Small Number Of Lipid Droplets Research Articles

Evaluation of brown adipose tissue with intermolecular double-quantum coherence magnetic resonance spectroscopy at 3.0T.

In the current study, we propose a single-voxel (SV) magnetic resonance spectroscopy (MRS) pulse sequence, based on intermolecular double-quantum coherence (iDQC), for in vivo specific assessment of brown adipose tissue (BAT) at 3T. The multilocular adipocyte, present in BAT, typically contains a large number of small lipid droplets surrounded by abundant intracellular water, while the monolocular adipocyte, present in white adipose tissue (WAT), accommodates only a single large lipid droplet with much less water content. The SV-iDQC sequence probes the spatial correlation between water and fat spins at a distance of about the size of an adipocyte, thus can be used for assessment of BAT, even when mixed with WAT and/or muscle tissues. This sequence for measurement of water-to-fat (water-fat) iDQC signals was tested on phantoms and mouse BAT and WAT tissues. It was then used to differentiate adipose tissues in the supraclavicular and subcutaneous regions of healthy youth human volunteers (n =6). Phantom results with water-fat emulsions demonstrated enhanced water-fat iDQC signal with increased voxel size, increased energy level of emulsification, or increased distribution balance of water and fat spins. The animal tissue experiments resulted in obvious water-fat iDQC signal in mouse BAT, while this signal was almost absent in the WAT spectrum. The optimal choice of the dipolar coupling distance for the observation was approximately 100 μm, as tested on both emulsion phantom and animal tissue. The water-fat iDQC signals observed in the supraclavicular adipose tissues were higher than in the subcutaneous adipose tissues in healthy young volunteers (0.43 ±0.36 vs. 0.10±0.06, p=0.06). It was concluded that the iDQC-based sequence has potential for assessment of mouse and human BAT at 3T, which is of interest for clinical research and the diagnosis of obesity and associated diseases.

Lipid content, mitochondrial activity and early embryo development in oocyte collected from crossbred cows (bos taurus indicus)

The objective of this research was to evaluate the effect of phenotypic predominance on lipid content, mitochondrial activity and early developmental competence as indicators of oocyte quality. Cumulus-oocyte complexes (COCs) were recovered through follicular aspiration, and underwent in vitro maturation (IVM), in vitro fertilization (IVF), and in vitro culture (IVC) of presumptive zygotes. Lipid content and mitochondrial activity in immature and IVM oocytes were determined. A maturation rate of 80.6% and 69.3% was found for oocytes predominantly B. indicus and predominantly B. taurus, respectively. Total fertilization rate was 27.6%; 26.1% for predominantly B. indicus oocytes and 29% for predominantly B. taurus oocytes. A total of 55.5% and 57.5% of cleaved embryos after 48 and 72 h post-insemination (hpi) in predominantly B. indicus group were observed, respectively. As for the predominantly B. taurus group, 48.6% and 60.4% of cleaved embryos were found after 48 and 72 hpi, respectively. In both groups, immature oocytes showed a greater amount of small lipidic droplets (p <0.0001); IVM decreased the number of small lipid droplets (p < 0.0001) and increased the number of medium and large lipid droplets (p < 0.0001). Predominantly B. indicus oocytes had a greater number of small and medium-sized lipid droplets, while there were no significant differences in large lipid droplets. IVM oocytes had higher mitochondrial activity than immature oocytes group (p < 0.05) without any effect of phenotypic predominance on this parameter. Assessment of lipid content was not a predictive factor of oocyte quality in crossbred cows.

Palmitoyl lactic acid induces adipogenesis and a brown fat-like phenotype in 3T3-L1 preadipocytes

Brown adipose tissue is specialized to generate heat by dissipating chemical energy and may provide novel strategies for obesity treatment in humans. Recently, advances in understanding the pharmacological and dietary agents that contribute to the browning of white adipose tissue have been made to alleviate obesity by promoting energy expenditure. Krill oil is widely used as a health supplement in humans. In this study, the components from krill oil that promote adipogenesis of 3T3-L1 cells were screened to reveal palmitoyl lactic acid (PLA) as a promoter of adipogenesis. The PLA-induced adipocytes contained large number of small lipid droplets. Moreover, similar to the peroxisome proliferator-activated receptor (PPAR)γ agonists, pioglitazone and rosiglitazone, PLA significantly enhances adipogenesis in the presence of dexamethasone compared with PLA alone. Treatment with PLA causes a brown fat-like phenotype in 3T3-L1 cells by enhanced expression of various brown/beige cell-specific genes, such as PR domain containing 16 (Prdm16) and peroxisome proliferative activated receptor, gamma, coactivator 1 alpha (Pgc1a), as well as adiponectin gene. The expression profile of the brown/beige cell-specific genes induced by PLA was similar to that of the PPARγ agonist in 3T3-L1 cells. Our findings suggest that PLA induces a brown fat-like phenotype and, thus, likely has therapeutic potential in treating obesity.

