Enhancing the take of injected adipose tissue by a simple method for concentrating fat cells

Injection of aspirated fat for the correction of tissue defects is a common procedure in plastic surgery. The reported rates of fat cell survival vary greatly in the medical literature, and different techniques of harvesting, processing, and reinjecting the fat cells are claimed to be responsible for these differences. However, there is no agreement concerning the best way to process the harvested fat before reinjection. The present study was initiated to examine and evaluate the effect of a simple method of isolating the fat particles on the outcome of fat graft survival. In this study, the nude mouse model was used to examine the survival and take of the fat graft concentrated before injection by the cumbersome recommended closed centrifugation technique in comparison with the authors' recommended open method, using an operating room cotton towel as a platform for concentrating the fat cells and separating them from fluids, oil, and debris. One milliliter of concentrated human fat cells preprocessed by towel separation was injected into the nuchal subcutis of 11 nude mice in the study group, and the same amount of fat that was preprocessed by centrifugation was injected into 11 control mice. Injected fat survived in both groups. No significant differences were found regarding fat graft weight and volume, although a tendency for better survival was noticed in the experimental group. Histologic evaluation of the grafts revealed significantly less fibrosis within the study group, meaning that the quality of the fat grafts was better. The authors found this method to be simple, cheap, and friendly to the surgeon in comparison with traditional processing using the centrifuge.     

The effect of interleukin-8 on the viability of injected adipose tissue in nude mice

Adipose tissue injection as a free graft for the correction of soft-tissue defects is a widespread procedure in plastic surgery. The main problem in achieving long-term soft-tissue augmentation is partial absorption of the injected fat and hence the need for overcorrection and re-injection. The purpose of this study was to improve the viability of the injected fat by the use of interleukin-8. The rationale for the use of interleukin-8 was its abilities to accelerate angiogenesis and attract inflammatory cells and fibroblasts, providing the injected adipocytes more feeding vessels and a well-established graft bed to enhance their viability. Human adipose tissue, obtained by suction-assisted lipectomy, was re-injected into the subcutis in the scalp of nude mice. Interleukin-8 (0.25 ng) was injected subcutaneously to the scalp as a preparation of the recipient site 24 hours before the fat injection and was added to the fat graft itself (25 ng per 1 cc of injected fat). In the control group, pure fat without interleukin-8 was injected and no interleukin-8 was added for the preparation of the recipient site. One cubic centimeter of fat was injected in each animal in both the study and control groups. There were 10 animals in each group. The animals were euthanized 15 weeks after the procedure. Graft weight and volume were measured and histologic evaluation was performed. In addition, triglyceride content and adipose cell sizes were measured as parameters for fat cells viability. Histologic analysis demonstrated significantly less cyst formation in the group treated with interleukin-8. No significant differences were found between the groups with regard to graft weight and volume or the other histologic parameters investigated. No significant differences were demonstrated in adipose cell sizes and their triglyceride content. In conclusion, less cyst formation, indicating improved quality of the injected fat, can be obtained by the addition of interleukin-8. Further studies of various dosages of interleukin-8 and their long-term effect are required before these encouraging results could be applied clinically.     

Bombyx acid cysteine protease (BCP): hormonal regulation of biosynthesis and accumulation in the ovary

We previously reported purification of the cysteine protease from Bombyx eggs (BCP) and the occurrence of the enzyme in various tissues of this insect. In the present paper, we present a detailed analysis of stage-specific changes in activity of BCP between the fourth larval instar and pupal-adult development. A synthetic fluorescent peptide, carbobenzoxy-L-Phenylalanyl-L-Arginine4-methylcoumaryl-7-amide (Z-Phe-Arg-MCA), was used to assay proteolytic activity. When tissue extracts were treated with anti-BCP serum before assay of enzyme activity, most activity towards Z-Phe-Arg-MCA was removed from the extracts. Therefore proteolytic activity in the present experiments is due mainly to BCP. We used Western blot and Northern blot analyses to determine tissue and stage specific expression of the enzyme. In the 5th larval fat body and hemolymph, BCP activity dramatically increased at the time of spinning, returning to the basal level before ecdysis. Northern blot analysis showed that a 1.5 kilobase mRNA which hybridizes to BCPcDNA suddenly appears during this period. Similar results were obtained in 4th instar fat body. In pupal hemolymph and fat body, low basal activity of BCP was detected early (day 0 to day 3 after pupal ecdysis), followed by a pronounced increase to a maximum six days after ecdysis, before returning to the basal level. In ovariectomized female pupae, a significant amount of proteolytic activity accumulated in hemolymph, suggesting that the enzyme is synthesized in the fat body and transferred into the ovary along with vitellogenin. BCP activity increased three days after injection of 20-hydroxyecdysone into ligated pupae. Furthermore, putative BCPmRNA appeared in the fat body within 24 hours after injection. This increase was completely blocked by the administration of cycloheximide. The results suggest that, BCP is synthesized in extraovarian tissues such as fat body and ovarian follicle cells and accumulates in the ovary, thus representing a new class of yolk protein.     

