RESUMEN

The stress response is multifactorial and enrolls circuitries to build a coordinated reaction, leading to behavioral, endocrine, and autonomic changes. These changes are mainly related to the hypothalamus-pituitary-adrenal (HPA) axis activation and the organism's integrity. However, when self-regulation is ineffective, stress becomes harmful and predisposes the organism to pathologies. The chronic unpredictable stress (CUS) is a widely used experimental model since it induces physiological and behavioral changes and better mimics the stressors variability encountered in daily life. Corticotropin-releasing factor (CRF) and glucocorticoids (GCs) are deeply implicated in the CUS-induced physiological and behavioral changes. Nonetheless, the CUS modulation of CRF receptors and GR and the norepinephrine role in extra-hypothalamic brain areas were not well explored. Here, we show that 14 days of CUS induced a long-lasting HPA axis hyperactivity evidenced by plasmatic corticosterone increase and adrenal gland hypertrophy, which was dependent on both GCs and NE release induced by each stress session. CUS also increased CRF2 mRNA expression and GR protein levels in fundamental brain structures related to HPA regulation and behavior, such as the lateral septal nucleus intermedia part (LSI), ventromedial hypothalamic nucleus (VMH), and central nucleus of the amygdala (CeA). We also showed that NE participates in the CUS-induced increase in CRF2 and GR levels in the LSI, reinforcing the locus coeruleus (LC) involvement in the HPA axis modulation. Despite the CUS-induced molecular changes in essential areas related to anxiety-like behavior, this phenotype was not observed in CUS animals 24 h after the last stress session.

Asunto(s)

Encéfalo/metabolismo , Sistema Hipotálamo-Hipofisario/metabolismo , Sistema Hipófiso-Suprarrenal/metabolismo , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Receptores de Glucocorticoides/metabolismo , Estrés Psicológico/metabolismo , Animales , Enfermedad Crónica , Glucocorticoides/metabolismo , Masculino , Norepinefrina/metabolismo , Ratas , Ratas Wistar , Estrés Psicológico/psicología

RESUMEN

KEY POINTS: Parkinson's disease (PD) is associated with respiratory dysfunction. In the 6-OHDA rat model of PD this is seen as a reduction in respiratory frequency and minute ventilation during normoxia and hypercapnia stimulus. Respiratory dysfunction is caused by neuronal death of medullary respiratory nuclei in the 6-OHDA model of PD. Oxidative stress can be considered a strong candidate for neurodegeneration via miR-34c downregulation and pro-apoptotic signalling in respiratory neurons, preceding the functional impairment observed in the 6-OHDA model of PD. ABSTRACT: Parkinson's disease (PD) is a neurodegenerative disease caused by dopaminergic neuron death in the substantia nigra (SN). New evidence has revealed that this neurodegeneration is the result of complex interactions between genetic abnormalities, environmental toxins, mitochondrial dysfunction and disruption of the blood-brain barrier (BBB) in the SN. In addition to classic symptoms, PD patients also exhibit respiratory failure. Here, we investigated whether oxidative stress was associated with neurodegeneration in a respiratory group (RG) of 6-OHDA-treated rats, which act as a model of PD. We analysed how oxidative stress affected apoptotic signalling in the RG 30 days after 6-OHDA treatment, shortly before commencement of breathing impairment (40 days). After 30 days, a dihydroethidium assay showed increased oxidative stress in the RG, anti-apoptotic signalling, as shown by an increase in p-Akt and BcL-2 and a decrease in Bax in the caudal aspect of the nucleus of the solitary tract (cNTS), and a decrease in p-p38 and Bax levels in the retrotrapezoid nucleus (RTN); pro-apoptotic signalling was indicated by a decrease in p-Akt and BcL-2 and an increase in Bax in the rostral ventral respiratory group (rVRG) and pre-Botzinger complex (preBotC). miR-34c, a known oxidative stress protector, was downregulated in 6-OHDA animals in the RC. After 40 days of 6-OHDA, the NTS, rVRG, preBotC and RTN exhibited reduced NeuN immunoreactivity, no BBB disruption and an increase in thiobarbituric acid reactivity. We conclude that in the 6-OHDA model of PD, oxidative stress contributes to neurodegeneration in medullary respiratory neurons.

