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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the last several decades, the concept of "endocrinology" has been greatly changed. One major change was due to the discovery of peptide hormones secreted by the organs that were not "classical" endocrine organs. For example, corticotropin-releasing hormone and many neuropeptides are secreted by the neurons, atrial natriuretic peptide by the heart, endothelin-1 by the vascular endothelial cells, and leptin by the adipose tissues. Now, the brain, heart, vascular tissue and adipose tissue can be considered to be endocrine organs. Cardiovascular diseases and obesity are therefore important targets of the endocrine research. Adrenomedullin is a potent vasodilator peptide consisting of 52 amino acids. It was originally discovered from a human pheochromocytoma, and belongs to the calcitonin gene-related peptide (CGRP) family. Adrenomedullin is produced and secreted by various types of cells, for example, vascular endothelial and smooth muscle cells, cardiomyocytes, fibroblasts, macrophages, neurons, glial cells, and retinal pigment epithelial cells. Such ubiquitous expression has not been observed in other neuropeptides, including neuropeptide Y and CGRP. Expression of adrenomedullin is induced by hypoxia and proinflammatory cytokines. In addition to vasodilator actions, this peptide has central inhibitory actions on water drinking and salt appetite, effects on the secretion of some hormones and cytokines, inotropic actions and effects on cell growth and apoptosis. Adrenomedullin is produced by various non-endocrine tumors, as well as endocrine tumors, and acts as a growth stimulatory factor for the tumor cells. Adrenomedullin seems to be involved in the pathophysiology of many diseases, including ischemic heart diseases, inflammatory diseases, tumors, and even eye diseases. The adrenomedullin research implies that "the neuroendocrine system" exists in much broader types of cells than previously thought, and that the endocrine research is able to contribute to the understanding of the pathophysiology of many diseases.
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PMID:Adrenomedullin from a pheochromocytoma to the eye: implications of the adrenomedullin research for endocrinology in the 21st century. 1131 31

To compare the anorectic effectiveness of leptin and the amylin analogue salmon calcitonin (sCT), rodents were treated on 1 day with subcutaneous injections. In chow-fed C57Bl/6J mice, leptin and sCT reduced energy intake and acted additively. After C57Bl/6J mice had become leptin-resistant on being fed chocolate as a palatable high-caloric supplement to chow, their sCT-induced decrease in energy intake was more pronounced than in chow-fed mice with differential changes in the intake of chocolate (strong reduction) and chow (slight increase). Dose-response relationships for sCT-induced reductions in energy intake were analysed in chow-fed C57Bl/6J mice and two obese strains, ob/ob mice and melanocortin-4 receptor knockout (MC4-r-KO) mice, as well as in wild-type and fatty (fa/fa) rats. Compared to C57Bl/6J mice, reduction in food intake induced by sCT was attenuated in MC4-r-KO mice, and nearly absent in ob/ob mice, over the dose range investigated. Compared to C57Bl/6J mice, wild-type rats responded more sensitively to sCT and its efficiency was only slightly reduced in fatty (fa/fa) rats. Thus, while genetically induced failures of leptin signalling reduce the action of sCT, it effectively inhibits the intake of a palatable, high fat-high sugar diet even in states of diet-induced obesity with functional leptin resistance.
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PMID:Salmon calcitonin - a potent inhibitor of food intake in states of impaired leptin signalling in laboratory rodents. 1206 61

Blood glucose concentrations are unaffected by exercise despite very high rates of glucose flux. The plasma ionised calcium levels are even more tightly controlled after meals and during lactation. This implies 'integral control'. However, pairs of integral counterregulatory controllers (e.g. insulin and glucagon, or calcitonin and parathyroid hormone) cannot operate on the same controlled variable, unless there is some form of mutual inhibition. Flip-flop functional coupling between pancreatic alpha- and beta-cells via gap junctions may provide such a mechanism. Secretion of a common inhibitory chromogranin by the parathyroids and the thyroidal C-cells provides another. Here we describe how the insulin:glucagon flip-flop controller can be complemented by growth hormone, despite both being integral controllers. Homeostatic conflict is prevented by somatostatin-28 secretion from both the hypothalamus and the pancreatic islets. Our synthesis of the information pertaining to the glucose homeostat that has accumulated in the literature predicts that disruption of the flip-flop mechanism by the accumulation of amyloid in the pancreatic islets in type 2 diabetes mellitus will lead to hyperglucagonaemia, hyperinsulinaemia, insulin resistance, glucose intolerance and impaired insulin responsiveness to elevated blood glucose levels. It explains syndrome X (or metabolic syndrome) as incipient type 2 diabetes in which the glucose control system, while impaired, can still maintain blood glucose at the desired level. It also explains why it is characterised by high plasma insulin levels and low plasma growth hormone levels, despite normoglycaemia, and how this leads to central obesity, dyslipidaemia and cardiovascular disease in both syndrome X and type 2 diabetes.
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PMID:A reappraisal of the blood glucose homeostat which comprehensively explains the type 2 diabetes mellitus-syndrome X complex. 1271 5

