Abstract
Background
Postoperative cognitive decline (POCD) is a recognized clinical phenomenon characterized by cognitive impairments in patients following anesthesia and surgery, yet its underlying ...mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, learning, and memory via activation of TrkB-full length (TrkB-FL) receptors. It has been reported that an abnormal truncation of TrkB mediated by calpain results in dysregulation of BDNF/TrkB signaling and is associated with cognitive impairments in several neurodegenerative disorders. Calpains are Ca
2+
-dependent proteases, and overactivation of calpain is linked to neuronal death. Since one source of intracellular Ca
2+
is N-methyl-d-aspartate receptors (NMDARs) related and the function of NMDARs can be regulated by neuroinflammation, we therefore hypothesized that dysregulation of BDNF/TrkB signaling mediated by NMDAR/Ca
2+
/calpain might be involved in the pathogenesis of POCD.
Methods
In the present study, 16-month-old C57BL/6 mice were subjected to exploratory laparotomy with isoflurane anesthesia to establish the POCD animal model. For the interventional study, mice were treated with either NMDAR antagonist memantine or calpain inhibitor MDL-28170. Behavioral tests were performed by open field, Y maze, and fear conditioning tests from 5 to 8 days post-surgery. The levels of Iba-1, GFAP, interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), NMDARs, calpain, BDNF, TrkB, bax, bcl-2, caspase-3, and dendritic spine density were determined in the hippocampus.
Results
Anesthesia and surgery-induced neuroinflammation overactivated NMDARs and then triggered overactivation of calpain, which subsequently led to the truncation of TrkB-FL, BDNF/TrkB signaling dysregulation, dendritic spine loss, and cell apoptosis, contributing to cognitive impairments in aging mice. These abnormities were prevented by memantine or MDL-28170 treatment.
Conclusion
Collectively, our study supports the notion that NMDAR/Ca2+/calpain is mechanistically involved in anesthesia and surgery-induced BDNF/TrkB signaling disruption and cognitive impairments in aging mice, which provides one possible therapeutic target for POCD.
Few studies have investigated factors associated with acute postsurgical pain (APSP) trajectories, and whether the APSP trajectory can predict chronic postsurgical pain (CPSP) remains unclear. We ...aimed to identify the predictors of APSP trajectories in patients undergoing gastrointestinal surgery. Moreover, we hypothesised that APSP trajectories were independently associated with CPSP. We conducted a prospective cohort study of 282 patients undergoing gastrointestinal surgery to describe APSP trajectories. Psychological questionnaires were administered 1 day before surgery. Meanwhile, demographic characteristics and perioperative data were collected. Average pain intensity during the first 7 days after surgery was assessed by a numeric rating scale (NRS). Persistent pain intensity was evaluated at 3 and 6 months postoperatively by phone call interview. CPSP was defined as pain at the incision site or surrounding areas of surgery with a pain NRS score ≥ 1 at rest. The intercept and slope were calculated by linear regression using the least squares method. The predictors for the APSP trajectory and CPSP were determined using multiple linear regression and multivariate logistic regression, respectively. Body mass index, morphine milligram equivalent (MME) consumption, preoperative chronic pain and anxiety were predictors of the APSP trajectory intercept. Moreover, MME consumption and preoperative anxiety could independently predict the APSP trajectory slope. The incidence of CPSP at 3 and 6 months was 30.58% and 16.42% respectively. APSP trajectory and age were predictors of CPSP 3 months postoperatively, while female sex and preoperative anxiety were predictive factors of CPSP 6 months postoperatively. Preoperative anxiety and postoperative analgesic consumption can predict APSP trajectory. In addition, pain trajectory was associated with CPSP. Clinicians need to stay alert for these predictors and pay close attention to pain resolution.
Systemic inflammation induces cognitive impairments via unclear mechanisms. Accumulating evidence has demonstrated that a subset of neurons that express parvalbumin (PV) play a critical role in ...regulation of cognitive and emotional behavior. Thus, the aim of the present study was to test whether disruption of PV interneuron mediates systemic inflammation–induced depression-like behavior and working memory impairment by lipopolysaccharide (LPS) challenge. Here we showed that LPS induces depression-like behavior and working memory impairment, coinciding with increased PV expression, enhanced GABAergic transmission, and impaired long-term potentiation (LTP) in the hippocampus. Notably, systemic administration of NMDA (N–methyl–D–aspartate) receptor (NMDAR) antagonist ketamine was able to interfere with PV expression and reverse depression-like behavior and working memory impairment, which is probably mediated by reversing impaired LTP. In addition, flumazenil, a competitive antagonist acting at the benzodiazepine binding site of the GABAA receptor, also ameliorated these abnormal behaviors. Collectively, our study added growing evidence to the limited studies that overinhibition mediated by PV interneurons might play a critical role in LPS–induced depression-like behavior and working memory impairment.
