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1.
Braz J Med Biol Res ; 52(4): e8041, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30994731

RESUMO

Although normal aging has been related to several cognitive difficulties, other processes have been studied less, such as spatial memory. Our aim was to compare egocentric and allocentric memory in an elderly population using ecological tasks. Twenty-eight cognitively unimpaired participants performed Egocentric and Allocentric Spatial Memory Tasks, as well as Spatial Span from CANTAB, Benton's Judge of Line Orientation test (JoLO), and Montreal Cognitive Assessment test (MoCA). The results revealed that younger participants showed better performance than older participants on both the Egocentric and Allocentric Spatial Memory Tasks, although only the Egocentric test was able to discriminate between younger, middle, and older elderly participants. Learning effect was found in Allocentric Spatial Memory Task in younger and older groups, but not in the middle group. Allocentric and egocentric performance was not related to other visuospatial neuropsychological scores and gender did not influence performance in any task. Egocentric and Allocentric Spatial Memory Tasks may be useful tools in early screening for cognitive decline, as they are able to detect age differences in the cognitive unimpaired elderly population.


Assuntos
Envelhecimento Saudável/fisiologia , Envelhecimento Saudável/psicologia , Percepção Espacial/fisiologia , Memória Espacial/fisiologia , Análise e Desempenho de Tarefas , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Envelhecimento/psicologia , Análise de Variância , Disfunção Cognitiva/fisiopatologia , Disfunção Cognitiva/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fatores Sexuais , Navegação Espacial/fisiologia
2.
Behav Brain Res ; 359: 694-700, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30273614

RESUMO

Spatial memory allows us to locate objects and organisms in space and move through the environment. We frequently use two strategies for this purpose: egocentric, related to the viewer's perspective, and allocentric, associated with environmental cues. This ability is usually assessed by 2D or virtual reality-based tasks. Gender differences have been reported on these tasks. We designed two card-placing tasks with the aim of assessing egocentric and allocentric spatial memory in a real environment. This task makes it possible to separately compare egocentric and allocentric strategies, providing participants with 3D information naturally present in daily orientation activities. We will assess the performance of male and female young adults on the two strategies. Ninety-four subjects were recruited and performed egocentric and allocentric spatial memory card placing tasks. Spatial Span, forward and backward, was also assessed using the Cambridge Neuropsychological Assessment Battery (CANTAB), and the brief version of Benton's Judge of Line Orientation Test (JoLO) was used to evaluate the ability to judge spatial relations. Our results show that men outperformed women on both spatial memory tasks. Women performed better on Allocentric tasks than on Egocentric tasks, whereas men's scores did not show differences between strategies. Spatial memory performance on the card placing tasks was significantly correlated with performance on the backward visuospatial span from the CANTAB. This study supports the existence of gender differences in spatial memory functioning, and it provides novel tools for the neuropsychological assessment of spatial memory.


Assuntos
Memória Espacial , Adulto , Feminino , Humanos , Testes Psicológicos , Autoimagem , Fatores Sexuais , Adulto Jovem
3.
Appl Biochem Biotechnol ; 187(1): 101-115, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29948996

RESUMO

Avian eggshell membranes are good candidates as a matrix for immobilization procedures. Chicken eggshell, a waste material available from the poultry industry as a byproduct, is a very safe and cheap raw material. While pieces of eggshell membrane, or even particles from whole eggshell, have been previously used for these purposes, we report here the use of eggshell membrane powder for E. coli ß-galactosidase immobilization with glutaraldehyde as cross-linker. A kinetic characterization is provided for eggshell membrane powder-bound enzyme compared to free enzyme. Results show a remarkable similarity between bound and free enzyme and also that the immobilized enzyme is stable and can be reused several times. Moreover, bound enzyme is able to produce glucose from skim milk serum.


