Acute pre-operative ibuprofen improves cognition in a rat model for postoperative cognitive dysfunction

J147 affects cognition and anxiety after surgery in Zucker rats

Vulnerable patients are at risk for neuroinflammation-mediated post-operative complications, including depression (POD) and cognitive dysfunction (POCD). Zucker rats, expressing multiple risk factors for post-operative complications in humans, may provide a clinically relevant model to study pathophysiology and explore potential interventions. J147, a newly developed anti-dementia drug, was shown to prevent POCD in young healthy rats, and improved early post-surgical recovery in Zucker rats. Aim of the present study was to investigate POCD and the therapeutic potential of J147 in male Zucker rats. Risk factors in the Zucker rat strain were evaluated by comparison with lean littermates. Zucker rats were subjected to major abdominal surgery. Acute J147 treatment was provided by a single iv injection (10 mg/kg) at the start of surgery, while chronic J147 treatment was provided in the food (aimed at 30 mg/kg/day), starting one week before surgery and up to end of protocol. Effects on behavior were assessed, and plasma, urine and brain tissue were collected and processed for immunohistochemistry and molecular analyses. Indeed, Zucker rats displayed increased risk factors for POCD, including obesity, high plasma triglycerides, low grade systemic inflammation, impaired spatial learning and decreased neurogenesis. Surgery in Zucker rats reduced exploration and increased anxiety in the Open Field test, impaired short-term spatial memory, induced a shift in circadian rhythm and increased plasma neutrophil gelatinase-associated lipocalin (NGAL), microglia activity in the CA1 and blood brain barrier leakage. Chronic, but not acute J147 treatment reduced anxiety in the Open Field test and protected against the spatial memory decline. Moreover, chronic J147 increased glucose sensitivity. Acute J147 treatment improved long-term spatial memory and reversed the circadian rhythm shift. No anti-inflammatory effects were seen for J147. Although Zucker rats displayed risk factors, surgery did not induce extensive POCD. However, increased anxiety may indicate POD. Treatment with J147 showed positive effects on behavioral and metabolic parameters, but did not affect (neuro)inflammation. The mixed effect of acute and chronic treatment may suggest a combination for optimal treatment.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Obesity exacerbates postoperative cognitive dysfunction by activating the PARP1/NAD+/SIRT1 axis through oxidative stress

The purposes of this study were to explore the impact of obesity on postoperative cognitive dysfunction (POCD) and to investigate the underlying mechanism by which obesity exacerbates POCD. In this study, fifteen-month-old male C57BL/6 J mice were fed a High-fat diet for three months to establish obesity models. Internal fixation of tibial fractures under isoflurane inhalation was performed to construct a POCD animal model. Three days after surgery, mice were subjected to the Morris water maze (MWM) experiment to evaluate their learning and memory abilities. The findings from the MWM experiment revealed that in comparison to the Ad Libitum Surgical group (ALS), mice in the High-fat Surgical group (HFS) exhibited prolonged escape latencies and reduced platform crossings. These outcomes suggest the potential exacerbating role of obesity in cognitive impairment within the POCD mouse models. Immunofluorescence (IF) findings demonstrate that obesity intensifies anesthesia and surgery-induced oxidative stress levels within the hippocampus. Compared to the Ad Libitum Control group (ALC), an elevation in PARP1 expression and a reduction in the NAD+/NADH ratio and SIRT1 expression were observed in the hippocampus of mice from the ALS. Moreover, when contrasting the HFS group with the ALS group, increased PARP1 expression along with decreased NAD+/NADH ratio and SIRT1 expression were evident. In vitro studies found that compared with the Control group (CON), oil red staining and BODIPY probe staining showed significant lipid droplet aggregation in the palmitic acid (PA) group. IF results demonstrated that HT22 cells in the PA group experienced oxidative stress and activation of the PARP1/NAD+/SIRT1 axis in contrast to the CON group. Moreover, manipulation of PARP1 expression in HT22 cells through PARP1 lentivirus-based silencing or overexpression revealed a converse relationship between PARP1 expression levels and the NAD+/NADH ratio as well as SIRT1 expression levels. This study concludes that obesity may exacerbate POCD by triggering activation of the oxidative stress-induced PARP1/NAD+/SIRT1 axis.