Asunto(s)

Enfermedades Neurodegenerativas , Enfermedad de Parkinson , Animales , Neuronas Dopaminérgicas , Humanos , Estrés Oxidativo , Oxidopamina/toxicidad , Ratas , Sustancia Negra

RESUMEN

The hippocampus is a brain region that is rich in nicotinic acetylcholine receptors (nAChRs), especially the α7 subtype. The hippocampus is severely affected in disorders that have a neuroinflammatory component, such as Alzheimer's disease, Parkinson's disease, and schizophrenia. Previous studies demonstrated both in vivo and in vitro that nicotine inhibits immunological responses, including those that are triggered by the inflammatory agent lipopolysaccharide (LPS), the endotoxin of Gram-negative bacteria. The present study investigated whether chronically administered nicotine interferes with the nuclear binding of nuclear factor-κB (NF-κB) and the expression of LPS-induced inflammatory response genes. The results indicated that chronic nicotine administration (0.1mg/kg, s.c., 14days) inhibited the LPS-induced nuclear binding of NF-κB and mRNA expression levels of Tnf, Il1b, Nos2, and Tlr4. The presence of both the selective α7 nAChR antagonist methyllycaconitine (MLA; 5.0mg/kg i.p., 14days) and the nonselective nAChR antagonist mecamylamine (Meca; 1.0mg/kg, s.c., 14days) reversed the inhibitory effects of nicotine. These results suggest that the chronic activation of α7- and αxßy-containing nAChRs reduces acute inflammatory responses in the brain.

Asunto(s)

Hipocampo/efectos de los fármacos , Lipopolisacáridos/farmacología , FN-kappa B/metabolismo , Nicotina/farmacología , Agonistas Nicotínicos/farmacología , Transducción de Señal/efectos de los fármacos , Receptor Toll-Like 4/metabolismo , Aconitina/análogos & derivados , Aconitina/farmacología , Animales , Hipocampo/metabolismo , Inflamación/metabolismo , Masculino , Mecamilamina/farmacología , Ratas Wistar , Receptores Nicotínicos/metabolismo

RESUMEN

Environmental enrichment (EE) is an experimental animal model that enhances an animal's opportunity to interact with sensory, motor, and social stimuli, compared to standard laboratory conditions. A prominent benefit of EE is the reduction of stress-induced anxiety. The relationship between stress and the onset of anxiety-like behavior has been widely investigated in experimental research, showing a clear correlation with structural changes in the hippocampus and basolateral amygdala (BLA). However, the mechanisms by which EE exerts its protective roles in stress and anxiety remain unclear, and it is not known whether EE reduces the effects of acute stress on animal behavior shortly following the cessation of stress. We found that EE can prevent the emergence of anxiety-like symptoms in rats measured immediately after acute restraint stress (1 h) and this effect is not due to changes in systemic release of corticosterone. Rather, we found that stress promotes a rapid increase in the nuclear translocation of glucocorticoid receptor (GR) in the BLA, an effect prevented by previous EE exposure. Furthermore, we observed a reduction of ERK (a MAPK protein) and CREB activity in the BLA promoted by both EE and acute stress. Finally, we found that EE decreases the expression of the immediate-early gene EGR-1 in the BLA, indicating a possible reduction of neuronal activity in this region. Hyperactivity of BLA neurons has been reported to accompany anxiety-like behavior and changes in this process may be one of the mechanism by which EE exerts its protective effects against stress-induced anxiety.

Asunto(s)

Ansiedad/metabolismo , Complejo Nuclear Basolateral/metabolismo , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/fisiología , Ambiente , Sistema de Señalización de MAP Quinasas/fisiología , Receptores de Glucocorticoides/fisiología , Estrés Psicológico/metabolismo , Animales , Ansiedad/genética , Ansiedad/prevención & control , Proteína 1 de la Respuesta de Crecimiento Precoz/biosíntesis , Proteína 1 de la Respuesta de Crecimiento Precoz/genética , Genes Inmediatos-Precoces/fisiología , Masculino , Aprendizaje por Laberinto/fisiología , Distribución Aleatoria , Ratas , Ratas Wistar , Estrés Psicológico/genética

RESUMEN

The objective of this study was to identify species of rhizobia (from the IPA 403 and IPA 49 isolates), to assess the physico-chemical characteristics of the biopolymers produced by these rhizobia and to determine the soluble intracellular proteins that are present in these rhizobia. The polysaccharides containing acetyl and pyruvic acid groups that were produced by different strains that had been cultivated in yeast extract mannitol (YEM) medium for 132, 144, and 168 h were evaluated for yield, viscosity, and concentration. Based on the analysis of their partial 16S rDNA sequences, both isolates were identified as Rhizobium tropici. The polymers produced in liquid YEM medium were recovered, dried and weighed to determine culture yield. Soluble intracellular proteins were identified through the techniques of 2D-PAGE and mass spectrometry for cultures that were cultivated for 168 h. The largest biopolymer yield and the highest viscosity and concentration of acetyl and pyruvic acids were obtained from the IPA 403 isolate after 168 h of culture. The proteins that were identified for the CIAT 899 isolate included elongation factor TU, a chaperone; GroE/GroEs and a putative glycosyltransferase, all of which catalyze the production of polysaccharides. For the IPA 403 strain, dinitrogenase and nitrogenase iron proteins were found. In the IPA 49 strain, glyceraldehyde-3-phosphate dehydrogenase was found along with two other proteins, the beta subunit of an electron-transferring flavoprotein and a dehydrogenase.

