[Effects of exogenous carbon monoxide on neurocytes: experiment in vitro]

To study the effect of CO on neurocytes.

Human neuroblastoma cells of the line SH-SY5Y were cultured and exposed to CO of the concentrations of 100, 1000, and 10 000 ppm for 12 h, and some SH-SY5Y cells were cultured and exposed to 5% CO(2) to be used as control group. The cell viability was observed with MTT assay. The DNA content and percentage of apoptosis were measured by flow cytometry and DNA agarose gel electrophoresis. Laser scanning confocal microscopy (LSCM) was used to detect the reactive oxygen species and the reduction in mitochondrial membrane potential. The activation of caspase-3 was measured with the caspase-3 activity assay kit. The expression of Bax was detected with Western blotting.

After exposure to 1000 and 10 000 ppm CO for 12 h the viability of the cells decreased to 85.6 +/- 9.2 and 63.4 +/- 8.1 respectively (both P < 0.05), the apoptotic rates of the cells were 29.03% and 41.67% respectively, DNA agarose gel electrophoresis showed clear DNA ladder band, the caspase-3 activity increased by 129% and 443% respectively, LSCM showed that the number of the SH-SY5Y cells decreased and the fluorescence intensity inside the cells increased significantly (both P < 0.05), the red/green fluorescence ratio inside the cells decreased from the baseline level of (5.91 +/- 0.21) to (1.56 +/- 0.07) and (0.34 +/- 0.02) respectively, and the Bax protein expression increased greatly. However, 100 ppm CO had no obvious effects on the cell viability, reactive oxygen species, mitochondrial membrane potential, caspase-3 activity, and expression of Bax.

High concentration CO has direct cytotoxicity on neurocytes cultured in vitro, but low concentration CO does not induce marked injuries of neurocytes.