Electromyographic recordings of paraspinal muscles: Variations related to subcutaneous tissue thickness

The aim of this study was to assess the effect on EMG amplitude measures of variations in the thickness of underlying tissue between surface electrodes and the active muscle. 20 normal subjects with different amounts of subcutaneous tissue performed comparable constant force contractions for a 45-second period, during which paraspinal EMG recordings were taken. Three measures of subcutaneous tissue thickness were obtained from each subject: Body Mass Index, total body fat as calculated by Durnin's formula, and skinfold thickness at the recording sites. The results show that (i) the greater the thickness of subcutaneous tissue between the surface recording site and the contracting muscles, the lower the recorded electromyographic activity, and that (ii) up to 81.2% of the variance in the EMG measures can be explained by variation in the amount of subcutaneous tissue. These findings support the view that the absolute level of surface-recorded EMG cannot simply be taken at face value. The amplitude of the signal will be affected by, for example, the amount of body fat.Supported by the Physician's Services Inc. Foundation.     

Elevated AT1 receptor protein but lower angiotensin II-binding in adipose tissue of rats with monosodium glutamate-induced obesity.

Age-related hypertrophy of adipose tissue has been associated with a significant decrease in the number of angiotensin II receptors. The aim of this study was to investigate the characteristics of angiotensin II receptors in hypertrophic adipose tissue in animal obesity model using rats postnatally treated with monosodium glutamate. Angiotensin II is known to induce hypertrophy in several tissues of the cardiovascular system and might do the same in fat tissue. The expression and binding properties of angiotensin II AT(1) receptors in epididymal fat tissue of adult rats were studied using membrane-binding, RT-PCR, and immunoblotting. The amount of AT(1) receptor mRNA did not differ significantly between obese and control rats. Despite that glutamate-treated rats displayed approximately 4-times more AT(1) receptor immunoreactive protein content in fat tissue cell membranes than the controls did. In contrast, binding experiments showed a significant (40.3 +/- 6.2 %) decrease of (125)I-Sar(1)-Ile(8)-angiotensin II-binding to fat tissue cell membranes in obese rats compared to controls. In conclusion, the present study provides evidence for the low binding properties associated with an accumulation of AT(1) receptor protein in cell membranes of the fat tissue of rats with glutamate-induced obesity. Discrepancies among angiotensin II-binding, AT(1) receptor protein, and AT(1) receptor mRNA levels indicate a possible defect in the receptor protein, which remains to be identified. The results obtained support a role of angiotensin II and AT(1) receptors in the pathogenesis of obesity.     

Nutritional factors affecting quantity and quality of carcass fat in chickens.

Nonpathological fattening of a bird occurs when the amount of energy consumed exceeds its requirements for maintenance and growth. Dietary energy and protein levels, particularly the ratio of these two, are the main dietary factors affecting fatness. Consumption of diets low in protein results in excess energy intake and an increased hepatic lipogenesis. Excess protein has the opposite effect. It also increases the energy expenditure required to dispose of excess amino acids in the body. Severe deficiency of a specific amino acid does not increase fattening. The degree of fattening, particularly of the liver, induced by corticosterone injection is greater in birds fed diets containing a wide energy-to-protein ratio in comparison to a narrow ratio. The content of dietary fat per se does not affect carcass fat concentration although it alters the rate of liver fatty acid synthesis. The dietary fatty acid composition affects the composition of tissue fatty acids. Consumption of diets containing vegetable oils or high in protein increases the degree of unsaturation of tissue fat and thereby its susceptibility to oxidation. Dietary dl-alpha-tocopheryl acetate increases the stability of the lipids of adipose and muscle tissue of chicks with relatively saturated body fat, but the dietary effectiveness of this vitamin in improving the stability of tissues of birds having relatively unsaturated fat is limited.     

