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Co-Expression of Leptin and Oestrogen Receptors in the Preoptic-Hypothalamic Area

BIANCO-BORGES, B. Del; CABRAL, F. J.; FRANCI, C. R.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.15%
The interaction between the reproductive axis and energy balance suggests that leptin acts as a possible mediator. This hormone acts in the regulation of metabolism, feeding behaviour and reproduction. Animals homozygous for the gene `ob` (ob/ob) are obese and infertile, and these effects are reversed after systemic administration of leptin. Thus, the present study aimed to determine: (i) whether cells that express leptin also express oestrogen receptors of type-alpha (ER-alpha) or -beta (ER-beta) in the medial preoptic area (MPOA) and in the arcuate (ARC), dorsomedial (DMH) and ventromedial hypothalamic nucleus and (ii) whether there is change in the gene and protein expression of leptin in these brain areas in ovariectomised (OVX) animals when oestrogen-primed. Wistar female rats with normal oestrous cycles or ovariectomised oestrogen-primed or vehicle (oil)-primed were utilised. To determine whether there was a co-expression, immunofluorescence was utilised for double staining. Confocal microscopy was used to confirm the co-expression. The technique of real-time polymerase chain reaction and western blotting were employed to analyse gene and protein expression, respectively. The results obtained showed co-expression of leptin and ER-alpha in the MPOA and in the DMH...

Leptin and the Immune Response An Active Player or an Innocent Bystander?

GOLDBERG, Anna Carla; GOLDBERG-ELIASCHEWITZ, Freddy; SOGAYAR, Mari Cleide; GENRE, Julieta; RIZZO, Luiz Vicente
Fonte: BLACKWELL PUBLISHING Publicador: BLACKWELL PUBLISHING
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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Leptin is involved in the control of energy storage by the body. Low serum leptin levels, as seen in starvation, are associated with impaired inflammatory T cell responses that can be reversed by exogenous leptin. Common variable immunodeficiency (CVID) is characterized by hypogammaglobulinemia and recurrent infections. Several defects in T cell function have also been described, and allergy, autoimmune disease, and lymphomas or other malignancies can be present. Previous studies in Brazilian CVID patients have shown that, in contrast with mononuclear cells from healthy controls, CVID cells cultured with phytohemagglutinin and added leptin increased the proliferative response and decreased activation-induced apoptosis. Interleukin (IL)-2 and especially IL-4 production also increased significantly, although the effects of exposure to leptin were not observed uniformly in CVID patients. The majority, however, responded in some degree, and some exhibited completely restored values of the four parameters. These remarkable results indicate leptin could be used to improve immune function in these patients. On the other hand, we found no specific correlation between serum leptin levels and the number of infectious events over a 24-month period...

Central leptin replacement enhances chemorespiratory responses in leptin-deficient mice independent of changes in body weight

Bassi, Mirian; Giusti, Humberto; Leite, Cristiane Mota; Anselmo-Franci, Janete A.; do Carmo, Jussara M.; da Silva, Alexandre A.; Hall, John E.; Colombari, Eduardo; Glass, Mogens L.
Fonte: SPRINGER; NEW YORK Publicador: SPRINGER; NEW YORK
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.17%
Previous studies showed that leptin-deficient (ob/ob) mice develop obesity and impaired ventilatory responses to CO2 . In this study, we examined if leptin replacement improves chemorespiratory responses to hypercapnia (7 % CO2) in ob/ob mice and if these effects were due to changes in body weight or to the direct effects of leptin in the central nervous system (CNS). was measured via plethysmography in obese leptin-deficient- (ob/ob) and wild-type- (WT) mice before and after leptin (10 mu g/2 mu l day) or vehicle (phosphate buffer solution) were microinjected into the fourth ventricle for four consecutive days. Although baseline was similar between groups, obese ob/ob mice exhibited attenuated compared to WT mice (134 +/- 9 versus 196 +/- 10 ml min(-1)). Fourth ventricle leptin treatment in obese ob/ob mice significantly improved (from 131 +/- 15 to 197 +/- 10 ml min(-1)) by increasing tidal volume (from 0.38 +/- 0.03 to 0.55 +/- 0.02 ml, vehicle and leptin, respectively). Subcutaneous leptin administration at the same dose administered centrally did not change in ob/ob mice. Central leptin treatment in WT had no effect on . Since the fourth ventricle leptin treatment decreased body weight in ob/ob mice, we also examined in lean pair-weighted ob/ob mice and found it to be impaired compared to WT mice. Thus...

