Factors affecting executive function performance of Brazilian elderly in the Stroop test.

Aging is related to a decrease in physiological abilities, especially cognitive functions. To unravel further evidence of age-related cognitive decline, we analyzed which physical and functional variables are predictors of cognitive performance in a sample of 498 Brazilian elderly (67.26% women). To do so, we used the Stroop test as a tool to evaluate executive functions and the General functional fitness index (GFFI) to evaluate the functional fitness of the participants. A linear regression analysis revealed that female sex (ß=-0.097; t=-2.286; P=0.023), younger age (ß=0.205; t=4.606; P<0.0001), more years of education (ß=-0.280; t=-6.358; P<0.0001), and higher GFFI (ß=-0.101; t=-2.347; P<0.02) were predictors of better cognitive performance. Body mass index (kg/m2) and nutritional status (underweight, eutrophic, overweight, or obese) were not predictors of cognitive performance. Interestingly, among the GFFI tasks, muscle strength influenced the test execution time, both in upper and lower limbs (elbow flexion: ß=-0.201; t=-4.672; P<0.0001; sit-to-stand: ß=-0.125; t=-2.580; P<0.01). Our findings showed that: 1) women performed the Stroop test faster than men; 2) the older the person, the lower was the cognitive performance; 3) the higher the education, the better the test execution time; and 4) higher scores in the GFFI were associated with a better performance in the Stroop test. Therefore, gender, age, education, and functional fitness and capacity were predictors of cognitive performance in the elderly.

Factors affecting executive function performance of Brazilian elderly in the Stroop test

Aging is related to a decrease in physiological abilities, especially cognitive functions. To unravel further evidence of age-related cognitive decline, we analyzed which physical and functional variables are predictors of cognitive performance in a sample of 498 Brazilian elderly (67.26% women). To do so, we used the Stroop test as a tool to evaluate executive functions and the General functional fitness index (GFFI) to evaluate the functional fitness of the participants. A linear regression analysis revealed that female sex (β=-0.097; t=-2.286; P=0.023), younger age (β=0.205; t=4.606; P<0.0001), more years of education (β=-0.280; t=-6.358; P<0.0001), and higher GFFI (β=-0.101; t=-2.347; P<0.02) were predictors of better cognitive performance. Body mass index (kg/m2) and nutritional status (underweight, eutrophic, overweight, or obese) were not predictors of cognitive performance. Interestingly, among the GFFI tasks, muscle strength influenced the test execution time, both in upper and lower limbs (elbow flexion: β=-0.201; t=-4.672; P<0.0001; sit-to-stand: β=-0.125; t=-2.580; P<0.01). Our findings showed that: 1) women performed the Stroop test faster than men; 2) the older the person, the lower was the cognitive performance; 3) the higher the education, the better the test execution time; and 4) higher scores in the GFFI were associated with a better performance in the Stroop test. Therefore, gender, age, education, and functional fitness and capacity were predictors of cognitive performance in the elderly.

A single episode of high intensity sound inhibits long-term potentiation in the hippocampus of rats.

Exposure to loud sounds has become increasingly common. The most common consequences of loud sound exposure are deafness and tinnitus, but emotional and cognitive problems are also associated with loud sound exposure. Loud sounds can activate the hipothalamic-pituitary-adrenal axis resulting in the secretion of corticosterone, which affects hippocampal synaptic plasticity. Previously we have shown that long-term exposure to short episodes of high intensity sound inhibited hippocampal long-term potentiation (LTP) without affecting spatial learning and memory. Here we aimed to study the impact of short term loud sound exposure on hippocampal synaptic plasticity and function. We found that a single minute of 110 dB sound inhibits hippocampal Schaffer-CA1 LTP for 24 hours. This effect did not occur with an 80-dB sound exposure, was not correlated with corticosterone secretion and was also observed in the perforant-dentate gyrus synapse. We found that despite the deficit in the LTP these animals presented normal spatial learning and memory and fear conditioning. We conclude that a single episode of high-intensity sound impairs hippocampal LTP, without impairing memory and learning. Our results show that the hippocampus is very responsive to loud sounds which can have a potential, but not yet identified, impact on its function.

