Oxidative stress and mitochondrial dysfunction contributes to postoperative cognitive dysfunction in elderly rats

Can supplementation with antioxidants improve cognitive functions in patients with multiple sclerosis? A literature review

Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease of the central nervous system (CNS) with a complex and multifactorial pathophysiology. Although these mechanisms are not yet fully elucidated, it is established that oxidative stress (OS) plays a key role in driving neurodegeneration in MS. These pathological mechanisms contribute to a wide range of symptoms, including motor and sensory deficits, as well as cognitive impairment. The impairments in cognitive functions can cause a major burden for these patients and significantly affect their quality of life. For example, memory is one of the most frequently impaired cognitive domains in MS. These deficits often correlate with biomarkers of neurodegeneration and disease progression. Despite the substantial burden of cognitive impairment in MS, no established treatments currently exist to prevent or mitigate cognitive decline in these patients, aside from the disease-modifying treatments. Several clinical trials have investigated the potential of antioxidant supplementation to improve cognitive outcomes in MS patients. However, their findings are often controversial. This review discusses trials evaluating the effects of supplementation with various antioxidants, including Ginkgo biloba, melatonin, omega-3 fatty acids, vitamins A, N-acetylcysteine, lipoic acid, xanthophylls, and crocin, on cognitive performance. We discuss the findings of these studies, highlight methodological limitations, and explore the underlying mechanisms by which these compounds may modulate cognition. These mechanisms range from mitigating OS, inflammation, and glutamate-induced neurotoxicity in the CNS to addressing secondary symptoms such as depression and fatigue, which are often linked to cognitive decline. By reviewing the current evidence, this review not only underscores the therapeutic potential and limitations of antioxidant supplementation but also provides guidance for future research to optimize study design and advance our understanding of cognitive preservation strategies in MS.

Short-Chain Fatty Acids Alleviate Perioperative Neurocognitive Disorders Through BDNF/PI3K/Akt Pathway in Middle-Aged Rats

Perioperative neurocognitive disorders (PND), characterized by persistent cognitive impairment lasting from days to years, present substantial clinical challenges in elderly surgical populations, profoundly compromising functional independence, quality of life, and long-term prognosis. We aimed to investigate the effects of short-chain fatty acids (SCFAs) treatment on PND via mediating Brain-derived neurotrophic factor (BDNF)/Phosphatidylinositol3-kinase (PI3K)/Protein kinase B (Akt) pathway. Using 16S rDNA sequencing targeting the V3-V4 hypervariable regions, we first demonstrated significant gut microbiota dysbiosis in PND model rats, accompanied by altered SCFAs profiles. Subsequent fecal microbiota transplantation (FMT) experiments established causal relationships between PND-associated microbial alterations and spatial cognitive deficits. Mechanistically, SCFAs supplementation attenuated neuronal damage and restored synaptic plasticity, as evidenced by Nissl staining quantification (reduced chromatolysis), TUNEL assay (decreased apoptosis rate), and immunohistochemical analysis (upregulated NeuN expression). Molecular investigations revealed that SCFAs-mediated cognitive improvement involved BDNF upregulation and subsequent PI3K/Akt pathway activation, ultimately enhancing neuronal survival and synaptic integrity. Notably, PND animals exhibited characteristic neuropathological features including synaptic density reduction (PSD-95 downregulation), neuroinflammation amplification (IL-6 elevation), and apoptosis activation-all significantly reversed by SCFA intervention. Our findings establish a novel gut-brain axis mechanism wherein microbiota-derived SCFAs may exert neuroprotection through BDNF-dependent PI3K/Akt signaling, and offer potential therapeutic strategies for PND management.

Emerging Roles of Meningeal Lymphatic Vessels in Ischemic Stroke

This review highlights the emerging relevance of meningeal lymphatic vessels (MLVs) in the context of ischemic stroke, challenging the conventional view of a privileged immunological central nervous system. MLVs facilitate immunological surveillance by modulating the entry of peripheral immune cells into the meningeal compartment, a process not impeded by the blood-brain barrier. In ischemic stroke, these vessels play a crucial role in the neuroinflammatory cascade, contributing to immune responses by draining antigens and signals to cervical lymph nodes. Their involvement extends to potential contributions to resolving ischemia-induced cerebral edema, impacting fluid homeostasis. The dynamic interaction among MLVs, neuroinflammation, and fluid dynamics suggests promising therapeutic approaches. Targeting these vessels for immunomodulation, fluid drainage, and preserving blood-brain barrier integrity emerges as an innovative approach to improve ischemic stroke outcomes. However, successful clinical translation awaits further exploration of the therapeutic potential of these vessels. The multifaceted contributions of MLVs provide a compelling rationale for ongoing research, aiming to fully harness their therapeutic impact in ischemic stroke management.

Circulating Biomarkers to Predict Post-Operative Cognitive Decline in Patients Undergoing Coronary Artery Bypass Grafting

Post-operative cognitive decline (POCD) is characterized by impairments in cognitive functions. Coronary artery bypass grafting (CABG) is associated with a high risk of POCD due to its impact on neuroinflammation and oxidative stress. In this study, we investigated the dynamics of neurotrophic, inflammatory, and oxidative stress markers in a cohort of post-CABG patients to identify potential biomarkers for POCD. Blood samples were collected at baseline (immediately post-surgery) and at 3-month follow-up. Expression levels of NRF2 and other regulators of oxidative stress (GST, GSS, HMOX1, CAT, HSP27, and LOX-1), inflammatory mediators (IL-6, IP-10, and NFκB), and neuroprotective factor (BDNF) were analyzed. Cognitive assessments were performed using RBANS, TMT, TIB and MMSE. POCD patients exhibited an initial upregulation of NRF2-related antioxidant genes, which failed to sustain at 3-months follow-up, leading to a decline in HMOX1, IP-10 and BDNF protein levels, along with increased LOX-1 protein level and NFκB expression, indicating persistent oxidative stress and inflammation. In contrast, non-POCD patients demonstrated a sustained increase in antioxidant and neuroprotective markers, suggesting a more effective compensatory response. ROC analysis identified HMOX1 and BDNF as significant predictors of POCD, with LOX-1 and IP-10 emerging as diagnostic markers at follow-up. In conclusion, our findings highlight the dynamic regulation of oxidative stress and inflammatory pathways in POCD, emphasizing the failure of sustained neuroprotection in affected patients. Further large-scale studies are necessary to validate these findings, and biomarker-based screening could facilitate early risk stratification and targeted interventions to improve cognitive outcomes after cardiac surgery.

Mitophagy in perioperative neurocognitive disorder: mechanisms and therapeutic strategies

Perioperative neurocognitive disorder (PND) is a common neurological complication after surgery/anesthesia in elderly patients that affect postoperative outcome and long-term quality of life, which increases the cost of family and social resources. The pathological mechanism of PND is complex and not fully understood, and the methods of prevention and treatment of PND are very limited, so it is particularly important to analyze the mechanism of PND. Research indicates that mitochondrial dysfunction is pivotal in the initiation and progression of PND, although the precise mechanisms remain elusive and could involve disrupted mitophagy. We reviewed recent studies on the link between mitophagy and PND, highlighting the role of key proteins in abnormal mitophagy and discussing therapeutic strategies aimed at mitophagy regulation. This provides insights into the mechanisms underlying PND and potential therapeutic targets.

The role of clock control of DRP1 activity involved in postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a prevalent clinical issue following anesthesia and surgery. The onset of POCD, which is closely linked to circadian rhythm disturbance in previous studies, yet the underlying mechanism remains elusive. There is increasing evidence showed that mitochondrial architecture is coordinated by the circadian clock which DRP1 playing a crucial role. Nonetheless, how DRP1's mediation of mitochondrial dynamics influences POCD through circadian rhythm disruption is still unclear. To investigate this, mice were subjected to 6 h of 1.5 % isoflurane anesthesia from Zeitgeber Time ZT 14 to ZT20 to induce POCD. HT-22 cells underwent prolonged exposure to isoflurane in vitro. Cognitive function was assessed using the Y-maze and fear conditioning tests. Q-PCR and Western blot analyses were performed to measure relative protein expression. Mice's gross movement rhythms were continuously monitored using Mini-Mitter. Mitochondrial morphology was examined via Mito-Tracker imaging. ATP and ROS level were measured to evaluate mitochondrial function. Isoflurane anesthesia compromised the clock control of DRP1 activity in the hippocampus. This disruption of DRP1 phosphorylation rhythm impaired circadian ATP production, affected mitochondrial morphology and function, exacerbated circadian rhythm disturbances, and ultimately led to cognitive deficits in mice. Pretreatment with Mdivi-1, a specific DRP1 inhibitor, managed to reconstruct mitochondrial morphology and function, restore circadian ATP production and rhythm, thereby alleviating the cognitive impairment induced by isoflurane anesthesia. This study suggests that circadian DRP1 activity's regulation of mitochondrial energy metabolism in the hippocampus may play a significant role in the pathogenesis of POCD in mice.

