High and Low-Frequency Stimulation Effect on Epileptiform Activity in Brain Slices.

Background: Neurostimulation is one of the new therapeutic approaches in patients with drug-resistant epilepsy, and despite its high efficiency, its mechanism of action is still unclear. On the one hand, electrical stimulation in the human brain is immoral; on the other hand, the creation of the epilepsy model in laboratory animals affects the entire brain network. As a result, one of the ways to achieve the neurostimulation mechanism is to use epileptiform activity models In vitro. In vitro models, by accessing the local network from the whole brain, we can understand the mechanisms of action of neurostimulation. Methods: A literature search using scientific databases including PubMed, Google Scholar, and Scopus, using "Neurostimulation" and "epileptiform activity" combined with "high-frequency stimulation", " low-frequency stimulation ", and "brain slices" as keywords were conducted, related concepts to the topic gathered and are used in this paper. Results: Electrical stimulation causes neuronal depolarization and the release of GABAA, which inhibits neuronal firing. Also, electrical stimulation inhibits the nervous tissue downstream of the stimulation site by preventing the passage of nervous activity from the upstream to the downstream of the axon. Conclusion: Neurostimulation techniques consisting of LFS and HFS have a potential role in treating epileptiform activity, with some studies having positive results. Further investigations with larger sample sizes and standardized outcome measures can be conducted to validate the results of previous studies.

Biological functions and molecular interactions of Wnt/ß-catenin in breast cancer: Revisiting signaling networks.

Changes in lifestyle such as physical activity and eating habits have been one of the main reasons for development of various diseases in modern world, especially cancer. However, role of genetic factors in initiation of cancer cannot be ignored and Wnt/ß-catenin signaling is such factor that can affect tumor progression. Breast tumor is the most malignant tumor in females and it causes high mortality and morbidity around the world. The survival and prognosis of patients are not still desirable, although there have been advances in introducing new kinds of therapies and diagnosis. The present review provides an update of Wnt/ß-catenin function in breast cancer malignancy. The upregulation of Wnt is commonly observed during progression of breast tumor and confirms that tumor cells are dependent on this pathway Wnt/ß-catenin induction prevents apoptosis that is of importance for mediating drug resistance. Furthermore, Wnt/ß-catenin signaling induces DNA damage repair in ameliorating radio-resistance. Wnt/ß-catenin enhances proliferation and metastasis of breast tumor. Wnt/ß-catenin induces EMT and elevates MMP expression. Furthermore, Wnt/ß-catenin participates in tumor microenvironment remodeling and due to its tumor-promoting factor, drugs for its suppression have been developed. Different kinds of upstream mediators Wnt/ß-catenin signaling in breast cancer have been recognized that their targeting is a therapeutic approach. Finally, Wnt/ß-catenin can be considered as a biomarker in clinical trials.

Effect of low frequency stimulation of olfactory bulb on seizure severity, learning, and memory in kindled rats.

Low frequency deep brain electrical stimulation (LFS) is a potential therapeutic strategy to control seizures in epilepsy patients. Given the functional connection of the olfactory bulb with the hippocampal formation, in this study the effect of applying LFS in the olfactory bulb on seizure severity, and learning and memory was investigated in hippocampal kindling. In male Wistar rats (250-300 g), a tripolar electrode was inserted in the CA1 region of the right hippocampus to apply kindling stimulations and record the afterdischarges (ADs). Two bipolar electrodes were also inserted bilaterally into the olfactory bulbs for applying LFS. In the kindled group, the animals received daily kindling stimulations to produce stage 5 seizures for three consecutive days. In one group of subjects, LFS was administered 2-3 min after the last kindling stimulation. Within this group, subjects were divided into two subgroups: one subgroup received two and the other subgroup received four packages of LFS protocol. Obtained data showed that bilateral LFS application to the left and right olfactory bulb reduced seizure severity. Among the protocols, applying four packages of LFS had a greater anticonvulsant effect compared to applying two packages LFS. Applying LFS in the olfactory bulb of kindled subject restored performance on measures that test short- and long-term memory - the Y maze and Morris water maze test - and applying four packages of LFS was more effective than two. These results indicated that applying LFS to the olfactory bulb had anticonvulsant effects and ameliorated the seizure-induced impairment of working and spatial memory. These effects appear to be depended on the number of applied LFS and were greater by increasing the number of LFS.