Central leptin replacement enhances chemorespiratory responses in leptin-deficient mice independent of changes in body weight

Bassi, Mirian; Giusti, Humberto; Leite, Cristiane Mota; Anselmo-Franci, Janete A.; do Carmo, Jussara M.; da Silva, Alexandre A.; Hall, John E.; Colombari, Eduardo; Glass, Mogens L.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 145-153
Português
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37.16%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 04/01934-8; Previous studies showed that leptin-deficient (ob/ob) mice develop obesity and impaired ventilatory responses to CO2 . In this study, we examined if leptin replacement improves chemorespiratory responses to hypercapnia (7 % CO2) in ob/ob mice and if these effects were due to changes in body weight or to the direct effects of leptin in the central nervous system (CNS). was measured via plethysmography in obese leptin-deficient- (ob/ob) and wild-type- (WT) mice before and after leptin (10 mu g/2 mu l day) or vehicle (phosphate buffer solution) were microinjected into the fourth ventricle for four consecutive days. Although baseline was similar between groups, obese ob/ob mice exhibited attenuated compared to WT mice (134 +/- 9 versus 196 +/- 10 ml min(-1)). Fourth ventricle leptin treatment in obese ob/ob mice significantly improved (from 131 +/- 15 to 197 +/- 10 ml min(-1)) by increasing tidal volume (from 0.38 +/- 0.03 to 0.55 +/- 0.02 ml, vehicle and leptin, respectively). Subcutaneous leptin administration at the same dose administered centrally did not change in ob/ob mice. Central leptin treatment in WT had no effect on . Since the fourth ventricle leptin treatment decreased body weight in ob/ob mice...

Influence of dexamethasone and weight loss on the regulation of serum leptin levels in obese individuals

Lerario,D.D.G.; Ferreira,S.R.G.; Miranda,W.L.; Chacra,A.R.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2001 Português
Relevância na Pesquisa
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The adipocyte hormone leptin is thought to serve as a signal to the central nervous system reflecting the status of fat stores. Serum leptin levels and adipocyte leptin messenger RNA levels are clearly increased in obesity. Nevertheless, the factors regulating leptin production are not fully understood. The aim of this study was to determine the effects of in vivo administration of the synthetic glucocorticoid dexamethasone and weight loss on serum leptin levels in two independent protocols. Twenty-five obese subjects were studied (18 women and 7 men, mean age 26.6 ± 6 years, BMI 31.1 ± 2.5 kg/m², %fat 40.3 ± 8.3) and compared at baseline to 22 healthy individuals. Serum levels of leptin, insulin, proinsulin and glucose were assessed at baseline and after ingestion of dexamethasone, 4 mg per day (2 mg, twice daily) for two consecutive days. To study the effects of weight loss on serum leptin, 17 of the obese subjects were submitted to a low-calorie dietary intervention trial for 8 weeks and again blood samples were collected. Serum leptin levels were significantly higher in the obese group compared to the control group and a high positive correlation between leptinemia and the magnitude of fat mass was found (r = 0.88, P<0.0001). After dexamethasone...

Increasing leptin level in abstaining alcohol-dependent women

Toffolo, Mayla Cardoso Fernandes; Marli?re, Cl?udia Aparecida; Freitas, S?lvia Nascimento de; Nemer, Aline Silva de Aguiar
Fonte: Universidade Federal de Ouro Preto Publicador: Universidade Federal de Ouro Preto
Tipo: Artigo publicado em periodico
Português
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Introduction : Leptin, hormone secreted by the fat tissue, changes the signaling of dopamine in the nucleus accumbens, which directly affects the sensitivity of reward and modulation of bstinence. Aims:To evaluate the level of serum leptin and its rela-tion to nutritional status among alcoholic abstainers and non-abstinent. Methods: Patients of both sexes, over 18 years old and who used alcohol as their primary drug were included in the study. Abstaining patients were separated according to the time without the use of the drug as A2 (1-3 month-abstainers) and A3 (4 month and over-abstainers). Waist circumference (WC), body fat percentage (%BF) and weight and height were measured to calculate Body Mass Index (BMI). Blood samples were collected for leptin measurement. Results:Mean levels of leptin, leptin/BMI, leptin/%BF were higher in all women categories. Abstaining women (A2) also showed higher leptin, leptin/BMI and leptin/ %BF than non-abstinent (p = 0.039; p = 0.023; p = 0.023). Statistical differences were also shown among abstaining women A2 and A3 as well a significant positive associa-tion between leptin levels and BMI and leptin and WC in active female drinkers (leptin ? BMI: r = 0.91; p < 0.01; leptin ? WC: r = 0.87; p = 0.001). However...

