Novelty facilitates the persistence of aversive memory extinction by dopamine regulation in the hippocampus and ventral tegmental area.

Aversive memory extinction comprises a novel learning that blocks retrieving a previously formed traumatic memory. In this sense, aversive memory extinction is an excellent tool for decreasing fear responses. However, this tool it's not effective in the long term because of original memory spontaneous recovery. Thus, searching for alternative strategies that strengthen extinction learning is essential. In the current study, we evaluated the effects of a novel context (i.e., novelty) exposure on aversive memory extinction enhancement over days and the dopaminergic system requirement. Given the purpose, experiments were conducted using 3-month-old male Wistar rats. Animals were trained in inhibitory avoidance (IA). Twenty-four hours later, rats were submitted to a weak extinction protocol. Still, 30 min before the first extinction session, animals were submitted to an exploration of a novel context for 5 min. After, memory retention and persistence were evaluated 24 h, 3, 7, 14, and 21 days later. The exposition of a novel context caused a decrease in aversive responses in all days analyzed and an increase in dopamine levels in the hippocampus. The intrahippocampal infusion of dopamine in the CA1 area or the stimulation of the ventral tegmental area (VTA) by a glutamatergic agonist (NMDA) showed similar effects of novelty. In contrast, VTA inhibition by a gabaergic agonist (muscimol) impaired the persistence of extinction learning induced by novelty exposition and caused a decrease in hippocampal dopamine levels. In summary, we show that novel context exposure promotes persistent aversive memory extinction, revealing the significant role of the dopaminergic system.

Neuroprotective effects of strength training in a neuroinflammatory animal model.

BACKGROUND: The preventive role of muscular strength on diminishing neuroinflammation is yet unknown. In this study, the role of the prophylactic muscular strength exercise was investigated in order to verify whether it would diminish cognitive alterations and modify the antioxidant intracellular scenery in an animal neuroinflammatory model in of the CA1 region of the hippocampus. METHODS: The animals received muscular strength training (SE) three times a week for eight weeks. Subsequently, the stereotaxic surgery was performed with an intra-hippocampal infusion of either saline solution (SAL) or lipopolysaccharide (LPS). Next, we performed the behavioral tests: object recognition and social recognition. Then, the animals were euthanized, and their hippocampus and prefrontal cortex were collected. In another moment, we performed the dosage of the antioxidant activity and histological analysis. RESULTS: The results showed that the muscular strength exercises could show a beneficial prophylactic effect in the cognitive deficiencies caused by acute neuroinflammation. Regarding oxidative stress, there was an increase in catalase enzyme activity (CAT) in the group (SE + LPS) compared to the control groups (p < 0.05). As for the cognitive alterations, there were found in the (SE + LPS) group, diminishing the mnemonic hazard of the discriminative and social memories compared to the control groups (p < 0.05). CONCLUSION: We concluded, therefore, that the exercise performed prophylactically presents a protective effect capable of minimizing such mnemonic deficits and increasing catalase enzyme activity in rats that suffered a local neuroinflammatory process in the hippocampus.

Concurrent exercise does not prevent recognition memory deficits induced by beta-amyloid in rats.

Alzheimer's disease affects thousands of people worldwide. Alternatives aiming to prevent the disease or reduce its symptoms include different physical exercise configurations. Here we investigate the potential of concurrent exercise to prevent recognition memory deficits in an Alzheimer's disease-like model induced by the hippocampal beta-amyloid (Aß) injection in Wistar rats. We demonstrate that the concurrent exercise, which included running and strength exercises performed in the same exercise session, is ineffective in preventing recognition memory deficits in the Aß rats. Besides, higher levels of reactive oxygen species were found in the concurrent exercise group's hippocampus. The running exercise administrated alone prevented recognition memory impairments.

Multicomponent Training Prevents Memory Deficit Related to Amyloid-ß Protein-Induced Neurotoxicity.

BACKGROUND: Alzheimer's disease (AD) is characterized by the accumulation of the amyloid-ß peptide in the brain, leading to early oxidative stress and neurotoxicity. It has been suggested that physical exercise could be beneficial in preventing AD, but studies with multicomponent training are scanty. OBJECTIVE: Verify the effects of multicomponent exercise training to prevent deficits in recognition memory related to Aß neurotoxicity. METHODS: We subjected Wistar rats to multicomponent training (including aerobic and anaerobic physical exercise and cognitive exercise) and then infused amyloid-ß peptide into their hippocampus. RESULTS: We show that long-term multicomponent training prevents the amyloid-ß-associated neurotoxicity in the hippocampus. It reduces hippocampal lipid peroxidation, restores antioxidant capacity, and increases glutathione levels, finally preventing recognition memory deficits. CONCLUSION: Multicomponent training avoids memory deficits related to amyloid-ß neurotoxicity on an animal model.

Student assessment of online tools to foster engagement during the COVID-19 quarantine.

As a result of the installation of the COVID-19 (coronavirus disease 19) pandemic, online education has become an important teaching alternative, and new challenges about how to teach were found. Here we report our experience in offering an online course to review Human Physiology. We proposed synchronous and asynchronous activities using different online tools to address topics considered key to understanding the different systems of human physiology. The students considered important the use of this type of methodology, which uses different online tools to help understand the Human Physiology contents. The students highlighted the use of the Lt platform, Zoom, Mentimeter, and YouTube as the preferred online tools to use in physiology learning.