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Rod-derived cone viability factor (RdCVF) is an inactive thioredoxin secreted by rod photoreceptors that protects cones from degeneration. Because the secondary loss of cones in retinitis pigmentosa (RP) leads to blindness, the administration of RdCVF is a promising therapy for this untreatable neurodegenerative disease. Here, we investigated the mechanism underlying the protective role of RdCVF in RP. We show that RdCVF acts through binding to Basigin-1 (BSG1), a transmembrane protein expressed specifically by photoreceptors. BSG1 binds to the glucose transporter GLUT1, resulting in increased glucose entry into cones. Increased glucose promotes cone survival by stimulation of aerobic glycolysis. Moreover, a missense mutation of RdCVF results in its inability to bind to BSG1, stimulate glucose uptake, and prevent secondary cone death in a model of RP. Our data uncover an entirely novel mechanism of neuroprotection through the stimulation of glucose metabolism.
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Proteínas do Olho/metabolismo , Glicólise , Tiorredoxinas/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Basigina/genética , Basigina/metabolismo , Proteínas do Olho/genética , Glucose/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Humanos , Camundongos , Mutação de Sentido Incorreto , Retina/metabolismo , Células Fotorreceptoras Retinianas Cones/citologia , Células Fotorreceptoras Retinianas Cones/metabolismo , Retinose Pigmentar/metabolismo , Tiorredoxinas/genéticaRESUMO
In line with the first law of thermodynamics, Bernoulli's principle states that the total energy in a fluid is the same at all points. We applied Bernoulli's principle to understand the relationship between intracranial pressure (ICP) and intracranial fluids. We analyzed simple fluid physics along a tube to describe the interplay between pressure and velocity. Bernoulli's equation demonstrates that a fluid does not flow along a gradient of pressure or velocity; a fluid flows along a gradient of energy from a high-energy region to a low-energy region. A fluid can even flow against a pressure gradient or a velocity gradient. Pressure and velocity represent part of the total energy. Cerebral blood perfusion is not driven by pressure but by energy: the blood flows from high-energy to lower-energy regions. Hydrocephalus is related to increased cerebrospinal fluid (CSF) resistance (i.e., energy transfer) at various points. Identification of the energy transfer within the CSF circuit is important in understanding and treating CSF-related disorders. Bernoulli's principle is not an abstract concept far from clinical practice. We should be aware that pressure is easy to measure, but it does not induce resumption of fluid flow. Even at the bedside, energy is the key to understanding ICP and fluid dynamics.
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Líquido Cefalorraquidiano/fisiologia , Circulação Cerebrovascular/fisiologia , Hidrodinâmica , Pressão Intracraniana/fisiologia , Humanos , TermodinâmicaRESUMO
In pathophysiology and clinical practice, the intracranial pressure (ICP) profiles in the supratentorial and infratentorial compartments are unclear. We know that the pressure within the skull is unevenly distributed, with demonstrated ICP gradients. We recorded and characterised the supra- and infratentorial ICP patterns to understand what drives the transtentorial ICP gradient.A 70-year-old man was operated on for acute cerebellar infarction. One supratentorial probe and one cerebellar probe were implanted. Both signals were recorded concurrently and analysed off-line. We calculated mean ICP, ICP pulse amplitude, respiratory waves, slow waves and the RAP index of supra- and infratentorial ICP signals. Then, we measured transtentorial difference and performed correlation analysis for every index.Supratentorial ICP mean was 8.5 mmHg lower than infratentorial ICP, but the difference lessens for higher values. Both signals across the tentorium showed close correlation. Supra- and infratentorial pulse amplitude, respiratory waves and slow waves also showed a high degree of correlation. The compensatory reserve (RAP) showed good correlation. In this case report, we demonstrate that the mean value of ICP is higher in the posterior fossa, with a strong correlation across the tentorium. All other ICP-derived parameters display a symmetrical profile.
