Induction of brain injury and depression in rats by chronic unpredictable stress associated with the augmentation of nitrosative stress and apoptosis / Inducción de lesión cerebral y depresión en ratas por estrés crónico impredecible asociado con el aumento del estrés nitrosativo y la apoptosis

SUMMARY: Repeated stress is a risk factor for memory impairment and neurological abnormalities in both humans and animals. We sought to investigate the extent of (i) brain tissue injury; (ii) nitrosative and oxidative stress in brain tissue homogenates; (iii) apoptotic and survival biomarkers in brain tissue homogenates; and (iv) immobility and climbing abilities, induced over a period of three weeks by chronic unpredictable stress (CUS). Wistar rats were either left untreated (Control group) or exposed to a variety of unpredictable stressors daily before being sacrificed after 3 weeks (model group). Assessment of depression-like behavior was performed and animals were then culled and harvested brain tissues were stained with basic histological staining and examined under light microscopy. In addition, brain tissue homogenates were prepared and assayed for these parameters; inducible nitric oxide synthase (iNOS), malondialdehyde (MDA), superoxide dismutase (SOD), caspase-3, and B-cell lymphoma 2 (Bcl-2). Histology images showed CUS induced profound damage to the cerebral cortex as demonstrated by severe neuronal damage with shrunken cells, disrupted atrophic nuclei, perineuronal vacuolation and swollen glial cells. CUS also significantly (p<0.05) induced iNOS, MDA, and caspase-3, whereas SOD and Bcl-2 brain tissue levels were inhibited by CUS. In addition, data from the depression-like behavior, forced swimming test showed significant (p<0.05) increase in animal immobility and decrease in climbing ability in the model group of rats. Thus, here we demonstrated a reliable rat model of chronic stress-induced brain injury, which can further be used to investigate beneficial drugs or agents used for a period of three weeks to protect against CUS-induced brain damage.

RESUMEN: El estrés crónico es un factor de riesgo para el deterioro de la memoria y las anomalías neurológicas tanto en humanos como en animales. Intentamos investigar el alcance de lesión del tejido cerebral; (ii) estrés nitrosativo y oxidativo en homogeneizados de tejido cerebral; (iii) biomarcadores apoptóticos y de supervivencia en homogeneizados de tejido cerebral; y (iv) inmovilidad y habilidades de escalada, inducidas durante un período de tres semanas por estrés crónico impredecible (ECI). Se dejaron sin tratamiento (grupo control) ratas Wistar, o se expusieron a una variedad de factores estresantes impredecibles diariamente antes de ser sacrificadas después de 3 semanas (grupo modelo). Se realizó una evaluación del comportamiento similar a la depresión y luego se sacrificaron los animales y se tiñeron los tejidos cerebrales con tinción histológica básica y se examinaron con microscopía óptica. Además, se prepararon homogeneizados de tejido cerebral y se analizaron los siguientes parámetros; óxido nítrico sintasa inducible (iNOS), malondialdehído (MDA), superóxido dismutasa (SOD), caspasa- 3 y linfoma de células B 2 (Bcl-2). Las imágenes histológicas mostraron que el CUS indujo un daño profundo en la corteza cerebral como lo demuestra el daño neuronal severo con células encogidas, núcleos atróficos alterados, vacuolación perineuronal y células gliales inflamadas. ECI también indujo significativamente (p <0,05) iNOS, MDA y caspase-3, mientras que los niveles de tejido cerebral SOD y Bcl-2 fueron inhibidos por ECI. Además, los datos del comportamiento similar a la de- presión, la prueba de natación forzada mostró un aumento significativo (p <0,05) en la inmovilidad animal y una disminución en la capacidad de escalada en el grupo modelo de ratas. Por lo tanto, aquí demostramos un modelo confiable de daño cerebral crónico en rata inducido por el estrés, que se puede utilizar para investigar medicamentos o agentes beneficiosos usados durante un período de tres semanas para proteger el daño cerebral inducido por ECI.