Short chain fatty acids mediates complement C1q pathway alleviation of perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is one of the most common postoperative complications, which can lead to a harmful impact on self-dependence, longer hospital stays, increased medical costs, morbidity, and mortality amongst older adults. Microglia can modulate synapse elimination involved in the complement component protein 1q (C1q) pathway to induce cognitive dysfunction, which is significantly improved by short chain fatty acids (SCFAs) treatment. Here we investigate the effects of SCFAs treatment on PND via mediating C1q complement pathway. High-throughput sequencing of 16S rDNA from fecal samples of male SD rats was applied to assess the changes in gut microbiota. Fecal microbiota transplantation (FMT) was performed to investigate whether gut microbiota from PND rats could alter cognitive impairment. The blood from the rat tail vein was collected to measure the SCFAs concentrations. Hippocampal and brain tissue samples were obtained to perform Western blots, Golgi and immunofluorescence staining. Primary microglia treated with SCFAs or Histone deacetylase inhibitor were cultured to measure microglial activation states and the expression of acetylated histone. The 16S rDNA sequencing results showed that PND rats had the significant changes in the species diversity of the gut microbiota and the metabolite of specifc species. Gut microbiota from PND rats could alter spatial learning and memory, and meanwhile, the changed SCFAs concentrations in plasma were involved. The synapse elimination in PND rats was strikingly reversed by SCFAs treatment involved in modulation complement C1q via suppressing neuroinflammation. This suggests that a link between gut microbiota dysbiosis and cognitive function impairment is involved in synapse elimination via mediating complement C1q pathway. SCFAs treatment can alleviate PND, the mechanisms of which may be associated with regulating complement C1q pathway.

Inhibition of STAT3 phosphorylation attenuates perioperative neurocognitive disorders in mice with D-galactose-induced aging by regulating pro-inflammatory reactive astrocytes

BACKGROUND

Perioperative Neurocognitive Disorders (PND) are associated withanesthesia and surgery, especially in the elderly. Astrocyte activation in old mice correlates with PND development. These cells can switch to a pro-inflammatory or an anti-inflammatory phenotype, regulated by the STAT3 pathway. It remains unclear whether STAT3 can alleviate PND symptoms in elderly mice by modulating the transitions between these astrocyte phenotypes.

METHODS

Senescence was induced in eight-week-old male C57BL/6J mice with D-galactose, followed by tibial fracture surgery under anesthesia to model PND. On the third postoperative day, cognitive function was assessed using fear conditioning, synaptic plasticity using Golgi/ electrophysiology, and astrocyte phenotype /STAT3/pSTAT3(phosphorylated STAT3) using Western blot/immunofluorescence. The content of neurotrophic factors, including brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), was also measured. Primary astrocytes were stimulated with the conditioned medium referred to as ACM to induce pro-inflammatory reactive astrocytes. Stattic, an inhibitor of STAT3 phosphorylation, was used to investigate its effects on astrocyte phenotypic transformation and hippocampus-dependent learning and memory in aging mice, both in vitro and in vivo.

RESULTS

On the third postoperative day, pSTAT3 levels and pro-inflammatory astrocytes increased in the hippocampal CA1 region, with no change in total STAT3 or anti-inflammatory astrocytes, accompanied by a decrease in GDNF and BDNF.ACM treatment of primary astrocytes promoted pro-inflammatory phenotype conversion, which was inhibited by stattic without affecting anti-inflammatory phenotype. Intraperitoneal injection of stattic in mice reduced the accumulation of pro-inflammatory astrocytes, increased the levels of BDNF and GDNF, enhanced synaptic plasticity, and improved hippocampus-dependent learning and memory functions in anesthesia-induced senescent mice, without altering anti-inflammatory astrocytes.

CONCLUSIONS

Inhibiting STAT3 phosphorylation may improve synaptic plasticity in the CA1 region of the hippocampus by modulating pro-inflammatory astrocytes, thereby alleviating perioperative neurocognitive dysfunction in D-galactose-induced aging mice.

Nrf2 Ameliorates Sevoflurane-Induced Cognitive Deficits in Aged Mice by Inhibiting Neuroinflammation in the Hippocampus

Perioperative neurocognitive disorders (PND), common complications that occur after anesthetized surgery in elderly patients, are major challenges to our rapidly growing aging population. The transcription factor known as nuclear factor erythroid-2-related factor 2 (Nrf2) is an essential component of the cellular antioxidant response, purportedly contributing to the preservation of cognitive functions such as learning and memory. Nevertheless, the function and intracellular processes involving Nrf2 in PND remain largely unknown. Therefore, we evaluate the influence and fundamental mechanism of Nrf2 on PND in aged mice. To establish the postoperative neurocognitive dysfunction (PND) model, aged mice were subjected to anesthesia via inhalation of 3% sevoflurane for a duration of 2 h. The role of Nrf2 in PND was investigated by administering microinjections of either the adeno-associated virus (AAV)-Nrf2 vector or a null virus vector into the hippocampal CA1 region of aged mice 28 days before exposure to sevoflurane. Various assays including enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining, and western blotting were employed to assess levels of pro-inflammatory cytokines, microglial activation, and the oxidative stress response. Furthermore, synaptic plasticity was evaluated through long-term potentiation (LTP) recording and Golgi staining techniques. Elevated expression of Nrf2 within the hippocampal CA1 region ameliorated sevoflurane-induced cognitive deficits, synaptic plasticity anomalies, and the oxidative stress reaction in aged mice. Furthermore, the activation of microglia and the release of pro-inflammatory cytokines (including IL-6, TNF-α, and IL-1β) within the hippocampus post-sevoflurane exposure were modulated in an Nrf2-dependent fashion. Based on the findings from present research, we conclude that Nrf2 ameliorates sevoflurane-induced cognitive dysfunction by inhibiting hippocampal neuroinflammation, thereby proposing a potential therapeutic target for PND.

Identification of Key Genes in Esketamine's Therapeutic Effects on Perioperative Neurocognitive Disorders via Transcriptome Sequencing

Background

Esketamine ameliorates propofol-induced brain damage and cognitive impairment in mice. However, the precise role and underlying mechanism of esketamine in perioperative neurocognitive disorders (PND) remain unclear. Therefore, this study aimed to investigate the key genes associated with the role of esketamine in PND through animal modeling and transcriptome sequencing.

Methods

The present study established a mice model of PND and administered esketamine intervention to the model, and mice were divided into control, surgical group, and surgical group with esketamine. Behavioral assessments were conducted using the Morris water maze and Y maze paradigms, while transcriptome sequencing was performed on hippocampal samples obtained from 3 groups. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were performed on sequencing data to identify candidate genes related to esketamine treating PND. Thereafter, protein-protein interaction (PPI) network analysis was implemented to select key genes. The genes obtained from each step were subjected to enrichment analysis, and a regulatory network for key genes was constructed.

Results

The Morris water maze and Y maze findings demonstrated the successful construction of our PND model, and indicated that esketamine exhibits a certain therapeutic efficacy for PND. Ank1, Cbln4, L1cam, Gap43, and Shh were designated as key genes for subsequent analysis. The 5 key genes were significantly enriched in cholesterol biosynthesis, nonsense mediated decay (NMD), formation of a pool of free 40s subunits, major pathway of rRNA processing in the nucleolus and cytosol, among others. Notably, the miRNAs, mmu-mir-155-5p and mmu-mir-1a-3p, functionally co-regulated the expression of Ank1, Gap43, and L1cam.

Conclusion

We uncovered the therapeutic efficacy of esketamine in treating PND and identified 5 key genes (Ank1, Cbln4, L1cam, Gap43, and Shh) that contribute to its therapeutic effects, providing a valuable reference for further mechanistic studies on esketamine's treatment of PND.

Improved early postoperative cognition in elderly gastrointestinal patients: a randomized controlled trial on the role of ultrasound-guided stellate ganglion block

Background

This study evaluates the impact of ultrasound-guided stellate ganglion block (SGB) on early postoperative cognitive dysfunction (POCD) in elderly patients who underwent laparoscopic gastrointestinal (GI) surgery, as well as its potential effect on oxidative stress and inflammatory responses.

Methods

In this randomized controlled trial, 104 elderly patients scheduled for elective laparoscopic GI surgery were randomized to receive ultrasound-guided SGB before general anesthesia (SGB group) or general anesthesia alone (control group). A total of 98 patients completed the study. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) preoperatively, and on postoperative days one and three. The perioperative recordings included mean arterial pressure, heart rate, and the bispectral index. Blood samples were analyzed for interleukin-6 (IL-6), superoxide dismutase (SOD), and malondialdehyde (MDA).

Results

The SGB group had a significantly lower incidence of POCD on postoperative day one (p < 0.05). IL-6 and MDA levels were significantly lower, while SOD levels were higher in the SGB group, when compared to the control group (p < 0.05). MDA levels were notably lower on postoperative day three in the SGB group (p < 0.05). Both groups showed significant changes in IL-6, SOD and MDA levels, when compared to preoperative values. The hemodynamic indicators showed a slight reduction in intraoperative blood pressure and decreased numerical rating scale scores on the first postoperative day without significant differences in other indicators.

Conclusion

Preoperative SGB reduces early POCD in elderly patients who undergo laparoscopic GI surgery, possibly through the inhibition of oxidative stress and inflammatory responses.

