Protective role of pentobarbital pretreatment for NMDA-R activated lipid peroxidation is derived from the synergistic effect on endogenous anti-oxidant in the hippocampus of rats

We have attempted to explore the neuroprotective effectiveness of PBT by measuring anti-oxidant ability in the hippocampus of rats in a freely moving state. Anti-oxidant ability was examined utilizing the principle that blood–brain barrier-permeable nitroxide radicals (PCAM) injected i.p. lose their paramagnetism in an exponential decay correlated with anti-oxidant ability in the brain. The half-life of PCAM was used as the indicator of the hippocampal anti-oxidant ability. While the half-life was statistically prolonged when infused with 0.1 mM NMDA without PBT, the half-life was almost the same as in the control when infused with NMDA under anesthesia with PBT. In addition, the half-life under only PBT anesthesia was the shortest of all the groups. Our findings, therefore, suggested that PBT anesthesia not only suppresses NMDA-R activated free radical generation but also synergistically enhances the increased basal endogenous anti-oxidant ability in the hippocampus.