Assuntos
Casca de Ovo/química , Enzimas Imobilizadas/metabolismo , Pós , Resíduos , beta-Galactosidase/metabolismo , Animais , Galinhas , Escherichia coli/enzimologia , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Leite/química
4.
Braz. j. med. biol. res ; 52(4): e8041, 2019. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1001510

RESUMO

Although normal aging has been related to several cognitive difficulties, other processes have been studied less, such as spatial memory. Our aim was to compare egocentric and allocentric memory in an elderly population using ecological tasks. Twenty-eight cognitively unimpaired participants performed Egocentric and Allocentric Spatial Memory Tasks, as well as Spatial Span from CANTAB, Benton's Judge of Line Orientation test (JoLO), and Montreal Cognitive Assessment test (MoCA). The results revealed that younger participants showed better performance than older participants on both the Egocentric and Allocentric Spatial Memory Tasks, although only the Egocentric test was able to discriminate between younger, middle, and older elderly participants. Learning effect was found in Allocentric Spatial Memory Task in younger and older groups, but not in the middle group. Allocentric and egocentric performance was not related to other visuospatial neuropsychological scores and gender did not influence performance in any task. Egocentric and Allocentric Spatial Memory Tasks may be useful tools in early screening for cognitive decline, as they are able to detect age differences in the cognitive unimpaired elderly population.

5.
J Struct Biol ; 196(2): 187-196, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27717839

RESUMO

Biominerals are inorganic-organic hybrid composites formed via self-assembled bottom up processes under mild conditions. Biominerals show interesting physical properties, controlled hierarchical structures and robust remodeling or repair mechanisms. Biological processes associated with biominerals remain to be developed into practical engineering processes. Therefore, the formation of biominerals is inspiring for the design of materials, especially those fabricated at ambient temperatures. The study described herein involves the influence of chicken outer eggshell membrane on the type of calcium carbonate (CaCO3) polymorph deposited on the shell of the land snail Helix aspersa during the repair process after an injury. A piece of snail shell was removed by perforating a hole from the largest body whorl. The operated area was left either uncovered or covered with either a thermoplastic flexible polyolefin-based film Parafilm® or a piece of chicken eggshell membrane. The repaired shells of control and experimental animals were analyzed using SEM, EDS, Raman and FTIR spectroscopies. We found that in the presence of eggshell membrane, the polymorph deposited on the substratum during the first hours resembles calcite, the polymorph present in eggshell normal formation, but at 24 and 48h, when snail mantle cells produced their normal organic matrix (mainly ß-chitin plus proteins and proteoglycans), the polymorph deposited is aragonite, the characteristic polymorph of Helix shell. Therefore, the eggshell membrane influences the type of polymorph, but only in the initial stages of biomineral deposition, before an organic matrix layer is deposited by the snail.


Assuntos
Calcificação Fisiológica , Casca de Ovo/ultraestrutura , Membranas/fisiologia , Animais , Galinhas , Membranas/química , Microscopia , Caramujos , Análise Espectral , Cicatrização
6.
J Struct Biol ; 191(3): 263-71, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26276577

RESUMO

Comparative analyzes of biomineralization models have being crucial for the understanding of the functional properties of biominerals and the elucidation of the processes through which biomacromolecules control the synthesis and structural organization of inorganic mineral-based biomaterials. Among calcium carbonate-containing bioceramics, egg, mollusk and echinoderm shells, and crustacean carapaces, have being fairly well characterized. However, Thoraceca barnacles, although being crustacea, showing molting cycle, build a quite stable and heavily mineralized shell that completely surround the animal, which is for life firmly cemented to the substratum. This makes barnacles an interesting model for studying processes of biomineralization. Here we studied the main microstructural and ultrastructural features of Austromegabalanus psittacus barnacle shell, characterize the occurrence of specific proteoglycans (keratan-, dermatan- and chondroitin-6-sulfate proteoglycans) in different soluble and insoluble organic fractions extracted from the shell, and tested them for their ability to crystallize calcium carbonate in vitro. Our results indicate that, in the barnacle model, proteoglycans are good candidates for the modification of the calcite crystal morphology, although the cooperative effect of some additional proteins in the shell could not be excluded.