Fine needle aspiration cytology in feline skeletal muscle as a diagnostic tool for extramedullary plasmacytoma / Citologia aspirativa por agulha fina no músculo esquelético felino como ferramenta diagnóstica para o plasmocitoma extramedular

Extramedullary noncutaneous plasmacytoma (ENP) is a myeloproliferative disorder of plasma cells that rarely affects cats. This paper describes an ENP case revealed by fine needle aspiration cytology (FNAC) of the mass in the skeletal muscle of an 8-month-old, male, mixed breed cat, which had a nodule in the left hind limb. The rapid immunoassay test confirmed the presence of feline leukemia virus (FeLV). The animal necropsy macroscopically showed the nodule came from the semimembranosus muscle. Histopathological examination ratified the cytological findings. Thus, this paper alerts to the existence of plasmacytoma located in the skeletal muscle of feline species. FNAC is a quick and efficient method for diagnosis of ENP.(AU)

O plasmocitoma extramedular (PEM) não cutâneo é um distúrbio mieloproliferativo de plasmócitos que raramente acomete felinos. Este trabalho descreve um caso de PEM no músculo esquelético de um gato, macho, sem raça definida, de oito meses de idade, que apresentava um aumento de volume no membro pélvico esquerdo. A citologia aspirativa por agulha fina (CAAF) da massa revelou tratar-se de PEM. O teste imunoenzimático rápido confirmou a presença do vírus da leucemia felina (FeLV). Na necropsia do animal, macroscopicamente, percebeu-se que o nódulo era originário do músculo semimembranoso. O exame histopatológico ratificou os achados citológicos. Desta forma, alerta-se para a existência de plasmocitoma com localização em músculo esquelético na espécie felina, sendo a CAAF um método alternativo rápido e eficaz para o seu diagnóstico.(AU)

Genetic ACE I/D and ACTN3 R577X polymorphisms and adolescent idiopathic scoliosis.

The etiology of adolescent idiopathic scoliosis remains unknown. Angiotensin-converting enzyme and α-actinin-3 polymorphisms influence the characteristics of muscle fibers. The aim of this study was to examine the association between idiopathic scoliosis and genetic polymorphism of angiotensin-converting enzyme and α-actinin-3. Ninety-seven females with scoliosis, and 137 healthy, age-matched control females were studied. The presence of polymorphisms was determined by PCR. A χ2 test was used to analyze differences, and odds ratios were estimated. The frequencies of ACE genotypes in the scoliotic group were 46.4% DD, 45.4% ID, and 8.2% II, while in the control group they were 40.1% DD, 43.8% ID, and 16.1% II (P = 0.197). The D allele had a frequency of 69.1% in patients with idiopathic scoliosis and 62% in the control group (P = 0.116). The frequencies of ACTN3 genotypes in females with scoliosis were 31.8% RR, 49.4% RX, and 18.8% XX, while in the control group they were 35% RR, 49% RX, and 16% XX (P = 0.810). The frequency of the R allele was 56.4% in the scoliotic group and 59.6% in the control group (P = 0.518). There was no statistically significant association between angiotensin-converting enzyme or α-actinin-3 polymorphisms and the presence of adolescent idiopathic scoliosis in females.

Inhibition of long-term potentiation in the schaffer-CA1 pathway by repetitive high-intensity sound stimulation.

High-intensity sound can induce seizures in susceptible animals. After repeated acoustic stimuli changes in behavioural seizure repertoire and epileptic EEG activity might be seen in recruited limbic and forebrain structures, a phenomenon known as audiogenic kindling. It is postulated that audiogenic kindling can produce synaptic plasticity events leading to the spread of epileptogenic activity to the limbic system. In order to test this hypothesis, we investigated if long-term potentiation (LTP) of hippocampal Schaffer-CA1 synapses and spatial navigation memory are altered by a repeated high-intensity sound stimulation (HISS) protocol, consisting of one-minute 120 dB broadband noise applied twice a day for 10 days, in normal Wistar rats and in audiogenic seizure-prone rats (Wistar Audiogenic Rats - WARs). After HISS all WARs exhibited midbrain seizures and 50% of these animals developed limbic recruitment, while only 26% of Wistar rats presented midbrain seizures and none of them had limbic recruitment. In naïve animals, LTP in hippocampal CA1 neurons was induced by 50- or 100-Hz high-frequency stimulation of Schaffer fibres in slices from both Wistar and WAR animals similarly. Surprisingly, HISS suppressed LTP in CA1 neurons in slices from Wistar rats that did not present any seizure, and inhibited LTP in slices from Wistar rats with only midbrain seizures. However HISS had no effect on LTP in CA1 neurons from slices of WARs. Interestingly HISS did not alter spatial navigation and memory in both strains. These findings show that repeated high-intensity sound stimulation prevent LTP of Schaffer-CA1 synapses from Wistar rats, without affecting spatial memory. This effect was not seen in hippocampi from audiogenic seizure-prone WARs. In WARs the link between auditory stimulation and hippocampal LTP seems to be disrupted which could be relevant for the susceptibility to seizures in this strain.

