Hércules Rezende Freitas

Glutathione-Induced Calcium Shifts in Chick Retinal Glial Cells.

Neuroglia interactions are essential for the nervous system and in the retina Müller cells interact with most of the neurons in a symbiotic manner. Glutathione (GSH) is a low-molecular weight compound that undertakes major antioxidant roles in neurons and glia, however, whether this compound could act as a signaling molecule in neurons and/or glia is currently unknown. Here we used embryonic avian retina to obtain mixed retinal cells or purified Müller glia cells in culture to evaluate calcium shifts induced by GSH. A dose response curve (0.1–10mM) showed that 5–10mM GSH, induced calcium shifts exclusively in glial cells (later labeled and identified as 2M6 positive cells), while neurons responded to 50mM KCl (labeled as βIII tubulin positive cells). BBG 100nM, a P2X7 blocker, inhibited the effects of GSH on Müller glia. However, addition of DNQX 70μM and MK-801 20μM, non-NMDA and NMDA blockers, had no effect on GSH calcium induced shift. Oxidized glutathione (GSSG) at 5mM failed to induce calcium mobilization in glia cells, indicating that the antioxidant and/or structural features of GSH are essential to promote elevations in cytoplasmic calcium levels. Indeed, a short GSH pulse (60s) protects Müller glia from oxidative damage after 30 min of incubation with 0.1% H2O2. Finally, GSH induced GABA release from chick embryonic retina, mixed neuron-glia or from Müller cell cultures, which were inhibited by BBG or in the absence of sodium. GSH also induced propidium iodide uptake in Müller cells in culture in a P2X7 receptor dependent manner. Our data suggest that GSH, in addition to antioxidant effects, could act signaling calcium shifts at the millimolar range particularly in Müller glia, and could regulate the release of GABA, with additional protective effects on retinal neuron-glial circuit.

Fatty Acids, Antioxidants and Physical Activity in Brain Aging

Polyunsaturated fatty acids and antioxidants are important mediators in the central nervous system. Lipid derivatives may control the production of proinflammatory agents and regulate NF-κB activity, microglial activation, and fatty acid oxidation; on the other hand, antioxidants, such as glutathione and ascorbate, have been shown to signal through transmitter receptors and protect against acute and chronic oxidative stress, modulating the activity of different signaling pathways. Several authors have investigated the role of these nutrients in the brains of the young and the aged in degenerative diseases such as Alzheimer’s and Parkinson’s, and during brain aging due to adiposity- and physical inactivity-mediated metabolic disturbances, chronic inflammation, and oxidative stress. Through a literature review, we aimed to highlight recent data on the role of adiposity, fatty acids, antioxidants, and physical inactivity in the pathophysiology of the brain and in the molecular mechanisms of senescence. Data indicate the complexity and necessity of endogenous/dietary antioxidants for the maintenance of redox status and the control of neuroglial signaling under stress. Recent studies also indicate that omega-3 and -6 fatty acids act in a competitive manner to generate mediators for energy metabolism, influencing feeding behavior, neural plasticity, and memory during aging. Finding pharmacological or dietary resources that mitigate or prevent neurodegenerative affections continues to be a great challenge and requires additional effort from researchers, clinicians, and nutritionists in the field.

Polyunsaturated fatty acids and endocannabinoids in health and disease.

Polyunsaturated fatty acids (PUFAs) are lipid derivatives of omega-3 (docosahexaenoic acid, DHA, and eicosapentaenoic acid, EPA) or of omega-6 (arachidonic acid, ARA) synthesized from membrane phospholipids and used as a precursor for endocannabinoids (ECs). They mediate significant effects in the fine-tune adjustment of body homeostasis. Phyto- and synthetic cannabinoids also rule the daily life of billions worldwide, as they are involved in obesity, depression and drug addiction. Consequently, there is growing interest to reveal novel active compounds in this field. Cloning of cannabinoid receptors in the 90s and the identification of the endogenous mediators arachidonylethanolamide (anandamide, AEA) and 2-arachidonyglycerol (2-AG), led to the characterization of the endocannabinoid system (ECS), together with their metabolizing enzymes and membrane transporters. Today, the ECS is known to be involved in diverse functions such as appetite control, food intake, energy balance, neuroprotection, neurodegenerative diseases, stroke, mood disorders, emesis, modulation of pain, inflammatory responses, as well as in cancer therapy. Western diet as well as restriction of micronutrients and fatty acids, such as DHA, could be related to altered production of pro-inflammatory mediators (e.g. eicosanoids) and ECs, contributing to the progression of cardiovascular diseases, diabetes, obesity, depression or impairing conditions, such as Alzheimer’ s disease. Here we review how diets based in PUFAs might be linked to ECS and to the maintenance of central and peripheral metabolism, brain plasticity, memory and learning, blood flow, and genesis of neural cells.