Assuntos
Exoesqueleto/ultraestrutura , Proteoglicanas/ultraestrutura , Thoracica/ultraestrutura , Animais , Materiais Biocompatíveis/metabolismo , Carbonato de Cálcio/metabolismo , Cristalização
7.
Behav Brain Res ; 292: 44-9, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26072392

RESUMO

Contextual memory implies recognition based on the association between past and present events experienced. It is important for daily functioning and dysfunctional in many neuropsychological disturbances. The network related to this memory is still open for debate, even though it has been associated with medial temporal lobe regions, including the perirhinal, entorhinal and temporal association cortices, as well as the hippocampus and prefrontal cortex. Our work tries to elucidate whether a change in the context, such as differences in the amount of stimuli presented on the walls and floor of an open field during object exploration, affects the recognition of an object that has been experienced before, and whether this context manipulation could be linked to changes in c-Fos expression. For this purpose, we used a one-trial novel-object recognition task. The animals were divided into two different experimental conditions; in the OR-NORMAL group, the sample and probe test were performed in the same context. However, in the OR-CONTEXT group, the probe test was performed in a different context. Our results showed that the OR-NORMAL group presented a greater exploration of objects than the OR-CONTEXT group. However, both groups presented significant exploration of the novel object. To label the brain regions involved in novel-object recognition under these conditions, we marked the expression of c-Fos protein. Results suggest that a neural circuit that includes the hippocampus, entorhinal and temporal association cortices is involved in the recognition of the novel-object in a novel context.


Assuntos
Hipocampo/fisiologia , Memória/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Reconhecimento Psicológico/fisiologia , Animais , Comportamento Animal/fisiologia , Córtex Entorrinal/fisiologia , Comportamento Exploratório/fisiologia , Hipocampo/metabolismo , Masculino , Córtex Pré-Frontal/fisiologia , Ratos , Ratos Wistar , Lobo Temporal/fisiologia , Percepção Visual/fisiologia
8.
Neurosci Lett ; 600: 153-7, 2015 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-26071902

RESUMO

Reversal learning has been studied as the process of learning to inhibit previously rewarded actions. These behavioral studies are usually performed during the day, when animals are in their daily period rest. However, how day or night affects spatial reversal learning and the brain regions involved in the learning process are still unknown. We conducted two experiments using the Morris Water Maze under different light-conditions: naïve group (CN, n=8), day group (DY, n=8), control DY group (CDY, n=8) night group (NG, n=8), and control NG group (CNG, n=7). Distance covered, velocity and latencies to reach the platform were examined. After completing these tasks, cytochrome c-oxidase activity (CO) in several brain limbic system structures was compared between groups. There were no behavioral differences in the time of day when the animals were trained. However, the metabolic brain consumption was higher in rats trained in the day condition. This CO increase was supported by the prefrontal cortex, thalamus, dorsal and ventral striatum, hippocampus and entorhinal cortex, revealing their role in the performance of the spatial reversal learning task. Finally, the orbitofrontal cortex has been revealed as a key structure in reversal learning execution.


Assuntos
Ritmo Circadiano , Sistema Límbico/fisiologia , Reversão de Aprendizagem/efeitos dos fármacos , Animais , Escuridão , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Inibição Psicológica , Luz , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Córtex Pré-Frontal/fisiologia , Ratos Wistar
9.
Physiol Behav ; 149: 220-8, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26048304

RESUMO

Hepatic encephalopathy (HE) is a neurological complication observed in patients with liver disease. Patients who suffer from HE present neuropsychiatric, neuromuscular and behavioral symptoms. Animal models proposed to study HE resulting from cirrhosis mimic the clinical characteristics of cirrhosis and portal hypertension, and require the administration of hepatotoxins such as thioacetamide (TAA). The aim of this study was to assess the effects of a high protein diet on motor function, anxiety and memory processes in a model of cirrhosis induced by TAA administration. In addition, we used cytochrome c-oxidase (COx) histochemistry to assess the metabolic activity of the limbic system regions. Male rats were distributed into groups: control, animals with cirrhosis, Control rats receiving a high protein diet, and animals with cirrhosis receiving a high protein diet. Results showed preserved motor function and normal anxiety levels in all the groups. The animals with cirrhosis showed an impairment in active avoidance behavior and spatial memory, regardless of the diet they received. However, the animals with cirrhosis and a high protein diet showed longer escape latencies on the spatial memory task. The model of cirrhosis presented an under-activation of the dentate gyrus and CA3 hippocampal subfields and the medial part of the medial mammillary nucleus. The results suggest that a high protein intake worsens spatial memory deficits shown by the TAA-induced model of cirrhosis. However, high protein ingestion has no influence on the COx hypoactivity associated with the model.


