Objective: To study the involvement of excitatory amino acid system in astrocytes activation caused by dimethoate.
Methods: Pure-cultured astrocytes were gained by three passages from primary cultured rat nerve cells, then treated with 10(-6),10(-5),10(-4) mol/L dimethoate for 48 h, 50 micromol/L and 100 micromol/L MK801, a NMDA receptor blocker, was used to intervene the effects induced by 10(-4) mol/L dimethoate. HPLC-FLD was utilized to measure the concentrations of excitatory amino acid (EAA), RT-PCR was used to detect the expression levels of NR2B, GLT-1, GLAST, GFAP and S100beta mRNA, and immunofluorescence staining method was applied to measure the expression levels of GFAP and S100beta proteins.
Results: The expression levels of GLAST mRNA in all exposure groups were 67.8%, 68.6% and 76.2% of control level, respectively, which were significantly lower than that of control group (P < 0.05); The concentrations of EAA significantly decreased in 10(-4) mol/L dimethoate group, as compared with control group (P < 0.01); the expression levels of GFAP mRNA in 10(-4) mol/L dimethoate group, of S100beta mRNA in 10(-5) mol/L dimethoate group, of GFAP protein in 10(-4) mol/L and 10(-5) mol/L dimethoate groups and S100beta protein in 10(-4) mol/L dimethoate group were significantly higher than those in control group (P < 0.01). The expression levels of GLT-1 and GLAST mRNA in 10(-4) mol/L dimethoate plus 50 micromol/L or 100 micromol/L MK801 groups increased significantly, as compared with 10(-4) mol/L dimethoate group (P < 0.01), the expression levels of NR2B mRNA in 10(-4) mol/L dimethoate plus 50 micromol/L or 100 micromol/L MK801 groups increased significantly, as compared with control group (P < 0.05 or P < 0.01); the concentration of Glu in 10(-4) mol/L dimethoate plus 100 micromol/L MK801 group increased significantly, as compared with 10(-4) mol/L dimethoate group (P < 0.01); the expression levels of GFAP mRNA and protein in 10(-4) mol/L dimethoate plus 50 micromol/L or 100 micromol/L MK801 groups decreased significantly (P < 0.01); S100beta protein expression level in 50 micromol/L MK801 intervention group was significantly higher than thatl in control group (P < 0.01).
Conclusion: Excitatory amino acid system involved in astrocytes activation caused by dimethoate. MK801 was useful to control astrocytes gliosis.