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Infarto Encefálico/fisiopatologia , Doenças Cerebelares/fisiopatologia , Pressão Intracraniana/fisiologia , Idoso , Infarto Encefálico/cirurgia , Doenças Cerebelares/cirurgia , Humanos , Masculino , Monitorização Fisiológica , Medula EspinalRESUMO
Leptin is an adipocyte-derived hormone that controls energy balance by acting primarily in the CNS, but its action is lost in common forms of obesity due to central leptin resistance. One potential mechanism for such leptin resistance is an increased hypothalamic expression of Suppressor of cytokine signaling 3 (Socs3), a feedback inhibitor of the Jak-Stat pathway that prevents Stat3 activation. Ample studies have confirmed the important role of Socs3 in leptin resistance and obesity. However, the degree to which Socs3 participates in the regulation of energy homeostasis in nonobese conditions remains largely undetermined. In this study, using adult mice maintained under standard diet, we demonstrate that Socs3 deficiency in the mediobasal hypothalamus (MBH) reduces food intake, protects against body weight gain, and limits adiposity, suggesting that Socs3 is necessary for normal body weight maintenance. Mechanistically, MBH Socs3-deficient mice display increased hindbrain sensitivity to endogenous, meal-related satiety signals, mediated by oxytocin signaling. Thus, oxytocin signaling likely mediates the effect of hypothalamic leptin on satiety circuits of the caudal brainstem. This provides an anatomical substrate for the effect of leptin on meal size, and more generally, a mechanism for how the brain controls short-term food intake as a function of the energetic stores available in the organism to maintain energy homeostasis. Any dysfunction in this pathway could potentially lead to overeating and obesity.
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Hipotálamo/metabolismo , Ocitocina/metabolismo , Rombencéfalo/metabolismo , Resposta de Saciedade/fisiologia , Transdução de Sinais/fisiologia , Proteínas Supressoras da Sinalização de Citocina/genética , Animais , Devazepida/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Ingestão de Alimentos/fisiologia , Antagonistas de Hormônios/farmacologia , Hipotálamo/efeitos dos fármacos , Leptina/metabolismo , Camundongos , Receptores da Colecistocinina/antagonistas & inibidores , Rombencéfalo/efeitos dos fármacos , Resposta de Saciedade/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/metabolismoRESUMO
Neural stem cells (NSCs) persist in specific brain germinative niches and sustain neurogenesis throughout life in adult mammals. In addition to the two major stem cell niches in the subventricular zone and the hippocampal dentate gyrus, the area postrema located in the brainstem has been identified as a neurogenic zone as well. NSCs are regulated by signals from the microenvironment that adjust stem cell response to the needs of the organism. Evidence accumulated over the past decade indicates that Ca2+ channels play pivotal functions in NSC maintenance. In this study, we explored in area postrema NSCs the presence and roles of a subset of Ca2+ channels, the store-operated Ca2+ channels (SOCs) that have the capacity to transduce extracellular signals into Ca2+ signals. Our data show that NSCs derived from the area postrema express TRPC1 and Orai1, known to form SOCs, as well as their activator STIM1. Ca2+ imaging indicated that NSCs exhibit store-operated Ca2+ entries (SOCEs). Pharmacological blockade of SOCEs with SKF-96365, YM-58483 (also known as BTP2) or GSK-7975A resulted in decreased NSC proliferation and self-renewal, indicating a major role for SOCs in maintaining NSC activity within the area postrema. Furthermore, our results show that leptin, an adipose tissue-derived hormone whose ability to control energy homeostasis is dependent on the area postrema, decreased SOCEs and reduced self-renewal of NSCs in the area postrema. As aberrant SOC function has been linked to an increasing number of diseases, including brain disorders, our study opens new perspectives for NSCs in brain pathophysiology.