Asunto(s)

Proteínas Bacterianas/química , Biopolímeros/biosíntesis , Biopolímeros/química , Rhizobium tropici/metabolismo , Proteínas Bacterianas/metabolismo , Medios de Cultivo , ADN Bacteriano/análisis , ADN Bacteriano/genética , ADN Ribosómico/análisis , ADN Ribosómico/genética , Electroforesis en Gel Bidimensional , Espectrometría de Masas/métodos , ARN Ribosómico 16S/genética , Rhizobium tropici/clasificación , Rhizobium tropici/genética , Rhizobium tropici/crecimiento & desarrollo , Viscosidad

RESUMEN

Drug abuse is a concerning health problem in adults and has been recognized as a major problem in adolescents. Induction of immediate-early genes (IEG), such as c-Fos or Egr-1, is used to identify brain areas that become activated in response to various stimuli, including addictive drugs. It is known that the environment can alter the response to drugs of abuse. Accordingly, environmental cues may trigger drug-seeking behavior when the drug is repeatedly administered in a given environment. The goal of this study was first to examine for age differences in context-dependent sensitization and then evaluate IEG expression in different brain regions. For this, groups of mice received i.p. ethanol (2.0 g/kg) or saline in the test apparatus, while other groups received the solutions in the home cage, for 15 days. One week after this treatment phase, mice were challenged with ethanol injection. Acutely, ethanol increased both locomotor activity and IEG expression in different brain regions, indistinctly, in adolescent and adult mice. However, adults exhibited a typical context-dependent behavioral sensitization following repeated ethanol treatment, while adolescent mice presented gradually smaller locomotion across treatment, when ethanol was administered in a paired regimen with environment. Conversely, ethanol-treated adolescents expressed context-independent behavioral sensitization. Overall, repeated ethanol administration desensitized IEG expression in both adolescent and adult mice, but this effect was greatest in the nucleus accumbens and prefrontal cortex of adolescents treated in the context-dependent paradigm. These results suggest developmental differences in the sensitivity to the conditioned and unconditioned locomotor effects of ethanol.

Asunto(s)

Envejecimiento , Encéfalo/efectos de los fármacos , Depresores del Sistema Nervioso Central/farmacología , Ambiente , Etanol/farmacología , Actividad Motora/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Encéfalo/fisiología , Depresores del Sistema Nervioso Central/sangre , Señales (Psicología) , Proteína 1 de la Respuesta de Crecimiento Precoz/metabolismo , Etanol/sangre , Genes Inmediatos-Precoces/efectos de los fármacos , Hipocampo/efectos de los fármacos , Hipocampo/fisiología , Locomoción/efectos de los fármacos , Locomoción/fisiología , Masculino , Ratones , Actividad Motora/fisiología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Núcleo Accumbens/efectos de los fármacos , Núcleo Accumbens/fisiología , Corteza Prefrontal/efectos de los fármacos , Corteza Prefrontal/fisiología , Proteínas Proto-Oncogénicas c-fos/metabolismo

RESUMEN

Centipedes have a venom gland connected to a pair of forceps, which are used to arrest preys. Human victims bitten by centipedes usually manifest burning pain, paresthesia and edema, which may develop into superficial necrosis. The aim of this work was to characterize and compare toxic activities found in venoms of three species of Brazilian centipedes-Otostigmus pradoi, Cryptops iheringi and Scolopendra viridicornis. By SDS-PAGE (4-20%), important differences were noticed among venoms (between 7 and 205kDa). Few bands showed feeble caseinolytic, fibrinogenolytic and gelatinolytic activities by zymography, but strong hyaluronidase activity was observed in S. viridicornis and O. pradoi venoms. In addition, such activities could be inhibited by o-phenanthroline, indicating that these enzymes are metalloproteinases. All venoms induced nociception, edema and myotoxicity in mice, but only S. viridicornis induced mild hemorrhagic activity. No coagulant activity was detected in centipede venoms. Low phospholipase A(2) activity was observed exclusively in S. viridicornis and O. pradoi venoms, but these venoms had intense direct hemolytic activity on human erythrocytes. Cross-reactivity among venoms was observed using species-specific sera raised in rabbits. Differences were noticed among centipede venoms, but S. viridicornis is indeed the most toxic venom and thereby it could induce a more severe envenomation.