Biomimetic injectable HUVEC‐adipocytes/collagen/alginate microsphere co‐cultures for adipose tissue engineering

Engineering adipose tissue that has the ability to engraft and establish a vascular supply is a laudable goal that has broad clinical relevance, particularly for tissue reconstruction. In this article, we developed novel microtissues from surface‐coated adipocyte/collagen/alginate microspheres and human umbilical vein endothelial cells (HUVECs) co‐cultures that resembled the components and structure of natural adipose tissue. Firstly, collagen/alginate hydrogel microspheres embedded with viable adipocytes were obtained to mimic fat lobules. Secondly, collagen fibrils were allowed to self‐assemble on the surface of the microspheres to mimic collagen fibrils surrounding the fat lobules in the natural adipose tissue and facilitate HUVEC attachment and co‐cultures formation. Thirdly, the channels formed by the gap among the microspheres served as the room for in vitro prevascularization and in vivo blood vessel development. The endothelial cell layer outside the microspheres was a starting point of rapid vascular ingrowth. Adipose tissue formation was analyzed for 12 weeks at 4‐week intervals by subcutaneous injection into the head of node mice. The vasculature in the regenerated tissue showed functional anastomosis with host blood vessels. Long‐term stability of volume and weight of the injection was observed, indicating that the vasculature formed within the constructs benefited the formation, maturity, and maintenance of adipose tissue. This study provides a microsurgical method for adipose regeneration and construction of biomimetic model for drug screening studies. Biotechnol. Bioeng. 2013; 110: 1430–1443. © 2012 Wiley Periodicals, Inc.     

The effect of hyperbaric oxygenation on the viability of human fat injected into nude mice

Autologous free-fat injection for the correction of soft-tissue defects has become a common procedure in plastic surgery. The main shortcoming of this method for achieving permanent soft-tissue augmentation is the partial absorption of the injected fat, an occurrence that leads to the need for both overcorrection and repeated fat reinjection. Improving the oxygenation of the injected fat has been suggested as a means of helping to overcome the initial critical phase that occurs postinjection (when the fat cells are nourished by osmosis), increasing phagocyte activity, accelerating fibroblast activity and collagen formation, and enhancing angiogenesis. In addition, the hyperbaric oxygen-mediated decrement in endothelial leukocyte adhesion will decrease cytokine release, thereby reducing edema and inflammatory responses. The purpose of the present study was to examine the effect of hyperbaric oxygenation on improving the viability of injected fat. Adipose tissue obtained from human breasts by suction-assisted lipectomy was injected into the subcuticular nuchal region in nude mice. The mice were then exposed to daily hyperbaric oxygen treatments, breathing 100% oxygen at 2 atmospheres absolute (ATA) for 90 minutes. The duration of the administered hyperbaric oxygen therapy was 5, 10, or 15 days, according to the study group. Mice exposed to normobaric air alone served as the control group, and each group included 10 animals. The rats were killed 15 weeks after fat injection. The grafts were dissected out, weight and volume were measured, and histologic evaluation was performed. In all of the study groups, at least part of the injected fat survived, giving the desired clinical outcome. No significant differences could be found between the groups regarding fat weight and volume. Histopathologic examination of the dissected grafts demonstrated a significantly better integrity of the fat tissue in the group that received hyperbaric oxygen for 5 days (p = 0.047). This finding was manifested by the presence of well-organized, intact fat cells, along with a normal appearance of the fibrous septa and blood vessels. The worst results were found in animals treated by hyperbaric oxygenation for 15 consecutive days. An inverse correlation was found between an increased dose of the high-pressure oxygen and fat tissue integrity (r = -0.87, p = 0.076). The toxic effects of highly reactive oxygen species on fat cells might explain the failure of an excessively high dose of hyperbaric oxygen to provide any beneficial outcome. The clinical relevance of these results should be further investigated.     

Isolation of two human fibroblastic cell populations with multiple but distinct potential of mesenchymal differentiation by ceiling culture of mature fat cells from subcutaneous adipose tissue

Adipose tissue is a source of adult multipotent stem cells that can differentiate along mesenchymal lineage. When mature fat cells obtained from human subcutaneous adipose tissue were maintained with attachment to the ceiling surface of culture flasks filled with medium, two fibroblastic cell populations appeared at the ceiling and the bottom surface. Both populations were positive to CD13, CD90, and CD105, moderately positive to CD9, CD166, and CD54, negative to CD31. CD34, CD66b, CD106, and CD117, exhibited potential of unlimited proliferation, and differentiated along mesenchymal lineage to produce adipocytes, osteoblasts, and chondrocytes. The population that appeared at the ceiling surface showed higher potential of adipogenic differentiation. These observations showed that the cells tightly attached to mature fat cells can generate two fibroblastic cell populations with multiple but distinct potential of differentiation. Since enough number of both populations for clinical transplantation can be easily obtained by maintaining fat cells from a small amount of subcutaneous adipose tissue, this method has an advantage in preparing autologous cells for patients needing repair of damaged tissues by reconstructive therapy.     

