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Rodent self-grooming is a stereotyped behavior that can rise due to stressors such as novelty. In the present study, the occurrence of a rebound effect was investigated by means of manipulation of contextual novelty and of the possibility of self-grooming (with an Elizabethan collar which blocked head-body contact). Fourty-six male rats were submitted to an experiment latter replicated with 43 females. Half of the animals were submitted to habituation sessions (30 min) to the test box in three days. The other half was similarly handled but habituated to small cages. On the fourth day, rats from both conditions were assigned to Elizabethan or sham collar groups. Each animal was observed for 15 min with its respective collar and for other 15 min with no collars. Increased locomotion was observed in the rats not habituated to the test box. Such habituation did not affect any grooming parameter. On the other hand, the animals wearing Elizabethan collars during the first half of the test, as compared to those which wore sham collars, showed increased self-grooming during the second half of the test (i.e., with no collars). Females showed pretty similar results. Present results, thus, evidence a rebound effect in self-grooming.

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The literature presents several instances of interaction between the nervous system (NS) and the immune system (IS). These interactions are promoted by several molecules, such as cytokines and hormones, with modulating action for both the NS and IS. In this sense, the two systems may influence each other: changes in behavior may be accompanied by alterations in the IS (e.g., immunosuppression) and immunological disorders, such as infections, may modulate behavior (e.g., anxiety and depression). Considering that chronic stress, in addition to affecting behavior, also modulates the IS and that there is evidence that moderate intensity physical exercise (PE) protects physical and mental health, the objective of this review is to explore the influence of moderate-intensity PE on behavior and immunity. Level of Evidence V; Expert opinion.

A literatura apresenta diversas instâncias de interação entre o sistema nervoso (SN) e o sistema imunológico (SI). Essas interações são promovidas por diversas moléculas, como citocinas e hormônios com ação moduladora tanto para o SN quanto o SI. Nesse sentido, os dois sistemas podem ter influência mútua: as alterações do comportamento podem ser acompanhadas por alterações do SI (por exemplo, imunossupressão), e distúrbios imunológicos como infecções, podem modular o comportamento (por exemplo, ansiedade e depressão). Considerando que o estresse crônico, além de afetar o comportamento, modula o SI e que há evidências de que o exercício físico (EF) de intensidade moderada ajuda a proteger a saúde física e mental, o objetivo da presente revisão é explorar a influência do EF de intensidade moderada sobre o comportamento e a imunidade. Nível de Evidência V; Opinião do especialista.

La literatura presenta diversas instancias de interacción entre el sistema nervioso (SN) y el sistema inmune (SI). Estas interacciones son promovidas por diversas moléculas, como citosinas y hormonas, con acción moduladora tanto para el SN como para el SI. En este sentido, los dos sistemas pueden influenciarse mutuamente: los cambios en el comportamiento pueden ser acompañados por alteraciones en el SI (inmunosupresión) y los disturbios inmunológicos, como infecciones, pueden modular el comportamiento (ej. ansiedad y depresión). Considerando que el estrés crónico, además de impactar el comportamiento, también modula el SI y que hay evidencias de que el ejercicio físico (EF) de intensidad moderada es un protector para la salud física y mental, el objetivo de la presente revisión es explotar la influencia del EF de intensidad moderada en el comportamiento y la inmunidad. Nivel de Evidencia V; Opinión del especialista.

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Abstract Previous studies have shown that depression and anxiety are associated to changes in the recognition of facial expression. In the present research, a non-clinical sample was evaluated with respect to trait and state anxiety and depression symptoms. In the experimental task, participants evaluated facial expressions of happiness, anger, sadness, and fear, presented at four intensities (25, 50, 75, and 100%), as well as the neutral face. Results showed that the trait anxiety was associated with a better recognition of anger, fear, and happiness. For depression, we only found differences between groups for emotional attribution to neutral faces, in which participants scoring high in depression were more likely to attribute fear to neutral faces. Findings indicate an improvement of the recognition of happiness, anger, and fear in trait anxiety, whereas symptoms of depression and state anxiety were associated to changes in the evaluation of neutral faces in non-clinical individuals.