The perilipin 2 (PLIN2) gene Ser251Pro missense mutation is associated with reduced insulin secretion and increased insulin sensitivity in Italian obese subjects.

Perilipin 2 (PLIN2), a member of the family of perilipin lipid droplets coating proteins, is very widely expressed. The Ser251Pro (rs35568725) missense mutation in exon 6 of PLIN2 gene was previously associated with increased lipid accumulation, decreased lipolysis and increased number of small lipid droplets per cell. Furthermore, the Pro251 mutation was associated with decreased plasma triglyceride and very low density lipoprotein concentrations in population studies. The aim of this study was to evaluate the effect of the Ser251Pro mutation of PLIN2 gene in a cohort with a higher predisposition to obesity-associated metabolic alterations, such as insulin resistance, decreased insulin-secretion, hyperglycaemia, and dyslipidaemia. A large cohort (N = 1692) of Italian obese subjects (mean body mass index = 41kg/m(2) ) was genotyped for the Ser251Pro mutation. All participants underwent oral glucose tolerance tests (OGTT), with measurement of glucose and insulin levels. Indices of insulin resistance and of insulin secretion were also calculated. Clinical and biochemical parameters were collected for all participants. We observed that insulin concentration was significantly reduced at 120min after the administration of glucose in Pro251 allele carriers, whereas glucose levels were similar in Pro251 allele carriers and non-carriers throughout the OGTT. Furthermore, the CIR120 index of insulin secretion was significantly lower (P < 0.035) and the ISI index of insulin-sensitivity was significantly higher (P < 0.031) in carriers of the Pro251 allele. When we analysed men and women separately to test for gender-specific associations, we observed that in women insulin levels were significantly lower in Pro251 allele carriers compared with wild-type subjects throughout the whole OGTT. In men, we confirmed a significant reduction in insulin concentration only at 120min after the OGTT. No significant differences between genotype groups regarding triglyceride levels and anyother clinical and metabolic parameters were observed. We observed a strong significant association between the PLIN2 Pro251 mutation and lower insulin secretion associated with an increased insulin sensitivity. Copyright © 2015 John Wiley & Sons, Ltd.

Ultra-structural morphology of long-term cultivated white adipose tissue-derived stem cells.

White adipose tissue was long perceived as a passive lipid storage depot but it is now considered as an active and important endocrine organ. It also harbours not only adipocytes and vascular cells but also a wide array of immunologically active cells, including macrophages and lymphocytes, which may induce obesity-related inflammation. Recently, adipose tissue has been reported as a source of adult mesenchymal stem cells with wide use in regenerative medicine and tissue engineering. Their relatively non-complicated procurement and collection (often performed as liposuction during aesthetic surgery) and grand plasticity support this idea even more. We focused our research on exploring the issues of isolation and long-term cultivation of mesenchymal stem cells obtained from adipose tissue. Ultra-structural morphology of the cells cultivated in vitro has been studied and analysed in several cultivation time periods and following serial passages--up to 30 passages. In the first passages they had ultra-structural characteristics of cells with high proteosynthetic activity. Within the cytoplasm, big number of small lipid droplets and between them, sparsely placed, small and inconspicuous, electron-dense, lamellar bodies, which resembled myelin figures were observed. The cells from the later passages contained high number of lamellar electron-dense structures, which filled out almost the entire cytoplasm. In between, mitochondria were often found. These bodies were sometimes small and resembled myelin figures, but several of them reached huge dimensions (more than 1 µm) and their lamellar structure was not distinguishable. We did not have an answer to the question about their function, but they probably represented the evidence of active metabolism of lipids present in the cytoplasm of these cells or represented residual bodies, which arise after the breakdown of cellular organelles, notably mitochondria during long-term cultivation.

HO-1 Upregulation Attenuates Adipocyte Dysfunction, Obesity, and Isoprostane Levels in Mice Fed High Fructose Diets.