Leptina em f??meas su??nas: rela????o com status reprodutivo e causas de descarte; Leptina em f??meas su??nas: rela????o com status reprodutivo e causas de descarte; Leptin in swine females: relationship between reproductive status and culling causes; Leptin in swine females: relationship between reproductive status and culling causes

MOREIRA, Fabiana
Fonte: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR Publicador: Universidade Federal de Pelotas; Veterin??ria; Programa de P??s-Gradua????o em Veterin??ria; UFPel; BR
Tipo: Tese de Doutorado Formato: application/pdf
Português
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Leptin is a multifunctional peptidic hormone, primarily produced by the adipose tissue, which has receptors (Ob-Rs) in reproductive organs, hypothalamus and hypophysis, acting in the appetite regulation and energetic expenditure, potentially influencing the expression of the reproductive function, at puberty and lactation. Reproductive failure are the main causes for female culling, representing 30% to 40%,of the total female culling. Thus, post-mortem evaluation of the genital organs at slaughter may have an important diagnostic value, helping on the identification of the stage of female`s estrous cycle and aiding the interpretation of reproductive abnormalities. Its long form receptor (OBR-b) performs signal transduction in several cell types via mitogen- activated protein kinases (MAPK) cascade, such as ERK 1/2 and p38. The first stage of this thesis is aimed to evaluate the presence of leptin and MPAK in oocites of pubertal sows and prepubertal gilts. Ovaries from 10 pubertal sows and 10 prepubertal gilts were collected at a slaughterhouse. Slides were analyzed for the presence of oocites included in primordial/primary (OIPF), secondary (OISF) and tertiary follicles (OITF). Immunohistochemistry (IHC) was performed with polyclonal antibodies anti-leptin and anti-phospho-MAPK (ERK 1/2 and p38). The second stage involved 28 pubertal sows and the analyses were performed in hypothalamic neurons...

Effects of leptin administration and feed restriction on thecal leucocytes in the preovulatory rat ovary and the effects of leptin on meiotic maturation, granulosa cell proliferation, steroid hormone and PGE2 release in cultured rat ovarian follicles

Duggal, P.; Ryan, N.; Van Der Hoek, K.; Ritter, L.; Armstrong, D.; Magoffin, D.; Norman, R.
Fonte: Journals of Reproduction Fertility Ltd Publicador: Journals of Reproduction Fertility Ltd
Tipo: Artigo de Revista Científica
Publicado em //2002 Português
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Leptin is expressed by adipocytes and is thought to play a role in regulating food intake and in reproduction. It has been demonstrated that acute leptin administration to immature gonadotrophin-primed rats in vivo inhibits ovulation and causes a decline in food intake. However, feed restriction alone does not inhibit ovulation. Two experiments were designed to investigate the mechanism of leptin-induced inhibition of ovulation. In the first experiment, which was prompted by the importance of ovarian leucocytes in ovulation, the role of leucocytes in leptin-induced inhibition of ovulation was investigated. The second experiment investigated whether high leptin concentrations could inhibit other factors important to ovulation, such as meiotic competence of oocytes, granulosa cell proliferation, steroid or PGE(2) release, and interleukin 1beta production, in vitro. In the first experiment, the populations of neutrophils and monocytes-macrophages in the preovulatory follicles of gonadotrophin-primed, leptin-treated and -untreated rats were examined. A decrease in food intake, as a result of either leptin treatment or feed restriction, specifically reduced the numbers of neutrophils and monocytes-macrophages infiltrating the theca interna of preovulatory follicles without affecting the numbers found in the stroma. The findings show that reduced infiltration of thecal neutrophils and macrophages into preovulatory follicles is a response to reduced food intake. Furthermore...

