Adipocytes express a functional system for serotonin synthesis, reuptake and receptor activation

Aims: Serotonergic pathways in the central nervous system (CNS) are activated in the regulation of food intake and body weight. We hypothesized that adipocytes, like other cells of mesenchymal origin, possess serotonin receptors and thus could be regulated by peripherally circulating serotonin. Methods: In vivo studies: four Sprague–Dawley rats were given daily serotonin (5HT) injections subcutaneously (s.c., 25 mg/kg) for 5 days; four controls received saline. In a long‐term study, 12 rats were given serotonin s.c. for 4 months, 10 controls received saline. Body weight was registered throughout the studies, and visceral adipose tissue and plasma were collected and analysed. Adipocytes were isolated from normal rat visceral abdominal adipose tissue and analysed for the expression of serotonin receptors, the serotonin transporter (5HTT/SERT), activation of serotonin synthesis (tryptophan hydroxylase 1, Tph1) and secretion and serotonin‐induced leptin regulation by RT‐PCR and protein analyses. Results: Hyperserotoninergic rats had significantly lower body weight (?7.4 and ?6.8%) and plasma leptin levels (?44 and ?38%) than controls, after both short‐ and long‐term serotonin treatment, respectively, whereas plasma ghrelin levels were unaffected. Compared to controls, serotonin induced a 40‐fold upregulation of 5HTT mRNA in visceral adipose tissue after 5 days of treatment. In vitro experiments showed that adipocytes express serotonin receptors, Tph1 and 5HTT, synthesize and secrete serotonin and that serotonin regulates leptin in mature adipocytes. Conclusions: These findings show that serotonin may regulate adipocyte function in a direct manner via the blood circulation and/or paracrine and autocrine mechanisms, and not only indirectly via the CNS as previously assumed.     

阿糖胞苷对人骨髓细胞长期培养的影响

人骨髓细胞长期培养加入３５μｇ／ｍｌ阿糖胞苷并孵育１小时后中止，然后继续培养，４周龄ＬＴＨＭＣ的造血被抑制；但１８周龄ＬＴＨＭＣ则表现为培养上清液中非粘附细胞数上升，１４天达高峰，基质层出现造血区，原已退缩的基质层有新的基质细胞生长。提示１８周龄ＬＴＨＭＣ仍有造血潜力，其基质层仍存在造血干细胞。     

Characterization of Bone Marrow Stromal Cells in Suspension and Monolayer Cultures

S ummary . Aspirated marrow fragments from healthy adult baboons were cultured in a simple liquid suspension tissue culture system. During the incubation period, haemopoietic cells were discharged from the fragments and settled to the floor of the culture vessels, thus allowing a separation of marrow stromal elements, retained within the fragments. Cells associated with the marrow stroma in vitro were of four main types: adipocytes, macrophages, plasma cells and unidentified lipid-laden cells related to fibroblasts. These last cells were capable of DNA synthesis in vitro , and were morphologically and functionally distinguishable from typical marrow macrophages. Macrophages were characterized by their phagocytic properties. Plasma cells were capable of prolonged survival and immunoglobulin output in vitro .
In monolayer cultures of disaggregated fragment cell suspensions, the lipid-laden stromal cells rapidly assumed fibroblast-like morphology. Fibroblastic proliferation to confluent monolayers was seen within a few days. Plasma cells reorientated themselves around these cells to form rosettes, and bridge communications between the two cell types were seen frequently. Plasma cell immunoglobulin output rate per cell appeared to be potentiated by this association.     

Factors involved in white‐to‐brown adipose tissue conversion and in thermogenesis: a review

Obesity is the result of energy intake chronically exceeding energy expenditure. Classical treatments against obesity do not provide a satisfactory long‐term outcome for the majority of patients. After the demonstration of functional brown adipose tissue in human adults, great effort is being devoted to develop therapies based on the adipose tissue itself, through the conversion of fat‐accumulating white adipose tissue into energy‐dissipating brown adipose tissue. Anti‐obesity treatments that exploit endogenous, pharmacological and nutritional factors to drive such conversion are especially in demand. In the present review, we summarize the current knowledge about the various molecules that can be applied in promoting white‐to‐brown adipose tissue conversion and energy expenditure and the cellular mechanisms involved.     