Regulation of Postoperative Cognitive Dysfunction by Glutathione Under Various Pathways: A Narrative Review

Postoperative cognitive dysfunction (POCD) is a common neurological complication after surgery and general anesthesia, and the incidence increases with age. Will have a negative impact on patients, family and society. At present, neuroinflammation and oxidative stress are the main recognized mechanisms. Glutathione (GSH) is a powerful reducing agent and may be related to POCD.

DATA COLLECTION

Using medical search engines such as PubMed, Web of Science, we analyzed articles on topics such as: POCD, GSH, microglia, astrocyte, oligodendrocyte, ferroptosis, BDNF, Neuroinflammation, oxidative stress. The above topics are searched in databases using Boolean operations. We included original articles, reviews and other article types such as medical books.

RESULTS

According to the reviewed literature, GSH may be a treatment for POCD.

CONCLUSIONS

Specific and targeted therapies for POCD still sparse, therefore, the implementation of preventive strategies appears to remain the optimal attitude. Further research is needed for a better understanding of GSH and POCD.

ABC Family Gene Polymorphisms and Cognitive Functions Interact to Influence Antidepressant Efficacy

INTRODUCTION

The importance of identifying relevant indicators of antidepressant efficacy is highlighted by the low response rates to antidepressant treatment for depression. The ABC gene family, encoding ATP-dependent transport proteins facilitating the transport of psychotropic drugs, has drawn attention. This study delved into the relationship between antidepressant efficacy and seven single nucleotide polymorphisms of ABCB1 and ABCB6 genes.

METHODS

A total of 549 depressed patients participated in the study, and all completed a 6-week course of antidepressant treatment. Cognitive function was assessed at baseline and post-treatment. Patients were categorized based on post-treatment HAMD-17 scores (with HAMD≤7 indicating remission), and comparisons were made between different groups in terms of allelic gene frequencies and genotypes. Logistic regression was used to explore the interaction between cognitive function and genotype on efficacy. Dual-luciferase reporter assays were performed to compare the regulatory effects of rs1109866 allele variants on the ABCB6 promoter.

RESULTS

There were no notable differences in allelic gene frequencies and genotypes between the remission and non-remission groups. Nonetheless, a significant interaction was identified between the rs1109866 genotype and language fluency-related indicators concerning efficacy (p=0.029) before correction. The dual-luciferase reporter assays demonstrated markedly higher fluorescence intensity of rs1109866-C compared to that of rs1109866-T (p<0.001).

DISCUSSION

Relying solely on genetic polymorphisms of ABC family genes as predictors of antidepressant treatment response may not be sufficient. However, the interaction between the rs1109866 and cognition plays a pivotal role. The potentially enhanced transcriptional activity of rs1109866-C might offer insight into its impact on antidepressant efficacy.

Current Progress on Postoperative Cognitive Dysfunction: An Update

Postoperative cognitive dysfunction (POCD) represents a significant clinical concern, particularly among elderly surgical patients. It is characterized by a decline in cognitive performance, affecting memory, attention, coordination, orientation, verbal fluency, and executive function. This decline in cognitive abilities leads to longer hospital stays and increased mortality. This review provides a comprehensive overview of the current progress in understanding the relevant pathogenic factors, possible pathogenic mechanisms, diagnosing, prevention and treatment of POCD, as well as suggesting future research directions. It discusses neuronal damage, susceptible genes, central cholinergic system, central nervous system (CNS) inflammation, stress response and glucocorticoids, and oxidative stress in the development of POCD, aiming to uncover the pathological mechanism and develop effective treatment strategies for POCD.

The potential mechanism of mitochondrial homeostasis in postoperative neurocognitive disorders: an in-depth review

Postoperative neurocognitive disorders (PND) are the most common neurological disorders following surgery and anaesthesia before and within 12 months after surgery, with a high prevalence in the geriatric population. PND can severely deteriorate the quality of life of patients, especially among the elderly, mainly manifested as memory loss, attention, decline and language comprehension disorders, mostly in elderly patients, with an incidence as high as 31%. Previous studies have also raised the possibility of accelerated cognitive decline and underlying neuropathological processes associated with diseases that affect cognitive performance (e.g. Alzheimer's dementia) for reasons related to anaesthesia and surgery. Currently, most research on PND has focused on various molecular pathways, especially in the geriatric population. The various hypotheses that have been proposed regarding the mechanisms imply peripheral neuroinflammation, oxidative stress, mitochondrial homeostasis, synaptic function, autophagy disorder, blood-brain barrier dysfunction, the microbiota-gut-brain axis and lack of neurotrophic support. However, the underlying pathogenesis and molecular mechanisms of PND have not yet been uncovered. Recent research has focused on mitochondrial homeostasis. In this paper, we present a review of various studies to better understand and characterize the mechanisms of associated cognitive dysfunction. As the biochemical basis of PND becomes more clearly defined, future treatments based on mitochondrial homeostasis modulation can prove to be very promising.

Emerging Insights into Postoperative Neurocognitive Disorders: The Role of Signaling Across the Gut-Brain Axis

The pathophysiological regulatory mechanisms in postoperative neurocognitive disorders (PNCDs) are intricately complex. Currently, the pathogenesis of PNCDs has not been fully elucidated. The mechanism involved may include a variety of factors, such as neuroinflammation, oxidative stress, and neuroendocrine dysregulation. Research into the gut microbiota-induced regulations on brain functions is increasingly becoming a focal point of exploration. Emerging evidence has shown that intestinal bacteria may play an essential role in maintaining the homeostasis of various physiological systems and regulating disease occurrence. Recent studies have confirmed the association of the gut-brain axis with central nervous system diseases. However, the regulatory effects of this axis in the pathogenesis of PNCDs remain unclear. Therefore, this paper intends to review the bidirectional signaling and mechanism of the gut-brain axis in PNCDs, summarize the latest research progress, and discuss the possible mechanism of intestinal bacteria affecting nervous system diseases. This review is aimed at providing a scientific reference for predicting the clinical risk of PNCD patients and identifying early diagnostic markers and prevention targets.

Oxidative stress and mitochondrial dysfunction contributes to postoperative cognitive dysfunction in elderly rats dependent on NLRP3 activation

Postoperative cognitive dysfunction (POCD), a complication following procedures such as orthopedic surgery, is associated with a worsened prognosis, especially in the elderly population. Several mechanisms have been proposed for communication between the immune system and the brain after surgery. In an experimental tibial fracture (TF) model, we aimed to understand the role of the NLR family pyrin domain containing 3 (NLRP3) on oxidative stress and mitochondrial dysfunction as mechanisms underlying POCD in aged and adult rats. Adult or aged male Wistar rats were subjected to the TF model and received intracerebroventricular saline or MCC950 (140 ng/kg), a specific small-molecule inhibitor that selectively blocks activation of the NLRP3 inflammasome. We followed the control (sham) and TF groups treated with MCC950 or saline for seven days to determine cognitive function and survival. The prefrontal cortex and hippocampus were isolated for NLRP3 evaluation, cytokine analysis, oxidative stress measurements, myeloperoxidase activity, nitric oxide formation, mitochondrial respiratory chain enzymes, and succinate dehydrogenase (SDH) activity. Seven days after TF induction, NLRP3 levels increased in the hippocampus and prefrontal cortex in both ages, showed an enhancement in aged rats compared to adults, and experienced a reversal with MCC950 administration. The administration of MCC950 restored memory, IL-1β and IL-10 levels, nitrite/nitrate, lipid peroxidation in the hippocampus and prefrontal cortex, and preserved catalase activity in the prefrontal cortex in aged rats. At the same age, the complex I activity alteration in both regions and complex II, IV, and SDH in the prefrontal cortex were reversed. In conclusion, NLRP3 activation contributes to POCD development because it is intrinsically involved in mitochondrial dysfunction and oxidative stress after orthopedic surgery in aged rats.

Unraveling the role and mechanism of mitochondria in postoperative cognitive dysfunction: a narrative review

Postoperative cognitive dysfunction (POCD) is a frequent neurological complication encountered during the perioperative period with unclear mechanisms and no effective treatments. Recent research into the pathogenesis of POCD has primarily focused on neuroinflammation, oxidative stress, changes in neural synaptic plasticity and neurotransmitter imbalances. Given the high-energy metabolism of neurons and their critical dependency on mitochondria, mitochondrial dysfunction directly affects neuronal function. Additionally, as the primary organelles generating reactive oxygen species, mitochondria are closely linked to the pathological processes of neuroinflammation. Surgery and anesthesia can induce mitochondrial dysfunction, increase mitochondrial oxidative stress, and disrupt mitochondrial quality-control mechanisms via various pathways, hence serving as key initiators of the POCD pathological process. We conducted a review on the role and potential mechanisms of mitochondria in postoperative cognitive dysfunction by consulting relevant literature from the PubMed and EMBASE databases spanning the past 25 years. Our findings indicate that surgery and anesthesia can inhibit mitochondrial respiration, thereby reducing ATP production, decreasing mitochondrial membrane potential, promoting mitochondrial fission, inducing mitochondrial calcium buffering abnormalities and iron accumulation, inhibiting mitophagy, and increasing mitochondrial oxidative stress. Mitochondrial dysfunction and damage can ultimately lead to impaired neuronal function, abnormal synaptic transmission, impaired synthesis and release of neurotransmitters, and even neuronal death, resulting in cognitive dysfunction. Targeted mitochondrial therapies have shown positive outcomes, holding promise as a novel treatment for POCD.