Background. Fructose metabolism is an unregulated metabolic pathway and excessive fructose consumption is known to activate ROS. HO-1 is a potent antioxidant gene that plays a key role in decreasing ROS and isoprostanes. We examined whether the fructose-mediated increase in adipocyte dysfunction involves an increase in isoprostanes and that pharmacological induction of HO-1 would decrease both isoprostane levels and adipogenesis. Methods and Results. We examined the effect of fructose, on adipogenesis in human MSCs in the presence and absence of CoPP, an inducer of HO-1. Fructose increased adipogenesis and the number of large lipid droplets while decreasing the number of small lipid droplets (P < 0.05). Levels of heme and isoprostane in fructose treated MSC-derived adipocytes were increased. CoPP reversed these effects and markedly increased HO-1 and the Wnt signaling pathway. The high fructose diet increased heme levels in adipose tissue and increased circulating isoprostane levels (P < 0.05 versus control). Fructose diets decreased HO-1 and adiponectin levels in adipose tissue. Induction of HO-1 by CoPP decreased isoprostane synthesis (P < 0.05 versus fructose). Conclusion. Fructose treatment resulted in increased isoprostane production and adipocyte dysfunction, which was reversed by the increased expression of HO-1.

Ultrastructural characteristics of the vascular wall components of ruptured atherosclerotic abdominal aortic aneurysm

The aim of this study was to determine the ultrastructural characteristics of cell populations and extracellular matrix components in the wall of ruptured atherosclerotic abdominal aortic aneurysm (AAA). We analyzed 20 samples of ruptured AAA. For orientation to the light microscopy, we used routine histochemical techniques by standard procedures. For ultrastructural analysis, we applied transmission electron microscopy (TEM). Our results have shown that ruptured AAA is characterized by the remains of an advanced atherosclerotic lesion in the intima followed by a complete absence of endothelial cells, the disruption of basal membrane and disruption of internal elastic lamina. On plaque margins as well as in the inner media we observed smooth muscle cells (SMCs) that posses a euchromatic nucleus, a well-developed granulated endoplasmic reticulum around the nucleus and reduced myofilaments. The remains of the ruptured lipid core were acellular in all samples; however, on the lateral sides of ruptured plaque we observed a presence of two types of foam cells (FCs), spindle- and star-shaped. Fusiform FCs possess a well-differentiated basal lamina, caveolae and electron dense bodies, followed by a small number of lipid droplets in the cytoplasm. Star-shaped FCs contain a large number of lipid droplets and do not possess basal lamina. On the inner margins of the plaque, we observed a large number of cells undergoing apoptosis and necrosis, extracellular lipid droplets as well as a large number of lymphocytes. The media was thinned out with disorganized elastic lamellas, while the adventitia exhibited leukocyte infiltration. The presented results suggest that atherosclerotic plaque in ruptured AAA contains vascular SMC synthetic phenotype and two different types of FCs: some were derived from monocyte/macrophage lineage, while others were derived from SMCs of synthetic phenotype. The striking plaque hypocellularity was the result of apoptosis and necrosis of different cell populations.

Giant hibernoma of the thoracic pleura and chest wall

Hibernoma is a rare tumor containing prominent brown adipocytes that resemble normal brown fat. Brown fat (versus white fat) is predominantly found in hibernating mammals and infants. Brown fat adipocytes contain a higher number of small lipid droplets and a much denser concentration of mitochondria. The tumor can occur in a variety of locations however the extremities, followed by the head and neck, have been the most common sights. All variants of hibernoma described have followed a benign course with the majority presenting as a small, lobulated, nontender lesions. We present a case of a giant hibernoma arising from the pleura which invaded the intra and extra-thoracic chest.

Angiotensin II type 2 receptor promotes adipocyte differentiation and restores adipocyte size in high-fat/high-fructose diet-induced insulin resistance in rats

