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S Cinti

Publications and source records attributed to S Cinti.

At least 37 records · Page 2Linked to original sources
PubMed2000

Expression of human alpha 2-adrenergic receptors in adipose tissue of beta 3-adrenergic receptor-deficient mice promotes diet-induced obesity.

Catecholamines play an important role in controlling white adipose tissue function and development. beta- and alpha 2-adrenergic receptors (ARs) couple positively and negatively, respectively, to adenylyl cyclase and are co-expressed in human adipocytes. Previous studies have demonstrated increased adipocyte alpha 2/beta-AR balance in obesity, and it has been proposed that increased alpha 2-ARs in adipose tissue with or without decreased beta-ARs may contribute mechanistically to the development of increased fat mass. To critically test this hypothesis, adipocyte alpha 2/beta-AR balance was genetically manipulated in mice. Human alpha 2A-ARs were transgenically expressed in the adipose tissue of mice that were either homozygous (-/-) or heterozygous (+/-) for a disrupted beta 3-AR allele. Mice expressing alpha 2-ARs in fat, in the absence of beta 3-ARs (beta 3-AR -/- background), developed high fat diet-induced obesity. Strikingly, this effect was due entirely to adipocyte hyperplasia and required the presence of alpha2-ARs, the absence of beta 3-ARs, and a high fat diet. Of note, obese alpha 2-transgenic beta 3 -/- mice failed to develop insulin resistance, which may reflect the fact that expanded fat mass was due to adipocyte hyperplasia and not adipocyte hypertrophy. In summary, we have demonstrated that increased alpha 2/beta-AR balance in adipocytes promotes obesity by stimulating adipocyte hyperplasia. This study also demonstrates one way in which two genes (alpha 2 and beta 3-AR) and diet interact to influence fat mass.

Adipose Tissue↗
PubMed2000

Tumor necrosis factor alpha mediates apoptosis of brown adipocytes and defective brown adipocyte function in obesity.

Severe quantitative and qualitative brown adipocyte defects are common in obesity. To investigate whether aberrant expression of tumor necrosis factor alpha (TNF-alpha) in obesity is involved in functional brown fat atrophy, we have studied genetically obese (ob/ob) mice with targeted null mutations in the genes encoding the two TNF receptors. The absence of both TNF receptors or p55 receptor alone resulted in a significant reduction in brown adipocyte apoptosis and an increase in beta(3)-adrenoreceptor and uncoupling protein-1 expression in obese mice. Increased numbers of multilocular functionally active brown adipocytes, and improved thermoregulation was also observed in obese animals lacking TNF-alpha function. These results indicate that TNF-alpha plays an important role in multiple aspects of brown adipose tissue biology and mediates the abnormalities that occur at this site in obesity.

Adaptation, Physiological↗
PubMed2000

Anatomy of the adipose organ.

In rats and mice the adipose organ consists of several subcutaneous and visceral depots. Some areas of these depots are brown and correspond to brown adipose tissue, while most are white and correspond to white adipose tissue. The number of brown adipocytes found in white areas varies with age, strain and environmental conditions. Brown and white adipocyte precursors are morphologically dissimilar. Together with a rich vascular supply, brown areas receive abundant noradrenergic parenchymal innervation. The gross anatomy and histology of the organ vary considerably in different physiological (cold acclimation, warm acclimation, fasting, lactation) and pathological (obesity) conditions, and many important genes, such as leptin and uncoupling protein 1, are also expressed differently in the two cell types. These basic mechanisms should be taken into account when addressing the physiopathology of obesity and its treatment.

Acclimatization↗
PubMed2000

Secretory granules of endocrine and chief cells of human stomach mucosa contain leptin.

BACKGROUND: Leptin plays an important role in the control of food intake and body weight homeostasis. In humans, leptin is produced by adipocytes, placental cells and secretory cells of the mammary epithelium. Recently, it has been reported that stomach glands produce leptin in rats. OBJECTIVE: To test the expression of leptin protein in human stomach and localize, by immunocytochemistry, the specific cell type producing leptin. DESIGN: Endoscopic stomach biopsies of six patients were used to investigate leptin production in the fundic epithelium using reverse transcription polymerase chain reaction (RT-PCR) of RNA. Leptin protein was detected by immunoblot analysis and localized by immunohistochemistry and ultrastructural immunocytochemistry (immunogold method). RESULTS: Human gastric epithelium expresses leptin mRNA and leptin protein. The cells in the lower half of the stomach glands were immunoreactive for leptin. Ultrastructural immunocytochemistry showed leptin immunoreactivity in the pepsinogen granules of chief cells, but the granules of a specific endocrine cell type in the basal portion of the glands were also positive. CONCLUSIONS: Our results suggest that gastric leptin could function in the short-term system to control feeding behaviour and is probably secreted in the stomach lumen by chief cells and into the stomach circulation by a special type of endocrine cell.