Astrocytic phagocytosis in the medial prefrontal cortex jeopardises postoperative memory consolidation in mice

Memory impairment is one of the main characteristics of postoperative cognitive dysfunction. It remains elusive how postoperative pathological changes of the brain link to the memory impairment. The clinical setting of perioperation was mimicked via partial hepatectomy under sevoflurane anaesthesia together with preoperative restraint stress (Hep-Sev-stress) in mice. Memory changes were assessed with fear conditioning. The medial prefrontal cortex (mPFC)-dorsal hippocampus connectivity was evaluated with injecting neurotracer 28 days before surgery. Astrocytic activation was limited via injecting AAV-GFAP-hM4Di-eGFP into the mPFC. Astrocytic and microglial phagocytosis of synapses were visualised with co-labelling hippocampal neuronal axon terminals with PSD-95 and S100β or Iba1. Neuroinflammation and oxidative stress status were also detected. Hep-Sev-stress impaired the memory consolidation (mean [standard error], 49.91 [2.55]% vs. 35.40 [3.97]% in the contextual memory, p = 0.007; 40.72 [2.78]% vs. 27.77 [2.22]% in cued memory, p = 0.002) and the cued memory retrieval (39.00 [3.08]% vs. 24.11 [2.06]%, p = 0.001) in mice when compared with these in the naïve controls. Hep-Sev-stress damaged the connectivity from the dorsal hippocampus to mPFC but not from the mPFC to the dorsal hippocampus and increased the astrocytic but not microglial phagocytosis of hippocampal neuronal axon terminals in the mPFC. The intervention also induced neuroinflammation and oxidative stress in the dorsal hippocampus and the mPFC in a regional-dependent manner. Limiting astrocyte activation in the mPFC alleviated memory consolidation impairment induced by Hep-Sev-stress. Postoperative memory consolidation was impaired due to astrocytic phagocytosis-induced connectivity injury from the dorsal hippocampus to the medial prefrontal cortex.

Updated insights into the NLRP3 inflammasome in postoperative cognitive dysfunction: emerging mechanisms and treatments

Postoperative cognitive dysfunction (POCD) poses a significant threat to patients undergoing anesthesia and surgery, particularly elderly patients. It is characterized by diminished cognitive functions post surgery, such as impaired memory and decreased concentration. The potential risk factors for POCD include age, surgical trauma, anesthetic type, and overall health condition; however, the precise mechanisms underlying POCD remain elusive. Recent studies suggest that neuroinflammation might be a primary pathogenic factor. NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasomes are implicated in exacerbating POCD by promoting the release of inflammatory factors and proteins that initiate pyroptosis, further influencing the disease process. The regulation of NLRP3 inflammasome activity, including its activation and degradation, is tightly controlled through multiple pathways and mechanisms. In addition, autophagy, a protective mechanism, regulates the NLRP3 inflammasome to control the progression of POCD. This review reviews recent findings on the role of the NLRP3 inflammasome in POCD pathogenesis and discusses therapeutic strategies aimed at reducing NLRP3 sources, inhibiting cellular pyroptosis, and enhancing autophagy.

Tryptophan-rich diet and its effects on Htr7+ Tregs in alleviating neuroinflammation and cognitive impairment induced by lipopolysaccharide

BACKGROUND

Neuroinflammation is a vital pathogenic mechanism for neurodegenerative diseases such as Alzheimer's, schizophrenia, and age-related cognitive decline. Regulatory T cells (Tregs) exhibit potent anti-inflammatory properties and can modulate neurodegenerative diseases arising from central nervous system inflammatory responses. However, the role of Tregs in neuroinflammation-related cognitive dysfunction remains unclear. It is highly plausible that Htr7+ Tregs expressing unique genes associated with the nervous system, including the Htr7 gene encoding the serotonin receptor 5-HT7, play a pivotal role.

METHODS

Mice were given a tryptophan-rich diet (with a tryptophan content of 0.6%) or a normal diet (with a tryptophan content of 0.16%). The neuroinflammation-mediated cognitive dysfunction model was established by intracerebroventricular injection of lipopolysaccharide (LPS) in 8-week-old C57BL/6J mice. The activation and infiltration of Tregs were measured using flow cytometry. Primary Tregs were cocultured separately with primary CD8+ T cells and primary microglia for in vitro validation of the impact of 5-HT and 5-HT7 receptor on Tregs. Prior to their transfer into recombination activating gene 1 (Rag1-/-) mice, Tregs were ex vivo transfected with lentivirus to knock down the expression of Htr7.

RESULTS

In this study, the tryptophan-rich diet was found to reverse LPS-induced cognitive impairment and reduce the levels of 5-HT in peripheral blood. The tryptophan-rich diet led to increased levels of 5-HT in peripheral blood, which in turn promoted the proliferation and activation of Htr7+ Tregs. Additionally, the tryptophan-rich diet was also shown to attenuate LPS-mediated neuroinflammation by activating Htr7+ Tregs. Furthermore, 5-HT and 5-HT7 receptor were found to enhance the immunosuppressive effect of Tregs on CD8+ T cells and microglia. In Rag1-/- mice, Htr7+ Tregs were shown to alleviate LPS-induced neuroinflammation and cognitive impairment.

CONCLUSIONS

Our research revealed the ability of Htr7+ Tregs to mitigate neuroinflammation and prevent neuronal damage by suppressing the infiltration of CD8+ T cells into the brain and excessive activation of microglia, thereby ameliorating LPS-induced cognitive impairment. These insights may offer novel therapeutic targets involving Tregs for neuroinflammation and cognitive impairment.

Postoperative cognitive disorders and delirium in gynecologic surgery: Which surgery and anesthetic techniques to use to reduce the risk?

Despite their general good health, an increasing proportion of elderly individuals require surgery due to an increase in average lifespan. However, because of their increased vulnerability, these patients need to be handled carefully to make sure that surgery does not cause more harm than good. Age-related postoperative cognitive disorders (POCD) and postoperative delirium (POD), two serious consequences that are marked by adverse neuropsychologic alterations after surgery, are particularly dangerous for the elderly. In the context of gynecologic procedures, POCD and POD are examined in this narrative review. The main question is how to limit the rates of POCD and POD in older women undergoing gynecologic procedures by maximizing the risk-benefit balance. Three crucial endpoints are considered: (1) surgical procedures to lower the rates of POCD and POD, (2) anesthetic techniques to lessen the occurrence and (3) the identification of individuals at high risk for post-surgery cognitive impairments. Risks associated with laparoscopic gynecologic procedures include the Trendelenburg posture and CO2 exposure during pneumoperitoneum, despite statistical similarities in POD and POCD frequency between laparoscopic and laparotomy techniques. Numerous risk factors are associated with surgical interventions, such as blood loss, length of operation, and position holding, all of which reduce the chance of complications when they are minimized. In order to emphasize the essential role that anesthesia and surgery play in patient care, anesthesiologists are vital in making sure that anesthesia is given as sparingly and quickly as feasible. In addition, people who are genetically predisposed to POCD may be more susceptible to the disorder. The significance of a thorough strategy combining surgical and anesthetic concerns is highlighted in this article, in order to maximize results for senior patients having gynecologic surgery.

DNA damage induced PARP-1 overactivation confers paclitaxel-induced neuropathic pain by regulating mitochondrial oxidative metabolism

AIMS

Poly (ADP-ribose) polymerase (PARP) has been extensively investigated in human cancers. Recent studies verified that current available PARP inhibitors (Olaparib or Veliparib) provided clinical palliation of clinical patients suffering from paclitaxel-induced neuropathic pain (PINP). However, the underlying mechanism of PARP overactivation in the development of PINP remains to be investigated.

METHODS AND RESULTS

We reported induction of DNA oxidative damage, PARP-1 overactivation, and subsequent nicotinamide adenine dinucleotide (NAD+) depletion as crucial events in the pathogenesis of PINP. Therefore, we developed an Olaparib PROTAC to achieve the efficient degradation of PARP. Continuous intrathecal injection of Olaparib PROTAC protected against PINP by inhibiting the activity of PARP-1 in rats. PARP-1, but not PARP-2, was shown to be a crucial enzyme in the development of PINP. Specific inhibition of PARP-1 enhanced mitochondrial redox metabolism partly by upregulating the expression and deacetylase activity of sirtuin-3 (SIRT3) in the dorsal root ganglions and spinal cord in the PINP rats. Moreover, an increase in the NAD+ level was found to be a crucial mechanism by which PARP-1 inhibition enhanced SIRT3 activity.

CONCLUSION

The findings provide a novel insight into the mechanism of DNA oxidative damage in the development of PINP and implicate PARP-1 as a possible therapeutic target for clinical PINP treatment.