Spatial segregation between Chalceus guaporensis and Chalceus epakros (Osteichthyes: Characiformes) in the Madeira River, Amazon Basin / Segregação espacial entre Chalceus guaporensis e Chalceus epakros (Osteichthyes: Characiformes) no rio Madeira, Bacia Amazônica

Chalceus guaporensis is an endemic fish to the upper Madeira River whereas C. epakros is widespread in many rivers of the central and lower portions of the Amazon Basin, middle and upper Orinoco River Basin, the Essequibo River in Guyana and in the Nanay River in northern Peru. According to literature, both species do not occur in syntopy. We carried out ichthyological surveys along the Madeira River Basin and its rapids, and data on abundance, diet and habitat use were obtained for both species. Chalceus guaporensis and C. epakros are morphologically similar, occupying floodplain habitats and exploiting similar food resources. The former predominated upstream from the Jirau Fall, whereas the latter had most of its abundance bellow the last fall of the Madeira River; both species co-occurred along part of the rapids stretch and in the Machado River, but with strongly uneven abundances. This pattern may have developed in the past by speciation regarding the presence of the falls, while co-occurrence of the two species seems to be regulated by competitive interactions or maintained by slight differences in environmental requirements nowadays. The recent disruption of the Madeira River by two run-of-river dams built in cascade submerged a large portion of the rapids stretch and substituted it by semi-lenthic habitats created by the dam reservoirs, together with the construction of a fish passage. These environmental changes may allow the invasion of the upper reaches of the Madeira River by C. epakros, and disturb the population of endemic C. guaporensis.

Chalceus guaporensis é descrita como uma espécie endêmica do alto rio Madeira, enquanto C. epakros está amplamente distribuída em rios das porções central e inferior da bacia Amazônica, no médio e alto rio Orinoco, e nos rios Essequibo, na Guiana, e Nanay, no norte do Peru. A literatura não registra essas espécies como sintópicas. Expedições ictiológicas realizadas ao longo do rio Madeira e suas corredeiras nos deram a oportunidade de registrar a presença, abundância, habitat e dieta utilizadas por essas espécies. Chalceus guaporensis e C. epakros são muito similares morfologicamente, ocupam habitats inundáveis e apresentam espectro alimentar semelhante. A primeira espécie predominou a montante da cachoeira Jirau, enquanto que a segunda teve a maior parte de sua abundância registrada à jusante das cachoeiras do rio Madeira. Ambas espécies coocorreram ao longo de parte do trecho de corredeiras e no rio Machado, mas com abundâncias muito desiguais. Esse padrão pode ter se desenvolvido no passado, por especiação, em função da presença das corredeiras, enquanto a coocorrência das duas espécies parece ser regulada por interações competitivas ou mantida por diferenças sutis em requisitos ecológicos no tempo atual. O recente barramento do rio Madeira por duas hidrelétricas construídas em cascata submergiu uma grande porção do trecho de corredeiras e o substituiu por habitats semilênticos, criados pelos reservatórios das hidrelétricas a fio dágua, juntamente com a construção de uma passagem para peixes. Essas alterações ambientais podem permitir que C. epakros invada o trecho superior da bacia do rio Madeira, com possíveis impactos negativos sobre a população da espécie endêmica C. guaporensis.

Effect of Erythrina velutina and Erythrina mulungu in rats submitted to animal models of anxiety and depression

Erythrina velutina (EV) and Erythrina mulungu (EM), popularly used in Brazil as tranquilizing agents, were studied. The effects of acute and chronic oral treatment with a water:alcohol extract of EV (7:3, plant grounded stem bark; acute = 100, 200, 400 mg/kg; chronic = 50, 100, 200 mg/kg) were evaluated in rats (N = 11-12) submitted to the elevated T-maze (for avoidance and escape measurements) model of anxiety. This model was selected for its presumed capacity to elicit specific subtypes of anxiety disorders recognized in clinical practice: avoidance has been related to generalized anxiety and escape to panic. Additionally, animals were treated with the same doses of EV and EM (water:alcohol 7:3, inflorescence extract) and submitted to the forced swim test for the evaluation of antidepressant activity (N = 7-10). Both treatment regimens with EV impaired elevated T-maze avoidance latencies, without altering escape, in a way similar to the reference drug diazepam (avoidance 1, mean ± SEM, acute study: 131.1 ± 45.5 (control), 9.0 ± 3.3 (diazepam), 12.7 ± 2.9 (200 mg/kg), 28.8 ± 15.3 (400 mg/kg); chronic study: 131.7 ± 46.9 (control), 35.8 ± 29.7 (diazepam), 24.4 ± 10.4 (50 mg/kg), 29.7 ± 11.5 (200 mg/kg)). Neither EV nor EM altered measurements performed in the forced swim test, in contrast to the reference drug imipramine that significantly decreased immobility time after chronic treatment. These results were not due to motor alterations since no significant effects were detected in an open field. These observations suggest that EV exerts anxiolytic-like effects on a specific subset of defensive behaviors which have been associated with generalized anxiety disorder.