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Neural stem cells are the effectors of adult neurogenesis, which occurs in discrete restricted areas of adult mammalian brain. In ovine species, like in rodents, in vivo incorporation of labeled DNA precursor led to characterize neurogenic proliferation in the subventricular zone and progeny migration and differentiation into the olfactory bulb. The present study addresses directly the existence of neural stem cells in the neurogenic niche of the vagal centre (area postrema) by in vitro neurosphere assay and RT-qPCR of specific markers on ex-vivo adult tissue explants, comparatively with the canonical neurogenic niche: the subventricular zone (SVZ) of the forebrain. Explants defined from the neuroanatomical patterns of in vivo BrdU incorporation yielded expandable and self-renewing spheres from both SVZ and AP. Within SVZ though, the density of sphere-forming cells was higher in ventral SVZ (SVZ-V) than in its latero-dorsal (SVZ-D) and lateral (SVZ-L) regions, which differs from the distributions of neural stem cells in mouse and swine brains. Consistently, RT-qPCR of the biomarker of neural stem cells, Sox2, yields highest expression in SVZ-V ahead of SVZ-D, SVZ-L and AP. These results are discussed with regard to previously published dynamics of adult ovine neurogenesis in vivo, and in light of corresponding features in other mammalian species. This confirms existence of neurogenetic plasticity in the vagal complex of adult mammals.
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Células-Tronco Neurais , Animais , Ovinos , Camundongos , Suínos , Células-Tronco Neurais/metabolismo , Encéfalo/metabolismo , Ventrículos Laterais/metabolismo , Neurogênese , Diferenciação Celular , Carneiro Doméstico , Proliferação de CélulasRESUMO
Prostate cancer (PCa) is a major public health problem worldwide. Recent studies have suggested that ghrelin and its receptor could be involved in the susceptibility to several cancers such as PCa, leading to their use as an important predictive way for the clinical progression and prognosis of cancer. However, conflicting results of single nucleotide polymorphisms (SNPs) with ghrelin (GHRL) and its receptor (GHSR) genes were demonstrated in different studies. Thus, the present case-control study was undertaken to investigate the association of GHRL and GHSR polymorphisms with the susceptibility to sporadic PCa. A cohort of 120 PCa patients and 95 healthy subjects were enrolled in this study. Genotyping of six SNPs was performed: three tag SNPs in GHRL (rs696217, rs4684677, rs3491141) and three tag SNPs in the GHSR (rs2922126, rs572169, rs2948694) using TaqMan. The allele and genotype distribution, as well as haplotypes frequencies and linked disequilibrium (LD), were established. Multifactor dimensionality reduction (MDR) analysis was used to study gene-gene interactions between the six SNPs. Our results showed no significant association of the target polymorphisms with PCa (p > 0.05). Nevertheless, SNPs are often just markers that help identify or delimit specific genomic regions that may harbour functional variants rather than the variants causing the disease. Furthermore, we found that one GHSR rs2922126, namely the TT genotype, was significantly more frequent in PCa patients than in controls (p = 0.040). These data suggest that this genotype could be a PCa susceptibility genotype. MDR analyses revealed that the rs2922126 and rs572169 combination was the best model, with 81.08% accuracy (p = 0.0001) for predicting susceptibility to PCa. The results also showed a precision of 98.1% (p < 0.0001) and a PR-AUC of 1.00. Our findings provide new insights into the influence of GHRL and GHSR polymorphisms and significant evidence for gene-gene interactions in PCa susceptibility, and they may guide clinical decision-making to prevent overtreatment and enhance patients' quality of life.