Resumen Estudios han demostrado que la depresión y la ansiedad están asociados a cambios en el reconocimiento de la expresión facial. En la presente investigación, una muestra no clínica ha sido evaluada con respecto a la ansiedad rasgo y estado y los síntomas de depresión. En la tarea experimental, los participantes evaluaran expresiones faciales de alegría, ira, tristeza y miedo, presentadas en cuatro intensidades (25, 50, 75 y 100%), y el rostro neutro. Los resultados mostraron que la ansiedad rasgo se asoció con un mejor reconocimiento de la ira, miedo y alegría. Para la depresión, sólo se encontraron diferencias entre los grupos para la atribución emocional a rostros neutros, en el que los participantes que puntuaran alto en depresión eran más propensos a atribuir miedo a rostros neutros. Los resultados indican una mejora del reconocimiento de la alegría, ira y miedo en la ansiedad rasgo, mientras que los síntomas de depresión y ansiedad estado están asociados a cambios en la evaluación de rostros neutros en individuos no clínicos.

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Thigmotaxis, a tendency to be close to vertical surfaces, leads rats to avoid open arms in the elevated plus-maze. Evidences support a role in thigmotaxis for the vibrissal sense as well as for vision. In this study, sensory inputs for both senses were manipulated in order to identify which of them mainly contributes to thigmotaxis. This was achieved by manipulating the length of rats' mystacial vibrissae, the presence of walls in the "open" arms and their transparency. As expected, rats avoided arms which lacked walls. On the other hand, rats did not avoid "open" arms surrounded by transparent walls as one could expect if they were using mainly vision while exploring the maze. Furthermore, these "open" arms were explored similarly to arms surrounded by opaque walls. Acute vibrissotomy resulted in minor effects in rats tested in a conventional elevated plus-maze. These findings suggest that vibrissotomized rats seemed to be able to compensate the absence of mystacial vibrissae by means of other sensory pathways (tactile or non-tactile) and by adjusting some exploratory aspects. Thus, the current results indicate that rats rely more on other sensory cues than on vision in avoiding open arms in the elevated plus-maze.

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Endothelins are peptides described initially as potent vasoactive mediators. Recently, studies reported that endothelins can modulate the production and release of cytokines by immune cells. In turn, cytokines are involved in depression disorders and also in the effectiveness of some antidepressants. Therefore, we investigated the effects of treating mice with bosentan, a mixed endothelin receptor antagonist, in widely used models for assessing antidepressant activity of compounds, the forced swimming (FST) and the tail suspension tests (TST). Moreover, the influence of bosentan treatment on circulating IL-6 levels was also addressed after FST. The results show that bosentan treatment induced a bell shaped dose-dependent antidepressant-like effect with increase in circulating IL-6 levels in animals exposed to FST. Bosentan also presented antidepressant-like effect in TST. Similar results were obtained with nortriptyline treatment in the FST and TST. Possible anxiogenic effect of bosentan was excluded using the elevated plus maze test. Therefore, this is the first study to demonstrate the antidepressant-like activity of bosentan in mice, unveiling a previous unrecognized role of endothelin in depression and its possible relation with increased circulating IL-6 levels.

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No presente trabalho, os efeitos comportamentais e imunomoduladores da fluoxetina foram avaliados num modelo animal de depressão, o nado forçado. Nesse, o comportamento de flutuar é sensível a antidepressivos e é usado como índice de desespero comportamental. Foram utilizados dois grupos experimentais, sendo um grupo controle tratado com salina e outro grupo teste tratado com a fluoxetina, ambos administrados por via intra-peritoneal. Os animais foram tratados três vezes ao dia por 12 dias. Adicionalmente, a resposta imune humoral a uma imunoestimulação (hemácias de carneiro) foi avaliada. A fluoxetina provocou aumento no tempo em flutuação, queda na massa corporal e menor produção total de anticorpos. Os resultados indicam uma modulação simultânea do comportamento e do sistema imunológico pela fluoxetina.

In the present study, behavioral and immunomodulatory effects of fluoxetine were evaluated with the forced swim test, an animal model of depression. In this model, floating behavior is responsive to antidepressants and is used as a behavioral index of despair. During 12 days, three times a day, two groups were treated intraperitoneally with saline or fluoxetine. Additionally, the humoral immune response to immunostimulation (sheep red blood cells) was evaluated. The animals treated with fluoxetine floated longer, showed decreases in body mass and had lower total production of antibodies. The results indicate simultaneous modulation of behavior and antibody production by fluoxetine.