Expression of the long (OB-RB) and short (OB-RA) forms of the leptin receptor throughout the oestrous cycle in the mature rat ovary

Duggal, P.; Weitsman, S.; Magoffin, D.; Norman, R.
Fonte: Journals of Reproduction Fertility Ltd Publicador: Journals of Reproduction Fertility Ltd
Tipo: Artigo de Revista Científica
Publicado em //2002 Português
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Leptin is secreted by adipocytes and exerts its effects by interacting with the long form of the leptin receptor, OB-RB. The leptin protein and leptin receptors have been localized in the ovary, and acute leptin treatment directly inhibits ovulation in the rat ovary. It was hypothesized that expression of the leptin receptor gene varies throughout the oestrous cycle to modulate the sensitivity of the ovary to leptin. In this study, expression of genes for the long and short isoforms of the leptin receptor in the adult ovary was investigated at different stages of the rat oestrous cycle. Vaginal cytology was used to determine the stage of the oestrous cycle. Ovaries were collected and RNA was extracted for real-time RT-PCR analysis of leptin receptor gene expression. OB-RB gene expression was low in pro-oestrus (3.13 +/- 0.18 fg RNA per microg total DNA) and dioestrus II (2.52 +/- 0.19 fg RNA per microg total DNA) of the oestrous cycle, whereas expression was high in oestrus (5.9 +/- 0.27 fg RNA per microg total DNA) and dioestrus I (4.6 +/- 0.24 fg RNA per microg total DNA) (P < 0.001). Expression of the gene for the short form of the leptin receptor (OB-RA) was at a maximum in dioestrus I (65.5 +/- 0.8 fg RNA per ng total DNA), high in oestrus (39.0 +/- 0.8 fg RNA per ng total DNA) and low at pro-oestrus (5.0 +/- 0.2 fg RNA per ng total DNA) and dioestrus II (1.1 +/- 0.09 fg RNA per ng total DNA) (P < 0.001). Plasma oestradiol concentrations (pg ml-1) were highest at pro-oestrus (19.38 +/- 1.3)...

Body composition and age in African American and Caucasian women: relationship to plasma leptin levels and gonadal steroids

Perry, H.; Morley, J.; Horowitz, M.; Kaiser, F.; Miller, D.; Wittert, G.
Fonte: W B SAUNDERS CO Publicador: W B SAUNDERS CO
Tipo: Artigo de Revista Científica
Publicado em //1997 Português
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Leptin is a recently isolated peptide hormone released from adipocytes that has been postulated to play a role in appetite regulation and energy metabolism. Aging affects both food intake and body composition. Body composition is also affected by ethnicity. We have evaluated the relationships between serum leptin levels, age, body composition (by dual-energy x-ray absorptiometry), and hormonal parameters in a cross-sectional study of 94 women, 53 African-American (AAF) and 41 Caucasian (CF). Our hypotheses were as follows: (1) changes in body composition would be related to age in a sinusoidal pattern, (2) changes in serum leptin would parallel changes in body fat, (3) serum leptin levels would be influenced by body fat distribution, and (4) serum leptin would be related to serum concentrations of sex hormones. Serum leptin paralleled changes in body fat and body mass index (BMI) with age. In the entire group, serum leptin correlated closely with measures of body fat, including BMI and total fat mass, and there was no difference in leptin levels between the two ethnic groups. In simple regression analysis, serum leptin was related to both serum estradiol and testosterone. The relationship between serum leptin and trunk fat was linear in both groups...

Placental restriction increases adipose leptin gene expression and plasma leptin and alters their relationship to feeding activity in the young lamb

De Blasio, M.; Blache, D.; Gatford, K.; Robinson, J.; Owens, J.
Fonte: Int Pediatric Research Foundation Inc Publicador: Int Pediatric Research Foundation Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
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Low birth weight and catch-up growth predict increased adiposity in children and adults. This may be due in part to leptin resistance, as adults who were born small exhibit increased plasma leptin concentration relative to adiposity. Placental restriction (PR), a major cause of intrauterine growth restriction, reduces size at birth and increases feeding activity and adiposity by 6 wk in sheep. We hypothesized that PR would increase plasma leptin concentration and alter its relationship with feeding activity and adiposity in young lambs. Body size, plasma leptin, feeding activity, adiposity, leptin, and leptin receptor gene expression in adipose tissue were measured (12 control, 12 PR). PR reduced size at birth and increased adiposity. Plasma leptin concentration decreased with age, but to a lesser extent after PR and correlated positively with adiposity similarly in control and PR. PR increased plasma leptin concentration and perirenal adipose tissue leptin expression. Feeding activity correlated negatively with plasma leptin concentration in controls, but positively after PR. PR increases adipose tissue leptin expression and plasma leptin concentration, however, this increased abundance of peripheral leptin does not inhibit feeding activity (suckling event frequency)...

