Systemic Inflammation Disrupts Circadian Rhythms and Diurnal Neuroimmune Dynamics.

Circadian rhythms regulate physiological processes in approximately 24 h cycles, and their disruption is associated with various diseases. Inflammation may perturb circadian rhythms, though these interactions remain unclear. This study examined whether systemic inflammation induced by an intraperitoneal injection of lipopolysaccharide (LPS) could alter central and peripheral circadian rhythms and diurnal neuroimmune dynamics. Mice were randomly assigned to two groups: the saline control group and the LPS group. The diurnal expression of circadian clock genes and inflammatory cytokines were measured in the hypothalamus, hippocampus, and liver. Diurnal dynamic behaviors of microglia were also assessed. Our results revealed that the LPS perturbed circadian gene oscillations in the hypothalamus, hippocampus, and liver. Furthermore, systemic inflammation induced by the LPS could trigger neuroinflammation and perturb the diurnal dynamic behavior of microglia in the hippocampus. These findings shed light on the intricate link between inflammation and circadian disruption, underscoring their significance in relation to neurodegenerative diseases.

Cost Offset of Dapagliflozin in the US Medicare Population with Cardio-Kidney Metabolic Syndrome.

INTRODUCTION: Cardiovascular-kidney-metabolic (CKM) syndrome is highly prevalent in the US Medicare population and is projected to increase further. Sodium-glucose co-transporter 2 inhibitors have indications in chronic kidney disease (CKD), heart failure (HF), and type 2 diabetes (T2D), providing protective efficacy across conditions within CKM syndrome. The objective of this study was to develop a model to extrapolate key outcomes observed in pivotal clinical trials to the US Medicare population, and to assess the potential direct cost offsets associated with dapagliflozin therapy. METHODS: All US 2022 Medicare beneficiaries (≥ 65 years of age) eligible to receive dapagliflozin were estimated according to drug label indication and Medicare enrollment and claims data. Incidence of key outcomes from the dapagliflozin clinical program were modelled over a 4-year time horizon based on patient-level data with CKD, HF, and T2D. Published cost data of relevant clinical outcomes were used to calculate direct medical care cost-offset associated with treatment with dapagliflozin. RESULTS: In a population of 13.1 million patients with CKM syndrome, treatment with dapagliflozin in addition to historical standard of care (hSoC) versus hSoC alone led to fewer incidents of HF-related events (hospitalization for HF, 613,545; urgent HF visit, 98,896), renal events (kidney failure, 285,041; ≥ 50% sustained decline in kidney function, 375,137), and 450,355 fewer deaths (of which 225,346 and 13,206 incidences of cardiovascular and renal death were avoided). In total this led to medical care cost offsets of $99.3 billion versus treatment with hSoC only (dapagliflozin plus hSoC, $310.3 billion; hSoC, $211.0 billion). CONCLUSION: By extrapolating data from trials across multiple indications within CKM syndrome, this broader perspective shows that considerable medical care cost offsets may result through attenuated incidence of clinical events in CKD, T2D, and HF populations if treated with dapagliflozin in addition to hSoC over a 4-year time horizon. Graphical abstract available for this article.

Complement C3 From Astrocytes Plays Significant Roles in Sustained Activation of Microglia and Cognitive Dysfunctions Triggered by Systemic Inflammation After Laparotomy in Adult Male Mice.

Aberrant activation of complement cascades plays an important role in the progress of neurological disorders. Complement C3, the central complement component, has been implicated in synaptic loss and cognitive impairment. Recent study has shown that wound injury-induced systemic inflammation can trigger the increase of C3 in the brain. Our previous studies have demonstrated that laparotomy-triggered systemic inflammation could induce neuroinflammation and cognitive dysfunctions. Furthermore, sustained activation of microglia was observed even 14 days after laparotomy, while most of cytokines had returned to basal levels rapidly at the earlier time point. Although we have demonstrated that anti-inflammatory intervention successfully attenuated cognitive dysfunction by preventing increase of cytokines and activation of microglia, how sustained activation of microglia and cognitive dysfunction occur is still a mystery. In this study, we investigated the role of C3 in mediating activation of microglia and cognitive dysfunction by using laparotomy in adult male mouse only as the experimental model of systemic inflammation and AAV9-C3shRNA. Our data observed that laparotomy induced neurotoxic reactive astrocytes with an increase of C3 in the hippocampus. Furthermore, inhibition of C3 by AAV9-C3shRNA prevented synaptic engulfment by microglia and attenuated cognitive dysfunctions after laparotomy. Inhibition of C3 did not modulate activation of astrocytes and expression of various cytokines. Current findings demonstrated that C3 plays significant roles in sustained activation of microglia and cognitive dysfunctions, which suggests that C3 is the valuable molecule target to attenuate in neurological conditions characterised by neuroinflammation and cognitive dysfunction.