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No presente trabalho, os efeitos comportamentais e imunomoduladores da fluoxetina foram avaliados num modelo animal de depressão, o nado forçado. Nesse, o comportamento de flutuar é sensível a antidepressivos e é usado como índice de desespero comportamental. Foram utilizados dois grupos experimentais, sendo um grupo controle tratado com salina e outro grupo teste tratado com a fluoxetina, ambos administrados por via intra-peritoneal. Os animais foram tratados três vezes ao dia por 12 dias. Adicionalmente, a resposta imune humoral a uma imunoestimulação (hemácias de carneiro) foi avaliada. A fluoxetina provocou aumento no tempo em flutuação, queda na massa corporal e menor produção total de anticorpos. Os resultados indicam uma modulação simultânea do comportamento e do sistema imunológico pela fluoxetina.(AU)

In the present study, behavioral and immunomodulatory effects of fluoxetine were evaluated with the forced swim test, an animal model of depression. In this model, floating behavior is responsive to antidepressants and is used as a behavioral index of despair. During 12 days, three times a day, two groups were treated intraperitoneally with saline or fluoxetine. Additionally, the humoral immune response to immunostimulation (sheep red blood cells) was evaluated. The animals treated with fluoxetine floated longer, showed decreases in body mass and had lower total production of antibodies. The results indicate simultaneous modulation of behavior and antibody production by fluoxetine.(AU)

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Grooming behavior has been reported to be a response to novelty and other stressors. However, studies that sought to identify anxiety-related measures in the elevated plus-maze have not found grooming as a reliable index. Grooming has been implied with dearousal after a stressful experience. In the present work, a detailed investigation of this behavior was performed in a test with a longer duration (i.e., 10 min) than the usual duration in the elevated plus-maze. The level of anxiety was manipulated prior to the test by confining male rats to environments known to differ in the degree of aversive stimulation, including a familiar cage, a closed arm of the elevated plus-maze, and an open arm (i.e., the most aversive arm) of the elevated plus-maze. Grooming behavior was classified into three constituent elements: rostral grooming, head grooming, and body grooming. The groups were compared with regard to conventional measures of the elevated plus-maze and grooming behavior. Prior confinement to an open arm led to a delayed effect of decreased open-arm exploration undetectable during the first half of the test compared with rats previously confined to a closed arm. Prior confinement to an open arm also increased the total duration of grooming during the second half of the test. These increases were found to be partially attributable to increases in the rostral element of grooming. The percentage of interrupted bouts was also found to discriminate the group previously confined to an open arm. These results indicate that prolongation of the session can reveal effects that are otherwise undetectable and that under such conditions some grooming measures can be useful in the evaluation of anxiety-like behavior.

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Grooming behavior has been reported to be a response to novelty and other stressors. However, studies that sought to identify anxiety-related measures in the elevated plus-maze have not found grooming as a reliable index. Grooming has been implied with dearousal after a stressful experience. In the present work, a detailed investigation of this behavior was performed in a test with a longer duration (i.e., 10 min) than the usual duration in the elevated plus-maze. The level of anxiety was manipulated prior to the test by confining male rats to environments known to differ in the degree of aversive stimulation, including a familiar cage, a closed arm of the elevated plus-maze, and an open arm (i.e., the most aversive arm) of the elevated plus-maze. Grooming behavior was classified into three constituent elements: rostral grooming, head grooming, and body grooming. The groups were compared with regard to conventional measures of the elevated plus-maze and grooming behavior. Prior confinement to an open arm led to a delayed effect of decreased open-arm exploration undetectable during the first half of the test compared with rats previously confined to a closed arm. Prior confinement to an open arm also increased the total duration of grooming during the second half of the test. These increases were found to be partially attributable to increases in the rostral element of grooming. The percentage of interrupted bouts was also found to discriminate the group previously confined to an open arm. These results indicate that prolongation of the session can reveal effects that are otherwise undetectable and that under such conditions some grooming measures can be useful in the evaluation of anxiety-like behavior.(AU)

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The elevated plus-maze is an apparatus composed of enclosed and open (elevated) arms and time spent in the open arms by a rat can be increased/decreased by anxiolytic/anxiogenic agents. In the forced swim test, floating behavior is used as an index of behavioral despair and can be decreased by antidepressant agents. As the comorbidity between anxiety and depression is a remarkable issue in human behavioral disorders, a possible relationship between the behaviors seen in the cited tests is of great relevance. In the present study, fifty-four male rats (Rattus norvegicus) were submitted to a plus-maze session and to a 2-day forced swim protocol. According to their time in the open arms, they were divided into three groups: Low Open, Medium Open and High Open. Some plus-maze measures were found to be coherent with time in the open arms and are suggested to also be reliable anxiety indexes. In the forced swim test, the Low Open group showed decreases in floating duration from forced swim Session 1 to Session 2, an alteration opposite to that observed in the other groups (particularly, the Medium Open group). The Low Open group also showed increases in floating latency, again in sharp contrast with the alteration found in the other groups. Accordingly, positive and negative correlation were found between time in the open arms and floating duration and latency, respectively. Results are compared to previous studies and mediation of the effect by reactivity to aversive stimulation or alterations induced by open arm exposure is discussed.