Eating behaviours in youths: A comparison between female and male athletes and non-athletes.

This study compared the different factors associated with eating behaviors among young female and male athletes and non-athletes. A total of 580 female and male athletes and 362 female and male non-athletes between 10 and 19 years old participated. We used the subscales of the Eating Attitudes Test (EAT-26) to evaluate the factors associated with unhealthy eating behaviors. We found higher scores for females on the diet subscale compared with males, regardless of athletic group (P < 0.05). Non-athlete youths scored higher on this subscale compared with male athletes (P < 0.05). Our findings indicate higher scores for female athletes with regard to the bulimia and preoccupation with food subscale compared with other the groups (P < 0.05). Moreover, we observed that non-athlete males were more likely to engage in binge eating compared with athletes of the same sex (P < 0.05). Finally, females had higher scores on the oral self subscale than males, regardless of athletic group (P < 0.05). We concluded that the factors associated with eating behaviors differ with regard to sex and group.

In silico prediction of conserved vaccine targets in Streptococcus agalactiae strains isolated from fish, cattle, and human samples.

Streptococcus agalactiae (Lancefield group B; group B streptococci) is a major pathogen that causes meningoencephalitis in fish, mastitis in cows, and neonatal sepsis and meningitis in humans. The available prophylactic measures for conserving human and animal health are not totally effective and have limitations. Effective vaccines against the different serotypes or genotypes of pathogenic strains from the various hosts would be useful. We used an in silico strategy to identify conserved vaccine candidates in 15 genomes of group B streptococci strains isolated from human, bovine, and fish samples. The degree of conservation, subcellular localization, and immunogenic potential of S. agalactiae proteins were investigated. We identified 36 antigenic proteins that were conserved in all 15 genomes. Among these proteins, 5 and 23 were shared only by human or fish strains, respectively. These potential vaccine targets may help develop effective vaccines that will help prevent S. agalactiae infection.

Carbamazepine inhibits angiotensin I-converting enzyme, linking it to the pathogenesis of temporal lobe epilepsy.

We find that a common mutation that increases angiotensin I-converting enzyme activity occurs with higher frequency in male patients suffering from refractory temporal lobe epilepsy. However, in their brains, the activity of the enzyme is downregulated. As an explanation, we surprisingly find that carbamazepine, commonly used to treat epilepsy, is an inhibitor of the enzyme, thus providing a direct link between epilepsy and the renin-angiotensin and kallikrein-kinin systems.

The status of conservation of urban forests in eastern Amazonia.

This study aims to identify the remnant tree flora in six forest fragments in the metropolitan area of Belém and to analyze these fragments in terms of biological conservation, species richness and diversity in the local urban landscape. The fragments and their respective sampling areas were as follows: Amafrutas reserve (15 ha), Trambioca Is. reserve (2 ha), Bosque Rodrigues Alves city park (15 ha), Combu Is. reserve (10 ha), Gunma Park reserve (10 ha) and Mocambo reserve (5 ha). Inventories were built from lineal plots of 250 m² and included trees with DBH equal to or greater than 10 cm at a height of 1.3 m above ground. Sixty-nine families and 759 species, of which eight were officially listed as endangered (Brazilian National Flora: Ministry of Environment, Normative Instruction of September, 2008; Pará State Flora: Decree Nº. 802 of February 2008) were recorded. These endangered species are: Aspidosperma desmanthum Benth. ex Müll. Arg. (Apocynaceae), Cedrela odorata L. (Meliaceae), Eschweilera piresii S.A Mori (Lecythidaceae), Euxylophora paraensis Huber (Rutaceae), Hymenolobium excelsum Ducke (Leguminosae), Manilkara huberi (Ducke) Chevalier (Sapotaceae), Tabebuia impetiginosa (Mart. ex DC.) Standl. (Bignoniaceae), Mezilaurus itauba (Meisn.) Taub. ex Mez (Lauraceae) and Qualea coerulea Aubl. (Vochysiaceae). Emergency actions such as implementing management plans for already existing Conservation Units, the creation of new such units in areas of primary forest fragments (as in the case of the Amafrutas reserve), as well as the intensification of actions of surveillance and monitoring, should be undertaken by Federal, State, and Municipal environmental agencies so as to ensure the conservation of these last primary forest remnants in the metropolitan area of Belém.

