Study On Effects And Mechanics Of Formaldehyde Induced Neurotoxicity In Central Nervous System

Formaldehyde (FA), a kind of popular indoor air pollutant, is also an endogenous chemical. The effects of FA on human health include eyes and upper respiratory irritancy, allergy and immunological effects, genotoxicity and cancer, neurotoxicity et al. The present project explored the effects and the mechanics of fonnaldehyde induced neurotoxicity of central nervous system.The mice were exposed to 0 mg/m~3, 0.5 mg/m~3, 1.0 mg/m~3 and 3.0 mg/m~3 formaldehyde gas and tested in Morris water maze test. After the exposure, the level of oxidative damage was detected. Another two groups of mice were exposed to 3.0 mg/m~3 gasous formaldehyde and then the mRNA express levels of three subunits of NMDA receptor were detected with method of semi-quantitative RT-PCR.The result showed as below. In the hidden-platform acquisition train, Mice in each experimental group showed a clear decrease during the 7 days training. A two-way ANOVA (dayxdifferent experimental group) revealed a significant day effect (F=17.83, P<0.01) and formaldehyde exposure (F=8.84, P<0.01) but not did the dayxdifferent experimental group interaction (F=0.87, P>0.05). Subsequent multiple comparison testing was performed to analysis the significant differences between formaldehyde-inhaled groups. Results demonstrated that there were significant difference between 0 mg/m~3 and 3.0 mg/m~3 formaldehyde inhaled groups (P<0.01).In the Probe trail test mice of 0 mg/m~3 and 0.5mg/m~3 formaldehyde inhaled group spent more time in NE but little in others; a student t-test shows a significant difference between NE and other quarters (NE-SE, P<0.05; NE-NW, P<0.01; NE-SW, P<0.01). 0.5mg/m~3 group even spent more time in NE than control group and the difference was very signigicant(P<0.01). Although the time spent in NE was still longest, there was no significant difference compared with others in 1.0 mg/m~3 group. To 3.0mg/m~3 formaldehyde inhaled group, the time spent in SE was the longest; while it spent in NE was similar to SW and NW.In the oxidative damage level test, the contents of MDA increased significantly in 1.0 mg/m~3 and 3.0 mg/m~3 formaldehyde inhaled groups (P<0.01). The level of GSH and SOD activity were reduced significantly in 3.0 mg/m~3 groups (P<0.01).The mRNA express levels of NMDA receptor subunits were also changed, the formaldehyde inhalation significantly increased the level of Grinl and Grin2b(P<0.05, P<0.01) and decreased the level of GRin2a(P<0.01).In conclusion, the present study demonstrated that high concentration of gaseous formaldehyde induced neurotoxicity of central nervous system. The mechanism of it perhaps relate to oxidative damage of brain and NMDA receptor mediated damage of neurons.