Direct Assessments of the Antioxidant Effects of Propofol Medium Chain Triglyceride/Long Chain Triglyceride on the Brain of Stroke-prone Spontaneously Hypertensive Rats Using Electron Spin Resonance Spectroscopy

Abstract

Background Antioxidant anesthetics such as propofol (2,6-diisopropylphenol) directly inhibit lipid peroxidation via the generation of reactive oxygen species. Currently, there are no other studies regarding the direct effects of propofol medium chain triglyceride/long chain triglyceride (MCT/LCT) on reactive oxygen species generation or in experimental models of reactive oxygen species-induced oxidative stress in the brain. Methods The authors investigated the effects of propofol MCT/LCT on reactive oxygen species (hydroxyl radical or superoxide) by electron spin resonance spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide. The effects of propofol MCT/LCT on oxidative stress in the brain of Wistar-Kyoto rats or stroke-prone spontaneously hypertensive rats were investigated by using an in vivo L-band electron spin resonance system to monitor the decay rate of 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl as a nitroxyl spin probe. Results These studies provided direct evidence that propofol MCT/LCT inhibited hydroxyl radical generation, but not superoxide generation. Regarding the hydroxyl radical from the Fenton system, it is likely to be due to the scavenging effects of vehicle. Anesthesia with propofol MCT/LCT reduced the degree of the high oxidative stress in the brain of stroke-prone spontaneously hypertensive rats. Conclusion The current data show that propofol, mixed with clinical reagents (propofol MCT/LCT), resulted in the down-regulation of high oxidative stress due to scavenging hydroxyl radical, as demonstrated by in vitro or in vivo electron spin resonance analysis. These results led to reduced levels of hydroxyl radical, formed by brain injury such as stroke, and may therefore provide advantages for neuroprotection during anesthesia for craniotomy, e.g., in cases of brain disease.