Adult↗
PubMed2000

Leptin modulates extracellular matrix molecules and metalloproteinases: possible implications for trophoblast invasion.

Leptin is a circulating hormone which plays an important role in the regulation of energy balance, haemopoiesis and reproduction. Leptin and its receptor (leptin-R) are localized in human placental tissue but their function is not known. In this study we have investigated the expression of leptin and leptin-R in the human placenta with particular attention to extravillous cytotrophoblastic cell islands and cell columns which play a pivotal role in trophoblast invasion and placental growth. We demonstrate that leptin-R immunoreactivity shows a strong expression in the distal extravillous cytotrophoblastic cells of cell columns invading the basal plate, whereas leptin expression is homogeneously expressed in all the cellular components of cell columns. Since the invasive ability of the distally located extravillous cytotrophoblast of cell columns is known to be regulated by a variety of proteases and some extracellular matrix molecules, we tested the influence of leptin on the in-vitro production of matrix metalloproteinase (MMP)-2, MMP-9 and fetal fibronectin (fFN) by cytotrophoblastic cells. We demonstrate that leptin increases, in a dose-dependent manner, the secretion of immunoreactive MMP-2 and fFN and enhances the activity of MMP-9 in cultured cytotrophoblastic cells. Our results suggest that leptin and leptin-R could have a role in the invasive processes of the extravillous cytotrophoblastic cells by modulating the expression of MMPs. In addition, these results provide a foundation for studying pathological conditions characterized by insufficient or excessive trophoblast invasion.

Carrier Proteins↗
PubMed2000

Multilocular fat cells in WAT of CL-316243-treated rats derive directly from white adipocytes.

Multilocular, mitochondria-rich adipocytes appear in white adipose tissue (WAT) of rats treated with the beta3-adrenoceptor agonist, CL-316243 (CL). Objectives were to determine whether these multilocular adipocytes derived from cells that already existed in the WAT or from proliferation of precursor cells and whether new mitochondria contained in them were typical brown adipocyte mitochondria. Use of 5-bromodeoxyuridine to identify cells that had undergone mitosis during the CL treatment showed that most multilocular cells derived from cells already present in the WAT. Morphological techniques showed that at least a subpopulation of unilocular adipocytes underwent conversion to multilocular mitochondria-rich adipocytes. A small proportion of multilocular adipocytes ( approximately 8%) was positive for UCP1 by immunohistochemistry. Biochemical techniques showed that mitochondrial protein recovered from WAT increased 10-fold and protein isolated from brown adipose tissue (BAT) doubled in CL-treated rats. Stained gels showed a different protein composition of new mitochondria isolated from WAT from that of mitochondria isolated from BAT. Western blotting showed new mitochondria in WAT to contain both UCP1, but at a much lower concentration than in BAT mitochondria, and UCP3, at a higher concentration than that in BAT mitochondria. We hypothesize that multilocular adipocytes present at 7 days of CL treatment have two origins. First, most come from convertible unilocular adipocytes that become multilocular and make many mitochondria that contain UCP3. Second, some come from a cell that gives rise to more typical brown adipocytes that express UCP1.

Adipocytes↗
PubMed2000

Opposite effects of feeding a vitamin A-deficient diet and retinoic acid treatment on brown adipose tissue uncoupling protein 1 (UCP1), UCP2 and leptin expression.

The relationship between interscapular brown adipose tissue (IBAT) thermogenic potential and vitamin A status was investigated by studying the effects of feeding a vitamin A-deficient diet and all-trans retinoic acid (tRA) treatment on body weight and IBAT parameters in mice. Feeding a vitamin A-deficient diet tended to trigger opposite effects to those of tRA treatment, namely increased body weight, IBAT weight, adiposity and leptin mRNA expression, and reduced IBAT thermogenic potential in terms of uncoupling protein 1 (UCP1) mRNA and UCP2 mRNA expression. The results emphasize the importance of retinoids as physiological regulators of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1999

Granulocyte-macrophage colony-stimulating factor upregulates reduced 5-lipoxygenase metabolism in peripheral blood monocytes and neutrophils in acquired immunodeficiency syndrome.

Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway, which play a role in host defense, and are synthesized by both monocytes (peripheral blood monocyte [PBM]) and neutrophils (PMN). Because 5-LO metabolism is reduced in alveolar macrophages and PMN from acquired immunodeficiency syndrome (AIDS) subjects, we investigated the synthesis of LT by PBM and PMN from these subjects. There was a reduction (74.2% +/- 8.8% of control) in LT synthesis in PBM from human immunodeficiency virus (HIV)-infected compared with normal subjects. Expression of 5-LO (51.2% +/- 8.8% of control), and 5-LO activating protein (FLAP) (48.5% +/- 8.0% of control) was reduced in parallel. We hypothesized that this reduction in LT synthetic capacity in PBM and PMN was due to reduced cytokine production by CD4 T cells, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). We treated 10 AIDS subjects with GM-CSF for 5 days. PBM 5-LO metabolism ex vivo was selectively increased after GM-CSF therapy and was associated with increased 5-LO and FLAP expression. PMN leukotriene B(4) (LTB(4)) synthesis was also augmented and associated with increased 5-LO, FLAP, and cytosolic phospholipase A(2) expression. In conclusion, as previously demonstrated for PMN, PBM from AIDS subjects also demonstrate reduced 5-LO metabolism. GM-CSF therapy reversed this defect in both PBM and PMN. In view of the role of LT in antimicrobial function, cytokine administration in AIDS may play a role as adjunct therapy for infections.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Mechanisms controlling mitochondrial biogenesis and respiration through the thermogenic coactivator PGC-1.

Mitochondrial number and function are altered in response to external stimuli in eukaryotes. While several transcription/replication factors directly regulate mitochondrial genes, the coordination of these factors into a program responsive to the environment is not understood. We show here that PGC-1, a cold-inducible coactivator of nuclear receptors, stimulates mitochondrial biogenesis and respiration in muscle cells through an induction of uncoupling protein 2 (UCP-2) and through regulation of the nuclear respiratory factors (NRFs). PGC-1 stimulates a powerful induction of NRF-1 and NRF-2 gene expression; in addition, PGC-1 binds to and coactivates the transcriptional function of NRF-1 on the promoter for mitochondrial transcription factor A (mtTFA), a direct regulator of mitochondrial DNA replication/transcription. These data elucidate a pathway that directly links external physiological stimuli to the regulation of mitochondrial biogenesis and function.

3T3 Cells↗
PubMed1999

Role of sympathetic activity in controlling the expression of vascular endothelial growth factor in brown fat cells of lean and genetically obese rats.

The thermogenic activity of brown adipose tissue (BAT) is heavily dependent on high perfusion, through its dense vascular system. Angiogenesis must go hand-in-hand with BAT functions, but little is known about the factors controlling it. In the present study we demonstrate that: (a) vascular endothelial growth factor (VEGF) is synthesised and released in brown adipocytes in culture; (b) VEGF mRNA isoforms and protein appear in dispersed mature brown adipocytes and whole tissue; (c) VEGF expression is increased in BAT from cold-exposed rats, and in cultured brown adipocytes exposed to noradrenaline and the beta3-adrenoceptor agonists; (e) BAT from genetically obese (falfa) rats exhibits reduced expression of VEGF as well as a change in the ratio of mRNA isoforms. It is concluded that sympathetic control of VEGF expression via noradrenaline acting on beta3-adrenoceptors plays a major role in developmental and adaptive angiogenesis, and defects in this contribute to the reduced thermogenic capacity of BAT in genetic obesity.

Adipose Tissue, Brown↗
PubMed1999

Killing of Mycobacterium avium by neutrophils and monocytes from AIDS patients treated with recombinant granulocyte-macrophage colony-stimulating factor.

In this study, 30 AIDS patients without Mycobacterium avium infection were randomized to receive treatment with azithromycin (1200 mg), granulocyte-monocyte colony-stimulating factor (GM-CSF; 250 microg/m2/day for 5 days), or both agents. The M. avium killing capacity of neutrophils and monocytes harvested from each patient before intervention and during (day 4), and after therapy (day 8) was assessed. The mean virus load change in the groups receiving GM-CSF was +0.14 log human immunodeficiency virus RNA. After GM-CSF therapy, neither neutrophils nor monocytes could significantly reduce M. avium growth (P=.96 and.31, respectively). Bone pain, myalgia, presyncope, or fever occurred in 55% of patients receiving GM-CSF. Thus, the GM-CSF regimen used in this study did not affect virus load, frequently caused adverse reactions, and did not improve the M. avium killing capacity of neutrophils and monocytes. Future studies using a different GM-CSF regimen are indicated.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Lack of insulin receptors affects the formation of white adipose tissue in mice. A morphometric and ultrastructural analysis.