Effects of Oral β-caryophyllene (BCP) Treatment on Perioperative Neurocognitive Disorders: Attenuation of Neuroinflammation Associated with Microglial Activation and Reinforcement of Autophagy Activity in Aged Mice

Perioperative neurocognitive disorders (PND) are a constellation of cognitive impairments that arise following surgical procedures and anesthesia, with a higher incidence in elderly patients. PND is deeply entwined with microglia-mediated neuroinflammation and disrupted autophagy. β-caryophyllene (BCP) is a natural terpene that occurs widely in dietary plants, and possesses robust anti-inflammatory properties by selectively activating CB2 receptors (CB2R). Accordingly, the present study endeavors to investigate the potential of BCP in ameliorating PND in aged mice, by mitigating hippocampal neuroinflammation and improving autophagy. In this study, an abdominal surgery was utilized to induce perioperative neurocognitive disorders (PND) in aged mice. BCP was administered orally at a dosage of 200 mg/kg for seven consecutive days prior to the scheduled surgery. In order to explore the relationship between BCP and CB2 receptors (CB2R), a co-administration of intraperitoneal injections of the CB2R antagonist AM630 was implemented, 30 minutes preceding the oral gavage of BCP. Postoperative cognitive functions were assessed using Morris water maze (MWM) tests. The extent of hippocampal inflammation was examined by measuring the microglial marker Iba-1 protein levels, Iba-1 and GFAP immunoactivity, as well as IL-1β and IL-6 concentrations. Evaluation of autophagy activity was conducted based on the ratio of LC3B2/LC3B1 and protein levels of Beclin-1, p62, and phospho-mTOR (p-mTOR). After being orally administered BCP, the compromised behavioral performance of abdominal surgical interventions on aged mice was alleviated. This was evident by the extended escape latency, reduced time spent in the target quadrant, and fewer platform crossings observed through MWM testing. While hippocampal CB2R mRNA or protein expression remained unaffected by the abdominal surgical procedure, their levels were significantly upregulated in mice that were administered BCP. Moreover, the oral administration of BCP was able to reduce neuroinflammation in response to microglia activation, as evidenced by the decreased levels of Iba-1 protein and immunoactivity, as well as the reduction of IL-1β and IL-6 concentrations. Additionally, BCP intensified autophagic activity, as detected by increased LC3B2/LC3B1 ratio and Beclin-1 protein levels, coupled with decreased levels of p62 and p-mTOR in the hippocampus of aged mice. Conversely, the treatment of AM630 ameliorated the suppressive effect of BCP triggered by the neuroinflammation caused by microglial activation post-surgery in aged mice (increased Iba-1 protein levels and immunoactivity, accompanied by higher IL-1β and IL-6 concentrations). Furthermore, the pro-autophagy effect of BCP on aged mice following surgery was partially blocked by AM630, culminating in decreased LC3B2/LC3B1 ratio and Beclin-1 protein levels. However, the levels of p62 and p-mTOR remained unchanged by AM630. Our investigation unveils the remarkable therapeutic benefits of oral BCP administration for managing PND in aged mice through the attenuation of neuroinflammation associated with microglial activation and the fortification of autophagy activity. Hence, BCP holds great promise as a formidable candidate englobing various potential physiological mechanisms that would mitigate cognitive decline associated with aging.

Melatonin-Driven NLRP3 Inflammation Inhibition Via Regulation of NF-κB Nucleocytoplasmic Transport: Implications for Postoperative Cognitive Dysfunction

The aseptic inflammatory response of the central nervous system is one of the important causes of neurodegenerative diseases in individuals and is also recognized in postoperative cognitive dysfunction (POCD). Inflammasome is thought to be closely related to brain homeostasis. However, there are few drugs targeting the inflammasome to suppress inflammation in clinical practice. Here, we showed that the neuroinflammatory response mediated by the NLRP3 (NLR family, pyrin domain containing 3) inflammasome was involved in the pathological process of POCD. Melatonin protected mice from nerve damage by inhibiting activation of the NLRP3-caspase-1-interleukin 1 beta (IL-β) pathway and thus reduced the secretion of IL-1β inflammatory factors in microglia. Further research found that melatonin has a potential binding effect with NLRP3 protein, and at the same time could reduce the phosphorylation of nuclear factor kappa-B (NF-κB) and inhibit its nuclear translocation. The underlying mechanism was that melatonin inhibited the expression of acetylation of histone H3 and melatonin attenuated the binding of NF-κb to the NLRP3 promoter region 1-200 bp, where there are two potential binding target sites of NF-κb and NLRP3, namely the sequences 5'-GGGAACCCCC-3' and 5'-GGAAATCCA -3'. Therefore, we confirmed a novel mechanism of action of melatonin in the prevention and treatment of POCD.

