Objective:To investigate the level of excitatory amino acids in the cerebrospinal fluid and the effect of magnesium sulfate on the excitatory amino acids following traumatic brain injury. Methods:The Feeney′s model of the excitatory amino acids in the cerebrospinal fluid (glutamate and aspartate) were measured by amino acid analysis from rats in different time. Results:1. The glutamate and aspartate in the cerebrospinal fluid increased largely 2 hours after traumatic brain injury(P<0.05)

and then gradually decreased. Compared with sham control group

the concentration of excitatory amino acids at 12h after injury had no significant difference ( P>0.05).2.Magnesium inhibited strongly the releasing of the excitatory amino acids at 2h and 8h after the traumatic brain injury(P<0.05)

and it had no effect on the releasing of the excitatory amino acids at 12h

24h

48h

72h after traumatic brain injury(P>0.05).Conclusion:Plenty releasing of excitatory amino acid may play an important role at the phase of posttraumatic neuronal injury.Magnesium sulfate can inhibit early releasing of excitatory amino acids.Administering magnesium sulfate may be the optimal choice for treating traumatic brain injury.