Effects of postnatal protein malnutrition on learning and memory procedures.

Protein malnutrition induces structural, neurochemical and functional changes in the central nervous system leading to alterations in cognitive and behavioral development of rats. The aim of this work was to investigate the effects of postnatal protein malnutrition on learning and memory tasks. Previously malnourished (6% protein) and well-nourished rats (16% protein) were tested in three experiments: working memory tasks in the Morris water maze (Experiment I), recognition memory of objects (Experiment II), and working memory in the water T-maze (Experiment III). The results showed higher escape latencies in malnourished animals in Experiment I, lower recognition indexes of malnourished animals in Experiment II, and no differences due to diet in Experiment III. It is suggested that protein malnutrition imposed on early life of rats can produce impairments on both working memory in the Morris maze and recognition memory in the open field tests.

Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon.

*The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. *Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. *Total ecosystem respiration (R(eco)) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (R(auto))), were elevated on the TFE plot relative to the control. The increase in PCE and R(eco) was mainly caused by a rise in R(auto) from foliage and roots. Heterotrophic respiration did not differ substantially between plots. NPP was 2.4 +/- 1.4 t C ha(-1) yr(-1) lower on the TFE than the control. Ecosystem carbon use efficiency, the proportion of PCE invested in NPP, was lower in the TFE plot (0.24 +/- 0.04) than in the control (0.32 +/- 0.04). *Drought caused by the TFE treatment appeared to drive fundamental shifts in ecosystem C cycling with potentially important consequences for long-term forest C storage.

Plasma Kallikrein and Angiotensin I-converting enzyme N- and C-terminal domain activities are modulated by the insertion/deletion polymorphism.

Angiotensin I-converting enzyme (ACE) is recognized as one of the main effector molecules involved in blood pressure regulation. In the last few years some polymorphisms of ACE such as the insertion/deletion (I/D) polymorphism have been described, but their physiologic relevance is poorly understood. In addition, few studies investigated if the specific activity of ACE domain is related to the I/D polymorphism and if it can affect other systems. The aim of this study was to establish a biochemical and functional characterization of the I/D polymorphism and correlate this with the corresponding ACE activity. For this purpose, 119 male brazilian army recruits were genotyped and their ACE plasma activities evaluated from the C- and N-terminal catalytic domains using fluorescence resonance energy transfer (FRET) peptides, specific for the C-domain (Abz-LFK(Dnp)OH), N-domain (Abz-SDK(Dnp)P-OH) and both C- and N-domains (Abz-FRK(Dnp)P-OH). Plasma kallikrein activity was measured using Z-Phe-Arg-AMC as substrate and inhibited by selective plasma kallikrein inhibitor (PKSI). Some physiological parameters previously described related to the I/D polymorphism such as handgrip strength, blood pressure, heart rate and BMI were also evaluated. The genotype distribution was II n=27, ID n=64 and DD n=28. Total plasma ACE activity of both domains in II individuals was significantly lower in comparison to ID and DD. This pattern was also observed for C- and N-domain activities. Difference between ID and DD subjects was observed only with the N-domain specific substrate. Blood pressure, heart rate, handgrip strength and BMI were similar among the genotypes. This polymorphism also affected the plasma kallikrein activity and DD group presents high activity level. Thus, our data demonstrate that the I/D ACE polymorphism affects differently both ACE domains without effects on handgrip strength. Moreover, this polymorphism influences the kallikrein-kinin system of normotensive individuals.

Efficient method for obtaining Lep(ob)/Lep(ob)-derived animal models using adipose tissue transplantations.

