Effects of acupuncture on behavioral, cardiovascular and hormonal responses in restraint-stressed Wistar rats

Stress is a well-known entity and may be defined as a threat to the homeostasis of a being. In the present study, we evaluated the effects of acupuncture on the physiological responses induced by restraint stress. Acupuncture is an ancient therapeutic technique which is used in the treatment and prevention of diseases. Its proposed mechanisms of action are based on the principle of homeostasis. Adult male Wistar EPM-1 rats were divided into four groups: group I (N = 12), unrestrained rats with cannulas previously implanted into their femoral arteries for blood pressure and heart rate measurements; group II (N = 12), rats that were also cannulated and were submitted to 60-min immobilization; group III (N = 12), same as group II but with acupuncture needles implanted at points SP6, S36, REN17, P6 and DU20 during the immobilization period; group IV (N = 14), same as group III but with needles implanted at points not related to acupuncture (non-acupoints). During the 60-min immobilization period animals were assessed for stress-related behaviors, heart rate, blood pressure and plasma corticosterone, noradrenaline and adrenaline levels. Group III animals showed a significant reduction (60% on average, P<0.02) in restraint-induced behaviors when compared to groups II and IV. Data from cardiovascular and hormonal assessments indicated no differences between group III and group II and IV animals, but tended to be lower (50% reduction on average) in group I animals. We hypothesize that acupuncture at points SP6, S36, REN17, P6 and DU20 has an anxiolytic effect on restraint-induced stress that is not due to a sedative action

Gap effect and reaction time distribution: simple vs choice manual responses

It is well known that saccadic reaction times (SRT) are reduced when the target is preceded by the offset of the fixation point (FP) - the gap effect. Some authors have proposed that the FP offset also allows the saccadic system to generate a separate population of SRT, the express saccades. Nevertheless, there is no agreement as to whether the gap effect and express responses are also present for manual reaction times (MRT). We tested the gap effect and the MRT distribution in two different conditions, i.e., simple and choice MRT. In the choice MRT condition, subjects need to identify the side of the stimulus and to select the appropriate response, while in the simple MRT these stages are not necessary. We report that the gap effect was present in both conditions (22 ms for choice MRT condition; 15 ms for simple MRT condition), but, when analyzing the MRT distributions, we did not find any clear evidence for express manual responses. The main difference in MRT distribution between simple and choice conditions was a shift towards shorter values for simple MRT.

Effect of repeated restraint stress on memory in different tasks

The present study investigated the effect of repeated stress applied to female rats on memory evaluated by three behavioral tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Repeated stress had different effects on rat behavior when different tasks were considered. In the two-way active avoidance test the stressed animals presented memory of the task, but their memory scores were impaired when compared to all other groups. In the habituation to the open field, only the control group showed a significant difference in the number of rearings between training and testing sessions, which is interpreted as an adequate memory of the task. In the handled and chronically stressed animals, on the other hand, no memory was observed, suggesting that even a very mild repeated stress would be enough to alter habituation to this task. The performance in the inhibitory avoidance task presented no significant differences between groups. The findings suggest that repeated restraint stress might induce cognitive impairments that are dependent on the task and on stress intensity.

Restraint-induced hypoactivity in an elevated plus-maze

Rodents submitted to restraint stress show decreased activity in an elevated plus-maze (EPM) 24 h later. The objective of the present study was to determine if a certain amount of time is needed after stress for the development of these changes. We also wanted to verify if behavioral tolerance of repeated daily restraint would be detectable in this model. Male Wistar rats were restrained for 2 h and tested in the EPM 1, 2, 24 or 48 h later. Another group of animals was immobilized daily for 2 h for 7 days, being tested in the EPM 24 h after the last restraint period. Restraint induced a significant decrease in the percent of entries and time spent in the open arms, as well as a decrease in the number of enclosed arm entries. The significant effect in the number of entries and the percentage of time spent in the open arms disappeared when the data were submitted to analysis of covariance using the number of enclosed arm entries as a covariate. This suggests that the restraint-induced hypoactivity influences the measures of open arm exploration. The modifications of restraint-induced hypoactivity are evident 24 or 48 h, but not 1 or 2 h, after stress. In addition, rats stressed daily for seven days became tolerant to this effect.