Lack of insulin receptors in mice is associated with near-normal intrauterine growth, unlike patients with leprechaunism, in whom growth deficiency is a prominent clinical feature. Genetic crosses of insulin receptor- and insulin-like growth-factor-1 (IGF-1) receptor-deficient mice indicate, however, that insulin receptors play an important role in late gestational growth, and that absence of growth retardation in insulin receptor-deficient (IR-/-) mice may be due to a compensatory increase in IGF-1 receptor levels. In human fetuses, insulin has a paramount role in the generation and maintenance of adipose tissue, as demonstrated by changes associated with genetic and maternally caused fetal hyperinsulinaemia. In the present study, we have investigated whether genetic ablation of insulin receptors affects differentiation and trophism of white adipose tissue, the main target organ for the growth-promoting actions of fetal insulin. Histological, immunohistochemical, and ultrastructural analyses of white dermal adipose tissue were performed in newborn IR-/- mice, as well as normal (IR +/+ ) and heterozygous controls (IR+/-). Stereological measurements revealed a marked decrease of the adipose area in IR-/- mice compared to IR+/+ and IR+/- mice. Fat cell depletion resulted mainly from a reduction of adipocyte volume ( approximately 90 %), with a small decrease of adipocyte number. Electron microscopy analysis detected all stages of differentiation of the adipocyte precursor in IR-/- mice, suggesting that lack of insulin receptors is not associated with selective impairment of the adipocyte differentiation process. These data are consistent with a bi-modal action of fetal insulin receptors, one to mediate embryonic growth in response to IGF-2, and one to mediate adipose cell formation in response to insulin.

Adipose Tissue↗
PubMed1998

TH-, NPY-, SP-, and CGRP-immunoreactive nerves in interscapular brown adipose tissue of adult rats acclimated at different temperatures: an immunohistochemical study.

Interscapular brown adipose tissue (IBAT), a site of nonshivering thermogenesis in mammals, is neurally controlled. The co-existence of sympathetic and peptidergic innervation has been demonstrated in different brown adipose depots. We studied the morphological profile of IBAT innervation and tested by immunohistochemical methods whether cold and warm stimulation are accompanied by modifications in the density of parenchymal noradrenergic nerve fibers. We also studied the immunoreactivity of afferent fibers--which contain calcitonin gene-related peptide (CGRP) and substance P (SP)--in different functional conditions. IBAT was obtained from adult rats (6 weeks old) acclimated at different temperatures (4 degrees, 20 degrees, and 28 degrees C). Tissue activity was evaluated by studying the immunolocalization of uncoupling protein (UCP-1), a specific marker of brown adipose tissue. Noradrenergic and peptidergic innervation were seen to arise from morphologically different nerves. Fibers staining for tyrosine hydroxylase (TH) were thin, unmyelinated hilar nerves, and CGRP- and SP-positive fibers were in thick nerves containing both myelinated and unmyelinated fibers. Under cold stimulation, noradrenergic neurons produce greater amounts of TH, and their axons branch, resulting in increased parenchymal nerve fibers density. Neuropeptide Y (NPY) probably co-localizes with TH in noradrenergic neurons, but only in the perivascular nerve fiber network. The parenchymal distribution of NPY to interlobular arterioles and capillaries suggests that this peptide must have other functions besides that of innervating arteriovenous anastomoses, as hypothesized by other researchers. The different distribution of CGRP and SP suggests the existence of different sensory neuronal populations. The detection of CGRP at the parenchymal level is in line with the hypothesis of a trophic action of this peptide.

Acclimatization↗
PubMed1998

Neutrophils from AIDS patients treated with granulocyte colony-stimulating factor demonstrate enhanced killing of Mycobacterium avium.