Regulation of Cobalamin and Folate Metabolism by Methionine in Human Bone Marrow Cultures

In cobalamin deficiency folate metabolism is disturbed. In the liver this deranged metabolism can be overcome by methionine, however, methionine failed to overcome this abnormality in bone marrow cultures from cobalamin deficient patients. In cobalamin deficient E. coli mutant bacteria, methionine under different conditions could either inhibit or potentiate the growth of the organism. This study was therefore initiated to test the effect of methionine, under different conditions, on bone marrow cultures. The defective DNA synthesis in megaloblastic bone marrow due to cobalamin deficiency could be corrected by the in vitro addition of low 0.27 μmol (40 μg) but not high 6.7 μmol (1 mg) amounts of methionine. This was measured by the ability of deoxyuridine to suppress the ³H-thymidine incorporation into DNA. The effect of methionine in facilitating de novo DNA synthesis is probably due to the catalytic action of SAM which activates cobalamin dependent methyltransferase enzyme thus potentiating the effect of cobalamin. In contrast high concentrations of methionine may inhibit this enzyme.     

Fatty Acid Composition of Adipose Cells in Red and Yellow Marrow: A Possible Determinant of Haematopoietic Potential

The fatty acid composition of whole bone marrow and that of isolated, disaggregated adipose cells from red and yellow marrow was examined by gas chromatography. Consistent and significant shifts from myristic and palmatic acids (in red marrow) to their respective monounsaturated derivatives myristoleic and palmitoleic acids (in yellow marrow) were found. These differences in the fatty acids correlate with histochemical studies and lend further support to the concept that the composition of lipid in the adipose cells of bone marrow may determine their relative stability in relation to haematopoietic requirements.     

Dydrogesterone and norethisterone regulate expression of lipoprotein lipase and hormone-sensitive lipase in human subcutaneous abdominal adipocytes

AIM: In premenopausal women, hyperandrogenicity is associated with central obesity and an increased cardiovascular risk. The aim of this study was to investigate the effects of dydrogesterone (DYD) (a non-androgenic progestogen) and norethisterone (NET) (an androgenic progestogen) on lipoprotein lipase (LPL), hormone-sensitive lipase (HSL) and glycerol release in adipocytes isolated from subcutaneous abdominal adipose tissue. METHODS: Adipose tissue was obtained from 12 non-diabetic women, mean age 51 years (range 37-78) and mean body mass index 25.4 kg/m(2) (range 20.3-26.4). Adipocytes were treated with increasing doses of DYD and NET for 48 h prior to protein extraction. Effects on lipogenesis and lipolysis were assessed using western blotting to determine the expression of key enzymes, LPL (56 kDa) and HSL (84 kDa) respectively. Measurement of glycerol release into the medium provided an assessment of lipolytic activity. RESULTS: Expression of LPL was increased by DYD and NET (mean protein expression relative to control +/- s.e.), with greatest effect at 10(-8) M for DYD: 2.32 +/- 0.51 (p < 0.01) and 10(-8) M for NET: 2.06 +/- 0.19 (p < 0.01). In contrast, HSL expression was reduced by all concentrations of DYD, with maximal effect at 10(-9) M : 0.49 +/- 0.02 (p < 0.001). NET reduced HSL expression at all concentrations from 10(-9) M : 0.62 +/- 0.06 (p < 0.001) to 10(-7) M : 0.69 +/- 0.08 (p < 0.001). Glycerol measurements supported the HSL expression studies although they were not statistically significant (p > 0.05). CONCLUSIONS: DYD and NET significantly increased LPL expression relative to control, while significantly reducing HSL expression. At the concentrations studied, similar effects were observed with the androgenic NET and the non-androgenic DYD despite differing effects on the lipid profile when taken orally in combination with oestrogen. Further work examining the effects of different progestogens on body fat distribution may enable progestogen use to be tailored to maximize benefits and minimize potential harm.     