Interaction between repeated restraint stress and concomitant midazolam administration on sweet food ingestion in rats

Emotional changes can influence feeding behavior. Previous studies have shown that chronically stressed animals present increased ingestion of sweet food, an effect reversed by a single dose of diazepam administered before testing the animals. The aim of the present study was to evaluate the response of animals chronically treated with midazolam and/or submitted to repeated restraint stress upon the ingestion of sweet food. Male adult Wistar rats were divided into two groups: controls and exposed to restraint 1 h/day, 5 days/week for 40 days. Both groups were subdivided into two other groups treated or not with midazolam (0.06 mg/ml in their drinking water during the 40-day treatment). The animals were placed in a lighted area in the presence of 10 pellets of sweet food (Froot loops®). The number of ingested pellets was measured during a period of 3 min, in the presence or absence of fasting. The group chronically treated with midazolam alone presented increased ingestion when compared to control animals (control group: 2.0 ± 0.44 pellets and midazolam group: 3.60 ± 0.57 pellets). The group submitted to restraint stress presented an increased ingestion compared to controls (control group: 2.0 ± 0.44 pellets and stressed group: 4.18 ± 0.58 pellets). Chronically administered midazolam reduced the ingestion in stressed animals (stressed/water group: 4.18 ± 0.58 pellets; stressed/midazolam group: 3.2 ± 0.49 pellets). Thus, repeated stress increases appetite for sweet food independently of hunger and chronic administration of midazolam can decrease this behavioral effect.

Effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices

It has been suggested that glucocorticoids released during stress might impair neuronal function by decreasing glucose uptake by hippocampal neurons. Previous work has demonstrated that glucose uptake is reduced in hippocampal and cerebral cortex slices 24 h after exposure to acute stress, while no effect was observed after repeated stress. Here, we report the effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices and on plasma glucose and corticosterone levels. Male adult Wistar rats were exposed to restraint 1 h/day for 50 days in the chronic model. In the acute model there was a single exposure. Immediately or 24 h after stress, the animals were sacrificed and the hippocampus and cerebral cortex were dissected, sliced, and incubated with Krebs buffer, pH 7.4, containing 5 mM glucose and 0.2 µCi D-[U-14C] glucose. CO2 production from glucose was estimated. Trunk blood was also collected, and both corticosterone and glucose were measured. The results showed that corticosterone levels after exposure to acute restraint were increased, but the increase was smaller when the animals were submitted to repeated stress. Blood glucose levels increased after both acute and repeated stress. However, glucose utilization, measured as CO2 production in hippocampal and cerebral cortex slices, was the same in stressed and control groups under conditions of both acute and chronic stress. We conclude that, although stress may induce a decrease in glucose uptake, this effect is not sufficient to affect the energy metabolism of these cells.

Spectral analysis of the electromyograph of the erector spinae muscle before and after a dynamic manual load-lifting test

The aim of the present study was to assess the spectral behavior of the erector spinae muscle during isometric contractions performed before and after a dynamic manual load-lifting test carried out by the trunk in order to determine the capacity of muscle to perform this task. Nine healthy female students participated in the experiment. Their average age, height, and body mass (± SD) were 20 ± 1 years, 1.6 ± 0.03 m, and 53 ± 4 kg, respectively. The development of muscle fatigue was assessed by spectral analysis (median frequency) and root mean square with time. The test consisted of repeated bending movements from the trunk, starting from a 45º angle of flexion, with the application of approximately 15, 25 and 50% of maximum individual load, to the stand up position. The protocol used proved to be more reliable with loads exceeding 50% of the maximum for the identification of muscle fatigue by electromyography as a function of time. Most of the volunteers showed an increase in root mean square versus time on both the right (N = 7) and the left (N = 6) side, indicating a tendency to become fatigued. With respect to the changes in median frequency of the electromyographic signal, the loads used in this study had no significant effect on either the right or the left side of the erector spinae muscle at this frequency, suggesting that a higher amount and percentage of loads would produce more substantial results in the study of isotonic contractions.

Looking for the GAP effect in manual responses and the role of contextual influences in reaction time experiments