Neutrophils isolated from AIDS patients have demonstrated improved growth inhibition of Mycobacterium avium when incubated with exogenous granulocyte colony-stimulating factor (G-CSF). In this clinical study, 30 AIDS patients without M. avium infection were randomized to receive 5 days of treatment with rifabutin, G-CSF, or both agents. The M. avium killing capacity of neutrophils harvested from each patient before intervention, during (day 4), and after therapy (day 7) was assessed. The mean change in human immunodeficiency virus load in the group receiving G-CSF alone was -0.07 log of viral RNA. There was a 90% reduction in M. avium growth after therapy for patients treated with G-CSF alone (P=.01), 59% for patients treated with both agents (P=.06), and 11% for patients treated with rifabutin alone (P=.84). Thus, neutrophils isolated from AIDS patients treated with G-CSF demonstrated a significant enhancement of killing of M. avium; there was no notable effect on virus load.

AIDS-Related Opportunistic Infections↗
PubMed1998

Ultrastructural immunolocalization of leptin receptor in mouse brain.

Antibodies directed to amino acids 877-894 (M-18) and 32-51 (K-20) were used to localize leptin receptor by immunocytochemistry in mouse brain. Both antibodies stained several hypothalamic nuclei (paraventricular nucleus, supraoptic nucleus, supraoptic retrochiasmatic nucleus, suprachiasmatic nucleus, preoptic area, ventromedial nucleus, dorsomedial nucleus, lateral hypothalamus, arcuate nucleus, ventral and dorsal premammillary nuclei), the thalamic and amygdaloid nuclei, neurons of the neocortex and archicortex and the epithelial cells of the choroid plexus. While M-18 staining was concentrated in the Golgi area, with K-20 it was dispersed in the cytoplasm. Glial cells were stained only by K-20. These results suggest that the trans-membrane forms of the receptor are concentrated at the membrane level of the Golgi complex of neurons and in epithelial cells of the choroid plexus while the soluble form is dispersed in their cytoplasm. Glial cells express only the soluble form.

Animals↗
PubMed1998

Leptin and UCP1 genes are reciprocally regulated in brown adipose tissue.

In a previous work we showed that only unilocular brown adipocytes express leptin. In order to investigate the relationship between leptin gene expression, brown adipocyte activity (UCP1) and morphology, we studied brown adipose tissues of mice (C57BL, female, 7 weeks old) acclimated at different temperatures (19 degrees C and 28 degrees C). Northern blot analysis revealed higher leptin and lower UCP1 mRNA levels in mice exposed to 28 degrees C than in the group acclimated at 19 degrees C. Also protein expression (immunohistochemistry) differed in the two groups: at 28 degrees C brown adipocytes were positive for leptin and only weakly positive for UCP1, while at 19 degrees C they were leptin-negative and UCP1-positive. In the former group the morphology was mainly unilocular. Our data suggest that in brown adipocytes of warm-acclimated mice leptin expression is closely related to their hypoactive functional stage, as evidenced by their low level of UCP1 synthesis and the morphological rearrangement of the lipid content (unilocularity).

Adipose Tissue, Brown↗
PubMed1998

Sensory nerves affect the recruitment and differentiation of rat periovarian brown adipocytes during cold acclimation.

Rat periovarian adipose tissue contains a low number of uncoupling protein-expressing brown adipocytes scattered into lobules of white fat. Their increase following cold acclimation is matched by a major increase in noradrenergic and neuropeptide Y-, substance P- and calcitonin gene-related peptide-containing nerves. To ascertain whether periovarian fat is provided with sensory nerves, and whether any relationship exists between such nerves (in particular the calcitonin gene-related peptide-containing fibers found in cold-acclimated rats in close association with brown adipocytes) and brown fat recruitment, the effects of capsaicin desensitization on neuropeptide-containing nerves and brown adipocyte density were studied in the periovarian tissue of rats kept at 20 degrees C and on a group acclimated to 4 degrees C for 14 days. In both groups, systemic capsaicin administration considerably reduced the expression of substance P and calcitonin gene-related peptide in vascular-nerve bundles and parenchyma. In cold-acclimated rats, the increase in brown adipocyte density was significantly checked by capsaicin administration (21.11 versus 7.96 brown adipocytes/mm2, P<0.05). Finally, ultrastructural investigation showed the occurrence of brown adipocyte precursors filled with aggregates of glycogen and poorly differentiated multilocular adipocytes in capsaicin-treated cold-acclimated rats. These data suggest that periovarian adipose tissue is indeed provided with sensory neuropeptide-containing nerves and that they play a role in the recruitment and differentiation of brown adipocytes.

Acclimatization↗