ML365 ameliorates postoperative cognitive impairment in aged mice by inhibiting NLRP3 inflammasome activation in the hippocampus

The aim of this study was to examine the effects of ML365, a two-pore potassium channel (K2P) inhibitor, on postoperative cognitive impairment (POCD). A mouse model of POCD was constructed by subjecting aged C57BL/6 mice to exploratory laparotomy. Changes in cognitive function were assessed using the Morris water maze test. Western blotting and qPCR were used to detect hippocampal NLRP3, Caspase-1 and IL-1β expression levels on days 3 and 7 post-surgery. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) expression level was also assessed by western blotting. Pathological changes and nerve damage in the hippocampal CA1 and CA3 regions were detected by H&E staining, while the concentration of malondialdehyde (MDA) in the plasma was measured. We found that pretreatment with ML365 (administered intraperitoneally at a dose of 10 mg/kg) 30 min prior to exploratory laparotomy effectively ameliorated POCD in mice. ML365 pretreatment also reduced NLRP3, Caspase-1, ASC and IL-1β expression levels in the hippocampus, improved POCD-induced pathological changes in the hippocampal CA1 and CA3 areas of aged mice, and decreased levels of plasma MDA and oxidative stress. Together, our findings indicate that ML365 can alleviate POCD in mice by inhibiting NLRP3 inflammasome activation in the hippocampus.

Potential mechanisms of Shenmai injection against POCD based on network pharmacology and molecular docking

BACKGROUND

As the population ages, the number of patients with postoperative cognitive dysfunction increases. This study aims to investigate the mechanisms of Shenmai injection as a therapeutic strategy for postoperative cognitive dysfunction using a network pharmacology approach.

METHODS

Shenmai injection and its targets were retrieved from the Traditional Chinese Medicine Systems Pharmacology database. Postoperative cognitive dysfunction-associated protein targets were identified using the GeneCards and DisGeNET databases. Subsequently, a protein-protein interaction network was constructed using the String database. For treating postoperative cognitive dysfunction, the core targets of Shenmai injection were identified through topological analysis, followed by the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses performed for annotation. Molecular docking was performed on the screened core targets and components.

RESULTS

One hundred and eighty-two related targets of Shenmai injection in treating postoperative cognitive dysfunction were identified. Eleven active ingredients in Shenmai injection were detected to have a close connection with postoperative cognitive dysfunction-related targets. Additionally, Gene Ontology analysis revealed 10 biological processes, 10 cellular components and 10 molecular functions. The Kyoto Encyclopedia of Genes and Genomes analysis identified 20 signaling pathways. The docking results indicated five active ingredients from Shenmai injection can fit in the binding pockets of all three candidate targets.

CONCLUSIONS

Thus, the present work systematically explored the anti-postoperative cognitive dysfunction mechanism of potential targets and signaling pathways of Shenmai injection. These results provide an important reference for subsequent basic research on postoperative cognitive dysfunction.

Preoperative ketamine administration for prevention of postoperative neurocognitive disorders after major orthopedic surgery in elderly patients: A multicenter randomized blinded placebo-controlled trial

BACKGROUND

Preventive anesthetic impact on the high rates of postoperative neurocognitive disorders in elderly patients is debated. The Prevention of postOperative Cognitive dysfunction by Ketamine (POCK) study aimed to assess the effect of ketamine on this condition.

METHODS

This is a multicenter, randomized, double-blind, interventional study. Patients ≥60 years undergoing major orthopedic surgery were randomly assigned in a 1:1 ratio to receive preoperative ketamine 0.5 mg/kg as an intravenous bolus (n = 152) or placebo (n = 149) in random blocks stratified according to the study site, preoperative cognitive status and age. The primary outcome was the proportion of objective delayed neurocognitive recovery (dNR) defined as a decline of one or more neuropsychological assessment standard deviations on postoperative day 7. Secondary outcomes included a three-month incidence of objective postoperative neurocognitive disorder (POND), as well as delirium, anxiety, and symptoms of depression seven days and three months after surgery.

RESULTS

Among 301 patients included, 292 (97%) completed the trial. Objective dNR occurred in 50 (38.8%) patients in the ketamine group and 54 (40.9%) patients in the placebo group (OR [95% CI] 0.92 [0.56; 1.51], p = 0.73) on postoperative day 7. Incidence of objective POND three months after surgery did not differ significantly between the two groups nor did incidence of delirium, anxiety, apathy, and fatigue. Symptoms of depression were less frequent in the ketamine group three months after surgery (OR [95% CI] 0.34 [0.13-0.86]).

CONCLUSIONS

A single preoperative bolus of intravenous ketamine does not prevent the occurrence of dNR or POND in elderly patients scheduled for major orthopedic surgery. (Clinicaltrials.gov NCT02892916).

Cognitive Benefits of Folic Acid, Docosahexaenoic Acid, and a Combination of Both Nutrients in Mild Cognitive Impairment: Possible Alterations through Mitochondrial Function and DNA Damage

INTRODUCTION

It is uncertain whether folic acid (FA) combined with docosahexaenoic acid (DHA) could improve cognitive performance. This study evaluated the effects of a 12-month FA and DHA supplementation, in combination or alone, on cognitive function, DNA oxidative damage, and mitochondrial function in participants with mild cognitive impairment (MCI).

METHODS

This randomized, double-blind, placebo-controlled trial recruited MCI participants aged 60 years and older. Two hundred and eighty participants were randomly divided in equal proportion into four groups: FA + DHA (FA 800 μg/d + DHA 800 mg/d), FA (800 μg/d), DHA (800 mg/d), and placebo groups daily orally for 12 months. The primary outcome was cognitive function evaluated by the Wechsler Adult Intelligence Scale-Revised (WAIS-RC). Cognitive tests and blood mechanism-related biomarkers were determined at baseline and 12 months.

RESULTS

During the 12-month follow-up, scores of full intelligence quotient (βDHA: 1.302, 95% CI: 0.615, 1.990, p < 0.001; βFA: 1.992, 95% CI: 1.304, 2.679, p < 0.001; βFA+DHA: 2.777, 95% CI: 2.090, 3.465, p < 0.001), verbal intelligence quotient, and some subtests of the WAIS-RC were significantly improved in FA + DHA and single intervention groups compared to the placebo group. Moreover, the FA and DHA intervention combination was superior to either intervention alone (p < 0.001). Meanwhile, FA, DHA, and their combined use significantly decreased 8-OHdG level and increased mitochondrial DNA copy number compared to the placebo (p < 0.05).

CONCLUSIONS

Supplementation of FA and DHA, alone or combined, for 12 months can improve cognitive function in MCI participants, possibly through mitigating DNA oxidative damage and enhancing mitochondrial function. Combined supplementation may provide more cognitive benefit than supplementation alone.

Sepsis compromises post-ischemic stroke neurological recovery and is associated with sex differences

AIMS

Infection is a complication after stroke and outcomes vary by sex. Thus, we investigated if sepsis affects brain from ischemic stroke and sex involvement.

MAIN METHODS

Male and female Wistar rats, were submitted to middle cerebral artery occlusion (MCAO) and after 7 days sepsis to cecal ligation and perforation (CLP). Infarct size, neuroinflammation, oxidative stress, and mitochondrial activity were quantified 24 h after CLP in the prefrontal cortex and hippocampus. Survival and neurological score were assessed up to 15 days after MCAO or 8 days after CLP (starting at 2 h after MCAO) and memory at the end.

KEY FINDINGS

CLP decreased survival, increased neurological impairments in MCAO females. Early, in male sepsis following MCAO led to increased glial activation in the brain structures, and increased TNF-α and IL-1β in the hippocampus. All groups had higher IL-6 in both tissues, but the hippocampus had lower IL-10. CLP potentiated myeloperoxidase (MPO) in the prefrontal cortex of MCAO male and female. In MCAO+CLP, only male increased MPO and nitrite/nitrate in hippocampus. Males in all groups had protein oxidation in the prefrontal cortex, but only MCAO+CLP in the hippocampus. Catalase decreased in the prefrontal cortex and hippocampus of all males and females, and MCAO+CLP only increased this activity in males. Female MCAO+CLP had higher prefrontal cortex complex activity than males. In MCAO+CLP-induced long-term memory impairment only in females.

SIGNIFICANCE

The parameters evaluated for early sepsis after ischemic stroke show a worse outcome for males, while females are affected during long-term follow-up.

The role of anesthesia in peri‑operative neurocognitive disorders: Molecular mechanisms and preventive strategies

Peri-operative neurocognitive disorders (PNDs) include postoperative delirium (POD) and postoperative cognitive dysfunction (POCD). Children and the elderly are the two populations most vulnerable to the development of POD and POCD, which results in both high morbidity and mortality. There are many factors, including neuroinflammation and oxidative stress, that are associated with POD and POCD. General anesthesia is a major risk factor of PNDs. However, the molecular mechanisms of PNDs are poorly understood. Dexmedetomidine (DEX) is a useful sedative agent with analgesic properties, which significantly improves POCD in elderly patients. In this review, the current understanding of anesthesia in PNDs and the protective effects of DEX are summarized, and the underlying mechanisms are further discussed.

Serum proteomics study on cognitive impairment after cardiac valve replacement surgery: a prospective observational study

Objective

The incidence of perioperative neurocognitive disorders (PND) is high, especially after cardiac surgeries, and the underlying mechanisms remain elusive. Here, we conducted a prospective observational study to observe serum proteomics differences in PND patients after cardiac valve replacement surgery.

Methods

Two hundred and twenty-six patients who underwent cardiac valve surgery were included. They were categorized based on scoring into non-PND group (group non-P) and PND group (group P'). The risk factors associated with PND were analyzed. These patients were further divided into group C and group P by propensity score matching (PSM) to investigate the serum proteome related to the PND by serum proteomics.