Assuntos
Encéfalo/metabolismo , Transtornos Cognitivos/dietoterapia , Transtornos Cognitivos/etiologia , Cirrose Hepática/complicações , Cirrose Hepática/patologia , Proteínas/administração & dosagem , Análise de Variância , Animais , Aprendizagem por Associação/fisiologia , Peso Corporal , Modelos Animais de Doenças , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Comportamento Exploratório/fisiologia , Fígado/patologia , Cirrose Hepática/induzido quimicamente , Masculino , Aprendizagem em Labirinto/fisiologia , Atividade Motora/fisiologia , Ratos , Ratos Wistar , Tioacetamida/toxicidade
10.
Int J Pharm ; 487(1-2): 205-12, 2015 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-25899283

RESUMO

Nanoplatforms can optimize the efficacy and safety of chemotherapy, and thus cancer therapy. However, new approaches are encouraged in developing new nanomedicines against malignant cells. In this work, a reproducible methodology is described to prepare Δ(9)-tetrahidrocannabinol (Δ(9)-THC)-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles against lung cancer. The nanoformulation is further improved by surface functionalization with the biodegradable polymers chitosan and poly(ethylene glycol) (PEG) in order to optimize the biological fate and antitumor effect. Mean nanoparticle size (≈ 290 nm) increased upon coating with PEG, CS, and PEG-CS up to ≈ 590 nm, ≈ 745 nm, and ≈ 790 nm, respectively. Surface electrical charge was controlled by the type of polymeric coating onto the PLGA particles. Drug entrapment efficiencies (≈ 95%) were not affected by any of the polymeric coatings. On the opposite, the characteristic sustained (biphasic) Δ(9)-THC release from the particles can be accelerated or slowed down when using PEG or chitosan, respectively. Blood compatibility studies demonstrated the adequate in vivo safety margin of all of the PLGA-based nanoformulations, while protein adsorption investigations postulated the protective role of PEGylation against opsonization and plasma clearance. Cell viability studies comparing the activity of the nanoformulations against human A-549 and murine LL2 lung adenocarcinoma cells, and human embryo lung fibroblastic MRC-5 cells revealed a statistically significant selective cytotoxic effect toward the lung cancer cell lines. In addition, cytotoxicity assays in A-549 cells demonstrated the more intense anticancer activity of Δ(9)-THC-loaded PEGylated PLGA nanoparticles. These promising results were confirmed by in vivo studies in LL2 lung tumor-bearing immunocompetent C57BL/6 mice.


Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/uso terapêutico , Dronabinol/administração & dosagem , Dronabinol/uso terapêutico , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Química Farmacêutica , Quitosana , Composição de Medicamentos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Ácido Láctico , Teste de Materiais , Camundongos , Camundongos Endogâmicos C57BL , Nanopartículas , Tamanho da Partícula , Polietilenoglicóis , Ácido Poliglicólico , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Ensaios Antitumorais Modelo de Xenoenxerto
11.
Brain Res ; 1605: 59-69, 2015 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-25680583

