue, and a tendency to reach a balance between lipolysis and lipogenesis.
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    Role of PRDM16 in the activation of brown fat programming. Relevance to the development of obesity
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2013) Becerril, Sara; Gómez-Ambrosi, Javier; Martín, Marina; Moncada, Rafael; Sesma, Pilar; Burrell, María A.; Frühbeck, Gema
    From a histological and functional point of view, two types of adipose tissue can be identified. As opposed to the mainly unilocular white adipocytes, brown adipocytes possess plenty of small multilocular lipid droplets and dissipate energy as heat. Moreover, two distinct types of brown adipose cells exist. In vivo fate mapping experiments of brown adipose tissue (BAT) precursors suggest that classical brown adipocytes and skeletal myoblasts originate from a common mesenchymal, myogenic factor 5 (Myf5)-positive precursor cell. In addition to the classical brown adipocytes, thermogenic brown-like adipocytes (brite/beige cells) may appear within white adipose tissue (WAT) depots, sharing many of the morphological and functional features of brown adipocytes, but arising from a Myf5-negative lineage. In humans, the conversion of white fat cells into brite adipocytes could be a strategy to increase energy expenditure. The zinc finger transcription factor Prdm16 controls the bidirectional fate decision between brown adipocytes and myoblasts. Prdm16 determines the brown fat-like programme and thermogenesis in both brown and white adipose tissues. Moreover, the expression of this transcriptional regulator is strongly correlated with beige cell-selective genes. From a therapeutical point of view, the potential of inducing BAT or the transdifferentiation of WAT into beige cells by enhancing Prdm16 expression, as well as the identification of mechanisms of Prdm16 function and regulation represent potentially exciting new approaches for treatment or prevention of obesity and related diseases.
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    The effect of low and high plasma levels of insulin-like growth factor-1 (IGF-1) on the morphology of major organs: studies of Laron dwarf and bovine growth hormone transgenic (bGHTg) mice
    (F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2013) Piotrowska, Katarzyna; Borkowska, Sylwia J.; Wiszniewska, Barbara; Laszczyńska, Maria; Słuczanowska-Głąbowska, Sylwia; Havens, Aaron M.; Kopchick, John J.; Bartke, Andrzej; Taichman, Russel S.; Kucia, Magda; Ratajczak, Mariusz Z.
    It is well known that somatotrophic/insulin signaling affects lifespan in experimental animals. To study the effects of insulin-like growth factor-1 (IGF-1) plasma level on the morphology of major organs, we analyzed lung, heart, liver, kidney, bone marrow, and spleen isolated from 2-year-old growth hormone receptor knockout (GHR-KO) Laron dwarf mice (with low circulating plasma levels of IGF-1) and 6-month-old bovine growth hormone transgenic (bGHTg) mice (with high circulating plasma levels of IGF-1). The ages of the two mutant strains employed in our studies were selected based on their overall ~50% survival (Laron dwarf mice live up to ~4 years and bGHTg mice up to ~1 year). Morphological analysis of the organs of long-living 2-year-old Laron dwarf mice revealed a lower biological age for their organs compared with normal littermates, with more brown adipose tissue (BAT) surrounding the main body organs, lower levels of steatosis in liver, and a lower incidence of leukocyte infiltration in different organs. By contrast, the organs of 6-month-old, short-living bGHTg mice displayed several abnormalities in liver and kidney and a reduced content of BAT around vital organs.