When the offset of a visual stimulus (GAP condition) precedes the onset of a target, saccadic reaction times are reduced in relation to the condition with no offset (overlap condition) - the GAP effect. However, the existence of the GAP effect for manual responses is still controversial. In two experiments using both simple (Experiment 1, N = 18) and choice key-press procedures (Experiment 2, N = 12), we looked for the GAP effect in manual responses and investigated possible contextual influences on it. Participants were asked to respond to the imperative stimulus that would occur under different experimental contexts, created by varying the array of warning-stimulus intervals (0, 300 and 1000 ms) and conditions (GAP and overlap): i) intervals and conditions were randomized throughout the experiment; ii) conditions were run in different blocks and intervals were randomized; iii) intervals were run in different blocks and conditions were randomized. Our data showed that no GAP effect was obtained for any manipulation. The predictability of stimulus occurrence produced the strongest influence on response latencies. In Experiment 1, simple manual responses were shorter when the intervals were blocked (247 ms, P < 0.001) in relation to the other two contexts (274 and 279 ms). Despite the use of choice key-press procedures, Experiment 2 produced a similar pattern of results. A discussion addressing the critical conditions to obtain the GAP effect for distinct motor responses is presented. In short, our data stress the relevance of the temporal allocation of attention for behavioral performance.

Manual and semi-automatic quantification of in vivo ¹H-MRS data for the classification of human primary brain tumors

In vivo proton magnetic resonance spectroscopy (¹H-MRS) is a technique capable of assessing biochemical content and pathways in normal and pathological tissue. In the brain, ¹H-MRS complements the information given by magnetic resonance images. The main goal of the present study was to assess the accuracy of ¹H-MRS for the classification of brain tumors in a pilot study comparing results obtained by manual and semi-automatic quantification of metabolites. In vivo single-voxel ¹H-MRS was performed in 24 control subjects and 26 patients with brain neoplasms that included meningiomas, high-grade neuroglial tumors and pilocytic astrocytomas. Seven metabolite groups (lactate, lipids, N-acetyl-aspartate, glutamate and glutamine group, total creatine, total choline, myo-inositol) were evaluated in all spectra by two methods: a manual one consisting of integration of manually defined peak areas, and the advanced method for accurate, robust and efficient spectral fitting (AMARES), a semi-automatic quantification method implemented in the jMRUI software. Statistical methods included discriminant analysis and the leave-one-out cross-validation method. Both manual and semi-automatic analyses detected differences in metabolite content between tumor groups and controls (P < 0.005). The classification accuracy obtained with the manual method was 75% for high-grade neuroglial tumors, 55% for meningiomas and 56% for pilocytic astrocytomas, while for the semi-automatic method it was 78, 70, and 98%, respectively. Both methods classified all control subjects correctly. The study demonstrated that ¹H-MRS accurately differentiated normal from tumoral brain tissue and confirmed the superiority of the semi-automatic quantification method.

Brazil nut sorting for aflatoxin prevention: a comparison between automatic and manual shelling methods

The impact of automatic and manual shelling methods during manual/visual sorting of different batches of Brazil nuts from the 2010 and 2011 harvests was evaluated in order to investigate aflatoxin prevention.The samples were tested as follows: in-shell, shell, shelled, and pieces in order to evaluate the moisture content (mc), water activity (Aw), and total aflatoxin (LOD = 0.3 µg/kg and LOQ 0.85 µg/kg) at the Brazil nut processing plant. The results of aflatoxins obtained for the manually shelled nut samples ranged from 3.0 to 60.3 µg/g and from 2.0 to 31.0 µg/g for the automatically shelled samples. All samples showed levels of mc below the limit of 15%; on the other hand, shelled samples from both harvests showed levels of Aw above the limit. There were no significant differences concerning the manual or automatic shelling results during the sorting stages. On the other hand, the visual sorting was effective in decreasing the aflatoxin contamination in both methods.

Repercussão de um protocolo fisioterapêutico intradialítico na funcionalidade pulmonar, força de preensão manual e qualidade de vida de pacientes renais crônicos

