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Protective Effect of Edaravone on Glutamate-Induced Neurotoxicity in Spiral Ganglion Neurons

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ABSTRACT

Glutamate is an important excitatory neurotransmitter in mammalian brains, but excessive amount of glutamate can cause “excitotoxicity” and lead to neuronal death. As bipolar neurons, spiral ganglion neurons (SGNs) function as a “bridge” in transmitting auditory information from the ear to the brain and can be damaged by excessive glutamate which results in sensorineural hearing loss. In this study, edaravone, a free radical scavenger, elicited both preventative and therapeutic effects on SGNs against glutamate-induced cell damage that was tested by MTT assay and trypan blue staining. Ho.33342 and PI double staining revealed that apoptosis as well as necrosis took place during glutamate treatment, and apoptosis was the main type of cell death. Oxidative stress played an important role in glutamate-induced cell damage but pretreatment with edaravone alleviated cell death. Results of western blot demonstrated that mechanisms underlying the toxicity of glutamate and the protection of edaravone were related to the PI3K pathway and Bcl-2 protein family.

No MeSH data available.


Cytoprotection of edaravone on glutamate-induced apoptosis and necrosis in SGNs. (a) Untreated SGNs appeared blue intact nuclei. (b) SGNs were treated with glutamate for 10 min and then cultured for 24 h. Nuclei of apoptotic SGNs were obvious and stained brilliant-blue by Ho.33342. Nuclei of necrotic cells were labeled red by PI. (c) SGNs were pretreated with 500 μM edaravone 20 min before glutamate. (d and e) Apoptosis and necrosis rates of SGNs. ∗p < 0.05, versus glutamate-treated group.
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fig6: Cytoprotection of edaravone on glutamate-induced apoptosis and necrosis in SGNs. (a) Untreated SGNs appeared blue intact nuclei. (b) SGNs were treated with glutamate for 10 min and then cultured for 24 h. Nuclei of apoptotic SGNs were obvious and stained brilliant-blue by Ho.33342. Nuclei of necrotic cells were labeled red by PI. (c) SGNs were pretreated with 500 μM edaravone 20 min before glutamate. (d and e) Apoptosis and necrosis rates of SGNs. ∗p < 0.05, versus glutamate-treated group.

Mentions: Apoptosis and necrosis were detected using Ho.33342 and PI. Nuclei of apoptotic cells would be stained with brilliant-blue fluorescence by Ho.33342, while nuclei of necrotic cells would be stained with red fluorescence by PI. After treatment with 2 mM glutamate for 10 min, the cells were changed to normal medium and culture for additional 24 h. Then SGNs were fixed and stained with Ho.33342 and PI. Nuclei which were dyed brilliant-blue or red demonstrated the occurrence of apoptosis or necrosis. The percentages of necrotic cells and apoptotic cells with glutamate treatment were higher than those of the control group without any treatment. On the contrary, SGNs pretreated with edaravone compared to control group showed no obvious apoptosis and necrosis (Figure 6). So we came to the conclusion that glutamate could induce apoptosis and necrosis of SGNs, but edaravone could effectively alleviate cell death.


Protective Effect of Edaravone on Glutamate-Induced Neurotoxicity in Spiral Ganglion Neurons
Cytoprotection of edaravone on glutamate-induced apoptosis and necrosis in SGNs. (a) Untreated SGNs appeared blue intact nuclei. (b) SGNs were treated with glutamate for 10 min and then cultured for 24 h. Nuclei of apoptotic SGNs were obvious and stained brilliant-blue by Ho.33342. Nuclei of necrotic cells were labeled red by PI. (c) SGNs were pretreated with 500 μM edaravone 20 min before glutamate. (d and e) Apoptosis and necrosis rates of SGNs. ∗p < 0.05, versus glutamate-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
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fig6: Cytoprotection of edaravone on glutamate-induced apoptosis and necrosis in SGNs. (a) Untreated SGNs appeared blue intact nuclei. (b) SGNs were treated with glutamate for 10 min and then cultured for 24 h. Nuclei of apoptotic SGNs were obvious and stained brilliant-blue by Ho.33342. Nuclei of necrotic cells were labeled red by PI. (c) SGNs were pretreated with 500 μM edaravone 20 min before glutamate. (d and e) Apoptosis and necrosis rates of SGNs. ∗p < 0.05, versus glutamate-treated group.
Mentions: Apoptosis and necrosis were detected using Ho.33342 and PI. Nuclei of apoptotic cells would be stained with brilliant-blue fluorescence by Ho.33342, while nuclei of necrotic cells would be stained with red fluorescence by PI. After treatment with 2 mM glutamate for 10 min, the cells were changed to normal medium and culture for additional 24 h. Then SGNs were fixed and stained with Ho.33342 and PI. Nuclei which were dyed brilliant-blue or red demonstrated the occurrence of apoptosis or necrosis. The percentages of necrotic cells and apoptotic cells with glutamate treatment were higher than those of the control group without any treatment. On the contrary, SGNs pretreated with edaravone compared to control group showed no obvious apoptosis and necrosis (Figure 6). So we came to the conclusion that glutamate could induce apoptosis and necrosis of SGNs, but edaravone could effectively alleviate cell death.

View Article: PubMed Central - PubMed

ABSTRACT

Glutamate is an important excitatory neurotransmitter in mammalian brains, but excessive amount of glutamate can cause &ldquo;excitotoxicity&rdquo; and lead to neuronal death. As bipolar neurons, spiral ganglion neurons (SGNs) function as a &ldquo;bridge&rdquo; in transmitting auditory information from the ear to the brain and can be damaged by excessive glutamate which results in sensorineural hearing loss. In this study, edaravone, a free radical scavenger, elicited both preventative and therapeutic effects on SGNs against glutamate-induced cell damage that was tested by MTT assay and trypan blue staining. Ho.33342 and PI double staining revealed that apoptosis as well as necrosis took place during glutamate treatment, and apoptosis was the main type of cell death. Oxidative stress played an important role in glutamate-induced cell damage but pretreatment with edaravone alleviated cell death. Results of western blot demonstrated that mechanisms underlying the toxicity of glutamate and the protection of edaravone were related to the PI3K pathway and Bcl-2 protein family.

No MeSH data available.