IL-6 Enhances the Negative Impact of Cortisol on Cognition among Community-Dwelling Older People without Dementia

There is growing evidence that high basal cortisol levels and systemic inflammation independently contribute to cognitive decline among older people without dementia. The present cross-sectional study examined (a) the potential synergistic effect of cortisol levels and systemic inflammation on executive function and (b) whether this effect is more prominent among older people with mild cognitive impairment (MCI). A sub-sample of 99 patients with MCI and 84 older people without cognitive impairment (CNI) (aged 73.8 ± 7.0 years) were recruited from a large population-based cohort in Crete, Greece, and underwent comprehensive neuropsychiatric and neuropsychological evaluation and a single morning measurement of cortisol and IL-6 plasma levels. Using moderated regression models, we found that the relation between cortisol and executive function in the total sample was moderated by IL-6 levels (b = −0.994, p = 0.044) and diagnostic group separately (b = −0.632, p < 0.001). Moreover, the interaction between cortisol and IL-6 levels was significant only among persons with MCI (b = −0.562, p < 0.001). The synergistic effect of stress hormones and systemic inflammation on cognitive status appears to be stronger among older people who already display signs of cognitive decline. Targeting hypercortisolemia and inflammation may be a promising strategy toward improving the course of cognitive decline.

Minocycline Attenuates Sevoflurane-Induced Postoperative Cognitive Dysfunction in Aged Mice by Suppressing Hippocampal Apoptosis and the Notch Signaling Pathway-Mediated Neuroinflammation

Postoperative cognitive dysfunction (POCD), an important postoperative neurological complication, is very common and has an elevated incidence in elderly patients. Sevoflurane, an inhaled anesthetic, has been demonstrated to be associated with POCD in both clinical and animal studies. However, how to prevent POCD remains unclear. Minocycline, a commonly used antibiotic can cross the blood-brain barrier and exert an inhibitory effect on inflammation in the central nervous system. The present work aimed to examine the protective effect and mechanism of minocycline on sevoflurane-induced POCD in aged mice. We found that 3% sevoflurane administered 2 h a day for 3 consecutive days led to cognitive impairment in aged animals. Further investigation revealed that sevoflurane impaired synapse plasticity by causing apoptosis and neuroinflammation and thus induced cognitive dysfunction. However, minocycline pretreatment (50 mg/kg, i.p, 1 h prior to sevoflurane exposure) significantly attenuated learning and memory impairments associated with sevoflurane in aged animals by suppressing apoptosis and neuroinflammation. Moreover, a mechanistic analysis showed that minocycline suppressed sevoflurane-triggered neuroinflammation by inhibiting Notch signaling. Similar results were also obtained in vitro. Collectively, these findings suggested minocycline may be an effective drug for the prevention of sevoflurane-induced POCD in elderly patients.

Intricate role of sleep deprivation in modulating depression: focusing on BDNF, VEGF, serotonin, cortisol, and TNF-α

In this review article, we aimed to discuss intricate roles of SD in modulating depression in preclinical and clinical studies. Decades of research have shown the inconsistent effects of SD on depression, focusing on SD duration. However, inconsistent role of SD seems to be more complicated, and SD duration cannot be the only one factor. Regarding this issue, we chose some important factors involved in the effects of SD on cognitive functions and mood including brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), serotonin, cortisol, and tumor necrosis factor-alpha (TNF-α). It was concluded that SD has a wide-range of inconsistent effects on BDNF, VEGF, serotonin, and cortisol levels. It was noted that BDNF diurnal rhythm is significantly involved in the modulatory role of SD in depression. Furthermore, the important role of VEGF in blood-brain barrier permeability which is involved in modulating depression was discussed. It was also noted that there is a negative correlation between cortisol and BDNF that modulates depression. Eventually, it was concluded that TNF-α regulates sleep/wake cycle and is involved in the vulnerability to cognitive and behavioral impairments following SD. TNF-α also increases the permeability of the blood-brain barrier which is accompanied by depressive behavior. In sum, it was suggested that future studies should focus on these mechanisms/factors to better investigate the reasons behind intricate roles of SD in modulating depression.