As a promising anode candidate for lithium ion batteries (LIBs), MnO has attracted wide attentions owing to its theoretically high Li-storage capacity, lower working voltage and polarization than ...other oxides, low cost, environmental friendliness, and abundant resources. Herein, we develop a facile and low-cost strategy to fabricate a unique porous MnO@N-doped carbon (MnO@N-C) nanotube and demonstrate its outstanding Li-storage properties as anode material for LIBs. Benefiting from its unique 1D porous features, the prepared MnO@N-C electrodes exhibit high reversible specific capacity (971.8 mAh g−1 at 0.1 A g−1), superb high-rate capability (359.5 mAh g−1 at 30 A g−1) and remarkable cycling stability (441.5 mA h g−1 after 3500 cycles at 10 A g−1). Such superior electrochemical performance should be due to the high conductivity and protection effects of N-doped carbon layer, and adequate internal voids in the MnO@N-C to effectively accommodate the volume changes of MnO during cycling. In addition, it is also disclosed that the high capacity contribution arises from the pseudocapacitive charge storage.
Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction caused by many pathological events, including neuroinflammation and oxidative stress damage. Increasing evidence suggests that ...parvalbumin (PV) interneurons play a key role in the cognitive process, whereas the dysfunction of these interneurons has been implicated in a number of major psychiatric disorders. Here, we aimed to investigate whether enhanced inflammation and oxidative stress-mediated PV interneuron phenotype loss plays a role in sepsis-induced cognitive impairments.
Male C57BL/6 mice were subjected to cecal ligation and puncture or sham operation. For the interventional study, the animals were chronically treated with a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, apocynin, at 5 mg/kg. The mice were euthanized at the indicated time points, and the brain tissues were harvested for determination of the PV, membrane subunit of NADPH oxidase gp91(phox), and markers of oxidative stress (4-hydroxynonenal and malondialdehyde) and inflammation (tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, and IL-10). A separate cohort of animals was used to evaluate the behavioral alterations by the open field and fear conditioning tests. Primary hippocampal neuronal cultures were used to investigate the mechanisms underlying the dysfunction of PV interneurons.
Sepsis resulted in cognitive impairments, which was accompanied by selective phenotype loss of PV interneurons and increased gp91(phox), 4-hydroxynonenal, malondialdehyde, IL-1β, and IL-6 expressions. Notably, these abnormalities could be rescued by apocynin treatment.
Selective phenotype loss of PV interneurons, as a result of NADPH oxidase 2 (Nox2) activation, might partly contribute to cognitive impairments in a mouse model of SAE.
A prolonged isoflurane exposure may lead to cognitive decline in rodents. Neuregulin 1 (NRG1)-ErbB4 signaling plays a key role in the modulation of hippocampal synaptic plasticity through regulating ...the neurotransmission. The authors hypothesized that hippocampal NRG1-ErbB4 signaling is involved in isoflurane-induced cognitive impairments in aged mice.
Fourteen-month-old C57BL/6 mice were randomized to receive 100% O2 exposure, vehicle injection after 100% O2 exposure, vehicle injection after exposure to isoflurane carried by 100% O2, NRG1-β1 injection after exposure to isoflurane carried by 100% O2, and NRG1-β1 and an ErbB4 inhibitor AG1478 injection after exposure to isoflurane carried by 100% O2. Fear conditioning test was used to assess the cognitive function of mice 48-h postexposure. The brain tissues were harvested 48-h postexposure to determine the levels of NRG1, ErbB4, p-ErbB4, parvalbumin, and glutamic acid decarboxylase 67 in the hippocampus using Western blotting, enzyme-linked immunosorbent assay, and immunofluorescence.
The percentage of freezing time to context was decreased from 50.28 ± 11.53% to 30.82 ± 10.00%, and the hippocampal levels of NRG1, p-ErbB4/ErbB4, parvalbumin, and glutamic acid decarboxylase 67 were decreased from 172.79 ± 20.85 ng/g, 69.15 ± 12.20%, 101.68 ± 11.21%, and 104.71 ± 6.85% to 112.92 ± 16.65 ng/g, 42.26 ± 9.71%, 75.89 ± 10.26%, and 73.87 ± 16.89%, respectively, after isoflurane exposure. NRG1-β1 attenuated the isoflurane-induced hippocampus-dependent cognitive impairment and the declines in the hippocampal NRG1, p-ErbB4/ErbB4, parvalbumin, and glutamic acid decarboxylase 67. AG1478 inhibited the rescuing effects of NRG1-β1.
Disruption of NRG1-ErbB4 signaling in the parvalbumin-positive interneurons might, at least partially, contribute to the isoflurane-induced hippocampus-dependent cognitive impairment after exposure to isoflurane carried by 100% O2 in aged mice.
•Neonatal sevoflurane exposure caused significant cognitive impairment late in life.•Curcumin administration attenuated sevoflurane anesthesia induced neuronal apoptosis.•Curcumin administration ...attenuated sevoflurane anesthesia induced oxidative nitrosative stress.•Curcumin administration attenuated sevoflurane anesthesia induced neuroinflammation.•Curcumin administration attenuated sevoflurane anesthesia induced neurocognitive impairment.
