SARS-CoV-2-induced amyloidgenesis : not one, but three hypotheses for cerebral COVID-19 outcomes

The main neuropathological feature of Alzheimer’s disease (AD) is extracellular amyloid deposition in senile plaques, resulting from an imbalance between the production and clearance of amyloid beta peptides. Amyloid deposition is also found around cerebral blood vessels, termed cerebral amyloid angiopathy (CAA), in 90% of AD cases. Although the relationship between these two amyloid disorders is obvious, this does not make CAA a characteristic of AD, as 40% of the non-demented population presents this derangement. AD is predominantly sporadic; therefore, many factors contribute to its genesis. Herein, the starting point for discussion is the COVID-19 pandemic that we are experiencing and how SARS-CoV-2 may be able to, both directly and indirectly, contribute to CAA, with consequences for the outcome and extent of the disease. We highlight the role of astrocytes and endothelial cells in the process of amyloidgenesis, as well as the role of other amyloidgenic proteins, such as fibrinogen and serum amyloid A protein, in addition to the neuronal amyloid precursor protein. We discuss three independent hypotheses that complement each other to explain the cerebrovascular amyloidgenesis that may underlie long-term COVID-19 and new cases of dementia

Grape juice increases the BDNF levels but not alter the S100B levels in hippocampus and frontal cortex from male Wistar rats

Several studies have shown that a high consumption of vegetables and fruits is consistently associated with a low risk of oxidative stress-induced diseases, which includes some degenerative diseases such as amyotrophic lateral sclerosis, Alzheimer and Parkinson. Therefore, the objective of this study is to verify the effects of conventional and organic grape juice in the modulation of the neurotrophic factor (BDNF) and astrocytic markers protein (S100B) in hippocampus and frontal cortex of Wistar rats. In this study, 24 male Wistar rats were divided into three groups. To the first one, it was given organic purple grape juice; to the second, conventional grape juice, while the last one received only saline. After 30 days, all rats were sacrificed and hippocampus and frontal cortex were dissected. The animals that received organic and conventional grape juice showed, in frontal cortex, an elevated BNDF levels in relation to saline group. However, S100B levels did not change. These results showed that grape juices are able to modulate important marker in brain tissue, and could be an important factor to prevent brain diseases

Dieta cetogênica reduz o conteúdo de gangliosídios em hipotálamos de ratos jovens

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Effects of dexamethasone on the Li-pilocarpine model of epilepsy : protection against hippocampal inflammation and astrogliosis

Background: Temporal lobe epilepsy (TLE) is the most common form of partial epilepsy and is accompanied, in one third of cases, by resistance to antiepileptic drugs (AED). Most AED target neuronal activity modulated by ionic channels, and the steroid sensitivity of these channels has supported the use of corticosteroids as adjunctives to AED. Assuming the importance of astrocytes in neuronal activity, we investigated inflammatory and astroglial markers in the hippocampus, a key structure affected in TLE and in the Li-pilocarpine model of epilepsy. Methods: Initially, hippocampal slices were obtained from sham rats and rats subjected to the Li-pilocarpine model of epilepsy, at 1, 14, and 56 days after status epilepticus (SE), which correspond to the acute, silent, and chronic phases. Dexamethasone was added to the incubation medium to evaluate the secretion of S100B, an astrocyte-derived protein widely used as a marker of brain injury. In the second set of experiments, we evaluated the in vivo effect of dexamethasone, administrated at 2 days after SE, on hippocampal inflammatory (COX-1/2, PGE2, and cytokines) and astroglial parameters: GFAP, S100B, glutamine synthetase (GS) and water (AQP-4), and K+ (Kir 4.1) channels. Results: Basal S100B secretion and S100B secretion in high-K+ medium did not differ at 1, 14, and 56 days for the hippocampal slices from epileptic rats, in contrast to sham animal slices, where high-K+ medium decreased S100B secretion. Dexamethasone addition to the incubation medium per se induced a decrease in S100B secretion in sham and epileptic rats (1 and 56 days after SE induction). Following in vivo dexamethasone administration, inflammatory improvements were observed, astrogliosis was prevented (based on GFAP and S100B content), and astroglial dysfunction was partially abrogated (based on Kir 4.1 protein and GSH content). The GS decrease was not prevented by dexamethasone, and AQP-4 was not altered in this epileptic model. Conclusions: Changes in astroglial parameters emphasize the importance of these cells for understanding alterations and mechanisms of epileptic disorders in this model. In vivo dexamethasone administration prevented most of the parameters analyzed, reinforcing the importance of anti-inflammatory steroid therapy in the Li-pilocarpine model and possibly in other epileptic conditions in which neuroinflammation is present

