Inhibition of Calpain and Caspase-3 Prevented Apoptosis and Preserved Electrophysiological Properties of Voltage-gated and Ligand-gated Ion Channels in Rat Primary Cortical Neurons Exposed to Glutamate.
From: Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, P.O. Box 250606, Charleston, SC 29425, USA. raysk@musc.edu
Neuroscience
- Publish Date: May 2006
- ISSN: 0306-4522
- Volume: 139
- Issue: 2
- Pages: 577-95
- Medium: Print
- Language: English
- Citation (JAMA): Ray S K, Karmakar S, Nowak M W, et al. Inhibition of Calpain and Caspase-3 Prevented Apoptosis and Preserved Electrophysiological Properties of Voltage-gated and Ligand-gated Ion Channels in Rat Primary Cortical Neurons Exposed to Glutamate.. Neuroscience May 2006;139:577-95
Abstract
Glutamate toxicity in traumatic brain injury, ischemia, and Huntington’s disease causes cortical neuron death and dysfunction. We tested the efficacy of calpain and caspase-3 inhibitors alone and in combination to prevent neuronal death and preserve electrophysiological functions in rat primary cortical neurons following glutamate exposure. Cortical neurons exposed to 0.5 microM glutamate for 24 h committed mostly apoptotic death as determined by Wright staining and ApopTag assay. Levels of expression, formation of active forms, and activities of calpain and caspase-3 were increased following glutamate exposure. Also, in situ double labeling identified conformationally active caspase-3-p20 fragment and chromatin condensation in apoptotic neurons. Pretreatment of cortical neurons with 0.2 microM N-benzyloxylcarbonyl-Leu-Nle-aldehyde (calpain-specific inhibitor) and 100 microM N-benzyloxylcarbonyl-Asp(OCH3)-Glu(OCH3)-Val-Asp(OCH3)-fluoromethyl ketone (caspase-3-specific inhibitor) provided strong neuroprotection. Standard patch-clamp techniques were used to measure the whole-cell currents associated with Na+ channels, N-methyl-D-aspartate receptors, and kainate receptors. The lack of a change in capacitance indicated that neurons treated with inhibitor(s) plus glutamate did not undergo apoptotic shrinkage and maintained the same size as the control neurons. Whole-cell currents associated with Na+ channels, N-methyl-D-aspartate receptors, and kainate receptors were similar in amplitude and activation/inactivation kinetics for cells untreated and treated with inhibitor(s) and glutamate. Spontaneous synaptic activity as observed by miniature end-plate currents was also similar. Prevention of glutamate-induced apoptosis by calpain and caspase-3 inhibitors preserved normal activities of crucial ion channels such as Na+ channels, N-methyl-D-aspartate receptors, and kainate receptors in neurons. Our studies strongly imply that calpain and caspase-3 inhibitors may also provide functional neuroprotection in the animal models of traumatic brain injury and neurodegenerative diseases.
Mesh Headings (Keywords): Amino Acid Chloromethyl Ketones, Animals, Animals, Newborn, Apoptosis, Calpain, Caspase 3, Caspases, Cell Survival, Cells, Cultured, Cerebral Cortex, Chromatin, Cysteine Proteinase Inhibitors, DNA Fragmentation, Drug Interactions, Female, Glutamic Acid, Ion Channel Gating, Membrane Potentials, Neurons, Oligopeptides, Pregnancy, Rats, Rats, Sprague-Dawley
Check for Full Text / PubMed Unique Identifier (PMID): 16504408
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