Veränderung der Serumkonzentrationen von Leptin während und nach einer kurzandauernden körperlichen Maximalbelastung bei Sportlerinnen und Nichtsportlerinnen; Changes in serum leptin concentration amongst female athletes and non-athletes during and after a short period of maximum physical exercise

Phillips, Oliver
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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Einleitung: Mit der Entdeckung des "obese"-Gens (ob-Gen) und seines Genproduktes Leptin wurde ein "Sättigungsfaktor" identifiziert, der eine zentrale Rolle bei der Regulierung des Energiehaushaltes spielt, indem er das Gehirn über die peripheren Fettspeicher informiert und die weitere Nahrungsaufnahme reguliert. Dabei unterliegt die Leptinfreisetzung zahlreichen Einflüssen. Neben der Wirkung von Hormonen sowie der Nahrungsaufnahme ist die körperliche Belastung ein weiterer bekannter modulierender Faktor der Leptinsekretion. Da es als Folge einer intensiven körperlichen Belastung zu einer kurzfristigen Unterdrückung des Hungergefühls kommt, haben wir in dieser Studie untersucht, ob eine kurzandauernde körperliche Maximalbelastung von einer Erhöhung der Leptinkonzentration im Blut begleitet ist. Material und Methoden: Die Studie wurde an 55 weiblichen Probanden im Alter zwischen 18 und 41 Jahren durchgeführt. Vor Beginn der Belastung wurde der Gesamtkörperfettgehalt nach der Methode der Hautfaltendicke-Messung nach Buskirk bestimmt sowie der body mass index (BMI) errechnet. Die körperliche Belastung bestand aus einer standardisierten Laufbandbelastung, wobei vor Beginn, bei Erreichen der subjektiven körperlichen Erschöpfung und eine Stunde nach Beendigung der Belastung die Leptinhormonspiegel im Serum bestimmt wurden. Zudem erfolgte die Aufnahme der Laktatkonzentrationskurve während der Belastung zur Bestimmung der individuellen anaeroben Schwelle (IAS) sowie die Abnahme der Hämatokritwerte vor und nach der Belastung...

Gastric vagal afferent modulation by leptin is influenced by food intake status

Kentish, S.; O'Donnell, T.; Isaacs, N.; Young, R.; Li, H.; Harrington, A.; Brierley, S.; Wittert, G.; Blackshaw, L.; Page, A.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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Energy intake is strongly influenced by vagal afferent signals from the stomach, and is also modulated by leptin. Leptin may be secreted from gastric epithelial cells, so we aimed to determine the direct effect of leptin on gastric vagal afferents under different feeding conditions. Female C57BL/6 mice were fed standard laboratory diet, high-fat diet or were food restricted. The expression of leptin receptor (Lep-R) and its signal transduction molecules in vagal afferents was determined by retrograde tracing and reverse-transcription polymerase chain reaction, and the relationship between leptin-immunopositive cells and gastric vagal afferent endings determined by anterograde tracing and leptin immunohistochemistry. An in vitro preparation was used to determine the functional effects of leptin on gastric vagal afferents and the second messenger pathways involved. Leptin potentiated vagal mucosal afferent responses to tactile stimuli, and epithelial cells expressing leptin were found close to vagal mucosal endings. After fasting or diet-induced obesity, potentiation of mucosal afferents by leptin was lost and Lep-R expression reduced in the cell bodies of gastric mucosal afferents. These effects in diet-induced obese mice were accompanied by a reduction in anatomical vagal innervation of the gastric mucosa. In striking contrast...