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Various age-related diseases involve systemic inflammation, i.e. a stereotyped series of acute immune system responses, and aging itself is commonly associated with low-grade inflammation or inflamm'aging. Neuroinflammation is defined as inflammation-like processes inside the central nervous system, which this review discusses as a possible link between cardiovascular disease-related chronic inflammation and neurodegenerative diseases. To this aim, neuroinflammation mechanisms are first summarized, encompassing the cellular effectors and the molecular mediators. A comparative survey of the best-known physiological contexts of neuroinflammation (neurodegenerative diseases and transient ischemia) reveals some common features such as microglia activation. The recently published transcriptomic characterizations of microglia have pointed a marker core signature among neurodegenerative diseases, but also unraveled the discrepancies with neuroinflammations related with acute diseases of vascular origin. We next review the links between systemic inflammation and neuroinflammation, beginning with molecular features of respective pro-inflammatory cells, i.e. macrophages and microglia. Finally, we point out a gap of knowledge concerning the atherosclerosis-related neuroinflammation, which is for the most surprising given that atherosclerosis is established as a major risk factor for neurodegenerative diseases.
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Envelhecimento/genética , Fibrose Pulmonar Idiopática/genética , Doença Pulmonar Obstrutiva Crônica/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Envelhecimento/metabolismo , Envelhecimento/fisiologia , Comunicação Celular , Senescência Celular , Congressos como Assunto , Epigênese Genética/genética , Instabilidade Genômica/genética , Humanos , Fibrose Pulmonar Idiopática/metabolismo , Fibrose Pulmonar Idiopática/fisiopatologia , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Mitocôndrias/metabolismo , Deficiências na Proteostase/metabolismo , Doença Pulmonar Obstrutiva Crônica/metabolismo , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Sirtuínas/metabolismo , Células-Tronco , Serina-Treonina Quinases TOR/metabolismo , Encurtamento do Telômero/genéticaRESUMO
AIM: To present one-step customized cranioplasty for intraosseous meningiomas. CASE DESCRIPTION: The authors report the case of a 54-year-old woman with a consequent frontal intraosseous meningioma invading the superior sagittal sinus. The patient only suffered from local pain and cosmetic damage. A complete resection was scheduled with a one-step reconstruction of the frontal bone by a polyetheretherketone (PEEK) specific implant. This implant was computer-assisted designed and manufactured and verified by the surgeon before the intervention. During surgery, the resection was guided by a computer designed resection template and by the classic neuronavigation system. Cranioplasty has been considered optimal intraoperatively by surgeons. The patient, a few weeks after surgery, underwent a subcutaneous fluid collection, rapidly resolutive with a circumferential pressure bandage. Six months after surgery, the patient considered the surgery a success with a very good cosmetic result and a total regression of her local pain. CONCLUSION: One-step computer-assisted cranioplasty is a safe and effective procedure for large skull defects. PEEK specific implant for cranioplasty offer advantages compared to other materials that will be discussed under the scope of the one-step reconstruction.
Assuntos
Cetonas/administração & dosagem , Neoplasias Meníngeas/cirurgia , Meningioma/cirurgia , Polietilenoglicóis/administração & dosagem , Impressão Tridimensional , Próteses e Implantes , Neoplasias Cranianas/cirurgia , Benzofenonas , Materiais Biocompatíveis/administração & dosagem , Feminino , Osso Frontal/diagnóstico por imagem , Osso Frontal/cirurgia , Humanos , Neoplasias Meníngeas/diagnóstico por imagem , Meningioma/diagnóstico por imagem , Pessoa de Meia-Idade , Neuronavegação/métodos , Polímeros , Procedimentos de Cirurgia Plástica/métodos , Crânio/diagnóstico por imagem , Crânio/cirurgia , Neoplasias Cranianas/diagnóstico por imagemRESUMO
Coronavirus Disease 2019 (COVID-19) pandemic-triggered mortality is significantly higher in older than in younger populations worldwide. Alzheimer's disease (AD) is related to aging and was recently reported to be among the major risk factors for COVID-19 mortality in older people. The symptomatology of COVID-19 indicates that lethal outcomes of infection rely on neurogenic mechanisms. The present review compiles the available knowledge pointing to the convergence of COVID-19 complications with the mechanisms of autonomic dysfunctions in AD and aging. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is prone to neuroinvasion from the lung along the vagus nerve up to the brainstem autonomic nervous centers involved in the coupling of cardiovascular and respiratory rhythms. The brainstem autonomic network allows SARS-CoV-2 to trigger a neurogenic switch to hypertension and hypoventilation, which may act in synergy with aging- and AD-induced dysautonomias, along with an inflammatory "storm". The lethal outcomes of COVID-19, like in AD and unhealthy aging, likely rely on a critical hypoactivity of the efferent vagus nerve cholinergic pathway, which is involved in lowering cardiovascular pressure and systemic inflammation tone. We further discuss the emerging evidence supporting the use of 1) the non-invasive stimulation of vagus nerve as an additional therapeutic approach for severe COVID-19, and 2) the demonstrated vagal tone index, i.e., heart rate variability, via smartphone-based applications as a non-serological low-cost diagnostic of COVID-19. These two well-known medical approaches are already available and now deserve large-scale testing on human cohorts in the context of both AD and COVID-19.
