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Cyanide-induced neurotoxicity: calcium mediation of morphological changes in neuronal cells
E U Maduh1, J J Turek, J L Borowitz
1Department of Pharmacology and Toxicology, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana 47907.
Abstract:
Calcium channel blockade decreases the elevation of brain calcium as well as the tremors produced by cyanide in mice. To determine if cyanide-induced morphological changes could also be inhibited by calcium channel blockade, the effect of diltiazem was studied in cultured rat pheochromocytoma (PC12) cells, a neuronal model. Incubation with KCN (1 to 10 mM for 1 to 2 hr) caused depletion of secretory granules, alignment of remaining granules along the plasma membrane, and mitochondrial swelling. All these effects were inhibited by pretreatment with 0.01 mM diltiazem. Scanning electron microscopy revealed that cyanide (1 to 10 mM for 1 to 2 hr) produced loss of microvilli and bleb formation in PC12 cells. These changes were partially inhibited by preincubation with 0.01 mM diltiazem. Incubation of cells with 10 mM cyanide increased release of lactic dehydrogenase (LDH) into the culture media at 60 and 120 min. A decrease in cell viability, as determined by trypan blue dye exclusion, paralleled the release of LDH. At 120 min of cyanide incubation, 24% of the cells excluded dye. Both the release of LDH and decreased cell viability were attenuated by pretreatment with diltiazem. The results indicate that the influx of extracellular calcium is an important factor mediating cyanide-induced morphologic changes in neuronal cells.
Insights
Calcium channel blockers, like diltiazem, protect neuronal cells from cyanide toxicity by preventing calcium influx. This study shows diltiazem inhibits cyanide-induced cell damage and death, highlighting calcium
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Calcium channel blockade mitigates cyanide-induced tremors and brain calcium elevation in mice.
- Neuronal cells are susceptible to morphological damage from cyanide exposure.
Purpose of the Study:
- To investigate whether calcium channel blockade can inhibit cyanide-induced morphological changes in neuronal cells.
- To explore the role of extracellular calcium influx in mediating cyanide toxicity.
Main Methods:
- Cultured rat pheochromocytoma (PC12) cells were used as a neuronal model.
- Cells were exposed to potassium cyanide (KCN) with and without diltiazem pretreatment.
- Morphological changes were assessed using scanning electron microscopy.
- Cell viability and damage were measured by lactic dehydrogenase (LDH) release and trypan blue dye exclusion.
Main Results:
- Diltiazem inhibited KCN-induced depletion of secretory granules, mitochondrial swelling, loss of microvilli, and bleb formation.
- KCN exposure led to increased LDH release and decreased cell viability, which were attenuated by diltiazem.
- 24% of cells excluded trypan blue dye after 120 min of cyanide incubation, indicating reduced viability.
Conclusions:
- Calcium channel blockade, specifically with diltiazem, effectively protects neuronal cells from cyanide-induced morphological damage.
- The influx of extracellular calcium plays a critical role in mediating cyanide-induced cellular changes and toxicity in neuronal cells.