Nerves have been identified in bone. Their function has recently become the focus of intense study. Metabolic control of bone is influenced by the nervous system. Potential transmitters of this influence include glutamate, calcitonin gene-related protein (CGRP), substance P, vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating polypeptide (PACAP), leptin, and catecholamines. Disorders of nerves - central or peripheral--can have substantial influence on bone health and repair. Specifically considered are the potential neural influences at work in such conditions as osteoporosis, fracture healing, Charcot osteoarthropathy, musculoskeletal pain syndromes, heterotopic ossification, skeletal growth and development, and obesity-related increased bone density. In this article, we review the current state of experimental and clinical evidence implicating the role of nervous tissue in regulating bone biology and discuss the current understanding of molecular signaling between nervous and osseus tissue in the homeostatic maintenance of the skeleton.
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PMID:Bone and brain: a review of neural, hormonal, and musculoskeletal connections. 1529 19

Adrenomedullin (AM) expressed by and secreted from a variety of cells plays pluripotent roles in an autocrine/paracrine fashion. The present study was undertaken to explore the expression of AM and its receptor genes in adipose tissues, their changes during the development of obesity, and the process of preadipocyte differentiation. Both mature adipocytes and stromal vascular cells constituting adipose tissue expressed AM transcript. AM and its receptor component [calcitonin receptor-like receptor and receptor activity-modifying protein-2 (CRLR/RAMP2)] mRNAs were expressed in a variety of rat adipose tissues, including epididymal, mesenteric, retroperitoneal, and subcutaneous adipose tissue. AM mRNA levels in rat and human epididymal adipose tissue were about one-tenth of those in the kidney. Steady-state mRNA levels of AM and CRLR/RAMP2 in epididymal, mesenteric, and retroperitoneal adipose tissues in rats fed a high-fat diet for 4 wk were far greater than those in rats with normal diet accompanied by increased plasma AM levels, whereas steady-state AM mRNA levels conversely decreased in other organs, such as kidney and liver. AM mRNA expressed in a mouse preadipocyte cell line (3T3-L1) transiently decreased by day 3, returned to basal level by day 6, and then increased by day 9 during preadipocyte differentiation, which paralleled AM secretion from the cells. However, the addition of either exogenous AM or AM receptor antagonist calcitonin gene-related peptide-(8-37), to block endogenous AM did not affect lipid droplet accumulation during preadipocyte differentiation. The present study demonstrates for the first time that AM and its receptor component (CRLR/RAMP2) mRNAs were concomitantly expressed in various adipose tissues, whose tissue-specific upregulation was induced during the development of obesity. These data suggest that AM may act as a new member of adipokines, although its functional role, as well as its pathophysiological significance in obesity, remains to be determined.
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PMID:Concomitant expression of adrenomedullin and its receptor components in rat adipose tissues. 1531 11