Targeting neuroinflammation as a preventive and therapeutic approach for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is a common postoperative complication associated with regional or general anesthesia and surgery. Growing evidence in both patient and animal models of PND suggested that neuroinflammation plays a critical role in the development and progression of this problem, therefore, mounting efforts have been made to develop novel therapeutic approaches for PND by targeting specific factors or steps alongside the neuroinflammation. Multiple studies have shown that perioperative anti-neuroinflammatory strategies via administering pharmacologic agents or performing nonpharmacologic approaches exert benefits in the prevention and management of PND, although more clinical evidence is urgently needed to testify or confirm these results. Furthermore, long-term effects and outcomes with respect to cognitive functions and side effects are needed to be observed. In this review, we discuss recent preclinical and clinical studies published within a decade as potential preventive and therapeutic approaches targeting neuroinflammation for PND.

Effects of LncRNA GAS5/miR-137 general anesthesia on cognitive function by TCF4 inflammatory bodies in patients undergoing lumbar spinal canal decompression

Lumbar spinal stenosis is a common orthopedic disease in clinical practice at present. Postoperative cognitive dysfunction (POCD) refers to the phenomenon of impaired memory. However, whether long noncoding RNA (LncRNA) GAS5 contributes to the mechanism of cognitive function in undergoing lumbar spinal canal decompression remains unknown. Thus, the present study investigated the precise details of LncRNA GAS5 involvement in Postoperative cognitive dysfunction of patients undergoing lumbar spinal canal decompression. Patients undergoing lumbar spinal canal decompression with cognitive function and Normal healthy volunteers were obtained. C57BL/6 mice were maintained with a 2% concentration of sevoflurane in 100% oxygen at a flow rate of 2 L minute-1 for 4 hours. LncRNA GAS5 gene expression were up-regulated in patients undergoing lumbar spinal canal decompression. In mice model, LncRNA GAS5 gene expression also increased. LncRNA GAS5 promoted neuroinflammation in vitro model. LncRNA GAS5 raised cognitive impairment and increased neuroinflammation in mice model. LncRNA GAS5 suppressed miR-137 in vitro model. MiR-137 reduced neuroinflammation in vitro model. MiR-137 suppressed TCF4 protein expression in vitro model. Transcription factor TCF4 activates the expression of bHLH. Taking together, this experiment provide the first experimental and clinical evidence that LncRNA GAS5/miR-137 promoted anesthesia-induced cognitive function to increase inflammatory bodies in patients undergoing lumbar spinal canal decompression, suggesting it may be a biomarker of POCD and a potential therapeutic target for POCD.

Whole body vibration, an alternative for exercise to improve recovery from surgery?

Although exercise is usually associated with beneficial effects on physical and mental health, patients recovering from surgery may be hampered to perform active exercise. Whole body vibration (WBV) is suggested a passive alternative for physical training. Aim of the present study was to explore the therapeutic potential of WBV compared to physical exercise during early post-surgery recovery.

Male three months old Wistar rats underwent major abdominal surgery. Starting the day after surgery, rats were subjected to either daily WBV or exercise (treadmill running) for 15 consecutive days. Control rats underwent pseudo treatment. During the first week after surgery, effects of interventions were obtained from continuous recording of hemodynamic parameters, body temperature and activity (via an implanted transducer). Behavioral tests were performed during the second post-surgical week to evaluate anxiety-like behavior, short and long-term memory functions, cognitive flexibility and motor performance. Animals were sacrificed 15 days after surgery and brain tissue was collected for analysis of hippocampal neuroinflammation and neurogenesis.

Surgery significantly impacted all parameters measured during the first post-surgery week, irrespective of the type of surgery. Effect on cognitive performance was limited to cognitive flexibility; both WBV and exercise prevented the surgery-induced decline. Exercise, but not WBV increased anxiety-like behavior and grip strength. WBV as well as exercise prevented the surgery-induced declined neurogenesis, but surgery-associated hippocampal neuroinflammation was not affected.

Our results indicated that active exercise and WBV share similar therapeutic potentials in the prevention of surgery induced decline in cognitive flexibility and hippocampal neurogenesis. In contrast to exercise, WBV did not increase anxiety-like behavior. Since neither intervention affected hippocampal neuroinflammation, other mechanisms and/or brain areas may be involved in the behavioral effects. Taken together, we conclude that WBV may provide a relevant alternative to active exercise during the early stage of post-operative recovery.