P2X7 receptor large pore signaling in avian Müller glial cells

ATP is a pleiotropic molecule that promotes extra- and intracellular signaling to regulate numerous functions. This nucleotide activates purine and pyrimidine receptors at the plasma membrane, categorized as ionotropic P2X or G-protein-coupled receptor (GPCR) P2Y receptors. P2X are ligand-gated ion channel receptors, expressed in both retinal neurons and Müller cells leading to neuron-glia communication, calcium waves and neurovascular coupling. However, how P2X pore is formed upon ATP activation and how signaling pathways regulates the complex is still a matter of controversy. Here we studied the properties of the P2X7 receptor (P2X7R) using electrophysiology, single cell Ca2+ imaging, and dye uptake assay in purified avian Müller glia in culture. Our data show that ATP (or benzoyl-benzoyl ATP, BzATP) evoked large inward currents in patch-clamp studies while addition of P2X7R antagonist such as brilliant Blue G (BBG), abolished these currents. Ruthenium red (RU-2), a general transient receptor potential (TRP) inhibitor, reduced currents induced by ATP. Our data also point to the involvement of mitogen activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), Ca2+-calmodulin kinase II (CAMKII), microtubules or protein kinase C (PKC) modulating ATP-induced ionic current in Müller cells. We show that ATP induced Ca2+ influx, partially inhibited by P2X7R antagonists (oxidized ATP or BBG), and totally inhibited by blockers of other pores such as transient receptor potential (TRPs) or connexin hemichannel. Additionally, MAPK, PKC, PI3K or CAMKII inhibitors also are involved in the modulation of intracellular calcium signaling. Finally, ATP induced 80–90% of dye uptake in Muller glia cells, while oxidized ATP (oATP), BBG or A740003 inhibited this effect. We conclude that large conductance channel and other P2XRs are not involved in the ATP-induced dye uptake, but signaling pathways such as MAPK, PI3-K, microtubules or PKC are involved in pore formation.

Neuro-glial cannabinoid receptors modulate signaling in the embryonic avian retina

&NA; Endocannabinoids are endogenous lipids that activate selective G protein coupled receptors (CB1 and CB2), mostly found at neuronal presynaptic sites in the nervous system. One of the main consequences of the activation of CB receptors is a decrease in GABA or glutamate release, controlling cell excitability. Here we studied the expression of CB1 and CB2 receptors in E8C8 cultured retina cells (embryonic day 8 and 8 days in vitro) using immunocytochemistry and western blot analysis. We also evaluated their functions in terms of cyclic AMP (cAMP) production, single cell calcium imaging (SCCI) and GABA release induced in basal conditions or activated by l‐Aspartate (L‐ASP) in cell cultures or under ischemia in young chick retina. We show that both cannabinoid receptors are expressed in retinal neurons and glial cells. WIN 55,212‐2 (WIN, a CB1/CB2 agonist) decreased cAMP production in cultured avian embryonic retinal cells in basal conditions. WIN also led to a decrease in the number of glial cells that increased Ca2+ levels evoked by ATP, but had no effect in Ca2+ shifts in neuronal cells activated by KCl. Finally, WIN inhibited [3H]‐GABA release induced by KCl or L‐ASP, accumulated in amacrine cells, but had no effect in the amount of GABA released in an oxygen glucose deprivation (OGD) condition. Altogether, our data indicate that cannabinoid receptors function as regulators of avian retina signaling at critical embryonic stages during synapse formation. HighlightsBoth CB1 and CB2 are expressed in retinal neurons and glial cells in culture.WIN 55,212‐2 decreases cAMP production in retinal cells in basal conditions.WIN decreases the number of glial cells that increased Ca2+ evoked by ATP.WIN inhibited [3H]‐GABA release induced by KCl or L‐Aspartate.WIN had no effect in GABA released in an oxygen glucose deprivation condition in chick retina.

Glutathione induces GABA release through P2X7R activation on Müller glia

ABSTRACT The retinal tissue of warm-blooded vertebrates performs surprisingly complex and accurate transduction of visual information. To achieve precision, a multilayered neuroglia structure is established throughout the embryonic development, and the presence of radial Müller (glial) cells ensure differentiation, growth and survival for the neuronal elements within retinal environment. It is assumed that Müller cells serve as a dynamic reservoir of progenitors, capable of expressing transcription factors, differentiating and proliferating as either neuronal or glial cells depending on extrinsic cues. In the postnatal period, Müller glia may re-enter cell cycle and produce new retinal neurons in response to acute damage. In this context, glutathione (GSH), a virtually ubiquitous tripeptide antioxidant, which is found at milimolar concentrations in central glial cells, plays a vital role as a reducing agent, buffering radical oxygen species (ROS) and preventing cell death in severely injured retinal tissues. Despite its antioxidant role, data also point to GSH as a signaling agent, suggesting that GABA release and P2X7R-mediated calcium inwards occur in Müller cells in a GSH-enriched environment. These phenomena indicate a novel mechanistic response to damage in the vertebrate retinal tissue, particularly in neuron-glia networks.

