Change And Significance Of Nitric Oxide And Glutamic Acid In Cerebrospinal Fluid After Traumatic Brain Injury

Background: Neurotransmitters play important roles in secondary injury of nervous system. Nitric oxide (NO) and glutamic acid (Glu) are two important neurotransmitters in the brain. NO can be converted into superoxide anion after brain injury and do damage to neurons. Over-released Glu after brain injury can cause influx of calcium ions (Ca2 +) and result in overload of intracellular Ca2+, thereby activate nitric oxide synthase (NOS).The increased NO synthesis may activate cyclic guanosine monophosphate (cGMP) signal pathway. However, there is no study on the relationship between NO and Glu after traumatic brain injury. Objective: To study the dynamic change of NO and Glu after brain trauma, and try to explore the significance of NO and Glu on secondary brain injury.Methods: Twenty patients with traumatic brain injury were divided into two groups according clinical severity: minor group (n=10) and moderate, severe group(n=10 ). Five normal persons were acquired as control group. Dynamic concentrations of NO and Glu were determined. Changing trend of concentration of NO and Glu was observed. Comparisons among groups were performed by one-way ANOVA analysis. Differences were considered significant at a value of P<0.05 for all tests.Results: The concentrations of NO in cerebrospinal fluid increased significantly in the first, third and fifth day after traumatic brain injuries (p<0.05). The concentrations of Glu in cerebrospinal fluid also increased significantly in minor group in the first and third day and in moderate, severe group in first, third, fifth and seventh day (p<0.05). And the patients' GCS in the first day after traumatic brain injuries was negatively correlated to the levels of both NO and Glu in cerebrospinal fluid, respectively. (r=-0.887 and -0.824, p<0.05). There was the positive correlation between the level of NO and Glu in cerebrospinal fluid duringseven days after traumatic brain injuries (r=0.707, p<0.01).Conclusions: The concentrations of NO and Glu in cerebrospinal fluidsignificantly increase after traumatic brain injuries, and which accord withthe conditions of patients. The positive correlation of NO and Glu incerebrospinal fluid indicates that NO may mediate neurotoxicity of Gluafter traumatic brain injuries.