tetrodotoxin and Neurodegenerative-Diseases

In studying the mediators of VIP neurotrophism in the central nervous system, two glial proteins have been discovered. Both of these proteins contain short peptides that exhibit femtomolar potency in preventing neuronal cell death from a wide variety of neurotoxic substances. Extension of these peptides to models of oxidative stress or neurodegeneration in vivo have indicated significant efficacy in protection. These peptides, both as individual agents and in combination, have promise as possible protective agents in the treatment of human neurodegenerative disease and in pathologies involving oxidative stress.

Topics: Animals; Blood-Brain Barrier; Cell Death; Cells, Cultured; Central Nervous System; Dose-Response Relationship, Drug; Homeodomain Proteins; Humans; Nerve Tissue Proteins; Neurodegenerative Diseases; Neuroglia; Neurons; Neuropeptides; Neuroprotective Agents; Oligopeptides; Oxidative Stress; Peptides; Tetrodotoxin; Time Factors; Vasoactive Intestinal Peptide

We describe the synthesis of gramine derivatives and their pharmacological evaluation as multipotent drugs for the treatment of Alzheimer's disease. An innovative multitarget approach is presented, targeting both voltage-gated Ca(2+) channels, classically studied for neurodegenerative diseases, and Ser/Thr phosphatases, which have been marginally aimed, even despite their key role in protein τ dephosphorylation. Twenty-five compounds were synthesized, and mostly their neuroprotective profile exceeded that offered by the head compound gramine. In general, these compounds reduced the entry of Ca(2+) through VGCC, as measured by Fluo-4/AM and patch clamp techniques, and protected in Ca(2+) overload-induced models of neurotoxicity, like glutamate or veratridine exposures. Furthermore, we hypothesize that these compounds decrease τ hyperphosphorylation based on the maintenance of the Ser/Thr phosphatase activity and their neuroprotection against the damage caused by okadaic acid. Hence, we propose this multitarget approach as a new and promising strategy for the treatment of neurodegenerative diseases.

Topics: Alkaloids; Animals; Calcium Channels; Cattle; Cell Survival; Dose-Response Relationship, Drug; Hippocampus; Humans; Indole Alkaloids; Molecular Structure; Neurodegenerative Diseases; Phosphoprotein Phosphatases; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship; Tumor Cells, Cultured

Central neurons express persistent spontaneous electrical network activity both in the developing brain in vivo as well as in dissociated cultures. This electrical activity is important for the formation of connections among neurons, and for their survival. Prolonged suppression of the spontaneous activity using the sodium channel blocker tetrodotoxin (TTX) causes the death of the cultured neurons. In the present study, we investigated molecular mechanisms that may underlie the activity-suppressed slow degeneration of cortical neurons in culture. Already after 6-7 days of exposure to TTX, neurons begin to express apoptotic vacuoles and shrunken dendrites. Eventually, neurons activate p53, caspase-3 and BAX, hallmarks of neuronal apoptosis, before they die. This death is restricted to neurons, and no parallel process is seen in glial cells that co-exist in the culture. These experiments may lead to a better understanding of slow neuronal death, akin to that found in neurodegenerative diseases of the brain.

Topics: Action Potentials; Animals; Animals, Newborn; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Survival; Cells, Cultured; Cerebral Cortex; Dendrites; Models, Neurological; Nerve Degeneration; Neurodegenerative Diseases; Neurons; Rats; Rats, Wistar; Sodium Channel Blockers; Tetrodotoxin; Tumor Suppressor Protein p53; Vacuoles

Neural stem cell (NSC) transplantation has been proposed as a future therapy for neurodegenerative disorders. However, NSC transplantation will be hampered by the limited number of brain donors and the toxicity of immunosuppressive regimens that might be needed with allogeneic transplantation. These limitations may be avoided if NSCs can be generated from clinically accessible sources, such as bone marrow (BM) and peripheral blood samples, that are suitable for autologous transplantation. We report here that NSCs can be generated from human BM-derived mesenchymal stem cells (MSCs). When cultured in NSC culture conditions, 8% of MSCs were able to generate neurospheres. These MSC-derived neurospheres expressed characteristic NSC antigens, such as nestin and musashi-1, and were capable of self-renewal and multilineage differentiation into neurons, astrocytes, and oligodendrocytes. Furthermore, when these MSC-derived neurospheres were cocultured with primary astrocytes, they differentiate into neurons that possess both dendritic and axonal processes, form synapses, and are able to fire tetrodotoxin-sensitive action potentials. When these MSC-derived NSCs were switched back to MSC culture conditions, a small fraction of NSCs (averaging 4-5%) adhered to the culture flasks, proliferated, and displayed the morphology of MSCs. Those adherent cells expressed the characteristic MSC antigens and regained the ability to differentiate into multiple mesodermal lineages. Data presented in this study suggest that MSCs contain a small fraction (averaging 4-5%) of a bipotential stem cell population that is able to generate either MSCs or NSCs depending on the culture conditions.

Topics: Action Potentials; Adult; Astrocytes; Cell Differentiation; Cells, Cultured; Coculture Techniques; Female; Humans; Intermediate Filament Proteins; Male; Mesenchymal Stem Cells; Nerve Tissue; Nerve Tissue Proteins; Nestin; Neurodegenerative Diseases; Neurons; Oligodendroglia; RNA-Binding Proteins; Sodium Channel Blockers; Stem Cell Transplantation; Tetrodotoxin; Transplantation, Homologous