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Both whole body vibration (WBV) and running exercise restored the reduced cognitive flexibility caused by surgery.

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WBV as well as active exercise prevented surgery-induced declined neurogenesis.

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Active exercise, but not WBV, induced anxiety-like behavior after surgery.

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Neither WBV nor active exercise affected surgery-induced neuroinflammation.

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Neither WBV nor active exercise influenced hemodynamic recovery from surgery.

Effects of anesthetics on expression of dopamine and acetylcholine receptors in the rat brain in vivo

Dopamine D₂ and acetylcholine M₁ receptors might be related to post-operative cognitive dysfunction. The aim of the present study is to investigate whether several anesthetics which are used for general anesthesia and/or sedation, affect expression of dopamine D₂ and acetylcholine M₁ receptors in the rat brain. Thirty-six male rats aged 5-9 weeks old were divided into six groups (n = 6 in each group); five groups for anesthetics and one for control. The five groups were anesthetized with either dexmedetomidine 0.4 µg/kg/min, propofol 50 mg/kg/h, midazolam 25 mg/kg/h, sevoflurane 3.3%, or nitrous oxide 75% for 4 h. Then, the rats were decapitated, and the cerebral cortex, hippocampus, corpus striatum, brain stem, and cerebellum were collected from all rats. Then, real-time polymerase chain reaction was performed to examine the expression of Drd2 (cord dopamine D₂ receptor) and Chrm1 (cord acetylcholine M₁ receptor). There were no significant differences among the groups regarding Drd2 and Chrm1 mRNA expression of each region of the brain. Postsynaptic changes of dopamine D₂ and acetylcholine M₁ receptors due to administration of dexmedetomidine, propofol, midazolam, sevoflurane, and nitrous oxide are unlikely to occur at the doses of each anesthetic used in the present study.

Does Preoperative Cognitive Optimization Improve Postoperative Outcomes in the Elderly?

Perioperative neurocognitive disorder (PND) is a growing concern, affecting several million elderly patients each year in the United States, but strategies for its effective prevention have not yet been established. Humeidan et al. recently demonstrated that preoperative brain exercise resulted in a decrease in postoperative delirium incidence in elderly surgical patients, suggesting the potential of presurgical cognitive optimization to improve postoperative cognitive outcomes. This brief review summarizes the current knowledge regarding preoperative cognitive optimization and highlights landmark studies, as well as current ongoing studies, as the field is rapidly growing. This review further discusses the benefit of cognitive training in non-surgical elderly populations and the role of cognitive training in patients with preexisting cognitive impairment or dementia. The review also examines preclinical evidence in support of cognitive training, which can facilitate understanding of brain plasticity and the pathophysiology of PND. The literature suggests positive impacts of presurgical cognitive optimization, but further studies are encouraged to establish effective cognitive training programs for elderly presurgical patients.

The Effects of Intraoperative Hypothermia on Postoperative Cognitive Function in the Rat Hippocampus and Its Possible Mechanisms

Intraoperative hypothermia is a common complication during operations and is associated with several adverse events. Postoperative cognitive dysfunction (POCD) and its adverse consequences have drawn increasing attention in recent years. There are currently no relevant studies investigating the correlation between intraoperative hypothermia and POCD. The aim of this study was to assess the effects of intraoperative hypothermia on postoperative cognitive function in rats undergoing exploratory laparotomies and to investigate the possible related mechanisms. We used the Y-maze and Morris Water Maze (MWM) tests to assess the rats’ postoperative spatial working memory, spatial learning, and memory. The morphological changes in hippocampal neurons were examined by haematoxylin-eosin (HE) staining and hippocampal synaptic plasticity-related protein expression. Activity-regulated cytoskeletal-associated protein (Arc), cyclic adenosine monophosphate-response element-binding protein (CREB), S133-phosphorylated CREB (p-CREB [S133]), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor 1 (AMPAR1), and S831-phosphorylated AMPAR1 (p-AMPAR1 [S831]) were evaluated by Western blotting. Our results suggest a correlation between intraoperative hypothermia and POCD in rats and that intraoperative hypothermia may lead to POCD regarding impairments in spatial working memory, spatial learning, and memory. POCD induced by intraoperative hypothermia might be due to hippocampal neurons damage and decreased expression of synaptic plasticity-related proteins Arc, p-CREB (S133), and p-AMPAR1 (S831).