Neurosteroids are synthesized in the brain and have been demonstrated to modulate various cerebral functions. Allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one), a naturally occurring neurosteroid, and ganaxolone (3alpha-hydroxy-3beta-methyl-5alpha-pregnan-20-one), a synthetic derivative, are two neurosteroids acting as positive allosteric modulators of the GABA(A) receptor complex acting on a specific steroid recognition site. Both agents antagonize generalized tonic-clonic seizures in various animal models of epilepsy. Pregnenolone sulphate (3beta-hydroxy-5alpha-pregnen-20-one 3-sulphate; PS) is a negative allosteric modulator of GABA(A) receptors and a positive modulator of the NMDA receptors. We have evaluated the effects of such compounds in a genetic animal model of absence epilepsy, the WAG/Rij rat. Animals were chronically implanted with five frontoparietal cortical electrodes for electrocorticogram (EEG) recordings and bilateral guide cannulae into specific brain areas of the cortico-thalamic circuit in order to evaluate the effects of these compounds on the number and duration of epileptic spike-wave discharges (SWDs). The focal and bilateral microinjection of the two GABA(A) positive modulators into some thalamic nuclei (nucleus ventralis posteromedialis, nucleus reticularis thalami, nucleus ventralis posterolateralis was usually able to significantly worsen the occurrence of SWDs in WAG/Rij rats. Whereas both compounds were able to reduce the number and duration of SWDs when microinjected into the peri-oral region of the primary somatosensory cortex. The effects of PS were more complex depending on both the dose and the site of administration, generally, at low doses in thalamic nuclei and cortex, PS induced an increase of absence activity and a reduction at higher doses. These findings suggest that neurosteroids might play a role in absence epilepsies and that it might depend on the involvement of specific neuronal areas.
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http://dx.doi.org/10.1016/j.neuropharm.2006.02.011 | DOI Listing |
Neuroimage
December 2024
Institute of Population Health, University of Liverpool, United Kingdom; Hanse Wissenschaftskolleg, Delmenhorst, Germany. Electronic address:
Recent work has shown rapid microstructural brain changes in response to learning new tasks. These cognitive tasks tend to draw on multiple brain regions connected by white matter (WM) tracts. Therefore, behavioural performance change is likely to be the result of microstructural, functional activation, and connectivity changes in extended neural networks.
View Article and Find Full Text PDFBrain Cogn
December 2024
Department of Neuroscience, University of Padova, Italy; Padova Neuroscience Center, University of Padova, Italy. Electronic address:
Mixed Transcortical Aphasia (MTA) is an infrequent aphasic syndrome, characterized by poor comprehension and production in oral language abilities and poor performance in written language abilities. However, individuals with MTA typically retain the ability to repeat. Our patient, a woman who suffered from a left hemisphere ischemic stroke involving perisylvian areas, presented with repetition preserved for words, non-words, sentences and numbers, together with marginally preserved reading abilities.
View Article and Find Full Text PDFWorld Neurosurg
December 2024
Clinical and Translational Neuroscience Unit, Department of Neurology and Feil Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York, USA. Electronic address:
Providing specialized care to critically ill neurology patients has improved outcomes for patients with neurological emergencies; however, there are still some gaps in neurocritical care (NCC) that offer opportunities for improvement. Among these gaps, improving education of the multidisciplinary NCC team, targeting individualized treatments for neurologically critically ill patients, and reducing disparities for undeserved patients as well as disadvantaged areas are priorities to advance the field. This review focuses on the current challenges neurointensivists face, including difficulties in neuroprognostication, ethical challenges in end-of-life care, and neuropalliative care.
View Article and Find Full Text PDFComput Biol Med
December 2024
Center for Brain and Brain-Inspired Computing Research, School of Computer Science, Northwestern Polytechnical University, Xi'an, China. Electronic address:
Background: Studying influential nodes (I-nodes) in brain networks is of great significance in the field of brain imaging. Most existing studies consider brain connectivity hubs as I-nodes such as the regions of high centrality or rich-club organization. However, this approach relies heavily on prior knowledge from graph theory, which may overlook the intrinsic characteristics of the brain network, especially when its architecture is not fully understood.
View Article and Find Full Text PDFInflamm Regen
December 2024
Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
Vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) act together to regulate blood pressure and systemic blood flow by appropriately adjusting blood vessel diameter in response to biochemical or biomechanical stimuli. Ion channels that are expressed in these cells regulate membrane potential and cytosolic Ca concentration ([Ca]) in response to such stimuli. The subsets of these ion channels involved in Ca signaling often form molecular complexes with intracellular molecules via scaffolding proteins.
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