Results

The postoperative 6-week incidence of PND was 16.8%. Risk factors for PND include age, chronic illness, sufentanil dosage, and time of cardiopulmonary bypass (CPB). Proteomics identified 31 down-regulated proteins and six up-regulated proteins. Finally, GSTO1, IDH1, CAT, and PFN1 were found to be associated with PND.

Conclusion

The occurrence of PND can impact some oxidative stress proteins. This study provided data for future studies about PND to general anaesthesia and surgeries.

HIF1A overexpression caused by etomidate activates PGK1-induced oxidative stress in postoperative cognitive dysfunction

Etomidate (ETO), a hypnotic agent used for anesthesia induction, has been shown to induce long-lasting cognitive deficits. In the present study, we investigated whether ETO could activate the HIF1A/PGK1 pathway to antagonize oxidative damage in mice with postoperative cognitive dysfunction (POCD). A mouse model of ETO-mediated POCD was established, and pathological changes, apoptosis, and inflammatory factors in mouse hippocampal tissues were analyzed by HE staining, TUNEL assay, and ELISA. ETO was revealed to cause cognitive dysfunction in mice. Integrated database mining was conducted to screen out transcription factors that are both related to ETO and POCD. Hypoxia-inducible factor 1-alpha (HIF1A) was overexpressed in mice with POCD, and downregulation of HIF1A alleviated cognitive dysfunction in mice. HIF1A downregulation inhibited the transcription of phosphoglycerate kinase 1 (PGK1). Overexpression of PGK1 abated the alleviating effects of HIF1A knockdown on oxidative stress in mice with POCD. In addition, HIF1A activation of PGK1 induced oxidative stress and apoptosis in HT-22 cells while inhibiting cell viability. Taken together, we demonstrated that HIF1A activation of PGK1 induced oxidative stress in ETO-mediated POCD.

Role of Brain-Derived Neurotrophic Factor in Anxiety or Depression After Percutaneous Coronary Intervention

Anxiety or depression after percutaneous coronary intervention (PCI) is one of the key clinical problems in cardiology that need to be solved urgently. Brain-derived neurotrophic factor (BDNF) may be a potential biomarker for the pathogenesis and treatment of anxiety or depression after PCI. This article reviews the correlation between BDNF and cardiovascular system and nervous system from the aspects of synthesis, release and action site of BDNF, and focuses on the latest research progress of the mechanism of BDNF in anxiety or depression after PCI. It includes the specific mechanisms by which BDNF regulates the levels of inflammatory factors, reduces oxidative stress damage, and mediates multiple signaling pathways. In addition, this review summarizes the therapeutic potential of BDNF as a potential biomarker for anxiety or depression after PCI.

Latest advances and clinical application prospects of resveratrol therapy for neurocognitive disorders

Neurocognitive disorders, such as Alzheimer's disease, vascular dementia, and postoperative cognitive dysfunction, are non-psychiatric brain syndromes in which a significant decline in cognitive function causes great trauma to the mental status of the patient. The lack of effective treatments for neurocognitive disorders imposes a considerable burden on society, including a substantial economic impact. Over the past few decades, the identification of resveratrol, a natural plant compound, has provided researchers with an opportunity to formulate novel strategies for the treatment of neurocognitive disorders. This is because resveratrol effectively protects the brain of those with neurocognitive disorders by targeting some mechanisms such as inflammation and oxidative stress. This article reviews the status of recent research investigating the use of resveratrol for the treatment of different neurocognitive disorders. By examining the possible mechanisms of action of resveratrol and the shared mechanisms of different neurocognitive disorders, treatments for neurocognitive disorders may be further clarified.

Potential value of serum prealbumin and serum albumin in the identification of postoperative delirium in patients undergoing knee/hip replacement: an observational study and internal validation study

Background

Postoperative delirium (POD) is a common postoperative neurological complication that can lead to a variety of postoperative complications. At present, the pathogenesis of POD is unclear. This study aims to explore the relationship between serum prealbumin and serum albumin and POD and whether serum prealbumin and serum albumin influence POD through POD core pathology.

Objective

We enrolled 500 Chinese Han patients between September 2020 to January 2023. We analyzed the risk and protective factors of POD using the multivariate logistic regression. We also assessed the predictive power of serum prealbumin, serum albumin, and both in combination with CSF POD biomarkers. We used Stata MP16.0. to examine whether the association between serum prealbumin and serum albumin and POD was mediated by CSF POD biomarkers, and conducted an internal validation study to verify the accuracy of the combination of serum prealbumin + serum albumin + CSF POD biomarkers for predicting POD. The model was visualized using ROC curve and decision curve analysis (DCA). DynNom and Shiny packages were used to create an online calculator. Ten patients who had POD occurring from February 2023 to October 2023 were selected for internal verification.

Results

Finally, a total of 364 patients were included in our study. Levels of serum prealbumin, serum albumin in the POD group were lower than those in the NPOD group. The lever of serum prealbumin, serum albumin were protective factors for POD. The relationship between serum prealbumin, serum albumin and POD was partially mediated by T-tau (12.28%) and P-tau (20.61%). The model combining serum prealbumin and serum albumin and POD biomarkers exhibited a relatively better discriminatory ability to predict POD. DCA also showed that the combination of serum prealbumin and serum albumin and POD biomarkers brought high predictive benefits to patients. The dynamic online calculator can accurately predict the occurrence of POD in the internal validation study.

Conclusion

Preoperative low serum prealbumin and serum albumin levels were the preoperative risk factors for POD, which is partly mediated by T-tau and P-tau. The model combining serum prealbumin and serum albumin and CSF POD biomarkers can accurately predict the occurrence of POD.

Clinical trial registration

http://www.clinicaltrials.gov, identifier ChiCTR2000033439.

Hyperoxia and brain: the link between necessity and injury from a molecular perspective

Oxygen (O2) supplementation is commonly used to treat hypoxia in patients with respiratory failure. However, indiscriminate use can lead to hyperoxia, a condition detrimental to living tissues, particularly the brain. The brain is sensitive to reactive oxygen species (ROS) and inflammation caused by high concentrations of O2, which can result in brain damage and mitochondrial dysfunction, common features of neurodegenerative disorders. Hyperoxia leads to increased production of ROS, causing oxidative stress, an imbalance between oxidants and antioxidants, which can damage tissues. The brain is particularly vulnerable to oxidative stress due to its lipid composition, high O2 consumption rate, and low levels of antioxidant enzymes. Moreover, hyperoxia can cause vasoconstriction and decreased O2 supply to the brain, posing a challenge to redox balance and neurodegenerative processes. Studies have shown that the severity of hyperoxia-induced brain damage varies with inspired O2 concentration and duration of exposure. Therefore, careful evaluation of the balance between benefits and risks of O2 supplementation, especially in clinical settings, is crucial.

Liraglutide ameliorates delirium-like behaviors of aged mice undergoing cardiac surgery by mitigating microglia activation via promoting mitophagy

OBJECTIVE

Postoperative delirium (POD) is a prevalent complication in cardiac surgery patients, particularly the elderly, with neuroinflammation posited as a crucial contributing factor. We investigated the prophylactic effects of liraglutide, a GLP-1 analog, on delirium-like behaviors in aged mice undergoing cardiac surgery and explored the underlying mechanisms focusing on neuroinflammation, mitochondrial dysfunction, and synaptic plasticity.

METHODS

Using a cardiac ischemia-reperfusion animal model to mimic cardiac surgery, we assessed delirium-like behaviors, microglial activation, NLRP3 inflammasome activation, mitophagy, synaptic engulfment, and synaptic plasticity.

RESULTS

Cardiac surgery triggered delirium-like behaviors, concomitant with heightened microglial and NLRP3 inflammasome activation and impaired mitochondrial function and synaptic plasticity. Pretreatment with liraglutide ameliorated these adverse outcomes. Mechanistically, liraglutide enhanced mitophagy, thereby inhibiting NLRP3 inflammasome activation and subsequent microglial activation. Furthermore, liraglutide counteracted surgery-induced synaptic loss and impairment of synaptic plasticity.

CONCLUSION

Liraglutide exerts protective effects against delirium-like behaviors in aged mice post-cardiac surgery, potentially through bolstering microglia mitophagy, curtailing neuroinflammation, and preserving synaptic integrity. This highlights the potential of liraglutide as a promising perioperative strategy for delirium prevention in cardiac surgery patients.

Latest assessment methods for mitochondrial homeostasis in cognitive diseases

Mitochondria play an essential role in neural function, such as supporting normal energy metabolism, regulating reactive oxygen species, buffering physiological calcium loads, and maintaining the balance of morphology, subcellular distribution, and overall health through mitochondrial dynamics. Given the recent technological advances in the assessment of mitochondrial structure and functions, mitochondrial dysfunction has been regarded as the early and key pathophysiological mechanism of cognitive disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, mild cognitive impairment, and postoperative cognitive dysfunction. This review will focus on the recent advances in mitochondrial medicine and research methodology in the field of cognitive sciences, from the perspectives of energy metabolism, oxidative stress, calcium homeostasis, and mitochondrial dynamics (including fission-fusion, transport, and mitophagy).