RESUMO

The standard model of memory system consolidation supports the temporal reorganization of brain circuits underlying long-term memory storage, including interactions between the dorsal hippocampus and extra-hippocampal structures. In addition, several brain regions have been suggested to be involved in the retrieval of spatial memory. In particular, several authors reported a possible role of the ventral portion of the hippocampus together with the thalamus or the striatum in the persistence of this type of memory. Accordingly, the present study aimed to evaluate the contribution of different cortical and subcortical brain regions, and neural networks involved in spatial memory retrieval. For this purpose, we used cytochrome c oxidase quantitative histochemistry as a reliable method to measure brain oxidative metabolism. Animals were trained in a hidden platform task and tested for memory retention immediately after the last training session; one week after completing the task, they were also tested in a memory retrieval probe. Results showed that retrieval of the previously learned task was associated with increased levels of oxidative metabolism in the prefrontal cortex, the dorsal and ventral striatum, the anterodorsal thalamic nucleus and the dentate gyrus of the dorsal and ventral hippocampus. The analysis of functional interactions between brain regions suggest that the dorsal and ventral dentate gyrus could be involved in spatial memory retrieval. In addition, the results highlight the key role of the extended hippocampal system, thalamus and striatum in this process. Our study agrees with previous ones reporting interactions between the dorsal hippocampus and the prefrontal cortex during spatial memory retrieval. Furthermore, novel activation patterns of brain networks involving the aforementioned regions were found. These functional brain networks could underlie spatial memory retrieval evaluated in the Morris water maze task.


Assuntos
Núcleos Anteriores do Tálamo/fisiologia , Corpo Estriado/fisiologia , Giro Denteado/fisiologia , Memória Espacial/fisiologia , Animais , Complexo IV da Cadeia de Transporte de Elétrons , Hipocampo/fisiologia , Masculino , Aprendizagem em Labirinto/fisiologia , Rede Nervosa/fisiologia , Distribuição Aleatória , Ratos , Ratos Wistar
12.
Neuroscience ; 284: 1-10, 2015 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-25290018

RESUMO

The hippocampus has been established as a site of plasticity during the acquisition of spatial memory. The memory for spatial locations is impaired in patients who develop hepatic encephalopathy (HE). We wondered how the hippocampus can manage different hippocampal-dependent tasks in a type B model of the early evolutive phases of HE induced by triple portal vein ligation. We used a one-trial object-place recognition task that involves making judgements about whether a stimulus was encountered before in that location and a reversal learning task performed in the Morris water maze that involves reward-guided behavior and decision making. Our behavioral results showed impairments in the acquisition of both tasks by the portal hypertension group compared with the sham-operated group. To label brain areas related to these tasks, we marked the expression of the c-Fos protein and revealed high c-Fos immunoreactivity in cornu ammonis 1 (CA1), cornu ammonis 3 (CA3) and entorhinal (Ent) cortex of the PH group compared with the SHAM group in the object-place recognition task and a decrease in c-Fos-positive cells in the reversal task in the CA1, CA3, dentate gyrus (DG), cingulate (CG), prelimbic (PL), and infralimbic (IL) cortices in the PH group compared with the SHAM group. In conclusion, the study corroborated the pivotal role of the hippocampus in spatial memory deficits found in the early stages of type B HE and noted its differential contribution in each of the tasks.


Assuntos
Encefalopatia Hepática/patologia , Encefalopatia Hepática/fisiopatologia , Hipocampo/patologia , Análise de Variância , Animais , Modelos Animais de Doenças , Comportamento Exploratório/fisiologia , Ligadura/efeitos adversos , Masculino , Veia Porta/fisiopatologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Reversão de Aprendizagem/fisiologia
13.
Neuroscience ; 281: 110-23, 2014 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-25281878

RESUMO

We have studied the performance of a spatial reference memory task, the navigation strategy and the changes in the cytochrome c oxidase activity (COx) in different brain regions in exercised (forced exercise, 10 consecutive days, 15min/day) and non-exercised adult Wistar rats. The spatial learning task was carried out in the radial-arm water maze (RAWM) for four days with six daily trials, and on the fifth day, a probe session was run, in which we rotated the position of the distal cues 90° in a clockwise direction. During the four days of training, the exercised group showed shorter latency and distance traveled to find the platform, as well as fewer memory errors and reduced use of non-appropriate navigation strategies according to the protocol of the task (egocentric). Interestingly, the rotation of the cues did not affect the performance of the exercised group, in contrast to the non-exercised group, which spent more time in the center of the maze and traveled longer distance to find the platform. Finally, higher COx activity in the cingulate and the retrosplenial cortices, as well as in the dorsal CA1 and CA3 was found in the exercised group. All in all, it seems that the exercise favored the configuration of an efficient and accurate cognitive map of the environment, which was supported by our finding that the rotation of the cues, without altering their overall configuration, did not affect performance. The brain regions with higher COx activity in the exercised group seem to be involved in this function.