Asunto(s)

Venenos de Artrópodos/inmunología , Venenos de Artrópodos/toxicidad , Artrópodos/fisiología , Animales , Antivenenos/metabolismo , Venenos de Artrópodos/química , Reacciones Cruzadas/efectos de los fármacos , Reacciones Cruzadas/inmunología , Relación Dosis-Respuesta a Droga , Edema/inducido químicamente , Edema/patología , Eritrocitos/efectos de los fármacos , Hemólisis/efectos de los fármacos , Hemorragia/inducido químicamente , Hemorragia/patología , Humanos , Metaloproteasas/antagonistas & inhibidores , Metaloproteasas/metabolismo , Ratones , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/enzimología , Músculo Esquelético/fisiopatología , Dolor/inducido químicamente , Dolor/fisiopatología , Dimensión del Dolor , Fenantrolinas/farmacología , Fosfolipasas A/análisis , Fosfolipasas A/metabolismo , Conejos , Piel/efectos de los fármacos , Piel/patología

RESUMEN

Stingrays are elasmobranchs found along the seacoast and in some rivers of Brazil. Pain is the most conspicuous symptom observed in patients wounded by the bilaterally retroserrate stingers located in the tail, which are covered by glandular and integument tissues. In addition, cutaneous necrosis is commonly observed in injuries caused by freshwater stingrays. The aim of this work was to characterize and compare certain properties of tissue extracts obtained from the glandular tissues covering the stinger apparatus of Potamotrygon falkneri and Dasyatis guttata stingrays. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), tissue extracts have similar bands above 80 kDa, but most differences were observed below this molecular mass. Lethal, dermonecrotic and myotoxic activities were detected only in P. falkneri tissue extract. Edematogenic activity was similar and dose dependent in both tissue extracts. Nociceptive activity was verified in both tissue extracts, but P. falkneri presented a two-fold higher activity than D. guttata tissue extract. No direct hemolysis, phospholipase A2 and coagulant activities were observed in both tissue extracts. Antigenic cross-reactivity was noticed by ELISA and Western blotting, using antisera raised in rabbits. Species-specific sera reacted with several components of both tissue extracts, noticeably above 22kDa. Both tissue extracts presented gelatinolytic, caseinolytic and fibrinogenolytic activities, which were not caused by the action of metalloproteinases. Hyaluronidase activity was detected only in P. falkneri tissue extract. Our experimental observations suggest that P. falkneri tissue extract is more toxic than D. guttata tissue extract. These results may explain why injuries caused by freshwater stingrays are more severe in human accidents.

Asunto(s)

Epidermis/química , Peces Venenosos , Rajidae/metabolismo , Extractos de Tejidos/toxicidad , Pruebas de Toxicidad , Animales , Mordeduras y Picaduras , Brasil , Reacciones Cruzadas/inmunología , Relación Dosis-Respuesta a Droga , Edema/inducido químicamente , Edema/patología , Glándulas Exocrinas/química , Agua Dulce , Hemólisis/efectos de los fármacos , Longevidad/efectos de los fármacos , Masculino , Ratones , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patología , Fosfolipasas A2/análisis , Fosfolipasas A2/metabolismo , Conejos , Agua de Mar , Especificidad de la Especie , Extractos de Tejidos/química , Extractos de Tejidos/inmunología

RESUMEN

The ability of IgG(T) and IgGa subclasses--isolated by liquid chromatography from equine arachnidic antivenom (AAV)-to neutralize toxic activities of Loxosceles gaucho, Phoneutria nigriventer and Tityus serrulatus venoms as well as to remove venom toxins from circulation was investigated. These subclasses showed similar antibody titers against L. gaucho, P. nigriventer and T. serrulatus venoms, and by immunoblotting few differences were observed in the recognition pattern of venom antigens. IgG(T) and IgGa neutralized 100% lethality induced by L. gaucho and 50% of P. nigriventer venom, but IgGa failed to neutralize T. serrulatus venom, in contrast to IgG(T). Both subclasses neutralized local reactions and dermonecrosis induced by L. gaucho venom in rabbits. In mice, IgG(T) and IgGa partially neutralized the edematogenic activity induced by P. nigriventer and T. serrulatus venoms, but only IgG(T) neutralized (ca. 81%) the nociceptive activity induced by T. serrulatus venom. Both subclasses failed to neutralize nociceptive activity induced by P. nigriventer venom. IgG(T) reduced the serum venom levels of animals injected with L. gaucho, P. nigriventer or T. serrulatus venoms, while IgGa solely reduced L. gaucho and P. nigriventer venoms levels. Our results demostrate that IgG(T) and IgGa subclasses neutralize toxic activities induced by P. nigriventer, T. serrulatus and L. gaucho venoms with different efficacies, as well as depurate these venoms from circulation.