Prescreened Whole O Blood Group Walking Blood Bank Capabilities for Nontraditional Maritime Medical Receiving Platforms: A Case Series.

BACKGROUND: Tactical Combat Casualty Care (TCCC) guidelines recognize low-titer group O whole blood (LTOWB) as the resuscitative fluid of choice for combat wounded. Utilization of prescreened LTOWB in a walking blood bank (WBB) format has been well described by the Ranger O low-titer blood (ROLO) and the United States Marine Corps Valkyrie programs, but it has not been applied to the maritime setting. METHODS: We describe three WBB experiences of an expeditionary resuscitative surgical system (ERSS) team, attached to three nontraditional maritime medical receiving platforms, over 6 months. RESULTS: Significant variations were identified in the number of screened eligible donors, the number of LTOWB donors, and the timely arrival at WBB activation sites between the platforms. Overall, 95% and 84% of the screened eligible group O blood donors on the Arleigh Burke Class Destroyer (DDG) and Nimitz Class Aircraft Carrier (CVN), respectively, were determined to be LTOWB. However, only 37% of the eligible screened group O blood donors aboard the Harper's Ferry Class Dock Landing Ship (LSD) were found to be LTOWB. Of the eligible donors, 66% did not complete screening, with 52% citing a correctable reason for nonparticipation. CONCLUSION: LTOWB attained through WBBs may be the only practical resuscitative fluid on maritime platforms without inherent blood product storage capabilities to perform remote damage control resuscitation. Future efforts should focus on optimizing WBBs through capability development, education, and training efforts.

Time to Anticoagulation Reversal and Outcomes After Intracerebral Hemorrhage.

Importance: Intracerebral hemorrhage (ICH) is the deadliest stroke subtype, and mortality rates are especially high in anticoagulation-associated ICH. Recently, specific anticoagulation reversal strategies have been developed, but it is not clear whether there is a time-dependent treatment effect for door-to-treatment (DTT) times in clinical practice. Objective: To evaluate whether DTT time is associated with outcome among patients with anticoagulation-associated ICH treated with reversal interventions. Design, Setting, and Participants: This cohort study used data from the American Heart Association Get With The Guidelines-Stroke quality improvement registry. Patients with ICH who presented within 24 hours of symptom onset across 465 US hospitals from 2015 to 2021 were included. Data were analyzed from January to September 2023. Exposures: Anticoagulation-associated ICH. Main Outcomes and Measures: DTT times and outcomes were analyzed using logistic regression modeling, adjusted for demographic, history, baseline, and hospital characteristics, with hospital-specific random intercepts to account for clustering by site. The primary outcome of interest was the composite inpatient mortality and discharge to hospice. Additional prespecified secondary outcomes, including functional outcome (discharge modified Rankin Scale score, ambulatory status, and discharge venue), were also examined. Results: Of 9492 patients with anticoagulation-associated ICH and documented reversal intervention status, 4232 (44.6%) were female, and the median (IQR) age was 77 (68-84) years. A total of 7469 (78.7%) received reversal therapy, including 4616 of 5429 (85.0%) taking warfarin and 2856 of 4069 (70.2%) taking a non-vitamin K antagonist oral anticoagulant. For the 5224 patients taking a reversal intervention with documented workflow times, the median (IQR) onset-to-treatment time was 232 (142-482) minutes and the median (IQR) DTT time was 82 (58-117) minutes, with a DTT time of 60 minutes or less in 1449 (27.7%). A DTT time of 60 minutes or less was associated with decreased mortality and discharge to hospice (adjusted odds ratio, 0.82; 95% CI, 0.69-0.99) but no difference in functional outcome (ie, a modified Rankin Scale score of 0 to 3; adjusted odds ratio, 0.91; 95% CI, 0.67-1.24). Factors associated with a DTT time of 60 minutes or less included White race, higher systolic blood pressure, and lower stroke severity. Conclusions and Relevance: In US hospitals participating in Get With The Guidelines-Stroke, earlier anticoagulation reversal was associated with improved survival for patients with ICH. These findings support intensive efforts to accelerate evaluation and treatment for patients with this devastating form of stroke.