Assuntos
Comportamento Animal/fisiologia , Córtex Cerebral/enzimologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Hipocampo/enzimologia , Aprendizagem em Labirinto/fisiologia , Condicionamento Físico Animal/fisiologia , Memória Espacial/fisiologia , Animais , Masculino , Ratos , Ratos Wistar
14.
Exp Gerontol ; 58: 292-302, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25218493

RESUMO

Our aim was to assess the changes in the Synapsin I and glucocorticoid receptor (GR) expression induced by behavioral testing in the dorsal and ventral hippocampi of standard and enriched aged Wistar rats. The environmental enrichment (EE) was carried out 3h/day over a period of two months and then, the rats were tested in the elevated zero-maze (EZM) and radial-arm water maze (RAWM). Behavioral results showed that, even at an advanced age, EE was able to reduce anxiety-related behaviors and improve the performance in the RAWM. Regarding the neurobiological data, Synapsin I expression in the dorsal CA3, but not in the ventral, was enhanced both in enriched and standard rats when they performed the behavioral testing. Interestingly, the EE exposure was enough to increase Synapsin I in the ventral CA3. The analysis of GR in the dorsal hippocampus showed an increase of this receptor in the dDG both in enriched and standard rats when they performed the behavioral testing, whereas in the dCA1 and dCA3, the effect of the testing depended on the previous housing condition. In the ventral region, we found that the effects of EE were higher because on the one hand, the GR expression induced by the behavioral testing was enhanced in the dSUB, vCA1 and vCA3 when the rats were previously enriched and on the other hand, EE, regardless of the behavioral testing, increased the GR expression in the vDG and vSUB. Therefore, our results suggest that the effect of the behavioral testing on the neurobiological mechanisms studied is different depending on the previous housing condition of aged rats.


Assuntos
Envelhecimento , Ansiedade/prevenção & controle , Comportamento Animal , Hipocampo/metabolismo , Receptores de Glucocorticoides/metabolismo , Sinapsinas/metabolismo , Fatores Etários , Envelhecimento/metabolismo , Envelhecimento/psicologia , Animais , Ansiedade/metabolismo , Ansiedade/psicologia , Abrigo para Animais , Masculino , Aprendizagem em Labirinto , Atividade Motora , Ratos Wistar , Tempo de Reação , Fatores de Tempo
15.
Neurobiol Learn Mem ; 114: 16-25, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24727294

RESUMO

Currently, little is known about the effect of environmental enrichment (EE) on astrocytic plasticity, especially during aging. Given the newly discovered role of the astrocytes in regulating the synaptic transmission and thereby, the cognitive functions, we aimed to study the impact of EE on the performance in a spatial memory task and on the number and morphology of GFAP immunopositive cells in the dorsal hippocampus. After two months of EE (3 h/per day), the animals were tested in the Radial-Arm Water Maze (RAWM) for four days, with six daily trials. Next, we analyzed the changes in the GFAP immunopositive cells in CA1, CA3 and Dentate Gyrus (DG). Behavioral results showed that, even in advanced ages, EE improved the performance in a spatial memory task. Also, we found that aged rats submitted to EE had more GFAP immunopositive cells in the DG and more complex astrocytes, revealed by Sholl analysis, in all hippocampal subfields with respect to the other experimental conditions. Interestingly, the learning of a spatial memory task produced more morphological complexity and higher levels of GFAP immunopositive cells with regard to a standard control group, but not at the same level of the enriched groups. Thus, it is possible that the plastic changes found in the hippocampal astrocytes after EE are involved in a brain reserve to cope with age-related cognitive impairments.