Presencia y patrones de comportamiento del delfín manchado costero, Stenella attenuata (Cetacea: Delphinidae) en el Golfo de Papagayo, Costa Rica / Occurrence and behavioral patterns of the spotted coastal dolphin Stenella attenuata (Cetacea: Delphinidae) in the Gulf of Papagayo, Costa Rica

Dolphins are characterized by a significant behavioral versatility, which allows them to respond to environmental seasonality. Seasonal variation in dolphin behavior in tropical waters is not well known. Stenella attenuata graffmani is a resident dolphin in the clearly defined seasonal Gulf of Papagayo, Costa Rica, and we studied if dolphin group size, occurrence and behavioral patterns were associated with season and time of day in the gulf. Using strip transects we surveyed two locations for three consecutive years.School size ranged from 1 to 50 individuals, mean group size was 10.16 (SD =9.61) individuals. Overall, foraging activities were the most frequent, followed by social interactions and travel. From 6:00 AM to 9:00 AM we mostly observed social interactions, followed by feeding-socializing (9:00 AM-12:00 PM) and feeding exclusively (12:00 PM-3:00 PM). Social activities intensified afterwards (3:00 PM-6:00 PM). Behavior and gulf seasonality were associated (c 2 =90.52,gl =6,p<0.05,n =99). In the dry season (December- April) feeding predominated over other activities, but socializing was more frequent in the early rainy season (May-July). Larger groups (mean 12 dolphins) forage actively; smaller groups (mean 6 dolphins 6.51 ± 5.12) foraged more passively. Seasonal variation in dolphin activities are likely to be associated with food availability, as observed in the high number of groups involved in foraging behaviors, and a high investment in foraging activities during the dry season

Los delfines se caracterizan por una increíble versatilidad, la cual les ha permitido responder a los cambios estacionales de su ambiente. Dicha variación estacional en los patrones de comportamiento se considera poco conocida en delfines que habitan aguas tropicales. El delfín manchado (forma costera) Stenella attenuata graffmani, parece ser la única especie de cetáceo residente en el Golfo de Papagayo, área que se caracteriza por una estacionalidad muy bien definida. El objetivo de este trabajo es determinar si esta estacionalidad influencia el tamaño del grupo, la presencia y patrones de comportamiento de esta especie de delfín en el golfo. Usando transectos en banda se recorrieron dos localidades del Golfo de Papagayo. El tamaño del grupo varío de uno a 50 individuos, con una media de 10.16 (DS =9.61). Las actividades alimentarias fueron más intensas que las interacciones sociales y de desplazamiento, las cuales siguieron un ordenamiento diario y estacional. Se describieron dos técnicas principales de forrajeo las cuales parecen estar asociadas con el tamaño del grupo y localidad dentro del golfo. La variación diaria en los patrones de comportamiento parecen estar relacionados con la disponibilidad, distribución, y arreglo espacial de las presas. De igual manera, la variación estacional de estas actividades probablemente esta asociada por la disponibilidad de alimento, tal como ha sido observado en un mayor número de grupos y una mayor inversión de tiempo en actividades de alimentación durante la época seca y finales de las lluvias

Effects of prenatal exposure to a mild chronic variable stress on body weight, preweaning mortality and rat behavior