Downregulation of the glucose transporter GLUT 1 in the cerebral microvasculature contributes to postoperative neurocognitive disorders in aged mice.

INTRODUCTION: Glucose transporter 1 (GLUT1) is essential for glucose transport into the brain and is predominantly expressed in the cerebral microvasculature. Downregulation of GLUT1 precedes the development of cognitive impairment in neurodegenerative conditions. Surgical trauma induces blood-brain barrier (BBB) disruption, neuroinflammation, neuronal mitochondria dysfunction, and acute cognitive impairment. We hypothesized that surgery reduces the expression of GLUT1 in the BBB that in turn disrupts its integrity and contributes to metabolic dysregulation in the brain that culminates in postoperative cognitive impairment. METHODOLOGY: Using an abdominal surgery model in aged WT mice, we assessed the perioperative changes in cognitive performance, tight junction proteins expression, GLUT1 expression, and the associated metabolic effects in the hippocampus. Thereafter, we evaluated the effects of these parameters in aged mice with conditional overexpression of GLUT1, and then again in aged mice with conditional overexpression of GLUT1 with or without prior exposure to the GLUT1 inhibitor ST-31. RESULTS: We showed a significant decline in cognitive performance, along with GLUT1 reduction and diminished glucose metabolism, especially in the ATP level in the postoperative mice compared with controls. Overexpression of GLUT1 expression alleviated postoperative cognitive decline and improved metabolic profiles, especially in adenosine, but did not directly restore ATP generation to control levels. GLUT1 inhibition ameliorated the postoperative beneficial effects of GLUT1 overexpression. CONCLUSIONS: Surgery-induced GLUT1 reduction significantly contributes to postoperative cognitive deficits in aged mice by affecting glucose metabolism in the brain. It indicates the potential of targeting GLUT1 to ameliorate perioperative neurocognitive disorders.

Neuropathological signatures revealed by transcriptomic and proteomic analysis in Pten-deficient mouse models.

PTEN hamartoma tumour syndrome is characterised by mutations in the human PTEN gene. We performed transcriptomic and proteomic analyses of neural tissues and primary cultures from heterozygous and homozygous Pten-knockout mice. The somatosensory cortex of heterozygous Pten-knockout mice was enriched in immune response and oligodendrocyte development Gene Ontology (GO) terms. Parallel proteomic analysis revealed differentially expressed proteins (DEPs) related to dendritic spine development, keratinisation and hamartoma signatures. However, primary astrocytes (ASTs) from heterozygous Pten-knockout mice were enriched in the extracellular matrix GO term, while primary cortical neurons (PCNs) were enriched in immediate-early genes. In ASTs from homozygous Pten-knockout mice, cilium-related activity was enriched, while PCNs exhibited downregulation of forebrain neuron generation and differentiation, implying an altered excitatory/inhibitory balance. By integrating DEPs with pre-filtered differentially expressed genes, we identified the enrichment of traits of intelligence, cognitive function and schizophrenia, while DEPs in ASTs were significantly associated with intelligence and depression.

IL-1ß and TNF-α play an important role in modulating the risk of periodontitis and Alzheimer's disease.