THE SUBFORNICAL ORGAN AND AREA POSTREMA MEDIATE THE CENTRAL EFFECTS OF CIRCULATING LEPTIN

Smith, Pauline
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.16%
Leptin is an adipokine that acts centrally to regulate feeding behaviour, energy expenditure and autonomic function via activation of its receptor (ObRb) in nuclei in the central nervous system (CNS). This thesis investigates the involvement of two sensory circumventricular organs (CVOs), the subfornical organ (SFO) and area postrema (AP), in mediating the central effects of leptin using a variety of experimental approaches. We first show that acute electrical stimulation of the SFO elicits feeding in satiated rats, supporting a role for this specialized CNS structure in the control of food intake. We then demonstrate, using RT-PCR, the presence of ObRb mRNA in SFO and, using whole cell current clamp electrophysiology, reveal that leptin influences the excitability of individual SFO neurons, causing both excitatory and inhibitory responses. Furthermore, we find that leptin activates the same SFO neurons activated by amylin. Given the association between obesity and hypertension and the well-established role of the SFO in cardiovascular regulation, we show that leptin microinjection into the SFO decreases blood pressure in young rats, effects that are abolished in leptin-resistant, diet induced obese rats, suggesting that leptin-insensitivity in the SFO of obese...

Sinalização de leptina e regulação da pressão arterial em ratos obesos; Leptin signalling and blood pressure regulation in obese rats

Carla Grazielle Bueno Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/04/2014 Português
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A leptina é um polipeptídeo derivado do tecido adiposo e tem como principal função informar o estado nutricional do indivíduo a centros hipotalâmicos, que por sua vez regulam a ingestão e o gasto energético. Tais ações são orquestradas pela fosforilação do receptor ObRb em tyr 985 e 1138, sendo esta última relacionada ao metabolismo e à via da Stat3. Recentemente foi demonstrado que os altos níveis séricos de leptina, presentes na obesidade induzida por dieta hiperlipídica (DH), correlacionam-se fortemente com hipertensão arterial. Por outro lado, indivíduos obesos possuem resistência às ações metabólicas da leptina (saciedade e termogênese). Para investigar as vias moleculares hipotalâmicas que caracterizam a atividade seletiva da leptina sobre o efeito de aumento da pressão arterial, ratos Sprague Dawley adultos foram alimentados com ração padrão (RP) ou DH por três meses e submetidos à injeção crônica intracerebroventricular de leptina (2?g/dia) ou salina (2?l) por 10 dias. Pressão Arterial Sistêmica (PAS) , ingestão e gasto energético foram avaliados antes e depois do tratamento. O grupo RP+leptina teve redução de ingestão de 109,48±8,48 para 57,3±7,04 kcal/dia, aumento do gasto energético de 85...

Leptin in humans: lessons from translational research1234

Blüher, Susann; Mantzoros, Christos S
Fonte: American Society for Nutrition Publicador: American Society for Nutrition
Tipo: Artigo de Revista Científica
Português
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Leptin has emerged over the past decade as a key hormone in not only the regulation of food intake and energy expenditure but also in the regulation of neuroendocrine and immune function as well as the modulation of glucose and fat metabolism as shown by numerous observational and interventional studies in humans with (complete) congenital or relative leptin deficiency. These results have led to proof-of-concept studies that have investigated the effect of leptin administration in subjects with complete (congenital) leptin deficiency caused by mutations in the leptin gene as well as in humans with relative leptin deficiency, including states of lipoatrophy or negative energy balance and neuroendocrine dysfunction, as for instance seen with hypothalamic amenorrhea in states of exercise-induced weight loss. In those conditions, most neuroendocrine, metabolic, or immune disturbances can be restored by leptin administration. Leptin replacement therapy is thus a promising approach in several disease states, including congenital complete leptin deficiency, states of energy deprivation, including anorexia nervosa or milder forms of hypothalamic amenorrhea, as well as syndromes of insulin resistance seen in conditions such as congenital or acquired lipodystrophy. In contrast...

Regulación de la expresión de leptina y su acción en células placentarias; Regulation of leptin expression and its action in placental cells

Maymó, Julieta L.
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2010 Português
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37.21%
Conocida inicialmente como la “hormona de la gordura” por su asociación con la saciedad y el balance energético del organismo, la leptina, una proteína de 16 kDa, también es reconocida actualmente por el papel fundamental que posee en la biología reproductiva. La expresión de la leptina y de sus receptores, descubierta originalmente en tejido adiposo, se ha evidenciado en otros tejidos tales como placenta, en donde la síntesis de leptina es altamente regulada. Los niveles de leptina aumentan tempranamente durante la gestación, aún antes de que se incremente el tejido adiposo, sugiriendo que existen otros factores que modulan su producción. Sin embargo, los mecanismos de acción de la leptina sobre la implantación y el crecimiento embrionario son aún desconocidos. El presente trabajo ha sido desarrollado con el objeto de estudiar las vías de transducción de señales activadas por leptina en placenta y para elucidar los mecanismos que median el efecto antiapoptótico de leptina. Más aún, dado que la leptina sería importante en la supervivencia celular y en el mantenimiento de la placenta, analizamos la regulación de la expresión de leptina en placenta por la hormona gonadotrofina coriónica y por AMPc. Se utilizaron como modelo las líneas celulares trofoblásticas JEG-3 y BeWo...