吉非贝齐对血脂异常兔血清脂肪细胞型脂肪酸结合蛋白的影响

目的观察吉非贝齐短期干预对高胆固醇血症兔血清及脂肪组织分泌脂肪细胞型脂肪酸结合蛋白(AFABP)的影响。方法 15只新西兰大白兔随机分为3组:对照组.高胆固醇组.吉非贝齐组,每组5只。用RT-PCR法测定脂肪组织AFABP mRNA的表达;ELISA法检测血清及脂肪组织培养液中AFABP水平。结果高胆固醇组和吉非贝齐组兔饲养第8周及第12周血清总胆固醇、低密度脂蛋白胆固醇水平明显高于对照组(P<0.01);吉非贝齐组兔第12周体重较第8周明显下降(P<0.05),同时血清和脂肪组织培养的上清液中AFABP水平明显低于高胆固醇组(P<0.05);高胆固醇组和吉非贝齐组脂肪组织AFABP mRNA的表达明显高于对照组,但吉非贝齐组兔脂肪组织AFABP mRNA的表达明显低于高胆固醇组(P<0.05)。结论吉非贝齐能降低高胆固醇饮食饲养兔体重,并降低血清及脂肪组织分泌的AFABP,这一作用可能有利于防治动脉粥样硬化及肥胖。     

Human Tissues as Source of Colony-Stimulating Factor in Human Bone Marrow Cultures

Human bone marrow cells were cultured by the agar method using feeder layers containing human tissue fragments of various origin. Colony stimulating factor (CSF) was shown to be released from all tissues tested (adipose tissue, skeletal muscle, peritoneum and vascular wall), and primary cultures of human fibroblasts could also stimulate colony growth. Colony growth of murine bone marrow cells was also stimulated by all feeder layers. Thus, the study demonstrates that monocytes and macrophages might not be the only source of CSF of possible importance for human granulopoiesis in vivo.     

Brown fat like gene expression in the epicardial fat depot correlates with circulating HDL-cholesterol and triglycerides in patients with coronary artery disease

Background

Recent evidence indicates that epicardial adipose tissue (EAT) expresses uncoupling protein-1 (UCP1), a marker of brown adipocytes. However, the putative effects of the presence of brown adipocytes in EAT remain unknown.

Methods

The mRNA expression of genes related to brown adipocyte-mediated thermogenesis was measured in the fat samples collected from the epicardial-, mediastinal- and subcutaneous-depots of patients undergoing coronary artery bypass grafting. Both univariate and multivariate analyses were then utilized to determine any association between gene expression and the anthropometrics and fasting blood chemistries of these patients.

Results

EAT exhibited significantly higher expression of UCP1 and cytochrome c oxidase subunit-IV (COX-IV) compared to mediastinal- and subcutaneous-fat depots (P ≤ 0.05). EAT expression of UCP1 (r = 0.50), COX-IV (r = 0.37) and lipoprotein lipase (LPL) (r = 0.58) positively associated with circulating levels of HDL-cholesterol (P ≤ 0.05). In addition, EAT expression of LPL, acyl coA dehydrogenase-short, -medium and -long chain genes associated negatively with circulating TG levels (P ≤ 0.05).

Conclusions

Abundance of UCP-1 in the EAT relative to other fat depots confirms the presence of brown adipocytes in human EAT. Furthermore, the correlations among the EAT expression of thermogenesis-related genes with the circulating HDL and TG levels indicate that presence of active brown adipocytes shares a functional association with the circulating plasma lipids in humans.     

Marrow culture in diffusion chambers in rabbits: III. Effect of endotoxin and leukocyte products on cell production

Soluble leukocyte products harvested from incubated peritoneal exudate leukocytes, injected intravenously or intramuscularly, increased production of granulocytes and macrophages in marrow in diffusion chambers implanted into the peritoneal cavity of rabbits. Red cell production in the chambers was not consistently affected. Endotoxin increased production of all cell types. Endotoxin tolerance induced by daily injection of endotoxin to host rabbits abolished granulopoietic stimulation by endotoxin given during the culture period but did not diminish the granulopoietic stimulation produced by injected leukocyte products. Attempts to induce tolerance to leukocyte products by daily injections did not reduce the granulopoietic stimulation produced by either endotoxin or leukocyte products injected during the culture period. Intraperitoneally administered leukocytes products markedly inhibited production of all cell types. Endotoxin or leukocyte products given to normal rabbits increased plasma colony stimulating activity (CSA); the increase occurred sooner after leukocyte products than after endotoxin. Endotoxin-tolerant animals showed no rise in CSA after endotoxin, but their response to leukocyte products was normal. Leukocyte products added to agar cultures neither supported nor inhibited colony growth but augmented CSA-stimulated colony production. Endotoxin, leukocyte products, and CSA are different and may interact in regulating granulopoiesis.     