Sevoflurane, a commonly used inhaled anesthetic, can induce neuronal apoptosis in the developing rodent brain and correlate with functional neurological impairment later in life. However, the mechanisms underlying these deleterious effects of sevoflurane remain unclear and no effective treatment is currently available. Herein, the authors investigated whether curcumin can prevent the sevoflurane anesthesia-induced cognitive impairment in mice. Six-day-old C57BL/6 mice were exposed to 3% sevoflurane 2h daily for 3 consecutive days and were treated with curcumin at the dose of 20mg/kg or vehicle 30min before the sevoflurane anesthesia from postnatal days 6 (P6) to P8. Cognitive functions were evaluated by open field, Morris water maze, and fear conditioning tests on P61, P63–69, and P77–78, respectively. In another separate experiment, mice were killed on day P8 or P78, and the brain tissues were harvested and then subjected to biochemistry studies. Our results showed that repeated neonatal sevoflurane exposure led to significant cognitive impairment later in life, which was associated with increased neuronal apoptosis, neuroinflammation, oxidative nitrosative stress, and decreased memory related proteins. By contrast, pre-administration of curcumin ameliorated early neuronal apoptosis, neuroinflammation, oxidative nitrosative stress, memory related proteins, and later cognitive dysfunction. In conclusion, our data suggested that curcumin pre-administration can prevent the sevoflurane exposure-induced cognitive impairment later in life, which may be partly attributed to its ability to attenuate the neural apoptosis, inflammation, and oxidative nitrosative stress in mouse brain.
Repeated neonatal exposures to sevoflurane induce long-term cognitive impairment that has been reported to have sex-dependent differences. Exercise promotes learning and memory by releasing lactate ...from the muscle. The study tested the hypothesis that lactate may improve long-term cognitive impairment induced by repeated neonatal exposures to sevoflurane through SIRT1-mediated regulation of adult hippocampal neurogenesis and synaptic plasticity. C57BL/6 mice of both genders were exposed to 3% sevoflurane for 2 h daily from postnatal day 6 (P6) to P8. In the intervention experiments, mice received lactate at 1 g/kg intraperitoneally once daily from P21 to P41. Behavioral tests including open field (OF), object location (OL), novel object recognition (NOR), and fear conditioning (FC) tests were performed to assess cognitive function. The number of 5-Bromo-2′- deoxyuridine positive (BrdU
+
) cells and BrdU
+
/DCX
+
(doublecortin) co-labeled cells, expressions of brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal-associated protein (Arc), early growth response 1 (Egr-1), SIRT1, PGC-1α and FNDC5, and long-term potentiation (LTP) were evaluated in the hippocampus. Repeated exposures to sevoflurane induced deficits in OL, NOR and contextual FC tests in male but not female mice. Similarly, adult hippocampal neurogenesis, synaptic plasticity-related proteins and hippocampal LTP were impaired after repeated exposures to sevoflurane in male but not female mice, which could rescue by lactate treatment. Our study suggests that repeated neonatal exposures to sevoflurane inhibit adult hippocampal neurogenesis and induce defects of synaptic plasticity in male but not female mice, which may contribute to long-term cognitive impairment. Lactate treatment rescues these abnormalities through activation of SIRT1.
Highlights • Anesthesia and surgery induced hippocampus-dependent memory impairments in aged mice. • Anesthesia and surgery induced microglial activation and subsequent neuroinflammation and ...down-regulation of BDNF expression. • Surgery-induced microglial activation was associated with Nox2 activation.
Plasmablastic lymphoma (PBL) is a rare but aggressive B-cell lymphoma subtype with poor prognosis. Knowledge about the etiology, clinicopathologic and molecular features, and outcomes of PBL is ...limited. This study aimed to examine the clinicopathologic characteristics, therapeutic approaches, and clinical outcomes of PBL patients in a Chinese population.
A total of 102 PBL patients were recruited from three cancer centers. The pathologic features and clinical outcomes of 56 patients with available treatment details and follow-up data were reviewed and analyzed. RNA sequencing was performed in 6 PBL and 11 diffuse large B-cell lymphoma (DLBCL) patients.
Most patients in our cohort were male (n = 36, 64.3%), and 35 patients presented with Ann Arbor stage I/II disease at diagnosis. All these patients showed negative findings for human immunodeficiency virus, and the vast majority of patients in our cohort were immunocompetent. Lymph nodes (n = 13, 23.2%) and gastrointestinal tract (n = 10, 17.9%) were the most commonly involved site at presentation. Post-treatment complete remission (CR) was the only prognostic factor affecting overall survival (OS) and progression-free survival (PFS) in the multivariate analysis. RNA-seq demonstrated that B-cell receptor (BCR), T-cell receptor (TCR), P53, calcium signaling, and Wnt signaling pathways were significantly downregulated in PBLs compared with GCB (or non-GCB) DLBCLs.
In this multicenter study in the Chinese population, PBL mainly occurred in immunocompetent individuals and most patients present with early-stage disease at diagnosis. Post-treatment CR was an important prognostic factor affecting OS and PFS. RNA-seq showed that the B-cell receptor (BCR), P53, calcium signaling, cell adhesion molecules, and Wnt signaling pathways significantly differed between PBL and GCB (or non-GCB) DLBCL, which provided theoretical basis for its pathogenesis and future treatment.
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