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Caloric restriction (CR) is the most effective intervention to improve health span and extend lifespan in preclinical models. This anti-aging effect of CR is related to attenuation of oxidative damage in various tissues, with divergent results in the brain. We addressed how brain oxidoreductive balance would be modulated in male Sprague-Dawley (SD) rats submitted to a 40% CR from 8 to 19 months of age, by reference to ad libitum-fed (AL) rats at 2 and 19 months of age. Four brain structures were compared: hippocampus, striatum, parietal cortex, cerebellum. Our CR diet elicits significant prevention of oxidative damages with the upregulation of antioxidant defenses (levels of glutathione [GSH], mRNAs of clusterin and of three key antioxidant enzymes) as compared to age-matched AL controls, in a strikingly region-specific pattern. CR also prevented a drastic rise of the glial fibrillary acidic protein in the hippocampus of old AL rats. Besides, the CR effects at age 19 months mainly consist in improving endogenous defenses before the onset of age-related redox alterations. These effects are more prominent in the hippocampus.
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Envelhecimento , Encéfalo/fisiologia , Restrição Calórica , Oxirredução , Estresse Oxidativo , Ração Animal , Animais , Antioxidantes/metabolismo , Encéfalo/metabolismo , Mapeamento Encefálico , Clusterina/metabolismo , Comportamento Alimentar , Proteína Glial Fibrilar Ácida/metabolismo , Glutarredoxinas/metabolismo , Glutationa/metabolismo , Hipocampo/patologia , Longevidade , Masculino , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase-1/metabolismo , Tiorredoxinas/metabolismoRESUMO
BACKGROUND: Diabetes is considered as a risk factor for Alzheimer's Disease, but it is yet unclear whether this pathological link is reciprocal. Although Alzheimer's disease and diabetes appear as entirely different pathological entities affecting the Central Nervous System and a peripheral organ (pancreas), respectively, they share a common pathological core. Recent evidence suggests that in the pancreas in the case of diabetes, as in the brain for Alzheimer's Disease, the initial pathological event may be the accumulation of toxic proteins yielding amyloidosis. Moreover, in both pathologies, amyloidosis is likely responsible for local inflammation, which acts as a driving force for cell death and tissue degeneration. These pathological events are all inter-connected and establish a vicious cycle resulting in the progressive character of both pathologies. OBJECTIVE: To address the literature supporting the hypothesis of a common pathological core for both diseases. DISCUSSION: We will focus on the analogies and differences between the disease-related inflammatory changes in a peripheral organ, such as the pancreas, versus those observed in the brain. Recent evidence suggesting an impact of peripheral inflammation on neuroinflammation in Alzheimer's disease will be presented. CONCLUSION: We propose that it is now necessary to consider whether neuroinflammation in Alzheimer's disease affects inflammation in the pancreas related to diabetes.