BACKGROUND: Systemic activation of the immune system can exert detrimental effects on the central nervous system. Periodontitis, a chronic disease of the oral cavity, is a common source of systemic inflammation. Neuroinflammation might be a result of this to accelerate progressive deterioration of neuronal functions during aging or exacerbate pre-existing neurodegenerative diseases, such as Alzheimer's disease. With advancing age, the progressive increase in the body's pro-inflammatory status favors the state of vulnerability to both periodontitis and Alzheimer's disease. In the present study, we sought to delineate the roles of cytokines in the pathogenesis of both diseases. METHODS: To examine the impacts of periodontitis on the onset and progression of Alzheimer's disease, 6-month-old female 3 × Tg-AD mice and their age-matched non-transgenic mice were employed. Periodontitis was induced using two different experimental models: heat-killed bacterial-induced periodontitis and ligature-induced periodontitis. To delineate the roles of pro-inflammatory cytokines in the pathogenesis of periodontitis and Alzheimer's disease, interleukin 1 beta (IL-1ß) and tumor necrosis factor-alpha (TNF-α) were also injected into the buccal mandibular vestibule of mice. RESULTS: Here, we show that IL-1ß and TNF-α were two of the most important and earliest cytokines upregulated upon periodontal infection. The systemic upregulation of these two cytokines promoted a pro-inflammatory environment in the brain contributing to the development of Alzheimer's disease-like pathology and cognitive dysfunctions. Periodontitis-induced systemic inflammation also enhanced brain inflammatory responses and subsequently exacerbated Alzheimer's disease pathology and cognitive impairment in 3 × Tg-AD mice. The role of inflammation in connecting periodontitis to Alzheimer's disease was further affirmed in the conventional magnetization transfer experiment in which increased glial responses resulting from periodontitis led to decreased magnetization transfer ratios in the brain of 3 × Tg-AD mice. CONCLUSIONS: Systemic inflammation resulting from periodontitis contributed to the development of Alzheimer's disease tau pathology and subsequently led to cognitive decline in non-transgenic mice. It also potentiated Alzheimer's disease pathological features and exacerbated impairment of cognitive function in 3 × Tg-AD mice. Taken together, this study provides convincing evidence that systemic inflammation serves as a connecting link between periodontitis and Alzheimer's disease.

Clinically relevant small-molecule promotes nerve repair and visual function recovery.

Adult mammalian injured axons regenerate over short-distance in the peripheral nervous system (PNS) while the axons in the central nervous system (CNS) are unable to regrow after injury. Here, we demonstrated that Lycium barbarum polysaccharides (LBP), purified from Wolfberry, accelerated long-distance axon regeneration after severe peripheral nerve injury (PNI) and optic nerve crush (ONC). LBP not only promoted intrinsic growth capacity of injured neurons and function recovery after severe PNI, but also induced robust retinal ganglion cell (RGC) survival and axon regeneration after ONC. By using LBP gene expression profile signatures to query a Connectivity map database, we identified a Food and Drug Administration (FDA)-approved small-molecule glycopyrrolate, which promoted PNS axon regeneration, RGC survival and sustained CNS axon regeneration, increased neural firing in the superior colliculus, and enhanced visual target re-innervations by regenerating RGC axons leading to a partial restoration of visual function after ONC. Our study provides insights into repurposing of FDA-approved small molecule for nerve repair and function recovery.

Gastric intestinal metaplasia development in African American predominant United States population.

BACKGROUND: Gastric cancer significantly contributes to cancer mortality globally. Gastric intestinal metaplasia (GIM) is a stage in the Correa cascade and a premalignant lesion of gastric cancer. The natural history of GIM formation and progression over time is not fully understood. Currently, there are no clear guidelines on GIM surveillance or management in the United States. AIM: To investigate factors associated with GIM development over time in African American-predominant study population. METHODS: This is a retrospective longitudinal study in a single tertiary hospital in Washington DC. We retrieved upper esophagogastroduodenoscopies (EGDs) with gastric biopsies from the pathology department database from January 2015 to December 2020. Patients included in the study had undergone two or more EGDs with gastric biopsy. Patients with no GIM at baseline were followed up until they developed GIM or until the last available EGD. Exclusion criteria consisted of patients age < 18, pregnancy, previous diagnosis of gastric cancer, and missing data including pathology results or endoscopy reports. The study population was divided into two groups based on GIM status. Univariate and multivariate Cox regression was used to estimate the hazard induced by patient demographics, EGD findings, and Helicobacter pylori (H. pylori) status on the GIM status. RESULTS: Of 2375 patients who had at least 1 EGD with gastric biopsy, 579 patients were included in the study. 138 patients developed GIM during the study follow-up period of 1087 d on average, compared to 857 d in patients without GIM (P = 0.247). The average age of GIM group was 64 years compared to 56 years in the non-GIM group (P < 0.001). In the GIM group, adding one year to the age increases the risk for GIM formation by 4% (P < 0.001). Over time, African Americans, Hispanic, and other ethnicities/races had an increased risk of GIM compared to Caucasians with a hazard ratio (HR) of 2.12 (1.16, 3.87), 2.79 (1.09, 7.13), and 3.19 (1.5, 6.76) respectively. No gender difference was observed between the study populations. Gastritis was associated with an increased risk for GIM development with an HR of 1.62 (1.07, 2.44). On the other hand, H. pylori infection did not increase the risk for GIM. CONCLUSION: An increase in age and non-Caucasian race/ethnicity are associated with an increased risk of GIM formation. The effect of H. pylori on GIM is limited in low prevalence areas.