Short-term protocols to obtain insulin-producing cells from rat adipose tissue : signaling pathways and in vivo effect

Studies using mesenchymal stromal cells (MSCs) as a source of insulin-secreting cells (IPCs) are a promising path in the pursuit for diabetes therapy. Here, we investigate three short-term differentiation protocols in order to generate IPCs from autologous adipose-derived stromal cells (ADSCs) with an expressive insulin-secreting profile in vitro and in vivo, as well as the signaling pathways involved in the chosen differentiation protocols. We extracted and cultured ADSCs and differentiated them into IPCs, using three different protocols with different inductors. Afterwards, the secretory profile was analyzed and IPCs differentiated in exendin-4/activin A medium, which presented the best secretory profile, was implanted in the kidney subcapsular region of diabetic rats. All protocols induced the differentiation, but media supplemented with exendin-4/activin A or resveratrol induced the expression and secretion of insulin more efficiently, and only the exendin-4/activin-A-supplemented medium generated an insulin secretion profile more like β-cells, in response to glucose. The PI3K/Akt pathway seems to play a negative role in IPC differentiation; however, the differentiation of ADSCs with exendin-4/activin A positively modulated the p38/MAPK pathway. Resveratrol medium activated the Jak/STAT3 pathway and generated IPCs apparently less sensitive to insulin and insulin-like receptors. Finally, the implant of IPCs with the best secretory behavior caused a decrease in hyperglycemia after one-week implantation in diabetic rats. Our data provide further information regarding the generation of IPCs from ADSCs and strengthen evidence to support the use of MSCs in regenerative medicine, specially the use of exendin-4/activin A to produce rapid and effectively IPCs with significant in vivo effects

Avaliação do dano ao DNA em ratos tratados com dieta cetogênica

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Impact of SARS-CoV-2 infection during pregnancy on postnatal brain development : the potential role of glial cells

Glial cells are crucial for maintaining central nervous system (CNS) homeostasis. They actively participate in immune responses, as well as form functional barriers, such as blood-brain barrier (BBB), which restrict the entry of pathogens and inflammatory mediators into the CNS. In general, viral infections during the gestational period can alter the embryonic and fetal environment, and the related inflammatory response may affect neurodevelopment and lead to behavioral dysfunction during later stage of life, as highlighted by our group for Zika virus infection. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) induces a cytokine storm and, during pregnancy, may be related to a more severe form of the coronavirus disease-19 (COVID-19) and also to higher preterm birth rates. SARS-CoV-2 can also affect the CNS by inducing neurochemical remodeling in neural cells, which can compromise neuronal plasticity and synaptic function. However, the impact of SARS-CoV-2 infection during pregnancy on postnatal CNS, including brain development during childhood and adulthood, remains undetermined. Our group has recently highlighted the impact of COVID-19 on the expression of molecular markers associated with neuropsychiatric disorders, which are strongly related to the inflammatory response. Thus, based on these relationships, we discussed the impact of SARS-CoV-2 infection either during pregnancy or in critical periods of neurodevelopment as a risk factor for neurological consequences in the offspring later in life, focusing on the potential role of glial cells. Thus, it is important to consider future and long-term public health concerns associated with SARS-CoV-2 infection during pregnancy