Asunto(s)

Antivenenos/farmacología , Inmunoglobulina G/farmacología , Venenos de Escorpión/antagonistas & inhibidores , Venenos de Araña/antagonistas & inhibidores , Arañas/química , Animales , Antivenenos/química , Cromatografía Liquida , Caballos/inmunología , Inmunoglobulina G/aislamiento & purificación , Ratones , Hidrolasas Diéster Fosfóricas/inmunología , Hidrolasas Diéster Fosfóricas/toxicidad , Venenos de Escorpión/inmunología , Venenos de Escorpión/toxicidad , Venenos de Araña/inmunología , Venenos de Araña/toxicidad , Arañas/metabolismo

RESUMEN

Although the anti-inflammatory actions of glucocorticoids (GCs) are well established in the periphery, these stress hormones can increase inflammation under some circumstances in the brain. The transcription factor nuclear factor-kappaB (NF-kappaB), which is inhibited by GCs, regulates numerous genes central to inflammation. In this study, the effects of stress, GCs, and NMDA receptors on lipopolysaccharide (LPS)-induced activation of NF-kappaB in the brain were investigated. One day after chronic unpredictable stress (CUS), nonstressed and CUS rats were treated with saline or LPS and killed 2 h later. CUS potentiated the increase in LPS-induced activation of NF-kappaB in frontal cortex and hippocampus but not in the hypothalamus. This stress effect was blocked by pretreatment of rats with RU-486, an antagonist of the GC receptor. MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate], an NMDA receptor antagonist, also reduced the effect of LPS in all three brain regions. However, the combined antagonism of both GC and NMDA receptors produced no further reduction in NF-kappaB activation when compared with the effect of each treatment alone. Our results indicate that stress, via GC secretion, can increase LPS-induced NF-kappaB activation in the frontal cortex and hippocampus, agreeing with a growing literature demonstrating proinflammatory effects of GCs.

Asunto(s)

Encefalitis/metabolismo , Lóbulo Frontal/metabolismo , Glucocorticoides/metabolismo , Hipocampo/metabolismo , FN-kappa B/metabolismo , Estrés Psicológico/complicaciones , Estrés Psicológico/metabolismo , Animales , Células Cultivadas , Enfermedad Crónica , Encefalitis/inducido químicamente , Hipocampo/efectos de los fármacos , Lipopolisacáridos , Masculino , Ratas , Ratas Wistar , Distribución Tisular

RESUMEN

The ability of IgG(T) and IgGa subclasses—isolated by liquid chromatography from equine arachnidic antivenom (AAV)—to neutralize toxic activities of Loxosceles gaucho, Phoneutria nigriventer and Tityus serrulatus venoms as well as to remove venom toxins from circulation was investigated. These subclasses showed similar antibody titers against L. gaucho, P. nigriventer and T. serrulatus venoms, and by immunoblotting few differences were observed in the recognition pattern of venom antigens. IgG(T) and IgGa neutralized 100% lethality induced by L. gaucho and 50% of P. nigriventer venom, but IgGa failed to neutralize T. serrulatus venom, in contrast to IgG(T). Both subclasses neutralized local reactions and dermonecrosis induced by L. gaucho venom in rabbits. In mice, IgG(T) and IgGa partially neutralized the edematogenic activity induced by P. nigriventer and T. serrulatus venoms, but only IgG(T) neutralized (ca. 81%) the nociceptive activity induced by T. serrulatus venom. Both subclasses failed to neutralize nociceptive activity induced by P. nigriventer venom. IgG(T) reduced the serum venom levels of animals injected with L. gaucho, P. nigriventer or T. serrulatus venoms, while IgGa solely reduced L. gaucho and P. nigriventer venoms levels. Our results demostrate that IgG(T) and IgGa subclasses neutralize toxic activities induced by P. nigriventer, T. serrulatus and L. gaucho venoms with different efficacies, as well as depurate these venoms from circulation.

Asunto(s)

Animales , Venenos de Araña/clasificación , Venenos de Araña/envenenamiento , Venenos de Araña/inmunología