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Doença de Alzheimer/patologia , Encéfalo/patologia , Diabetes Mellitus Tipo 2/patologia , Inflamação/patologia , Pâncreas/patologia , Idoso , Doença de Alzheimer/etiologia , Amiloidose/complicações , Amiloidose/patologia , Diabetes Mellitus Tipo 2/etiologia , Feminino , Humanos , Inflamação/complicações , Masculino , Fatores de RiscoRESUMO
The number of adult Leydig cells is one of the factors controlling testosterone secretion by sexually mature testis, and it depends on the proliferative capacity of prepubertal Leydig cells. We investigated here whether this capacity is controlled by leptin because this hormone regulates proliferation in other cell types and has a crucial role in male fertility. Our data show that prebupertal Leydig cells express the Ob/Rb form of leptin receptor and are thus direct targets of this hormone. The analysis of G1/S-phase cyclins by quantitative (real-time) RT-PCR and Western blot points to the leptin-induced decrease in cyclin A2 and subsequent increase in cyclin D1 expression that precedes a leptin-triggered decrease in the number of prepubertal Leydig cells. Quantitative assessments of DNA synthesis by bromodeoxyuridine incorporation and of cycling cell population by Ki67 immunocytochemistry indicate that leptin decreases the cell number by inhibiting cell division and increases mRNA levels of Leydig cell differentiation markers such as relaxin-like factor. Immunohistochemistry of cyclin D1 and relaxin-like factor pointed to the parallel increase of their expression coinciding with the onset of Leydig cell differentiation. Moreover, leptin-treated Leydig cells display increased expression of another differentiation marker (3beta-hydroxysteroid dehydrogenase) that is abolished by knocking down cyclin D1 with small interference RNA. Altogether, our data show that leptin inhibits division of prepubertal Leydig cells via a cyclin D-independent mechanism and suggest that cyclin D1 might be involved in leptin-induced differentiation of Leydig cells.
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Ciclina A/genética , Ciclinas/genética , Leptina/metabolismo , Células Intersticiais do Testículo/citologia , Células Intersticiais do Testículo/fisiologia , 3-Hidroxiesteroide Desidrogenases/genética , Fatores Etários , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Divisão Celular/efeitos dos fármacos , Divisão Celular/fisiologia , Células Cultivadas , Ciclina A2 , Ciclina D , Ciclina D2 , Ciclina D3 , Fase G1/efeitos dos fármacos , Fase G1/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Insulina/genética , Leptina/farmacologia , Células Intersticiais do Testículo/efeitos dos fármacos , Masculino , Proteínas/genética , RNA Interferente Pequeno , Ratos , Ratos Sprague-Dawley , Receptores de Superfície Celular/genética , Receptores para Leptina , Fase S/efeitos dos fármacos , Fase S/fisiologia , Maturidade SexualRESUMO
The dorsal vagal complex (DVC), an integrative center of autonomic functions located dorsally in the caudal brainstem, comprises the nucleus tractus solitarius (NTS), the area postrema (AP), and the dorsal motor nucleus of the vagus nerve (DMNX). Recently, this area of the brainstem was shown to retain, during adulthood, the expression of developmental markers, which is consistent with several forms of morphological and functional plasticity. These data led us to attempt to determine the structural organization and phenotypical characteristics of the astroglial compartment in the adult DVC. We report a strikingly high density of glial fibrillary acidic protein (GFAP) immunoreactive cells in the NTS and the DMNX compared to other brainstem structures. Furthermore, we observed a subpopulation of atypical GFAP+ cells in the NTS. These cells expressed vimentin and nestin and displayed unbranched processes that radiate rostrocaudally from cuboid cell bodies located in the 4th ventricle wall. Interestingly, these radiating cells were found in close association with neural progenitors whose proliferation was stimulated by intracerebroventricular injection of epidermal growth factor/basic fibroblast growth factor or lesion of the vagus nerve. Newly born neurons in the NTS identified by doublecortin (DCX) immunolabeling were also preferentially found in the vicinity of the radiating cells. Altogether, these results indicate that the adult NTS retains, during adulthood, astroglial cells that display morphological and phenotypical features seen during development. The overlap in the distribution of proliferative neural progenitors, newborn neurons, and radiating GFAP-positive cells suggest a possible role of the glial compartment of the NTS in functional plasticity in this structure.