INTRODUÇÃO: A doença renal crônica consiste na perda lenta, progressiva e irreversível da função renal. É considerada um problema social e economico, pois está relacionada a inúmeras doenças associadas, bem como a altos gastos em saúde pública. Sabe-se que os pacientes dialíticos passam por longos períodos de restrição da atividade física repercutindo em disfungoes nos mais diversos sistemas e na qualidade de vida (QV). OBJETIVO: Verificar os efeitos de uma intervenção fisioterapêutica nos pacientes em hemodiálise para: função da musculatura respiratória, força de preensão manual e QV. METODOLOGIA: Estudo experimental, não randomizado, quantitativo e qualitativo; amostra de 13 pacientes, 43,69 ± 9,28 anos, submetidos à hemodiálise na Santa Casa de Diamantina/MG, selecionados por conveniência. Todos realizaram avaliação das pressões respiratórias máximas (PImáx e PEmáx) e do pico de fluxo expiratório (PFE), antes e após a fisioterapia que consistiu de três sessões semanais, durante 2 meses de: exercícios para membros superiores, com técnica de FNP e respiração diafragmática; exercícios de fortalecimento para membros inferiores e exercícios com bola exercitadora para preensão manual. O tratamento estatístico foi realizado através do teste t de Student com valor de significância em p < 0,05. RESULTADOS: As médias respectivamente das variáveis pré- e pós-intervenção foram PI , (97,69 ± 28,3 cmH2O e 98,46 ± 23,399ªdriH2O) p = 0,93; PEmáx (83,07 ± 31,19 cmH2O e 88,46 ± 14,05 cmH2O) p = 0,46 e PFE (375,38 ± 75,23 L/min e 416,15 ± 57,37 L/min) p = 0,02. A media do dinamometro pré-intervenção: 57,23 ± 17,39 kgf e pósintervenção: 56,61 ± 16,09 kgf. No SF-36, que avalia QV, observou-se melhora dos oito domínios, exceto do item 'vitalidade'. De todas as variáveis mensuradas, somente o PFE mostrou-se estatisticamente significante. CONCLUSÃO: O protocolo fisioterapêutico proposto não promoveu melhoras expressivas, do ponto de vista estatístico, nas variáveis analisadas em pacientes submetidos à hemodiálise, justificando-se em parte ao número pequeno da amostra, tempo do protocolo e intervenções propostas.

Espessura do músculo adutor do polegar como preditor da força de preensão manual nos pacientes em hemodiálise

INTODUÇÃO: A espessura do músculo adutor do polegar (EMAP) tem sido sugerida como um novo marcador de estado nutricional em diversas populações. OBJETIVO: Diante da escassez de dados sobre o uso desse marcador nos pacientes com doença renal crônica, o objetivo deste estudo foi avaliar a EMAP e sua associação com indicadores nutricionais em pacientes em hemodiálise. MÉTODOS: Foram avaliados 73 pacientes em hemodiálise (52,3 ± 17 anos, sem função renal residual). A EMAP foi aferida no braço sem o acesso vascular com o auxílio de um adipômetro. A composição corporal (bioimpedância elétrica), a força de preensão manual (dinamômetro), o estado nutricional (Avaliação Global Subjetiva) e os exames laboratoriais (creatinina, proteína total e albumina) também foram avaliados. RESULTADOS: Indivíduos com valores de EMAP acima da mediana eram em maior proporção negros/pardos, jovens e possuíam maior força de preensão manual. A EMAP correlacionou-se positivamente com a força de preensão manual, albumina sérica e massa celular (%), e negativamente com a idade. Na análise de regressão linear ajustada para sexo, idade e tempo em hemodiálise, a EMAP esteve independentemente associada com a força de preensão manual. CONCLUSÃO: A EMAP foi capaz de predizer a força de preensão manual nos pacientes em hemodiálise, o que sugere a EMAP como um marcador promissor de estado nutricional nessa população.

Impacto da sessão de hemodiálise na força de preensão manual

Resumo Introdução: A força de preensão manual (FPM) é um método simples, confiável e com bom valor preditivo para avaliar a função muscular de pacientes submetidos à hemodiálise (HD). Porém, ainda não existe um consenso a respeito do momento mais apropriado para a aferição da medida, já que o desempenho da FPM pode ser influenciado pelas flutuações hidroeletrolíticas e de pressão arterial que acometem esses pacientes. Objetivo: Investigar o impacto da sessão de diálise sobre a FPM em pacientes submetidos à HD. Métodos: Trata-se de um estudo transversal com 156 pacientes [57,7% homens, idade mediana de 56,5 (42-67) anos, 28,8% diabéticos, IMC médio de 24,75 ± 4,5 kg/m2 e tempo em HD de 38 (19,25-72,75) meses]. Foram realizadas aferições da FPM com um dinamômetro nos minutos iniciais e ao término da sessão de HD. Os valores obtidos foram comparados com um padrão de referência nacional. Dados clínicos, demográficos e laboratoriais foram coletados do prontuário médico. Resultados: Foi observada uma redução significante da FPM após a sessão de HD (28,6 ± 11,4 kg para 27,7 ± 11,7 kg; p < 0,01). A prevalência de pacientes com FPM abaixo do percentil 30 aumentou de 44,9% para 55,1% (p < 0,01). A redução da pressão arterial durante a diálise foi o único fator que se associou com a redução da FPM. Conclusão: Os achados mostram que o processo de HD influencia negativamente a FPM.

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