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The set of answers emitted by the organisms in response to a real or potential danger is called the Anxiety State. This state, of evolutionary importance, appears when a strong danger or risk is detected, and in response to ambiguous threat stimuli that could be of innate or learned nature. A low level of anxiety is beneficial for the animals as a fundamental resource of protection of the individual against physical and social dangers. The neural basis responsible by such states would be the oldest cerebral areas, preserved in many species, that are crucial for the control of the emotions, and whosemalfunctions lead to mood disorders. Many experimental models have been developed to help the study of behaviors and neural basis of the anxiety state, providing tools that collaborate not only to the therapeutics of pathologies, but also to the better understanding of the world of the emotions.

El conjunto de respuestas emitidas por diferentes especies frente a un peligro real o potencial se conoce como Estado de Ansiedad. Este estado, de importancia evolutiva para las especies, aparece cuando se detecta un peligro o amenaza o ante la presencia de estímulos ambiguos, innatos o aprendidos, que indican una amenaza. Así, un determinado nivel de ansiedad es benéfico para los animales, siendo un recurso fundamental de protección contra peligros físicos y sociales. Los substratos neurales responsables por tales estados, corresponden a áreas cerebrales antiguas, preservadas en muchas especies y críticas para el control de las emociones que al sufrir alteraciones en su funcionamiento producen disturbios del comportamiento. Diversos modelos experimentales se han desarrollado para estudiar los componentes conductuales y sustratos neurales implicados en el estado de ansiedad y su utilización ya está suministrando herramientas para complementar la comprensión de diversas patologías y conocimiento del mundo de las emociones.

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Prenatal stress is a putative model for studying some psychopathological disorders. Indeed, submitting pregnant animals to stress leads to enhanced anxiety in the adult offspring. However, little is known about how prenatal stress effects interacts with anxiety throughout development. To study this issue, prenatally stressed rats were tested in the elevated plus-maze at different ages. During pregnancy female rats were submitted to uncontrollable electric foot shock sessions every other day or kept undisturbed (controls). After delivery, litters from control and stressed dams were left undisturbed from the 3rd to the 14th postnatal days. Male and female rats were tested in the elevated plus-maze at the ages of 30, 45 or 60 days. The following measures were taken in the elevated plus-maze: number of entries and time spent in the arms (or their extremities) and frequency and time spent in naturalistic behaviors (stretching, rearing, end exploring, grooming and head dipping). Decreases in the percentage of entries into and in the time spent (only females) in the open arms were shown by 60-day-old prenatally stressed rats, but not by 30- and 45-day old. Increased open arm ends exploration was shown by 45-day-old prenatally stressed males. Rearing behavior was found to increase with age, a phenomenon more pronounced in females. Additionally, at the younger ages prenatally stressed rats were heavier than controls, an effect which disappeared at young adulthood. In conclusion, anxiogenic prenatal stress effects in the elevated plus-maze could only be detected at early adulthood, not before. Nonetheless, at late adolescence (45 days of age) prenatal stress leaded to an anxiolytic-like effect which can be interpreted as increased risk-taking behavior.

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Prenatal stress and maternal separation are used in a large number of studies on early adversity consequences and present some similarities in their effects. The present work investigates the behavioral effects of these two procedures on two models of anxiety: the elevated plus-maze and the elevated T-maze. During pregnancy, female rats were submitted to uncontrollable electric foot shock sessions every other day or kept undisturbed. After delivery, litters from undisturbed dams were submitted to either 180-min daily periods of maternal separations from the 3-14th postnatal days or maintained with the dams all the time. Litters from the stressed dams were left undisturbed from the 3-14th postnatal days. Only males were tested. In adulthood, rats were tested in the elevated T-maze or in the elevated plus-maze. In the latter procedure half the subjects were submitted to a 60-min period of restraint immediately before being tested. The following measures were taken in the elevated plus-maze: frequency and time spent in entries into the arms, stretching, rearing, grooming and head dipping. In the T-maze measures of avoidance and escape latencies were used. Our data indicated that prenatal stress had more pronounced anxiogenic effects than maternal separation, as judged by reduced exploration of the open arms of the elevated plus-maze, but mainly after the restraint stress, and increase in avoidance latencies in the elevated T-maze. The other measures not directly involved in the elevated plus-maze arm exploration yielded similar results. Our data indicate that prenatal stress causes more anxiogenic effects in adulthood than maternal separation but, in the elevated plus-maze, these anxiogenic effects are better seen immediately after an acute stress.

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