Beta-adrenergic receptor activation increases GABA uptake in adolescent mice frontal cortex: Modulation by cannabinoid receptor agonist WIN55,212-2

&NA; GABA transporters regulate synaptic GABA levels and dysfunctions in this system might result in psychiatric disorders. The endocannabinoid system (ECS) is the main circuit breaker in the nervous system and may alter noradrenaline (NA) communication, which in turn modulates the release of GABA. However, a close relationship between these systems has not been recognized. We asked whether NA and ECS might control extracellular GABA levels in slices of frontal cortex (FC) of adolescent Swiss mice with 40 days after birth (PN40). Here we show that NA and isoproterenol (ISO), a beta‐adrenergic agonist, increased [3H]‐GABA uptake in mice FC, while alpha1‐adrenergic agonist phenylephrine had no effect. As GAT‐1 is expressed and fully functional at the FC, addition of NO‐711, a GAT‐1 inhibitor, dose dependently blocked [3H]‐GABA uptake. The increase of [3H]‐GABA uptake induced by ISO was also blocked by NO‐711. [3H]‐GABA release induced by 80 mM KCl was reduced by NO‐711, but not by removal of Ca2+. ISO also increased cyclic AMP (cAMP) levels and addition of WIN 55,212‐2, a mixed CB1/CB2 receptor agonist, inhibited the effect of ISO in GABA uptake increase, GAT‐1 expression and cAMP levels compared to control. Our data show that GABA transport increased by NA and ISO is negatively regulated by cannabinoid receptor agonist WIN55,212‐2. HighlightsNoradrenaline increases [3H]‐GABA uptake in adolescent mice Frontal Cortex.The increase of [3H]‐GABA uptake induced by isoproterenol (ISO) is blocked by NO‐711.[3H]‐GABA release induced by 80 mM KCl is reduced by NO‐711, but not by removal of Ca2+.WIN 55,212‐2 inhibited the effect of ISO in GABA uptake, GAT‐1 expression and cAMP levels.

Parenteral Nutrition in the Newborn: Associated Disorders and Nutritional Aspects

Citation: de Abreu Batista AC, Freitas HR (2016) Parenteral Nutrition in the Newborn: Associated Disorders and Nutritional Aspects. J Nutr Health Sci 3(1): 106. doi: 10.15744/2393-9060.3.106 Volume 3 | Issue 1 Journal of Nutrition and Health Sciences

MEDICAL AND NUTRITIONAL APPROACHES IN CHILDHOOD OBESITY

Obesity is a metabolic disorder, characteristic of countries where the nutritional transition process occurs more intensely. Currently, the number of obese children and adolescents has grown ominously, and the emergence of this disorder in childhood can result in negative consequences for adult life. In our review, a search for selected keywords in indexed databases was performed, inclusion/exclusion of selected works were applied for the acquisition of relevant documents, moreover, practices and standards of the PRISMA model (Preferring Reporting Items for Systematic Reviews and Meta-Analyses) were used to optimize the procedures for search and analysis of original content. This narrative review highlights the main representative aspects in the matter of antiobesogenic approaches in childhood, also highlighting the importance of prevention in pregnancy and post-natal periods, as well as indicating the role of a multidisciplinary team in this process.

Processos Crônicos e Agudos na Clínica Nutricional

Resumo A reabilitacao de dentes fraturados em nivel cervical e possivel desde que o seu remanescente dentario seja reforcado. Solucoes para este problema tem desafiado os dentistas. Entretanto, ha casos em que para ser preservada determinada estrutura, e necessaria a melhoria da sua resistencia fisica, principalmente nos casos em que a perda da estrutura dentinaria for grande. O reforco radicular e um procedimento viavel e eficaz para preservar elementos dentais que seriam extraidos. O presente trabalho tem por objetivo abordar a viabilidade clinica de se reabilitar a estetica e a funcao de um dente anterior, com perda de estrutura dental, por meio de reforco com pino de fibra de vidro associado a colagem da porcao coronaria, fraturada em nivel cervical, com cimento resinoso. Esse procedimento ate alguns anos atras era inviavel e apresentava pouco sucesso. Assim, para que seja possivel o sucesso do tratamento, deve ser realizada uma analise criteriosa do caso, com um estudo da relacao dos aspectos oclusais e especialmente ao remanescente dental. O presente relato reabilitou a estetica e funcao do elemento 13 por meio de reforco com pino de fibra de vidro associado a colagem da porcao coronaria, fraturada em nivel cervical, com cimento resinoso. Desta maneira, a tecnica pode ser usada com seguranca devido ao avanco da tecnologia adesiva. Palavras-chave: Cimentacao. Colagem Dentaria. Estetica Dentaria.