BACKGROUND: Leptin-deficient mice (Lep(ob)/Lep(ob), also known as ob/ob) are of great importance for studies of obesity, diabetes and other correlated pathologies. Thus, generation of animals carrying the Lep(ob) gene mutation as well as additional genomic modifications has been used to associate genes with metabolic diseases. However, the infertility of Lep(ob)/Lep(ob) mice impairs this kind of breeding experiment. OBJECTIVE: To propose a new method for production of Lep(ob)/Lep(ob) animals and Lep(ob)/Lep(ob)-derived animal models by restoring the fertility of Lep(ob)/Lep(ob) mice in a stable way through white adipose tissue transplantations. METHODS: For this purpose, 1 g of peri-gonadal adipose tissue from lean donors was used in subcutaneous transplantations of Lep(ob)/Lep(ob) animals and a crossing strategy was established to generate Lep(ob)/Lep(ob)-derived mice. RESULTS: The presented method reduced by four times the number of animals used to generate double transgenic models (from about 20 to 5 animals per double mutant produced) and minimized the number of genotyping steps (from 3 to 1 genotyping step, reducing the number of Lep gene genotyping assays from 83 to 6). CONCLUSION: The application of the adipose transplantation technique drastically improves both the production of Lep(ob)/Lep(ob) animals and the generation of Lep(ob)/Lep(ob)-derived animal models.

Differential response to gepirone but not to chlordiazepoxide in malnourished rats subjected to learned helplessness

The learned helplessness (LH) paradigm is characterized by learning deficits resulting from inescapable events. The aims of the present study were to determine if protein-calorie malnutrition (PCM) alters learning deficits induced by LH and if the neurochemical changes induced by malnutrition alter the reactivity to treatment with GABA-ergic and serotonergic drugs during LH. Well-nourished (W) and PCM Wistar rats (61 days old) were exposed or not to inescapable shocks (IS) and treated with gepirone (GEP, 0.0-7.5 mg/kg, intraperitoneally, N = 128) or chlordiazepoxide (0.0-7.5 mg/kg, intraperitoneally, N = 128) 72 h later, 30 min before the test session (30 trials of escape learning). The results showed that rats exposed to IS had higher escape latency than non-exposed rats (12.6 ± 2.2 vs 4.4 ± 0.8 s) and that malnutrition increased learning impairment produced by LH. GEP increased the escape latency of W animals exposed or non-exposed to IS, but did not affect the response of PCM animals, while chlordiazepoxide reduced the escape deficit of both W and PCM rats. The data suggest that PCM animals were more sensitive to the impairment produced by LH and that PCM led to neurochemical changes in the serotonergic system, resulting in hyporeactivity to the anxiogenic effects of GEP in the LH paradigm.

Differential response to gepirone but not to chlordiazepoxide in malnourished rats subjected to learned helplessness.

The learned helplessness (LH) paradigm is characterized by learning deficits resulting from inescapable events. The aims of the present study were to determine if protein-calorie malnutrition (PCM) alters learning deficits induced by LH and if the neurochemical changes induced by malnutrition alter the reactivity to treatment with GABA-ergic and serotonergic drugs during LH. Well-nourished (W) and PCM Wistar rats (61 days old) were exposed or not to inescapable shocks (IS) and treated with gepirone (GEP, 0.0-7.5 mg/kg, intraperitoneally, N = 128) or chlordiazepoxide (0.0-7.5 mg/kg, intraperitoneally, N = 128) 72 h later, 30 min before the test session (30 trials of escape learning). The results showed that rats exposed to IS had higher escape latency than non-exposed rats (12.6 +/- 2.2 vs 4.4 +/- 0.8 s) and that malnutrition increased learning impairment produced by LH. GEP increased the escape latency of W animals exposed or non-exposed to IS, but did not affect the response of PCM animals, while chlordiazepoxide reduced the escape deficit of both W and PCM rats. The data suggest that PCM animals were more sensitive to the impairment produced by LH and that PCM led to neurochemical changes in the serotonergic system, resulting in hyporeactivity to the anxiogenic effects of GEP in the LH paradigm.

Early postnatal protein malnutrition causes resistance to the anxiolytic effects of diazepam as assessed by the fear-potentiated startle test.

Given that protein malnutrition induces structural, neurochemical and functional changes in the CNS, the present study aimed to investigate the effects of different early periods of protein malnutrition on the behavior and reactivity to diazepam (DZ) in a model of anxiety: the fear-potentiated startle (FPS). Male Wistar rats (n = 110) from well-nourished (16 %-protein) or malnourished (6%-protein) litters were distributed in five different groups: W (well-nourished), M7 (malnourished for 7-days, since day 0), M14 (14-days), M21 (21-days) and M28 (28-days). The results obtained in FPS revealed that malnourished-animals acquired the startle response, irrespective of the time they were exposed to the diet. Besides, DZ reduced the startle amplitude in the noise-alone and light-noise trials. The data concerning the total freezing time showed that the expression of this response was affected by malnutrition and varied in accordance with the findings of previous studies in which malnutrition procedures was imposed for long periods (more than 50 days). Therefore, we suggest that early protein malnutrition: (a) did not produce deficits in the associative learning process of these animals in the FPS, and (b) decreased freezing time in the FPS and produce hyporeactivity to the effects of DZ in rats malnourished for 21 days or more, indicating alterations in the GABAergic neurotransmitter system.