Aplastic Anaemia with Marrow Defective in Formation of Fibroblastoid Cell Colonies in Vitro

The formation of fibroblastoid colonies by marrow cells in vitro has been used as a putative assay for a stem cell of haemopoietic stroma. Bone marrow from one patient with aplastic anaemia did not form any of these colonies, while its growth in diffusion chambers as an indirect measure of a haemopoietic stem cell was even better than normal. On the other hand, marrow from the other aplastic anaemia patient showed only quantitative decrease in the formation of fibroblastoid colonies and simultaneously grew very poorly in diffusion chambers. These patients were indistinguishable by the cytological examination of their marrow, however, the peripheral blood abnormalities were expressed less severely in the first patient. These results suggest the contribution of the defect in marrow cells, which form fibroblastoid colonies in vitro to the development of aplastic anaemia in these patients.     

Melatonin induces browning of inguinal white adipose tissue in Zucker diabetic fatty rats

Melatonin limits obesity in rodents without affecting food intake and activity, suggesting a thermogenic effect. Identification of brown fat (beige/brite) in white adipose tissue (WAT) prompted us to investigate whether melatonin is a brown‐fat inducer. We used Zücker diabetic fatty (ZDF) rats, a model of obesity‐related type 2 diabetes and a strain in which melatonin reduces obesity and improves their metabolic profiles. At 5 wk of age, ZDF rats and lean littermates (ZL) were subdivided into two groups, each composed of four rats: control and those treated with oral melatonin in the drinking water (10 mg/kg/day) for 6 wk. Melatonin induced browning of inguinal WAT in both ZDF and ZL rats. Hematoxylin–eosin staining showed patches of brown‐like adipocytes in inguinal WAT in ZDF rats and also increased the amounts in ZL animals. Inguinal skin temperature was similar in untreated lean and obese rats. Melatonin increased inguinal temperature by 1.36 ± 0.02°C in ZL and by 0.55 ± 0.04°C in ZDF rats and sensitized the thermogenic effect of acute cold exposure in both groups. Melatonin increased the amounts of thermogenic proteins, uncoupling protein 1 (UCP1) (by ~2‐fold, P < 0.01) and PGC‐1α (by 25%, P < 0.05) in extracts from beige inguinal areas in ZL rats. Melatonin also induced measurable amounts of UCP1 and stimulated by ~2‐fold the levels of PGC‐1α in ZDF animals. Locomotor activity and circulating irisin levels were not affected by melatonin. These results demonstrate that chronic oral melatonin drives WAT into a brown‐fat‐like function in ZDF rats. This may contribute to melatonin′s control of body weight and its metabolic benefits.     

Effects of Pineal Indoles and Arginine Vasotocin on Lipolysis and Lipogenesis in Isolated Adipocytes

The effects of arginine vasotocin and the pineal indoles melatonin, serotonin, N-acetylserotonin, hydroxytryptophol, methoxytryptophol, hydroxyindoleacetic acid, methoxyindoleacetic acid, and methoxytryptamine on lipolysis and lipogenesis in isolated adipocytes were studied. Basal lipolysis was inhibited by all the indoles tested at a dose of 1 mumole except hydroxytryptophol. Methoxytryptamine and serotonin inhibited hormone-induced lipolysis in a dose-dependent manner and exhibited the highest antilipolytic activity in isolated rat, rabbit, and hamster adipocytes. However, their antilipolytic activity could not be overcome by increasing the dose of the lipolytic hormone. Dibutyryl cyclic AMP-induced lipolysis was also inhibited. All the pineal indoles tested were capable of suppressing basal and insulin-stimulated lipogenesis in the dose range 0.33-3 nmole. At lower doses there was no effect. Arginine vasotocin at a dose of 25 nmole significantly augmented basal lipogenesis.     

Effect of Blood Derived Monocytes on the Promotion of in Vitro Erythropoietic Colony Growth in Human Bone Marrow Cultures

The effect of monocytes on the promotion of erythropoietic burst formation in human bone marrow methylcellulose cultures was studied in a burst-promoting activity (BPA)-poor system. Irradiated Ficoll-Isopaque separated blood mononuclear cells stimulated BFU-E growth proportionally to the number of irradiated cells added. Monocyte-depleted mononuclear cells stimulated as well as total mononuclear cells. Monocyte-concentrates stimulated when added at low concentrations. Monocyte-depleted mononuclear cells, although stimulatory at higher concentrations, did not stimulate at the concentrations used for monocyte-concentrates.