Insulin signalling in human adipose tissue

Adipose tissue is a critical regulator of energy balance and substrate metabolism, and synthesizes several different substances with endocrine or paracrine functions, which regulate the overall energetic homeostasis. An excessive amount of adipose tissue has been associated with the development of type 2 diabetes, premature atherosclerosis, and cardiovascular disease. It is believed that the adverse metabolic impact of visceral fat relies on a relative resistance to the action of insulin in this depot compared to other adipose tissue depots. However, information on insulin signalling reactions in human fat is limited. In this paper, we review the major insulin signalling pathways in adipocytes and their relevance for metabolic regulation, and discuss recent data indicating different signalling properties of visceral fat as compared to other fat depots, which may explain the metabolic and hormonal specificity of this fat tissue depot in humans.     

Protein synthesis in ‘fat body’ and ovary of the physogastric queen of Macrotermes subhyalinus

In the physogastric queen of Macrotermes subhyalinus the fat body, when incubated in vitro with [¹⁴C] amino acids, synthesizes proteins at a much slower rate than ovarian tissue under the same conditions. Only a very small amount of the labelled proteins is released into the incubation medium. Oxygen consumption of the queen fat body is higher than that of ovarian tissue and the fat body of the king. At 3 hr after injection of [¹⁴C] amino acids in vivo the total fat body of the queen contains three to six times less labelled proteins than the two entire ovaries. It is assumed that in contrast to other insects the physogastric termite queen synthesizes vitellogenins mainly in the ovarian follicle cells and not in the fat body.The fat body of the king with a high incorporation rate of [¹⁴C] amino acids and a rapid release of synthesized protein into the incubation medium is comparable to the fat body of other insects.     

Interactions of high density lipoprotein subclasses (HDL2 and HDLc) with dog adipocytes: selective effects of cholesterol and saturated fat feeding

Adipose tissue is a cholesterol storage organ and derives its cholesterol primarily from circulating lipoproteins. The present study shows that adipocytes isolated from canine omental fat tissue interact specifically with high density lipoprotein subfractions lacking or enriched in apolipoprotein E, namely canine high density lipoprotein-2 (HDL2) and HDLc, respectively. While 125I-labeled HDL2 binding was inhibited similarly by both excess unlabeled HDLc and HDL2, 125I-labeled HDLc interaction was inhibited by its homologous ligand only. Paired studies showed that the amount of HDLc associated with adipocytes was significantly higher compared to HDL2. The effect of a short-term cholesterol and saturated fat feeding on adipocyte-HDL interaction was examined using fat cells obtained from dogs before and again 3 weeks after a diet supplemented with cholesterol (1% w/w) and saturated fat (30% lard, w/w). Significant increases in body weight and omental fat cell weight occurred after fat feeding. The amount of 125I-labeled HDL2 that could be bound to adipocytes increased after the diet, whether expressed on a per cell basis (P less than 0.005) or per unit cell surface (P less than 0.025). The amount of cell-associated 125I-labeled HDLc, however, was not significantly affected by the cholesterol-rich diet. The characteristics of HDLc and HDL2 dissociation were assessed by examining the release of labeled lipoproteins from adipocytes preincubated with 125I-labeled HDLc and 125I-labeled HDL2. HDL2 dissociation from adipocytes was significantly decreased (P less than 0.05) following the diet and may explain in part the apparent increase in cell-associated 125I-labeled HDL2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of central or peripheral leptin administration on norepinephrine turnover in defined fat depots