A method for extracting plant roots from soil which facilitates rapid sample processing without compromising measurement accuracy.

This study evaluates a novel method for extracting roots from soil samples and applies it to estimate standing crop root mass (+/- confidence intervals) in an eastern Amazon rainforest. Roots were manually extracted from soil cores over a period of 40 min, which was split into 10 min time intervals. The pattern of cumulative extraction over time was used to predict root extraction beyond 40 min. A maximum-likelihood approach was used to calculate confidence intervals. The temporal prediction method added 21-32% to initial estimates of standing crop root mass. According to predictions, complete manual root extraction from 18 samples would have taken c. 239 h, compared with 12 h using the prediction method. Uncertainties (percentage difference between mean, and 10th and 90th percentiles) introduced by the prediction method were small (12-15%), compared with uncertainties caused by spatial variation in root mass (72-191%, for nine samples per plot surveyed). This method provides a way of increasing the number of root samples processed per unit time, without compromising measurement accuracy.

Effects of early protein malnutrition and scopolamine on learning and memory in the Morris water maze.

The present study investigated the effects of early protein malnutrition on the spatial learning and memory processes. The consequences of malnutrition for the cholinergic system were evaluated by comparing the performance of malnourished and control animals in the Morris water maze after treatment with scopolamine. The learning test consisted of placing the animal in the maze to escape to a submerged platform with 12 trials per day for two consecutive days. After 24 trials, the platform was removed, the rats were placed in the maze and the time spent by them in each quadrant was recorded. After 28 days the animals were tested in a single trial to verify the retention of the spatial information. In the first Experiment, scopolamine (0.0, 0.2, 0.4 and 0.6 mg/kg per ml. i.p.) was administered 20 min before the experimental sessions. In the second experiment, a dose of 0.6 mg/kg was administered after the sessions, during the period in which learning consolidation occurs. In the first experiment, there was a significant effect of the drug, with scopolamine impairing, learning in both nutritional conditions. In the saline condition, control animals presented a better performance when compared with malnourished animals. However, 28 days later, both groups increased their latencies. With 0.2 and 0.4 mg/kg of scopolamine, the performance of both nutritional groups was similar and with 0.6 mg/kg malnourished animals performed better than controls. In the second experiment, malnourished animals were also less reactive to the effects of scopolamine, resulting in lower impairments as compared to control animals. These data suggest long-term changes in learning and memory as the result of changes produced by protein malnutrition in the cholinergic neurotransmitter system.

The interaction of housing condition and acute immobilization stress on the elevated plus-maze behaviors of protein-malnourished rats.

Protein malnutrition induces structural, neurochemical and functional alterations in the central nervous system, leading to behavioral alterations. In the present study, we used the elevated plus-maze (EPM) as a measure of anxiety to evaluate the interaction between acute immobilization and housing conditions on the behavior of malnourished rats. Pups (6 males and 2 females) were fed by Wistar lactating dams receiving a 6% (undernourished) or 16% (well-nourished) protein diet. After weaning, the animals continued to receive the same diets ad libitum until 49 days of age when they started to receive a regular lab chow diet. From weaning to the end of the tests on day 70, the animals were housed under two different conditions, i.e., individual or in groups of three. On the 69th day, half of the animals were submitted to immobilization for 2 h, while the other half were undisturbed, and both groups were tested 24 h later for 5 min in the EPM. Independent of other factors, protein malnutrition increased, while immobilization and social isolation per se decreased, EPM exploration. Analysis of the interaction of diet vs immobilization vs housing conditions showed that the increased EPM exploration presented by the malnourished group was reversed by acute immobilization in animals reared in groups but not in animals reared individually. The interaction between immobilization and housing conditions suggests that living for a long time in social isolation is sufficiently stressful to reduce the responses to another anxiogenic procedure (immobilization), while living in groups prompts the animals to react to acute stress. Thus, it is suggested that housing condition can modulate the effects of an anxiogenic procedure on behavioral responses of malnourished rats in the EPM.