While investigating the reversible seasonal obesity of Siberian hamsters, direct sympathetic nervous system (SNS) postganglionic innervation of white adipose tissue (WAT) has been demonstrated using anterograde and retrograde tract tracers. The primary function of this innervation is lipid mobilization. The brain SNS outflow to WAT has been defined using the pseudorabies virus (PRV), a retrograde transneuronal tract tracer. These PRV-labelled SNS outflow neurons are extensively co-localized with melanocortin-4 receptor mRNA, which, combined with functional data, suggests their involvement in lipolysis. The SNS innervation of WAT also regulates fat cell number, as noradrenaline inhibits and WAT denervation stimulates fat cell proliferation in vitro and in vivo respectively. The sensory innervation of WAT has been demonstrated by retrograde tract tracing, electrophysiological recording and labelling of the sensory-associated neuropeptide calcitonin gene-related peptide in WAT. Local injections of the sensory nerve neurotoxin capsaicin into WAT selectively destroy this innervation. Just as surgical removal of WAT pads triggers compensatory increases in lipid accretion by non-excised WAT depots, capsaicin-induced sensory denervation triggers increases in lipid accretion of non-capsaicin-injected WAT depots, suggesting that these nerves convey information about body fat levels to the brain. Finally, parasympathetic nervous system innervation of WAT has been suggested, but the recent finding of no WAT immunoreactivity for the possible parasympathetic marker vesicular acetylcholine transporter (VAChT) argues against this claim. Collectively, these data suggest several roles for efferent and afferent neural innervation of WAT in body fat regulation.
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PMID:Brain-adipose tissue cross talk. 1587 23

White adipocyte proliferation is a hallmark of obesity, but it largely remains a mechanistic mystery. We and others previously demonstrated that surgical denervation of white adipose tissue (WAT) triggers increases in fat cell number, but it is unknown whether this was due to preadipocyte proliferation or maturation of existing preadipocytes that allowed them to be counted. In addition, surgical denervation severs not only sympathetic but also sensory innervation of WAT. Therefore, we tested whether sympathetic WAT denervation triggers adipocyte proliferation using 5-bromo-2'-deoxyuridine (BrdU) as a marker of proliferation and quantified BrdU-immunoreactive (ir) cells that were co-labeled with AD-3-ir, an adipocyte-specific membrane protein marker. The unilateral denervation model was used for all experiments where Siberian hamster inguinal WAT (IWAT) was unilaterally denervated, the contralateral pad was sham denervated serving as a within-animal control, and then BrdU was injected systemically for 6 days. When IWAT was surgically denervated, severing both sympathetic and sensory nerves, tyrosine hydroxylase (TH)-ir, a sympathetic nerve marker, and calcitonin gene-related peptide (CGRP)-ir, a sensory nerve marker, were significantly decreased, and BrdU+AD-3-ir adipocytes were increased approximately 300%. When IWAT was selectively sensory denervated via local microinjections of capsaicin, a sensory nerve-specific toxin, CGRP-ir, but not TH-ir, was decreased, and BrdU+AD-3-ir adipocytes were unchanged. When IWAT was selectively sympathetically denervated via local microinjections of 6-hydroxy-dopamine, a catecholaminergic-specific toxin, TH-ir, but not CGRP-ir, was significantly decreased, and BrdU+AD-3-ir adipocytes were increased approximately 400%. Collectively, these data provide the first direct evidence that sympathetic nerves inhibit white adipocyte proliferation in vivo.
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PMID:Sympathetic but not sensory denervation stimulates white adipocyte proliferation. 1688 21