Leptin preserves lean tissue but decreases adipose tissue by increasing lipolysis and/or inhibiting lipogenesis. The sympathetic nervous system (SNS) is a primary regulator of lipolysis, but it is not known if leptin increases norepinephrine turnover (NETO) in white adipose tissue. In this study, we examined the effect of leptin administered either as a chronic physiological dose (40 microg/day for 4 days from ip miniosmotic pumps) or as an acute injection in the third ventricle (1.5 microg injected two times daily for 2 days) on NETO and the size of brown and white fat depots in male Sprague Dawley rats. NETO was determined from the decline in tissue norepinephrine (NE) during 4 h following administration of the NE synthesis inhibitor alpha-methyl-para-tryrosine. The centrally injected leptin-treated animals demonstrated more dramatic reductions in food intake, body weight, and fat pad size and an increase in NETO compared with the peripherally infused animals. Neither route of leptin administration caused a uniform increase in NETO across all fat pads tested, and in both treatment conditions leptin decreased the size of certain fat pads independent of an increase in NETO. Similar discrepancies in white fat NETO were found for rats pair fed to leptin-treated animals. These results demonstrate that leptin acting either centrally or peripherally selectively increases sympathetic outflow to white fat depots and that a leptin-induced change in fat pad weight does not require an increase in NETO.     

Postnatal growth after intrauterine growth restriction alters central leptin signal and energy homeostasis

Intrauterine growth restriction (IUGR) is closely linked with metabolic diseases, appetite disorders and obesity at adulthood. Leptin, a major adipokine secreted by adipose tissue, circulates in direct proportion to body fat stores, enters the brain and regulates food intake and energy expenditure. Deficient leptin neuronal signalling favours weight gain by affecting central homeostatic circuitry. The aim of this study was to determine if leptin resistance was programmed by perinatal nutritional environment and to decipher potential cellular mechanisms underneath.We clearly demonstrated that 5 months old IUGR rats develop a decrease of leptin sentivity, characterized by no significant reduction of food intake following an intraperitoneal injection of leptin. Apart from the resistance to leptin injection, results obtained from IUGR rats submitted to rapid catch-up growth differed from those of IUGR rats with no catch-up since we observed, for the first group only, fat accumulation, increased appetite for food rich in fat and increased leptin synthesis. Centrally, the leptin resistant state of both groups was associated with a complex and not always similar changes in leptin receptor signalling steps. Leptin resistance in IUGR rats submitted to rapid catch-up was associated with alteration in AKT and mTOR pathways. Alternatively, in IUGR rats with no catch-up, leptin resistance was associated with low hypothalamic expression of LepRa and LepRb. This study reveals leptin resistance as an early marker of metabolic disorders that appears before any evidence of body weight increase in IUGR rats but whose mechanisms could depend of nutritional environment of the perinatal period.     

Macromastia: how much of it is fat?

A total of 25 patients who underwent bilateral breast reduction were included in this study. Each patient's age, weight, height, and amount of breast tissue removed from each breast were recorded. The body mass index was calculated for each patient. On the day of the operation, tissue samples (two each) were taken from the central, lateral, and preaxillary areas of the breast. One of the samples was weighed, placed in a closed glass container, and heated for 10 minutes in a microwave oven at full power. The liquid fat was separated from the solid residue, and the percentage of fat was calculated. The other sample from each area was examined grossly, and representative sections, corresponding to the distribution of fat and connective tissue, were submitted for evaluation. In these samples, the percentage of fat, gland, and connective tissue was estimated using low-magnification light microscopy. In this group of patients (who had an average age of 34 years and who were significantly overweight as determined by a mean body mass index of 28), it was found (using the microwave method) that there was a mean fat percentage of 61 percent in the central breast area, 74 percent in the lateral breast area, and 73 percent in the preaxillary area. Upon microscopic examination, the pathologist reported that fat accounted for 64 percent of the central breast area, 92 percent of the lateral breast area, and 94 percent of the preaxillary area. On average, the central breast area in macromastia patients had only seven percent gland and 29 percent connective tissue. The lateral and preaxillary areas of the breast had one to three percent gland and five percent connective tissue. The two methods had a significant (p < 0.05) positive correlation in the central breast area, but in the lateral and preaxillary regions, the correlation was poor. In the microscopic examination, there was a tendency to overestimate the amount of fat. Both methods of evaluation used in the study concur that the enlarged breast of macromastia consists primarily of fat and that the glandular element is rather small.     

Physiological activation of brown adipose tissue destabilizes thermogenin mRNA

The amount of mRNA coding for the brown fat specific uncoupling protein thermogenin was followed in the brown adipose tissue of adult mice. As expected, cold exposure or norepinephrine injection caused an increase in the amount of thermogenin mRNA. However, contrary to expectation, the half-life of thermogenin mRNA was dramatically reduced, from about 18 h to about 3 h, when the mice were cold exposed. This destabilization of thermogenin mRNA was not related to the activity of protein synthesis. It was concluded that in brown adipose tissue an unusual mechanism operates which leads to a destabilization of thermogenin mRNA under the same physiological conditions which increase thermogenin gene expression.     

