Hospitalization for major surgery or critical illness often associates with cognitive decline. Inflammation and dysregulation of the innate immune system can exert broad effects in the periphery and central nervous system (CNS), yet the mechanisms underlying memory impairment after surgery remain poorly understood and without effective therapy. Endogenous regulation of acute inflammation is providing novel approaches to treat several disease states including sepsis, pain, obesity and diabetes. Resolvins are potent endogenous lipid mediators biosynthesized during the resolution phase of acute inflammation that display immunoresolvent actions. Here, using a mouse model of surgery‐induced cognitive decline we report that orthopedic surgery affects hippocampal neuronal‐glial function, including synaptic transmission and plasticity. Systemic prophylaxis with aspirin‐triggered resolvin D1 (AT‐RvD1: 7 S ,8 R ,17 R ‐trihydroxy‐4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z ‐docosahexaenoic acid, as little as 100 ng dose per mouse) improved memory decline following surgery and abolished signs of synaptic dysfunction. Moreover, delayed administration 24 h after surgery also attenuated signs of neuronal dysfunction postoperatively. AT‐RvD1 also limited peripheral damage by modulating the release of systemic interleukin (IL)‐6 and improved other clinical markers of tissue injury. Collectively, these results demonstrate a novel role of AT‐RvD1 in modulating the proinflammatory milieu after aseptic injury and protecting the brain from neuroinflammation, synaptic dysfunction and cognitive decline. These findings provide novel and safer approaches to treat postoperative cognitive decline and potentially other forms of memory dysfunctions.—Terrando, N., Gómez‐Galán, M., Yang, T., Carlström, M., Gustavsson, D., Harding, R. E., Lindskog, M., Eriksson, L. I., Aspirin‐triggered resolvin D1 prevents surgery‐induced cognitive decline. FASEB J. 27, 3564–3571 (2013). www.fasebj.org

A patient with myoclonus–dystonia syndrome was treated by implanting electrodes in the internal segment of the globus pallidus (GPi) and applying deep brain stimulation. Surgery was done in two sessions. The most affected limb was treated first and the other limb one year later. Neuronal recordings showed that most pallidal neurones discharged in bursts at a relatively low firing rate (mean (SD), 46 (18) Hz) compared with cells in the GPi in patients with Parkinson’s disease. Neurones modified the rate and mode of discharge with dystonic postures and rapid involuntary contractions of limb muscles. Neurological examination at 24 months after surgery showed a decline of 47.8% and 78.5% in the Burke–Fahn–Marsden and disability rating scales, respectively.

The possibility that exposure to general anesthetics during early life results in long-term impairment of neural function attracted considerable interest over the past decade. Extensive laboratory data suggest that administration of these drugs during critical stages of central nervous system development can lead to cell death, impaired neurogenesis and synaptic growth as well as cognitive deficits. These observations are corroborated by several recent human epidemiological studies arguing that such cognitive impairment might also occur in humans. Despite the potential public health importance of this issue, several important questions remain open. Amongst them, how the duration of anesthesia exposure impact on outcome is as yet not fully elucidated. To gain insight into this question, here we focused on the short- and long-term impact of a 30-minute-long exposure to clinically relevant concentrations of sevoflurane in rat pups at two functionally distinct stages of the brain growth spurt. We show that this treatment paradigm induced developmental stage-dependent and brain region-specific acute but not lasting changes in dendritic spine densities. Electrophysiological recordings in hippocampal brain slices from adult animals exposed to anesthesia in the early postnatal period revealed larger paired-pulse facilitation but no changes in the long-term potentiation paradigm when compared to non-anesthetized controls. BrdU pulse and pulse-chase experiments demonstrated that neither proliferation nor differentiation and survival of hippocampal progenitors were affected by sevoflurane exposure. In addition, behavioral testing of short- and long-term memory showed no differences between control and sevoflurane-exposed animals. Overall, these results suggest that brief sevoflurane exposure during critical periods of early postnatal development, although it does not seem to exert major long-term effects on brain circuitry development, can induce subtle changes in synaptic plasticity and spine density of which the physiological significance remains to be determined.