Assuntos
Envelhecimento/psicologia , Astrócitos/fisiologia , Cognição/fisiologia , Giro Denteado/fisiologia , Meio Ambiente , Aprendizagem em Labirinto/fisiologia , Animais , Astrócitos/citologia , Forma Celular/fisiologia , Giro Denteado/citologia , Abrigo para Animais , Ratos , Ratos Wistar
16.
Physiol Behav ; 129: 118-29, 2014 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-24582669

RESUMO

Environmental enrichment (EE) produces a remarkable degree of structural and functional plasticity in the hippocampus and possible mediators of these changes, such as glucocorticoid receptors (GRs), are of considerable interest. GRs are richly expressed in the hippocampus and they are involved in the adaptation to stressors and facilitate active coping in anxious situations. In this study, we assessed the effect of an EE protocol (24h/day during 69days) in adult Wistar rats on the activity in the elevated-zero maze (EZM), performance in the holeboard task (HB) and we also examined the changes in the glucocorticoid receptors (GRs) expression in the dorsal hippocampus (CA1, CA3 and DG). Our EE protocol reduced anxious behaviors in the EZM, so the animals spent more time and made more entries into the open sections. In the HB task, the enriched group showed more explorative behavior, a reduction of anxiety-related behaviors and a better cognitive performance compared to non-enriched animals. With regard to the GR expression, the EE condition produced an increase in the number of immunopositive cells for GRs in CA1, CA3 and DG. These results suggest that the better performance of enriched animals could be mediated in part by the increase of GRs in the dorsal hippocampus, which may alter the hippocampal neuronal function and accordingly, the anxiety levels, the spatial memory performance and the exploration levels in these animals.


Assuntos
Ansiedade/metabolismo , Meio Ambiente , Comportamento Exploratório/fisiologia , Hipocampo/metabolismo , Memória/fisiologia , Receptores de Glucocorticoides/metabolismo , Animais , Região CA1 Hipocampal/metabolismo , Região CA3 Hipocampal/metabolismo , Giro Denteado/metabolismo , Abrigo para Animais , Imuno-Histoquímica , Masculino , Aprendizagem em Labirinto/fisiologia , Testes Neuropsicológicos , Análise de Componente Principal , Ratos Wistar , Análise e Desempenho de Tarefas
17.
Behav Brain Res ; 260: 101-10, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24315832

RESUMO

While the neuronal basis of spatial memory consolidation has been thoroughly studied, the substrates mediating the process of extinction remain largely unknown. This study aimed to evaluate the functional contribution of selected brain regions during the extinction of a previously acquired spatial memory task in the Morris water maze. For that purpose, we used adult male Wistar rats trained in a spatial reference memory task. Learning-related changes in c-Fos inmunoreactive cells after training were evaluated in cortical and subcortical regions. Results show that removal of the hidden platform in the water maze induced extinction of the previously reinforced escape behavior after 16 trials, without spontaneous recovery 24h later. Extinction was related with significantly higher numbers of c-Fos positive nuclei in amygdala nuclei and prefrontal cortex. On the other hand, the lateral mammillary bodies showed higher number of c-Fos positive cells than the control group. Therefore, in contrast with the results obtained in studies of classical conditioning, we show the involvement of diencephalic structures mediating this kind of learning. In summary, our findings suggest that medial prefrontal cortex, the amygdala complex and diencephalic structures like the lateral mammillary nuclei are relevant for the extinction of spatial memory.


Assuntos
Encéfalo/fisiologia , Extinção Psicológica/fisiologia , Aprendizagem em Labirinto/fisiologia , Memória/fisiologia , Percepção Espacial/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Contagem de Células , Núcleo Celular/metabolismo , Diencéfalo/fisiologia , Hipocampo/fisiologia , Imuno-Histoquímica , Masculino , Corpos Mamilares/fisiologia , Córtex Pré-Frontal/fisiologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Análise e Desempenho de Tarefas
18.
Food Chem ; 146: 597-602, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24176386

RESUMO

This study aims at developing a method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in rice grain samples by combining the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and determination by gas chromatography-mass spectrometry (GC-EI-MS). Quantification limits ranging from 1 to 5µgkg(-1) were obtained. Recoveries ranged from 70% to 106% for most of the 16 PAHs under analysis. The optimised methodology was applied to assess safety concerning the content of PAHs in white and parboiled rice samples, dried by gas and wood burning. Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the samples, naphthalene and phenanthrene were detected in all of them. Since cereals have been shown to be an important source of PAHs in the diet, methods that perform the evaluation of the quality of this food group become relevant.