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Astrócitos/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Neurônios/metabolismo , Núcleo Solitário/metabolismo , Células-Tronco/metabolismo , Animais , Astrócitos/citologia , Biomarcadores/metabolismo , Proliferação de Células , Proteína Duplacortina , Imuno-Histoquímica , Proteínas de Filamentos Intermediários/metabolismo , Masculino , Proteínas do Tecido Nervoso/metabolismo , Nestina , Neurônios/citologia , Ratos , Ratos Wistar , Núcleo Solitário/citologia , Células-Tronco/citologia , Vimentina/metabolismoRESUMO
The mechanism by which blood-borne peptide YY (3-36) (PYY(3-36)) and pancreatic polypeptide (PP) inhibit food intake is not clear and could implicate peripheral (vagal afferent pathways) and/or central (direct action on specific brain nuclei) mechanisms. To identify the primary brain structure(s) that could be activated after a peripheral injection of neuropeptide Y-related peptides, we investigated the distribution of radioactive materials using whole body autoradiography and coronal brain sections. Rats were injected with [125I] porcine (p) PYY(3-36) (i.p., 10 microCi) and killed after 30 min, 1, 2, or 4 h. After i.p. administration, significant amounts of radioactive materials were rapidly (<30 min) detected in the blood circulation and various tissues including the kidneys, liver, lung, heart, bone marrow, gastrointestinal tract, and thyroid gland, whereas in the brain, low but significant amounts of radioactive materials were detected at the level of the area postrema. Next, we investigated the distribution of radioactive labeling in the brain after i.v. injections of [125I]pPYY(3-36) (Y2 and Y5 subtypes), [125I] human (h) PP (Y4 and Y5 receptors), and [125I][Leu(31), Pro(34)] pPYY (Y1, Y4 and Y5 classes) in the rat brain. Fifteen minutes post injection, autoradiograms revealed positive signals only in the area postrema after the injection of [125I]-hPP and [125I][Leu(31), Pro(34)]pPYY. Whereas the presence of [125I]pPYY(3-36)-related labeling was detected in the area postrema, subfornical organ, and median eminence. In all other brain structures, including all hypothalamic nuclei and other circumventricular organs, near background level signals were detected. These data suggest that the inhibition of food intake observed after peripheral injections of pPYY(3-36) and hPP could involve receptor activation preferentially located at the level of the area postrema, a structure well-known to be involved in the modulation of food intake.
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Área Postrema/metabolismo , Polipeptídeo Pancreático/administração & dosagem , Polipeptídeo Pancreático/metabolismo , Peptídeo YY/administração & dosagem , Peptídeo YY/metabolismo , Animais , Área Postrema/citologia , Autorradiografia , Ingestão de Alimentos , Humanos , Radioisótopos do Iodo/química , Radioisótopos do Iodo/metabolismo , Masculino , Polipeptídeo Pancreático/química , Fragmentos de Peptídeos , Peptídeo YY/química , Ratos , Ratos Sprague-Dawley , Distribuição TecidualRESUMO
OBJECTIVE Electrostimulation in awake brain mapping is widely used to guide tumor removal, but methodologies can differ substantially across institutions. The authors studied electrostimulation brain mapping data to characterize the variability of the current intensity threshold across patients and the effect of its variations on the number, type, and surface area of the essential language areas detected. METHODS Over 7 years, the authors prospectively studied 100 adult patients who were undergoing intraoperative brain mapping during resection of left hemisphere tumors. In all 100 cases, the same protocol of electrostimulation brain mapping (a controlled naming task-bipolar stimulation with biphasic square wave pulses of 1-msec duration and 60-Hz trains, maximum train duration 6 sec) and electrocorticography was used to detect essential language areas. RESULTS The minimum positive thresholds of stimulation varied from patient to patient; the mean minimum intensity required to detect interference was 4.46 mA (range 1.5-9 mA), and in a substantial proportion of sites (13.5%) interference was detected only at intensities above 6 mA. The threshold varied within a given patient for different naming areas in 22% of cases. Stimulation of the