This study was aimed at establishing whether specific activation of angiotensin II (ANG II) type 2 receptor (AT2R) modulates adipocyte differentiation and function. In primary cultures of subcutaneous (SC) and retroperitoneal (RET) preadipocytes, both AT2R and AT1R were expressed at the mRNA and protein level. Cells were stimulated with ANG II or the AT2R agonist C21/M24, alone or in the presence of the AT1R antagonist losartan or the AT2R antagonist PD123,319. During differentiation, C21/M24 increased PPARγ expression in both RET and SC preadipocytes while the number of small lipid droplets and lipid accumulation solely increased in SC preadipocytes. In mature adipocytes, C21/M24 decreased the mean size of large lipid droplets. Upon abolishment of AT2R expression using AT2R-targeted shRNAs, expressions of AT2R, aP2, and PPARγ remained very low, and cells were unable to differentiate. In Wistar rats fed a 6-wk high-fat/high-fructose (HFHF) diet, a significant shift toward larger adipocytes was observed in RET and SC adipose tissue depots. C21/M24 treatments for 6 wk restored normal adipocyte size distribution in both these tissue depots. Moreover, C21/M24 and losartan decreased hyperinsulinemia and improved insulin sensitivity impaired by HFHF diet. A strong correlation between adipocyte size area and glucose infusion rate during euglycemic-hyperinsulinemic clamp was observed. These results indicate that AT2R is involved in early adipocyte differentiation, while in mature adipocytes and in a model of insulin resistance AT2R activation restores normal adipocyte morphology and improves insulin sensitivity.

Biopsied and vitrified bovine embryos viability is improved by trans10, cis12 conjugated linoleic acid supplementation during in vitro embryo culture

Bovine embryos cultured in serum-containing media abnormally accumulate lipids in the cytoplasm. This is well known to contribute to their higher susceptibility to cryopreservation and biopsied embryos are even further susceptible. We aimed to improve in vitro produced (IVP) embryos resistance to micromanipulation and cryopreservation by supplementing serum-containing media with trans-10, cis-12 conjugated linoleic acid ( t10, c12 CLA). The effect of t10, c12 CLA on lipid deposition and embryonic development was also tested. After in vitro maturation and fertilization (IVF day = D0), zygotes were cultured on granulosa cells + M199 + 10% serum + 100 μM GSH supplemented with 100 μM of t10, c12 CLA (CLA group, n = 1394) or without supplementation (control group, n = 1431). Samples of D7/D8 embryos were observed under Nomarsky microscopy for lipid droplets evaluation while others were biopsied and vitrified (group B-Control, n = 24; group B-CLA, n = 23). Non-biopsied embryos were also frozen (group NB-Control, n = 49; group NB-CLA, n = 45). Biopsied cells were used for embryo sex determination. Postwarming embryo survival and viability were determined at 0 and 24 h of culture, respectively. Supplementation of t10, c12 CLA did not influence cleavage, embryo sex ratio, D7/D8 embryo rate or morphological quality. CLA embryos had higher number of small lipid droplets ( P ≤ 0.003) and a smaller ( P < 0.001) fat embryo index being leaner ( P = 0.008) than control embryos. Embryo postwarming survival was higher in B-CLA than in B-control group (95.0 ± 7.0% versus 62.5 ± 7.9%; P < 0.001). After 24 h of culture, the viability (expansion rate) of biopsied embryos and nonbiopsied embryos, cultured with t10, c12 CLA was higher than control embryos (B-CLA = 64.6 ± 4.4% and B-control = 27.5 ± 2.5%, P = 0.01; NB-CLA = 86.0 ± 3.5% and NB-Control = 68.6 ± 7.0%, P = 0.05). Results showed that supplying t10, c12 CLA to serum-containing media decreases embryo cytoplasmic lipid deposition during in vitro culture and significantly improves resistance of IVP embryos to micromanipulation and cryopreservation.

Ultrastructure of the ovary, ovicapt and oviduct of the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890)

AbstractThe ultrastructural details are presented of the ovary, ovicapt and oviduct of the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890) from the intestine of the sand sole Solea lascaris. Oogonia, maturing oocytes and mature oocytes are surrounded by a syncytial interstitial cytoplasm, one of the distinctive traits of which is the presence of numerous myelin-like bodies. Oocyte inclusions comprise cortical granules and a small number of lipid droplets. The thickened, nucleated epithelium of the ovicapt lacks any apical structure and is a prolongation of the narrow ovarian epithelium. The muscular sphincter of the ovicapt is formed by a band of longitudinal muscles and bands of radial muscles at right angles to the longitudinal layer, and numerous myocytes surround the ovicapt wall. The oviduct of D. rudolphii is subdivided into three regions: (1) the proximal oviduct; (2) the fertilization chamber — the region distal to the point of entry of the duct from the seminal receptacle; and (3) the ovovitelline duct — the region distal to the point of entry of the duct from the vitelline reservoir. A comparative analysis is made between the structures of the ovary, ovicapt and oviduct of D. rudolphii and those of two other spathebothriideans, Cyathocephalus truncatus and Diplocotyle olrikii, with a discussion of ultrastructural traits that might be used as taxonomic criteria within the order Spathebothriidea.