Early stimulation has been shown to produce long-lasting effects in many species. Prenatal exposure to some strong stressors may affect development of the nervous system leading to behavioral impairment in adult life. The purpose of the present work was to study the postnatal harmful effects of exposure to variable mild stresses in rats during pregnancy. Female Holtzman rats were submitted daily to one session of a chronic variable stress (CVS) during pregnancy (prenatal stress; PS group). Control pregnant rats (C group) were undisturbed. The pups of PS and C dams were weighed and separated into two groups 48 h after delivery. One group was maintained with their own dams (PS group, N = 70; C group, N = 36) while the other PS pups were cross-fostered with C dams (PSF group, N = 47) and the other C pups were cross-fostered with PS dams (CF group, N = 58). Pups were undisturbed until weaning (postnatal day 28). The male offspring underwent motor activity tests (day 28), enriched environment tests (day 37) and social interaction tests (day 42) in an animal activity monitor. Body weight was recorded on days 2, 28 and 60. The PS pups showed lower birth weight than C pups (Duncan's test, 0.05). The PS pups suckling with their stressed mothers displayed greater preweaning mortality (C: 23 percent, PS: 60 percent; 2 test, 0.05) and lower body weight than controls at days 28 and 60 (Duncan's test, 0.05 and 0.01, respectively). The PS, PSF and CF groups showed lower motor activity scores than controls when tested at day 28 (Duncan's test, 0.01 for PS group and ;0.05 for CF and PSF groups). In the enriched environment test performed on day 37, between-group differences in total motor activity were not detected; however, the PS, CF and PSF groups displayed less exploration time than controls (Duncan's test, 0.05). Only the PS group showed impaired motor activity and impaired social behavior at day 42 (Duncan's test, 0.05). In fact, CVS treatment during gestation plus suckling with a previously stressed mother caused long-lasting physical and behavioral changes in rats. Cross-fostering PS-exposed pups to a dam which was not submitted to stress counteracted most of the harmful effects of the treatment. It is probable that prenatal stress plus suckling from a previously stressed mother can

The effect of baclofen on spontaneous and evoked behavioral expression of experimental neuropathic chronic pain

Baclofen (Beta-p-chlorophenyl-GABA) has been used in humans to treat spasticity, as well as trigeminal neuralgia Since GABA (gamma-aminobutyric acid) has been implicated in inhibitory and analgesic effects in the nervous system, it was of interest to study the effect of baclofen in experimental neuropathic pain. With this purpose, experiments were carried out in 17 neuropathic rats with constrictive sciatic injury, as described by Bennet and Xie (1988), taking as pain parameters scratching behaviour and the latency to the thermal nociceptive stimulus. The results showed that baclofen induces, in a dose-dependent manner, significant decrease (p<0.05) of scratching behaviour and significant increase (p<0.05) of the latency to the nociceptive thermal stimulus. The absence of antagonism of naloxone suggested a non-participation of an opioid-mediated mechanism in this analgesic effect of baclofen on experimental neuropathic pain.

Animal models for evaluation of behavior and molecular neurobiological changes with emphasis on spatial memory and cholinergic system impairments in chronic alcohol abuse

In this article we outline the use of experimental animal models to study aspects of memory processes. We describe some results obtained by our group and other laboratories in studies on memory aspects, using rats chronically treated with alcohol. At behavioral and biochemical levels, we focused respectively, on retrograde amnesia and central nervous cholinergic system. We also compare, at both levels, the direct and indirect (those related to thiamine deficiency) effects induced by chronic alcohol treatment.

Diversity of Trypanosoma cruzi stocks and clones derived from Chagas disease patients: I--Behavioral characterization in vitro

In this study, we isolated Trypanosoma cruzi from chronic Chagas heart disease and from megaesophagus patients. The parasite stock hSLU239 (heart disease) yielded clones h1 and h2, whereas stock mSEU142 (megaesophagus) yielded clones m1, m2, m3 and m4. The parasite growth kinetics, doubling time and differentiation in axenic liquid medium showed broad behavioral diversity. It was shown that a particular pattern of behavior for a parental stock could not necessarily be assigned for subsequent clones. This study indicates that i) each Chagas disease patient is infected with several T. cruzi populations; ii) clonal lines derived from patient samples may have different biological characteristics from the original isolate; and that iii) additional behavioral and/or molecular markers are required for further characterization of Trypanosoma cruzi stocks and clones derived from Chagas disease patients in order to identify correlations with pathology.