same naming area with greater intensities led to slight changes in the type of response in 19% of cases and different types of responses in 4.5%. Naming sites detected were located in subcentimeter cortical areas (50% were less than 20 mm2), but their extent varied with the intensity of stimulation. During a brain mapping session, the same intensity of stimulation reproduced the same type of interference in 94% of the cases. There was no statistically significant difference between the mean stimulation intensities required to produce interfereince in the left inferior frontal lobe (Broca's area), the supramarginal gyri, and the posterior temporal region. CONCLUSIONS Intrasubject and intersubject variations of the minimum thresholds of positive naming areas and changes in the type of response and in the size of these areas according to the intensity used may limit the interpretation of data from electrostimulation in awake brain mapping. To optimize the identification of language areas during electrostimulation brain mapping, it is important to use different intensities of stimulation at the maximum possible currents, avoiding afterdischarges. This could refine the clinical results and scientific data derived from these mapping sessions.
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Mapeamento Encefálico , Neoplasias Encefálicas/cirurgia , Córtex Cerebral/fisiopatologia , Estimulação Elétrica , Idioma , Adulto , Idoso , Neoplasias Encefálicas/fisiopatologia , Eletrocorticografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto JovemRESUMO
The dorsal vagal complex (DVC) is the satiety reflex-integrating center of adult mammals. Immobilization stress (IS) is known to elicit anorexia and to up-regulate BDNF expression in adult rat forebrain; intra-DVC delivery of BDNF was shown to elicit anorexia. Therefore, we addressed here whether IS would increase BDNF signaling in rat DVC by using PCR and western-blot on microdissected tissue extracts. Significant variations of BDNF expression in DVC after IS include exon V mRNA increase at 3 h, decreases of both protein and exon III mRNA at 24 h, and exon I mRNA decrease at 72 h. At the receptor level, IS elicited a highly significant induction of both full-length and truncated-1 TrkB mRNAs at 24 h after IS. In vivo recruitment of BDNF signaling in DVC during stress thus differs from hypothalamus, the relevance of which to anorexia is discussed.
Assuntos
Anorexia/metabolismo , Tronco Encefálico/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Regulação da Expressão Gênica/fisiologia , Análise de Variância , Animais , Anorexia/etiologia , Peso Corporal/fisiologia , Fator Neurotrófico Derivado do Encéfalo/genética , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptor trkB/genética , Receptor trkB/metabolismo , Restrição Física/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Estresse Fisiológico/complicações , Fatores de TempoRESUMO
Neurotrophins, and in particular BDNF, play important roles in proliferation, differentiation and survival of neurons during development, as well as in the synaptic activity and plasticity in many groups of mature neurons. Several lines of evidence suggest that BDNF and its high affinity receptor TrkB contribute to food intake and body weight control. In rodents, pharmacological treatments with BDNF induce reduction in food intake, whereas genetic models with an altered BDNF/TrkB signalling display hyperphagia and obesity. Genetic studies in humans have shown that mutations in the BDNF or TrkB genes may account for certain types of obesity or other forms of eating disorders. Since circulating levels of BDNF correlate with eating disorders in humans and peripheral BDNF treatments reduce hyperphagia and hyperglycaemia in obese diabetic rodents, an endocrine role of BDNF appears plausible and requires further investigation. A central anorectic action of BDNF has also been documented, with a primary focus on the hypothalamus and a more recent highlight on the brainstem integrator of energy homeostasis, the dorsal vagal complex. In this review, we will briefly present neurotrophins and their receptors and focus on experimental evidence which point out BDNF as a signalling component of food intake regulation, with a particular emphasis on the localization of the central anorectic action of BDNF.