Live Cell Analysis and Targeting of the Lipid Droplet-binding Adipocyte Differentiation-related Protein

Neutral lipid is stored in spherical organelles called lipid droplets that are bounded by a coat of proteins. The protein that is most frequently found at the surface of lipid droplets is adipocyte differentiation-related protein (ADRP). In this study, we demonstrate that fusion of either the human or mouse ADRP coding sequences to green fluorescent protein (GFP) does not disrupt the ability of the protein to associate with lipid droplets. Using this system to identify targeting elements, discontinuous segments within the coding region were required for directing ADRP to lipid droplets. GFP-tagged protein was employed also to examine the behavior of lipid droplets in live cells. Time lapse microscopy demonstrated that in HuH-7 cells, which are derived from a human hepatoma, a small number of lipid droplets could move rapidly, indicating transient association with intracellular transport pathways. Most lipid droplets did not show such movement but oscillated within a confined area; these droplets were in close association with the endoplasmic reticulum membrane and moved in concert with the endoplasmic reticulum. Fluorescence recovery analysis of GFP-tagged ADRP in live cells revealed that surface proteins do not rapidly diffuse between lipid droplets, even in conditions where they are closely packed. This system provides new insights into the properties of lipid droplets and their interaction with cellular processes.

Modulation of collagen synthesis by fat-storing cells, isolated from CCl4- or vitamin A-treated rats.

In an attempt to elucidate the role of fat-storing cells (FSCs) in liver fibrosis, we investigated the collagen synthesis by FSCs freshly isolated from rats treated with CCl4, with vitamin A, and from untreated rats. FSCs from CCl4-treated rats contained a small number of lipid droplets and an abundant rough endoplasmic reticulum (RER), while those from vitamin A-treated rats showed numerous large lipid droplets and scanty RER. The population doubling times of FSCs isolated from normal, CCl4-treated, and vitamin A-treated rats were 38 +/- 4.3, 24 +/- 2.5, and 48 +/- 6.3 hr, respectively. The rate of collagen synthesis by FSCs from CCl4-treated rats was four- to sixfold enhanced, while collagen synthesis by FSCs from vitamin A-treated rats was suppressed. The ratio of collagen type I to type III produced by FSCs from CCl4 rats was enhanced as compared with control rats (94.7:5.3 vs 87.6:12.4). Therefore, FSCs can be considered to play an important role in the pathogenesis of liver fibrosis.

Effect of acetaldehyde on collagen synthesis by fat-storing cells isolated from rats treated with carbon tetrachloride.

In an attempt to elucidate the role of fat-storing cells (FSCs) in alcoholic liver fibrosis, we examined the effects of ethanol and acetaldehyde on collagen synthesis by FSCs isolated from CCl4-treated or normal rats. Isolated FSCs from normal rats showed characteristic lipid droplets in the cytoplasm. FSCs from CCl4-treated rats showed an abundant rough endoplasmic reticulum and a small number of lipid droplets. Collagen synthesis by the cells from CCl4-treated rats was 4-5-fold enhanced as compared with untreated rats. Though ethanol had an inhibitory effect on collagen synthesis by FSCs, acetaldehyde stimulated collagen production by the cells from CCl4-induced hepatic fibrosis, whereas collagen synthesis by the cells from normal rats was not influenced by acetaldehyde. From these results, FSCs are morphologically and functionally changed in liver fibrosis, and the transitional state of FSCs might be important in the pathogenesis of alcoholic liver fibrosis.

Zinc deficiency affects the composition of the rat adrenal gland.

The response of the adrenal gland to zinc deficiency was examined in male weanling rats. In comparison with decapsulated adrenals from ad libitum fed controls, glands from zinc deficient rats had greater relative weight (mg/g body wt), DNA concentration, and total lipid and cholesterol concentrations as well as a smaller protein/DNA ratio. Several of these differences (protein/DNA and cholesterol concentration) could be attributed to the inanition accompanying zinc deficiency, as zinc deficient values were similar to those of pair fed controls. Values for total DNA and protein concentration were similar for all groups. Electron micrographs of the zona fasciculata showed a small number of lipid droplets in the adrenals from ad libitum fed controls, an increase in lipid droplets from pair fed controls, and an even more striking increase in lipid droplets from the zinc deficient adrenals. The increased adrenal lipid composition in the zinc deficient group may be secondary to enhanced steroidogenesis or a zinc deficiency-induced defect of lipid metabolism.