Neste estudo, foram obtidos estoques de Trypanosoma cruzi de pacientes chagásicos com a doença cardíaca ou com megaesôfago. O estoque hSLU239 (doença cardíaca) forneceu os clones h1 e h2, enquanto o estoque mSLU142 (megaesôfago) forneceu os clones m1, m2, m3 e m4. A cinética de crescimento do parasito, tempo de duplicação e diferenciação em meio líquido axênico mostraram ampla diversidade comportamental. Observou-se que um padrão particular de comportamento de um estoque parental podia não ser necessariamente encontrado na linhagem subclonal subseqüente. Este estudo indica que i) cada paciente chagásico é infectado com várias subpopulações de T. cruzi; ii) linhagens clonais derivadas de cada estoque do parasito podem ter características biológicas diferentes do isolado original de paciente chagásico; e que iii) marcadores comportamentais e/ou moleculares adicionais são necessários para melhor caracterização de estoques de T. cruzi e seus clones derivados de pacientes com doença de Chagas, a fim de identificar as possíveis correlações com a patologia.

Ecologia, epidemiologia e sociedade / Ecology, epidemiology and society

Foram três as razöes principais que me estimularam no sentido da elaboraçäo do presente livro. A primeira deveu-se à conveniência de se poder vir a dispor de textos mais abrangentes, em relaçäo a temas dos cursos de epidemiologia. A segunda, prendeu-se ao desejo de expor matéria que é costumeiramente encontrada em obras dessa especialidade, mas de maneira diferente, isto é, tratando de destacar princípios que, no meu ponto de vista, säo de fundamental importância. E a última, mas, nem por isso de menor significado, foi a obrigaçäo de, como Professor de Epidemiologia da Faculdade de Saúde Pública da Universidade de Säo Paulo, contribuir para a ampliaçäo dos horizontes na compreensäo desse campo de estudos. Ao menos entre aqueles que estäo agora se iniciando nas lides dessa especialidade. Assiste-se, hoje, ao aparecimento de tendências de pensamento que pretendem fragmentar a epidemiologia em diversos campos de investigaçäo. Eis que a sociedade nada mais é do que fenômeno ecológico, cujos fundamentos devem ser procurados na própria característica da vida. Os componentes físicos e biológicos do ambiente onde vive o homem somam-se aos da sociedade que este estabelece, na determinaçäo do seu estado de saúde e da sua qualidade de vida. Para se poder alcançar a satisfatória compreensäo da doutrina epidemiológica, há que se dominar embasamento ecológico a ser adquirido por todo aquele que pretenda ser epidemiologista. Por sua vez, o caminho que leva ao sociólogo de saúde pública implica obrigatória familiarizaçäo com esses conhecimentos epidemiológicos. O texto é dividido em 4 partes, as quais, objetivando seqüência lógica dentro da supracitada orientaçäo, perfazem 19 Capítulos, cada um deles precedido pelo respectivo índice, e um Epílogo. Ao lado disso encontra-se, em anexo, Glossário de termos técnicos de ecologia e de epidemiologia, com a pretensäo de se constituir em fonte útil para consulta. Foi possível contar com a colaboraçäo dos Professores Ruy Laurenti e Eduardo Massad que se encarregaram respectivamente de elaborar os Capítulos 17 e 19, da Parte IV, precipuamente dedicada a aspectos da prática epidemiológica.

Ecología poblacional de los triatominos / Population ecology of triatominae

Se revisan , aunque no eshaustivamente, los conocimientos existentes sobre ecología y dinámica poblacional de triatominos: influencia, en la regulación de sus poblaciones, de; les factores físicos ambientales (clima, temperatura, hábitat), de la alimentación, (en tanto regulador del tamaño de las poblaciones -densodependencia-), del comportamiento (en la búsqueda y orientación de hospedadores, disposición y ubicación de los diferentes individuos de una población: alta densidad local y factores de atracción), de los mecanismos de dispersión activa, y la efectividad de los enemigos naturales potenciales (posible control biológico); así como se analizan los cambios numéricos de las poblaciones de triatominos: abundancia poblacional, estructura de edades, tablas de vida y mortalidad y efectos relacionados a la densidad