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Propofol and dexmedetomidine are commonly used in clinical situations where neuroinflammation may be imminent or even established but comparative data on their effects on neuroinflammatory and cognitive parameters are lacking. Using a murine model of neuroinflammation induced by systemic lipopolysaccharide (LPS), this study compared the effects of these two agents on cognitive function, neuroinflammatory parameters, oxidative stress and neurotransmission. Male adult C57BL/6 N mice were anaesthetised with propofol or dexmedetomidine prior to intraperitoneal injection of LPS. Cognitive and motor function were assessed by the Y-maze and Rotarod tests respectively. Inflammatory responses were evaluated by relative levels of cytokine mRNA and immunoreactivity of glia cells. LPS caused a marked elevation in IL-1β and TNF-α levels both peripherally and in the brain, together with microglia activation (p <  0.05) and cognitive impairment. These changes were accompanied by an increase in 8-hydroxy-2'-deoxyguanosine (8-OHdG) (p <  0.05). Dexmedetomidine attenuated microglia activation (p <  0.05) and the elevation in 8-OHdG level (p <  0.05). Propofol did not affect cognition. However, both drugs lowered the number of vesicular glutamate transporter 1 (VGLUT 1), but was associated with higher levels of apoptosis and 8-OHdG (p <  0.05). Data from this study suggest dexmedetomidine and propofol have different anti-neuroinflammatory and neuroprotective profiles. However, neither drug can fully attenuate the effects of LPS induced cognitive impairment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Exposure to anesthetic agents has been linked to abnormal tau protein phosphorylation, an antecedent to the development of neurofibrillary tangles. This study evaluates the direct and indirect effects of dexmedetomidine. Primary culture of cortical neurons established from Sprague-Dawley (SD) rat embryos were exposed to dexmedetomidine for 1 or 6 hours, and the degree of tau phosphorylation at the AT8, AT180, and S396 sites was assessed by western blot analysis. To assess and compare their relative in vivo effects, the same agent was administered intravenously to 8 to 10 week old male SD rats and titrated to the loss of the righting reflex for 2 hours. After 1 hour of recovery, the rats were sacrificed and samples taken from the cortex and hippocampus were subjected to western blot and immunohistochemical analysis. The in vitro studies reviewed significant hyperphosphorylation only at the S396 site, and these changes have largely disappeared at 6 hours. With temperature maintenance, dexmedetomidine induced significant changes in hyperphosphorylation at the AT8 site in the cortex and hippocampus and at the AT180 in the hippocampus. The direct effect of anesthetic agents on fully differentiated cortical neurons is epitope-specific and short-lived. The in vivo effects are comparatively more complicated and depend not only on the phosphorylation site but the regions of the brain examined. These findings suggest that dexmedetomidine increases tau phosphorylation both in vitro and in vivo under normothermic conditions, and further studies are warranted to determine the long-term impact of this anesthetic on the tau pathology and even cognitive function.