Assuntos
Contaminação de Alimentos/análise , Oryza/química , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Sementes/química , Extração em Fase Sólida/métodos , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Policíclicos Aromáticos/análise , Extração em Fase Sólida/economia
19.
Brain Res Bull ; 98: 1-9, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23831916

RESUMO

We have studied the effect of an environmental enrichment (EE) protocol in adult Wistar rats on the activity in the elevated zero-maze (EZM), performance in the radial-arm water maze (RAWM) and we have also examined the changes in the neuronal metabolic activity of several brain regions related to anxiety response and spatial memory through cytochrome c oxidase histochemistry (COx). Our EE protocol had anxiolytic effect in the EZM; the animals spent more time and made more entries into the open quadrants, they had lower latency to enter into the open quadrant and lower levels of defecation. Also, the EE group showed fewer working memory and reference memory errors, as well as lesser distance travelled in the first day of the spatial training. In relation to the neuronal metabolic activity, EE reduced the COx activity in brain regions related to anxiety response, such as the infralimbic cortex, the paraventricular thalamic and hypothalamic nucleus, the basolateral amygdala, and the ventral hippocampus. Interestingly, there were no significant differences between groups in the dorsal hippocampus, more related to spatial cognition. These results suggest a beneficial effect of EE on spatial memory as a result of reducing anxiety levels and the COx activity in brain regions involved in anxiety response. We also found a differential pattern of activation inside the hippocampus, suggesting that the dorsal hippocampus has a preferential involvement in spatial learning and memory, whereas the ventral hippocampus has a role in anxiety response.


Assuntos
Ansiedade , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Meio Ambiente , Memória/fisiologia , Córtex Pré-Frontal/metabolismo , Percepção Espacial/fisiologia , Análise de Variância , Animais , Ansiedade/enzimologia , Ansiedade/patologia , Ansiedade/fisiopatologia , Modelos Animais de Doenças , Masculino , Aprendizagem em Labirinto/fisiologia , Ratos , Ratos Wistar , Estatística como Assunto , Fatores de Tempo
20.
Neuroscience ; 248: 43-53, 2013 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-23769820

RESUMO

We assessed the effect of 3h of environmental enrichment (EE) exposure per day started at different ages (3 and 18months old) on the performance in a spatial memory task and on brain regions involved in the spatial learning (SPL) process using the principal component analysis (PCA). The animals were tested in the four-arm radial water maze (4-RAWM) for 4days, with six daily trials. We used cytochrome c oxidase (COx) histochemistry to determine the brain oxidative metabolic changes related to age, SPL and EE. Behavioural results showed that the enriched groups, regardless of their age, achieved better performance in the spatial task. Interestingly, in the case of the distance travelled in the 4-RAWM, the effect of the EE was dependent on the age, so the young enriched group travelled a shorter distance compared to the aged enriched group. Respect to COx histochemistry results, we found that different brain mechanisms are triggered in aged rats to solve the spatial task, compared to young rats. PCA revealed the same brain functional network in both age groups, but the contribution of the brain regions involved in this network was slightly different depending on the age of the rats. Thus, in the aged group, brain regions involved in anxiety-like behaviour, such as the amygdala or the bed nucleus of the stria terminalis had more relevance; whereas in the young enriched group the frontal and the hippocampal subregions had more contribution.


Assuntos
Encéfalo/metabolismo , Meio Ambiente , Rede Nervosa/metabolismo , Memória Espacial/fisiologia , Animais , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Masculino , Ratos , Ratos Wistar
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