Is there a relationship between hippocampus-dependent memory and 5-ht2a receptors? Insights from a systematic review / Há uma relação entre a memória hipocampo-dependente e receptores 5-HT2a? Insights de uma revisão sistemática

This is a systematic review with the aim of analyzing the role of 5-HT2A receptors in hippocampal-dependent memory. In order to do this, we searched the PubMed, Science Direct, and Neuron databases between October 23 and 29, 2018, using the following descriptor combinations: memory, 5-HT2A, and hippocampus, present in the title, abstract, or keywords, with no restrictions on study date or language. Following search and selection, we analyzed risk of bias, and the results were subsequently synthesized according to the experimental model. Out of 40 articles, four were included in qualitative analysis. The data indicate that the 5-HT2A receptors in the hippocampus play an important role in the memory consolidation process, although they do not interfere in the encoding or retrieval processes of these memories. Additionally, chronic use of receptor agonists in models of Alzheimer’s disease also demonstrates better performance in the object recognition tests. The action of 5-HT2A receptors has also been shown to be important to aversive memory formation, thus attributing a prominent role to these receptors in hippocampal-dependent memory processes

Effects of chronic food stress on morphometry and expression of nuclear organizing regions in the adult rats hippocampus Chronic food stress on morphometry and expression of agnor in the rats hippocampus / Efeitos do estresse alimentar crônico na morfometria e expressão das regiões de organização nuclear nos ratos adultos hipocampo Testemunho crônico de alimentação sobre morfometria e expressão do agnor no hippocampus das taxas

The aim of this study was to verify the immediate and late effects of chronic food stress on the expression of Nuclear Organizing Regions (NORs) in hippocampal neurons. Twenty Wistar rats were separated into two groups: test (n = 10) and control (n = 10). Food stress started from the 60th day of life and lasted for a month. After this time the animals were anesthetized, euthanized and had their hippocampus dissected. The obtained hippocampus were histologically processed, stained by the HE technique for morphological description and by the AgNOR technique for NOR analysis. From each image the total number of neurons, the number of neurons with NOR in Dispersion (NND), the total number of NORs (NNOR), and then performed a ratio of NNOR by the total number of neurons to obtain the number Of NOR by neuron (NNN). Of the analyzed variants, the number of neurons was higher (p <0.001) in the stressed group (41.98 ± 17), when compared with the control group (33.57 ± 14). In addition, NND was also higher in the stressed group (4.523 ± 4.04) than the control group (1.4 ± 2.20) with p <0.001. Thus, we have that chronic food stress increases the number of granular neurons in the hippocampus in rats as well as increases the number of NOR in dispersion. 

Histomorfometric Analysis of Duodenum of Rats Submitted to Food Stress / Análise Histomorfométrica do Duodeno de Ratos Submetidos ao Estresse Alimentar

Stress was interpreted as a nonspecific reaction of the organism to a situation that would threaten its homeostasis. Several factors in the modern world can be related to this condition: the search for a perfect body, the labor market dispute or the pressure to conquer everything as fast as possible. Associated with these factors, one can add the intense, naturally stressful, routine in which man is inserted. At the experimental level, several effects are observed at a systemic and behavioral level in rats that have been submitted to food restriction models, finding that the gastrointestinal system is quite vulnerable to stress in general. In specific cases of food stress, it was observed that the manifestations vary according to the life stage of the animal and the applied model. In this sense, the present research aims to evaluate the influence of food restriction on the intestinal tunica morphology of rats submitted to a chronic food stress model. For this, 27 animals were divided into control (n = 11) and test (n = 16) groups. From the 60 th day of life, the test group was submitted to four stages, each one being performed in one day: 1) palatable diet; 2) visual stimulation to the diet, but without access; 3) fasting; 4) standard diet of the biotery. The four steps were repeated until the animals completed 90 days. In the morphometry of the duodenum were analyzed: length, width and area of vill, as well as area of intestinal gland (Lieberkühn). Statistical inference of data showed that the applied stress model affected the morphology of the stressed group, since the intestinal villi appeared wider and with less area in this group. The villi length as well as the intestinal gland area did not undergo morphological changes. The alterations found reinforce that the fasting process acts as a stressor and a predisposing factor for morphological alterations, as observed in other studies in our laboratory. However, there are not many studies in the literature that allow the knowledge of the consequences of this type of stress. In this case, further research is needed on the relationship between the gastrointestinal tract and the experimental model applied to elucidate such findings

Estudos morfológico e morfométrico do coração e da artéria aorta em ratos adultos desmamados precocemente / Morphological and morphometric studies of the heart and aorta artery in preciously weed adult rats

Objetivo: Realizar uma investigação acerca dos efeitos do desmame precoce sobre a morfologia e morfometria do coração e da artéria aorta de ratos adultos submetidos ao desmame precoce no 15° dia de vida pós-natal. Método: Foram utilizados 16 ratos machos da linhagem Wistar. Os grupos experimentais foram formados pelos grupos DP15 (desmame no 15° dia pós-natal) e C30 (desmame no 30° dia pós-natal), com o 8 ratos cada grupo. Após o desmame, os animais foram separados em gaiolas individuais e no 100° dia de vida pós-natal, foram eutanasiados através da pefusão intracardíaca. O coração e a artéria aorta foram coletados e posteriormente processados para a microscopia de luz. As análises foram realizadas a partir de fotomicrografias e do software ImageJ. Foram avaliados o número de cárdiomiócitos, a área nuclear e a espessura da aorta. Resultado: Os resultados mostraram que o desmame precoce promoveu alterações significativas nas variáveis analisadas, provocando a redução da área nuclear dos cardiomiócitos (C: 16,77µm ± 5,95; DP: 12,48µm ± 7,03), hiperplasia do miocárdio (C: 30,42µm ± 11,38; DP: 48,87µm ± 13,62), diminuição na espessura da artéria aorta (C: 168,56µm ± 46,61; DP: 113,81µm ± 28,01) (C: 130,69µm ± 40,75; DP: 81,62µm ± 19,89). Baseado em nossos resultados podemos sugerir que o desmame precoce é uma agressão perinatal capaz de provocar alterações na morfologia e morfometria do coração e da artéria aorta de ratos.