An integrated approach for increasing the survival of autologous fat grafts in the treatment of contour defects

Autologous fat grafting as a technique to correct soft-tissue defects is a controversial subject. The high percentage of fat resorption and the resulting need for additional grafting considerably reduce the value of this method. The purpose of this study was to evaluate the clinical application of tissue-culturing methodology in the handling of the lipocyte aspirate in an endeavor to improve the survival rate and therefore the take of the grafted lipocytes. The method consists of syringe aspiration of the lipocytes from the donor site, isolation of intact lipocytes by gentle centrifugation, suspension of the aspirate in an enriched cell culture medium, and injection of the cell suspension into preformed subdermal tunnels. A number of media were tested and shown to prolong the survival of lipocytes ex vivo using fluorescent acridine orange stain. Implementing the integrated cell culture techniques increased the lipocytes' viability, as indicated in clinical evaluation in which the amount of graft take ranged between 50 and 90 percent. The results of 15 patients with varied types of cases who were operated on using this new methodology show that the tissue defect was filled and remained so in postoperative follow-ups of 6 to 24 months. A three-dimensional CAT scan-aided evaluation method was developed and used in one of four case histories presented herein.     

Magnetic resonance imaging of total body fat

In this study we assessed different magneticresonance imaging (MRI) scanning regimes and examined some of theassumptions commonly made for measuring body fat content by MRI. Wholebody MRI was used to quantify and study different body fat depots in 67 women. The whole body MRI results showed that there was a significant variation in the percentage of total internal, as well as visceral, adipose tissue across a range of adiposity, which could not be predicted from total body fat and/or subcutaneous fat.Furthermore, variation in the amount of total, subcutaneous, andvisceral adipose tissue was not related to standard anthropometricmeasurements such as skinfold measurements, body mass index, andwaist-to-hip ratio. Finally, we show for the first time subjects with apercent body fat close to the theoretical maximum (68%). This studydemonstrates that the large variation in individual internal fatcontent cannot be predicted from either indirect methods or directimaging techniques, such as MRI or computed tomography, on the basis ofa single-slice sampling strategy.

     

In vitro study of the action of adipokinetic hormone in locusts

The in vitro study was performed in order to demonstrate the structural changes of lipophorin induced in vivo by the injection of adipokinetic hormone (AKH) into adult locusts. After many unsuccessful attempts, we have established the reconstructed incubation system in which purified lipophorin and apolipophorin-III (9 mol/mol lipophorin) are incubated with the fat body in the presence of AKH under a supply of excess oxygen. In this system, high density lipophorin (HDLp) originally present in the incubation medium can be transformed entirely into low density lipophorin (LDLp) due to the loading of an increased amount of diacylglycerol from the fat body. The LDLp formed in this incubation system was exactly the same as the LDLp formed in vivo by the injection of AKH, in terms of density, particle size, diacylglycerol content, and the association with apolipophorin-III (apoLp-III). In the absence of apoLp-III, AKH did not exhibit its function to any extent. It was also demonstrated that the transformation of HDLp to LDLp requires calcium ions. Moreover, it appears that, up to a certain limit, the increase of diacylglycerol content of lipophorin and the amount of apoLp-III associated with lipophorin is nearly proportional to the amount of apoLp-III added to the incubation medium.     

Regulation of ATGL expression mediated by leptin in vitro in porcine adipocyte lipolysis

Adipose triglyceride lipase (ATGL), as an adipose-enriched protein, is able to hydrolyze triglycerides and plays an important part in triglyceride lipolysis of fat tissue. Leptin, an adipocyte cytokine, can increase the fat decomposition process. Many phenomena indicate that ATGL has a close relationship with leptin’s promoting the hydrolysis of triglycerides. However, the regulatory mechanism of ATGL in leptin’s promoting fat hydrolysis has not been directly and systematically studied yet. This study demonstrated that ATGL was expressed in vitro by leptin regulation. The amount of ATGL mRNA increased and the amount of ATGL protein decreased based on a dose-dependent manner when leptin concentrations ranged from 5 to 50 ng/ml were used to treat fully differentiated porcine adipocytes for 3 h. In addition, this study revealed that JAK-STAT and MAPK signaling pathways, as well as PPARγ all played important roles in the ATGL expression mediated by leptin.