Analysis of quinolinic acid neurotoxicity to excitability of spiral ganglion cells and its mechanism in rat / 中华耳鼻咽喉头颈外科杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the neurotoxicity and its mechanism of quinolinic acid (QA) to spiral ganglion cells (SGC) and observe the protectable potential of MgCl(2) on SGC.</p><p><b>METHODS</b>SGC were cultured in vitro for 72 h, and then were divided into 4 groups control group, QA group (1 mmol/L QA), MK-801 group (1 mmol/L QA + 20 µmol/L MK-801)and MgCl(2) protected group (1 mmol/L QA + 1 mmol/L MgCl(2)). SGC apoptosis rate was analyzed by Annexin V staining and PI staining measurements after 24 h exposure to different medium. SGC cultured as methods above were divided into 4 groups as following 100 µmol/L QA, 1 mmol/L QA, 20 µmol/L MK-801+1 mmol/L QA and 1 mmol/L MgCl(2) + 1 mmol/L QA. The intracellular calcium concentration was measured by laser scanning confocal microscope finally.</p><p><b>RESULTS</b>Apoptosis rate in QA group was higher than that in both of control group (59.1% ± 7.5% vs 9.2% ± 0.9%, x ± s, q = 11.9, P < 0.05) and MgCl(2) group (59.1% ± 7.5% vs 27.5% ± 8.3%, q = 7.5, P < 0.05). There was no significant difference between apoptosis rate of control and MK-801 group (12.8% ± 5.7% vs 9.2% ± 0.9%, q = 0.9, P > 0.05). It was shown that there was a significant increase of Ca(2+) in SGC in the presence of QA by laser scanning confocal microscope. MK-801 may completely block the increase of Ca(2+), and the increase of Ca(2+) can be reduce by the application of MgCl(2).</p><p><b>CONCLUSIONS</b>QA might injure SGC by excessive activating NMDA receptors on the cell membrane. Mg(2+) may have the function to reduce the neurotoxicity of QA.</p>