Nitric oxide and antioxidant status in glucose and oxygen deprived neonatal and adult rat brain synaptosomes

Nitric oxide (NO) has been implicated in the process of cerebral ischemia/reperfusion injury. We have examined the production of NO, as reflected by nitrite (NO₂ ⁻)+nitrate (NO₃ ⁻) accumulation, from synaptosomes isolated from neonatal or adult rat brain and subjected to a period of glucose and oxygen deprivation. There was a significant increase in the amount of NO₂ ⁻+NO₃ ⁻ production from adult synaptosomes under these conditions, whereas there was no difference compared to control in the production of NO₂ ⁻+NO₃ ⁻ from the neonatal synaptosomes. The total antioxidant status of the synaptosomes at these different stages of brain development was found to be the same. These data suggest that the vulnerability of the adult brain to ischemia/reperfusion injury may be associated with the production of NO from nerve terminals. The ratios of antioxidant capacity to NO production under such conditions have been shown here to be different between the neonatal and adult nerve terminals. Thus the well documented resistance of neonatal brain to ischemia/reperfusion injury may involve the neonatal nerve terminal being under less oxidative stress than the adult.