Calcitonin is an endogenous regulator of calcium homeostasis, which acts principally on bone. At present, the principal indications for the therapeutic use of calcitonin are disorders involving hypercalcemia Paget's disease, acute pancreatitis, high-bone-turnover osteoporosis, pain associated with osteoporosis or bone metastases, and Sudeck's atrophy. The aim of this study was to compare the analgesic effects on postoperative pain of salmon calcitonin versus opioids administered epidurally. Our prospective study included 53 ASA I-II patients who were scheduled for total hip arthoplasty under epidural anaesthesia and who did not fulfill 1 or more of the exclusion criteria: a history of pituitary gland dysfunction; diabetes mellitus; obesity; contraindications to performing an epidural block and/or an allergy to calcitonin. These patients were randomly allocated into 3 groups (A, B, and C), each of which received postoperatively a different analgesic epidural mixture of 10 mL to control postoperative pain. Group A was given bupivacaine 0.5% (5 mL) + fentanyl 100 (2 mL) + NaCl 0.9% (3 mL). Group B was given bupivacaine 0.5% (5 mL) + salmon calcitonin 100IU (1 mL) + NaCl 0.9% (4 mL). Group C was given salmon calcitonin 100IU (1 mL) + NaCl 0.9% (9 mL). Perioperatively, 4 blood samples were taken from each patient at the following specific times: 1. Before the induction of anesthesia; 2. At the end of the operation and before the epidural administration of the analgesic mixture; 3. At the end of the first postoperative hour (1 hour after the administration of the analgesic mixture); and 4. At the end of the second postoperative hour (2 hours after the administration of the mixture). In each blood sample, glucose, cortisol, growth hormone, and prolactin plasma levels were determined in order to investigate the changes of these parameters as a result of the endocrine reaction to stress, and to pain relief. The analgesic solution was administered immediately after the second blood sample was taken. At the same time as the 4 blood samples were taken, haemodynamic parameters and pain scores were recorded. Epidural salmon calcitonin in combination with local anaesthetic produces an analgesic effect similar to fentanyl and with stable hemodynamic results. It also eliminates postoperative hyperglycaemia. The cortisol plasma level does not increase during the first postoperative hour, but increases significantly during the second postoperative hour. Growth hormone and prolactin plasma levels were stable in all patients in all 3 groups. This study shows that calcitonin is a suitable alternative for the treatment of acute postoperative pain.
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PMID:Epidural calcitonin: does it provide better postoperative analgesia? An analysis of the haemodynamic, endocrine, and nociceptive responses of salmon calcitonin and opioids in epidural anesthesia for hip arthroplasty surgery. 1715 40

Migraine is a common disorder, characterized by recurrent episodes of headache and associated symptoms. The full pathophysiology of migraine is incompletely delineated. Current theories suggest that it is a neurovascular disorder involving cortical depression, neurogenic inflammation and vasodilation. Various neuropeptides and cytokines have been implicated in the pathophysiology of migraine including calcitonin gene-related peptide, interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-alpha. There is evidence demonstrating an association between migraine and processes associated with inflammation, atherosclerosis, immunity and insulin sensitivity. Similarly, adiponectin, an adipocytokine secreted by adipose tissue, has protective roles against the development of insulin resistance, dyslipidaemia and atherosclerosis and exhibits anti-inflammatory properties. The anti-inflammatory activities of adiponectin include inhibition of IL-6 and TNF-induced IL-8 formation, as well as induction of the anti-inflammatory cytokines IL-10 and IL-1 receptor antagonist. Adiponectin levels are also inversely correlated with C-reactive protein (CRP), TNF-alpha and IL-6 levels. Likewise, recent studies have shown a possible correlation between CRP, TNF-alpha and IL-6 and migraine attacks. In addition, insulin sensitivity is impaired in migraine and obesity is a risk factor for the transformation from episodic to chronic migraine. In this review we discuss the basic science of adiponectin and its potential connection to the pathophysiology of migraine. Future research may focus on how adiponectin levels are potentially altered during migraine attacks, and how that information can be potentially translated into migraine therapy.
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PMID:Migraine and adiponectin: is there a connection? 1744 81

Migraine and obesity are associated in several ways. First, both are prevalent and disabling disorders influenced by genetic and environmental risk factors. Second, migraine with aura, as obesity, seems to be a risk factor for cardiovascular events. Finally, large population-based studies suggest that obesity is a risk factor for chronic migraine after adjusting for comorbidities. In this article, we discuss plausible mechanisms that may account for this association. Several of the inflammatory mediators that are increased in obese individuals are important in migraine pathophysiology, including interleukins and calcitonin gene-related peptide (CGRP). These mediators may increase the frequency, severity, and duration of migraine attacks per se, which in turn would cause central sensitization. Repeated central sensitization may be associated with permanent neuronal damage close to the periaqueductal gray area, with poor modulation to pain. Obesity is also a state of sympathetic activation, which may contribute to increase in headache frequency. Furthermore, the levels of adiponectin are decreased in obesity. At low but not normal levels, adiponectin is nociceptive. Shared biologic predisposition may also play a major role. Orexins modulate both pain and metabolism. Dysfunction in the orexins pathways seems to be a risk factor for both conditions. Finally, conditions that are comorbid to both states (e.g., depression, sleep apnea) may also make the relationship between both diseases more complex.
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PMID:Obesity, migraine, and chronic migraine: possible mechanisms of interaction. 1751 49


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