Effects of electroacupuncture on postoperative cognitive dysfunction and its underlying mechanisms: a literature review of rodent studies

With the aging of the population, the health of the elderly has become increasingly important. Postoperative cognitive dysfunction (POCD) is a common neurological complication in elderly patients following general anesthesia or surgery. It is characterized by cognitive decline that may persist for weeks, months, or even longer. Electroacupuncture (EA), a novel therapy that combines physical nerve stimulation with acupuncture treatment from traditional Chinese medicine, holds potential as a therapeutic intervention for preventing and treating POCD, particularly in elderly patients. Although the beneficial effects of EA on POCD have been explored in preclinical and clinical studies, the reliability of EA is limited by methodological shortcomings, and the underlying mechanisms remain largely unexplored. Therefore, we have synthesized existing evidence and proposed potential biological mechanisms underlying the effects of EA on neuroinflammation, oxidative stress, autophagy, the microbiota-gut-brain axis, and epigenetic modification. This review summarizes recent advances in EA and POCD, provides a theoretical foundation, explores potential molecular mechanisms for the prevention and treatment of POCD, and offers a basis for conducting relevant clinical trials.

Dietary Restriction Improves Perioperative Neurocognitive Disorders by Inhibiting Neuroinflammation and Gut Microbial Dysbiosis

Anesthesia/surgery have been identified as potential factors contributing to perioperative neurocognitive disorders, with a notably heightened risk observed in aging populations. One of the primary drivers of this impairment is believed to be neuroinflammation, specifically inflammation of hippocampal microglia. Dietary restriction has demonstrated a favorable impact on cognitive impairment across various disorders, primarily by quelling neuroinflammation. However, the precise influence of dietary restriction on perioperative neurocognitive disorders remains to be definitively ascertained. This investigation aims to explore the effects of dietary restriction on perioperative neurocognitive disorders and propose innovative therapeutic strategies for their management. The model of perioperative neurocognitive disorder was induced through exploratory laparotomy under isoflurane anesthesia. Cognitive performance was evaluated using the open field test, Barnes maze test, and fear conditioning test. The enzyme-linked immunosorbent assay (ELISA) was employed to quantify concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in both serum and hippocampal samples. The Western blot technique was utilized to assess expression levels of hippocampal PSD 95, Synaptophysin, TLR4, MyD88, and NF-kB p65. Microglial polarization was gauged using a combination of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence labeling techniques. We conducted 16S rRNA sequencing to investigate the impact of dietary restriction on the intestinal flora of aged mice following anesthesia/surgery. Our findings indicate that dietary restrictions have the potential to ameliorate anesthesia/surgery-induced cognitive dysfunction. This effect is achieved through the modulation of gut microbiota, suppression of inflammatory responses in hippocampal microglia, and facilitation of neuronal repair and regeneration.

Short-term hyperoxia induced mitochondrial respiratory chain complexes dysfunction and oxidative stress in lung of rats

BACKGROUND

Oxygen therapy is an alternative for many patients with hypoxemia. However, this practice can be dangerous as oxygen is closely associated with the development of oxidative stress.

METHODS

Male Wistar rats were exposed to hyperoxia with a 40% fraction of inspired oxygen (FIO2) and hyperoxia (FIO2 = 60%) for 120 min. Blood and lung tissue samples were collected for gas, oxidative stress, and inflammatory analyses.

RESULTS

Hyperoxia (FIO2 = 60%) increased PaCO2 and PaO2, decreased blood pH and caused thrombocytopenia and lymphocytosis. In lung tissue, neutrophil infiltration, nitric oxide concentration, carbonyl protein formation and the activity of complexes I and II of the mitochondrial respiratory chain increased. FIO2 = 60% decreased SOD activity and caused several histologic changes.

CONCLUSION

In conclusion, we have experimentally demonstrated that short-term exposure to high FIO2 can cause oxidative stress in the lung.

The cold-inducible RNA-binding protein-Thioredoxin 1 pathway ameliorates mitochondrial dysfunction and mitochondrial dynamin-related protein 1 level in the hippocampus of aged mice with perioperative neurocognitive dysfunction

BACKGROUND

As a multi-disease model, neuroinflammation, mitochondrial dysfunction, and oxidative stress might be involved in the pathogenic process of perioperative neurocognitive dysfunction (PND). Dynamin-related protein 1 (Drp1) could mediate mitochondrial fission and play important roles in mitochondrial dynamic homeostasis and mitochondria function. The Drp1 may be involved in PND development. The cold-inducible RNA-binding protein (Cirbp) could bind to the 3'-UTR of the thioredoxin 1 (Trx1) mRNA, control oxidative stress, and improve mitochondrial function. In this study, we hypothesized that the Cirbp-Trx1 pathway could ameliorate mitochondrial dysfunction and Drp1 levels in PND mice.

METHODS

Differentially expressed genes were screened using the Gene Expression Omnibus (GEO) database GSE95426 and validated using PCR. Eighteen-month-old C57BL/6 mice were subjected to tibial fracture surgery to generate a PND model. Cirbp was upregulated by hippocampal stereotaxic injections of over-Cirbp plasmid according to the manufacturer's instructions for the in vivo DNA transfection reagent. Cirbp expression was measured using western blot (WB) and immunofluorescence (IF). The Morris water maze (MWM) was used to assess cognitive function. After behavioral testing, the hippocampal tissue was extracted to examine changes in mitochondrial Drp1, mitochondrial function, neuroinflammation, and oxidative stress.

RESULTS

Differential gene screening showed that Cirbp expression was significantly downregulated (fold change >1.5, p = 0.003272) in the PND model. In this study, we also found that Cirbp protein levels were downregulated, accompanied by an impairment of cognition, a decrease in superoxide dismutase (SOD) activity, and an increase in malondialdehyde (MDA) content, mitochondrial Drp1 levels, neuroinflammation, and apoptosis. Cirbp overexpression increased Trx1 protein levels and reversed the damage. However, this protective effect was abolished by PX-12 treatment with a Trx1 inhibitor.

CONCLUSIONS

The Cirbp-Trx1 pathway may regulate mitochondrial dysfunction and mitochondrial Drp1 expression in the hippocampus of PND mice to ameliorate cognitive dysfunction.

Research progress on the association between MicroRNA and postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a significant complication following surgery. The precise mechanisms underlying POCD remain elusive, although it is speculated that they involve central nervous system inflammation, oxidative stress and cellular apoptosis. MicroRNAs (miRNAs), a class of non-coding RNAs widely distributed in eukaryotes, have been implicated in the pathogenesis of neurodegenerative disorders and could potentially impact POCD. This review explores the association between miRNAs and POCD and provides an overview of the progress of current research on miRNAs in the pathogenesis, diagnosis, and treatment of POCD.

Unveiling the role of astrocytes in postoperative cognitive dysfunction

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized by progressive cognitive decline and the accumulation of amyloid-beta plaques, tau tangles, and neuroinflammation in the brain. Postoperative cognitive dysfunction (POCD) is a prevalent and debilitating condition characterized by cognitive decline following neuroinflammation and oxidative stress induced by procedures. POCD and AD are two conditions that share similarities in the underlying mechanisms and pathophysiology. Compared to normal aging individuals, individuals with POCD are at a higher risk for developing AD. Emerging evidence suggests that astrocytes, the most abundant glial cells in the central nervous system, play a critical role in the pathogenesis of these conditions. Comprehensive functions of astrocyte in AD has been extensively explored, but very little is known about POCD may experience late-onset AD pathogenesis. Herein, in this context, we mainly explore the multifaceted roles of astrocytes in the context of POCD, highlighting their involvement in neuroinflammation, neurotransmitter regulation, synaptic plasticity and neurotrophic support, and discuss how POCD may augment the onset of AD. Additionally, we discuss potential therapeutic strategies targeting astrocytes to mitigate or prevent POCD, which hold promise for improving the quality of life for patients undergoing surgeries and against AD in the future.

Association between mixed exposure to endocrine-disrupting chemicals and cognitive function in elderly Americans

OBJECTIVES

Studies exploring the relationship between mixed exposure to endocrine-disrupting chemicals (EDCs) and cognition are limited, with even more scarce studies conducted in the elderly. The aim of this study was to investigate the association between mixed exposure to five categories of EDCs and cognition in elderly Americans.

STUDY DESIGN

Cross-sectional study.

METHODS

727 participants from the 2011-2014 National Health and Nutrition Examination Survey were incorporated into this study, and the levels of 47 EDC metabolites were measured. Cognitive function was assessed using immediate recall test (IRT), delayed recall test (DRT), animal fluency test (AFT), and digit symbol substitution test (DSST), and all the cognitive test scores were standardized. The individual and combined effects of EDC metabolites on the cognitive function in older adults were assessed using three analytical methods.

RESULTS

The results showed that exposure to perfluorononanoic acid, polychlorinated biphenyl (PCB) 199, and PCB 206 was associated with the z-scores on the cognitive tests. Negative associations between mixed exposure to EDCs and the AFT and Global z-scores and a positive relationship with the DRT z-score were found in the WQS regression. The BKMR results revealed a positive trend between the mixture of EDCs and the DRT z-score. However, compared to the median, exposure to mixtures in the 45th percentile and below was associated with a decreased DRT z-score.