Leptin Regulation of Thymopoiesis During Endotoxin-Induced Acute Thymic Atrophy

Gruver, Amanda Louise
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 4326221 bytes; application/pdf
Publicado em //2009 Português
Relevância na Pesquisa
37.18%

Thymus atrophy is highly inducible by stress and prolonged thymus atrophy can contribute to T cell deficiency or inhibit immune recovery after acute peripheral T cell depletion. Little is known regarding the mechanisms driving thymic involution or thymic reconstitution after acute stress. Leptin deficiency in mice results in chronic thymic atrophy, suppressed cell-mediated immunity, and decreased numbers of total lymphocytes, suggesting a role for leptin in regulating thymopoiesis and overall immune homeostasis. Exogenous leptin administration during stress has been shown to protect against thymic damage, yet the mechanisms governing these thymostimulatory effects are currently undefined. Studies herein define the impact of endotoxin-induced thymic damage in the stromal and lymphoid compartment of the thymus and systemic glucocorticoid and cytokine responses in the animal. We report here the novel finding that leptin receptor expression is restricted to medullary thymic epithelial cells in the normal thymus. Using a model of endotoxin-induced acute thymic involution and recovery, we have demonstrated a role for the metabolic hormone leptin in protection of medullary thymic epithelial cells from acute endotoxin-induced damage. We also demonstrated that systemic leptin treatment decreased endotoxin-induced apoptosis of double positive thymocytes and promoted proliferation of double negative thymocytes in vivo through a leptin receptor isoform b-specific mechanism. Leptin treatment increased thymic expression of IL-7...

Interaction between leptin and leptin receptor in gastric carcinoma: Gene ontology analysis

Wiwanitkit,V.
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/04/2007 Português
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Gastric carcinoma is a rare but important malignancy. The link between leptin, a cytokine that is elevated in obese individuals, and cancer development has been proposed. It is noted that leptin and its receptor may play a positive role in the progression in gastric cancer. However, the exact mechanism resulting form the interaction between leptin and leptin receptor has never been clarified. Here, the author used a new gene ontology technology to predict the molecular function and biological process due to the interaction between leptin and leptin receptor. Comparing to leptin and leptin receptor, the leptin-leptin receptor poses the same function and biological process as leptin receptor. This can confirm that leptin receptor has a significant suppressive effect on the expression of leptin. Loss of hormone activity and disturbance of normal cell signaling pathway of leptin can be seen. Blocking of receptor might be rational therapeutic strategy.

Increasing leptin level in abstaining alcohol-dependent women

Cardoso Fernandes Toffolo,M.; Aparecida Marliére,C.; Nascimento de Freitas,S.; Silva de Aguiar Nemer,A.
Fonte: Nutrición Hospitalaria Publicador: Nutrición Hospitalaria
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/06/2012 Português
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Introduction: Leptin, hormone secreted by the fat tissue, changes the signaling of dopamine in the nucleus accumbens, which directly affects the sensitivity of reward and modulation of abstinence. Aims: To evaluate the level of serum leptin and its relation to nutritional status among alcoholic abstainers and non-abstinent. Methods: Patients of both sexes, over 18 years old and who used alcohol as their primary drug were included in the study. Abstaining patients were separated according to the time without the use of the drug as A2 (1-3 month-abstainers) and A3 (4 month and over-abstainers). Waist circumference (WC), body fat percentage (%BF) and weight and height were measured to calculate Body Mass Index (BMI). Blood samples were collected for leptin measurement. Results: Mean levels of leptin, leptin/BMI, leptin/%BF were higher in all women categories. Abstaining women (A2) also showed higher leptin, leptin/BMI and leptin/ %BF than non-abstinent (p = 0.039; p = 0.023; p = 0.023). Statistical differences were also shown among abstaining women A2 and A3 as well a significant positive association between leptin levels and BMI and leptin and WC in active female drinkers (leptin x BMI: r = 0.91; p < 0.01; leptin x WC: r = 0.87; p = 0.001). However...