CONCLUSIONS

Mixed exposure to EDCs may adversely affect the global cognitive function in elderly individuals. Necessary measures are needed to restrict EDCs use to protect the cognitive health of older adults.

Nicotinamide mononucleotide pretreatment improves long-term isoflurane anesthesia-induced cognitive impairment in mice

Postoperative cognitive dysfunction (POCD) is characterized by impaired cognitive function following general anesthesia and surgery. Oxidative stress is a significant pathophysiological manifestation underlying POCD. Previous studies have reported that the decline of nicotinamide adenine dinucleotide (NAD+) -dependent sirtuin 1 (SIRT1) contributes to the activation of oxidative stress. In this study, we investigated whether pretreatment of nicotinamide mononucleotide (NMN), an NAD+ intermediate, improves oxidative stress and cognitive function in POCD. The animal model of POCD was established in C57BL/6 J mice through 6 h isoflurane anesthesia-induced cognitive impairment. Mice were intraperitoneally injected with NMN for 7 days prior to anesthesia, after which oxidative stress and cognitive function were assessed. The level of oxidative stress was determined using flow cytometry analysis and assey kits. The fear condition test and the Y-maze test were utilized to evaluate contextual and spatial memory. Our results showed that cognitive impairment and increased oxidative stress were observed in POCD mice, as well as downregulation of NAD+ levels and related protein expressions of SIRT1 and nicotinamide phosphoribosyltransferase (NAMPT) in the hippocampus. And NMN supplementation could effectively prevent the decline of NAD+ and related proteins, and reduce oxidative stress and cognitive disorders after POCD. Mechanistically, the findings suggested that protection on cognitive function mediated by NMN pretreatment in POCD mice may be regulated by NAD+-SIRT1 signaling pathway. This study indicated that NMN preconditioning reduced oxidative stress damage and alleviated cognitive impairment in POCD mice.

A Set of Possible Markers for Monitoring Heart Failure and Cognitive Impairment Associated: A Review of Literature from the Past 5 Years

BACKGROUND

Heart failure is an epidemiologically relevant disease because of the aging population and widespread lifestyles that promote it. In addition to the acute event, it is possible for the disease to become chronic with periodic flare-ups. It is essential to study pathology from a diagnostic and prognostic point of view and to identify parameters for effective monitoring. In addition, heart failure is associated with multiple comorbidities, including cognitive impairment, which is monitored clinically but not through specific biomarkers in these patients. The purpose of this review is to gather the most recent scientific evidence on a few possible biomarkers previously identified for monitoring heart failure and associated cognitive impairment.

METHODS

We surveyed studies inherent to a set of previously identified markers, evaluating English-language articles from the past five years conducted in adult heart failure patient populations. We used the databases PubMed, Web of Sciences, and Cochrane Library for search studies, and we considered articles published in journals with an impact factor greater than five in the publication year.

RESULTS

Among the biomarkers evaluated, a concordant indication for serial measurements for heart failure monitoring emerged only for interleukin-6. For the other markers, there is still little evidence available, which is interesting but sometimes conflicting. Interesting studies have also emerged for biomarkers of cognitive decline assessed in patients with heart failure, confirming the hypotheses of the increasingly studied heart-brain correlation.

CONCLUSION

Certainly, further studies in large populations are needed to identify effective biomarkers for monitoring heart failure and associated cognitive impairment.

Electroacupuncture pretreatment preserves telomerase reverse transcriptase function and alleviates postoperative cognitive dysfunction by suppressing oxidative stress and neuroinflammation in aged mice

BACKGROUND

Elderly patients often exhibit postoperative cognitive dysfunction (POCD), a postsurgical decline in memory and executive function. Oxidative stress and neuroinflammation, both pathological characteristics of the aged brain, contribute to this decline. This study posits that electroacupuncture (EA) stimulation, an effective antioxidant and anti-inflammatory modality, may enhance telomerase reverse transcriptase (TERT) function, the catalytic subunit of telomerase known for its protective properties against cellular senescence and oxidative damage, to alleviate POCD in aged mice.

METHODS

The animal POCD model was created by subjecting aged mice to abdominal surgery, followed by EA pretreatment at the Baihui acupoint (GV20). Postoperative cognitive function was gauged using the Morris water maze (MWM) test. Hippocampal TERT mRNA levels and telomerase activity were determined through qPCR and a Telomerase PCR ELISA kit, respectively. Oxidative stress was assessed through superoxide dismutase (SOD), reactive oxygen species (ROS), and malondialdehyde (MDA) levels. Iba-1 immunostaining determined the quantity of hippocampal microglia. Additionally, western blotting assessed TERT, autophagy markers, and proinflammatory cytokines at the protein level.

RESULTS

Abdominal surgery in aged mice significantly decreased telomerase activity and TERT mRNA and protein levels, but increased oxidative stress and neuroinflammation and decreased autophagy in the hippocampus. EA-pretreated mice demonstrated improved postoperative cognitive performance, enhanced telomerase activity, increased TERT protein expression, improved TERT mitochondrial localization, and reduced oxidative damage, autophagy dysfunction, and neuroinflammation. The neuroprotective benefits of EA pretreatment were diminished following TERT knockdown.

CONCLUSIONS

Our findings underscore the significance of TERT function preservation in alleviating surgery-induced oxidative stress and neuroinflammation in aged mice. A novel neuroprotective mechanism of EA stimulation is highlighted, whereby modulation of TERT and telomerase activity reduces oxidative damage and neuroinflammation. Consequently, maintaining TERT function via EA treatment could serve as an effective strategy for managing POCD in elderly patients.

The locus coeruleus-dorsal hippocampal CA1 pathway is involved in depression-induced perioperative neurocognitive disorders in adult mice

BACKGROUND

Patients undergoing surgical anesthesia increasingly suffer from preoperative depression. Clinical studies have shown that depression is a risk factor for perioperative neurocognitive disorders (PNDs) in elder patients. However, the underlying mechanism, especially at the neural circuit level, remains poorly understood.

METHODS

Right carotid artery separation under sevoflurane and chronic social defeat stress (CSDS) in adult mice were used to establish surgical anesthesia and chronic depression models. Cognitive function was assessed by the Y maze and novel object recognition tests. A chemogenetic approach was used to modulate the locus coeruleus-dorsal hippocampal CA1 (LC-dCA1) circuit. Hippocampal synaptic alterations were evaluated by Golgi staining and whole-cell patch clamp recording.

RESULTS

We found that CSDS induced synaptic impairments in dorsal hippocampal CA1 pyramidal neurons and cognitive deficits in adult mice after surgery under sevoflurane. Chemogenetic activation of the LC-dCA1 pathway significantly alleviated the CSDS-induced synaptic impairments and cognitive dysfunction. On the contrary, inhibition of this pathway could mimic CSDS-induced deficits. Furthermore, we showed that dopamine played an important role in CSDS-induced PNDs in adult mice after surgery/sevoflurane.

CONCLUSION

Overall, our results have demonstrated a vital role for the LC-dCA1 pathway in CSDS-induced PNDs in adult mice undergoing surgery with sevoflurane anesthesia.

SESN2 attenuates sevoflurane-induced cognitive impairment and neuroinflammation in rats

Long-term use of sevoflurane, an inhalation anesthetic, could negatively impact cognitive function. Current studies have suggested that cognitive impairment induced by sevoflurane may be associated with neuroinflammation. Sestrin2 (SESN2), which belongs to a family of stress-inducible genes, has been reported to exert neuroprotective effects against brain injury. However, its role and underlying mechanisms in sevoflurane-induced cognitive dysfunction in aged rats remain unknown. A sevoflurane-induced aging rat injury model with or without SESN2 overexpression was constructed. The learning and memory abilities of rats were evaluated by the MWM test. ELISA assay and qRT-PCR were conducted to analyze the level of pro-inflammatory factors in the hippocampus. Levels of oxidative stress markers were measured by DHE staining or kit methods. Neuronal apoptosis in the hippocampus was detected using TUNEL assay. Expression of proteins were analyzed by western blot. Sevoflurane exposure caused elevated protein level of SESN2 in hippocampus and cognitive impairment of aged rats. Importantly, overexpression of SESN2 alleviated sevoflurane-induced cognitive dysfunction and inhibited the production of pro-inflammatory factors, oxidative stress, and neuronal apoptosis in the hippocampus. Furthermore, SESN2 overexpression suppressed NLRP3 inflammasome activation induced by sevoflurane. These findings suggested that SESN2 could exert neuroprotective against sevoflurane-induced nerve injury of aged rats through anti-oxidant and anti-inflammatory effects.

Postoperative cognitive dysfunction-current research progress

Postoperative cognitive dysfunction (POCD) commonly occurs after surgery, particularly in elderly individuals. It is characterized by a notable decline in cognitive performance, encompassing memory, attention, coordination, orientation, verbal fluency, and executive function. This reduction in cognitive abilities contributes to extended hospital stays and heightened mortality. The prevalence of POCD can reach 40% within 1 week following cardiovascular surgery and remains as high as 17% 3 months post-surgery. Furthermore, POCD exacerbates the long-term risk of Alzheimer's disease (AD). As a result, numerous studies have been conducted to investigate the molecular mechanisms underlying POCD and potential preventive strategies. This article provides a review of the research progress on POCD.