The role of PKC/PKR in aging, Alzheimer's disease, and perioperative neurocognitive disorders.

Background: The incidence of perioperative neurocognitive disorders (PNDs) is reportedly higher in older patients. Mitochondrial and synaptic dysfunctions have consistently been demonstrated in models of aging and neurodegenerative diseases; nonetheless, their role in PND is not well understood. Methods: The Morris water maze and elevated plus maze tests were used to assess the learning and memory abilities of both C57BL/6 and 3×Tg-AD mice of different ages (8 and 18 months). PND was induced by laparotomy in C57BL/6 mice and 3×Tg-AD mice (8 months old). Markers associated with neuroinflammation, mitochondrial function, synaptic function, and autophagy were assessed postoperatively. The roles of protein kinase C (PKC) and double-stranded RNA-dependent protein kinase (PKR) were further demonstrated by using PKC-sensitive inhibitor bisindolylmaleimide X (BIMX) or PKR-/- mice. Results: Significant cognitive impairment was accompanied by mitochondrial dysfunction and autophagy inactivation in both aged C57BL/6 and 3×Tg-AD mice. Laparotomy induced a significant neuroinflammatory response and synaptic protein loss in the hippocampus. Cognitive and neuropathological changes induced by aging or laparotomy were further exacerbated in 3×Tg-AD mice. Deficits in postoperative cognition, hippocampal mitochondria, autophagy, and synapse were significantly attenuated after pharmacological inhibition of PKC or genetic deletion of PKR. Conclusions: Our findings suggest similar pathogenic features in aging, Alzheimer's disease, and PND, including altered mitochondrial homeostasis and autophagy dysregulation. In addition, laparotomy may exacerbate cognitive deficits associated with distinct neuronal inflammation, mitochondrial dysfunction, and neuronal loss independent of genetic background. The dysregulation of PKC/PKR activity may participate in the pathogenesis of these neurodegenerative diseases.

Distribution and inter-regional relationship of amyloid-beta plaque deposition in a 5xFAD mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia. Although previous studies have selectively investigated the localization of amyloid-beta (Aß) deposition in certain brain regions, a comprehensive characterization of the rostro-caudal distribution of Aß plaques in the brain and their inter-regional correlation remain unexplored. Our results demonstrated remarkable working and spatial memory deficits in 9-month-old 5xFAD mice compared to wildtype mice. High Aß plaque load was detected in the somatosensory cortex, piriform cortex, thalamus, and dorsal/ventral hippocampus; moderate levels of Aß plaques were observed in the motor cortex, orbital cortex, visual cortex, and retrosplenial dysgranular cortex; and low levels of Aß plaques were located in the amygdala, and the cerebellum; but no Aß plaques were found in the hypothalamus, raphe nuclei, vestibular nucleus, and cuneate nucleus. Interestingly, the deposition of Aß plaques was positively associated with brain inter-regions including the prefrontal cortex, somatosensory cortex, medial amygdala, thalamus, and the hippocampus. In conclusion, this study provides a comprehensive morphological profile of Aß deposition in the brain and its inter-regional correlation. This suggests an association between Aß plaque deposition and specific brain regions in AD pathogenesis.

Leukocyte invasion of the brain after peripheral trauma in zebrafish (Danio rerio).

Despite well-known systemic immune reactions in peripheral trauma, little is known about their roles in posttraumatic neurological disorders, such as anxiety, sickness, and cognitive impairment. Leukocyte invasion of the brain, a common denominator of systemic inflammation, is involved in neurological disorders that occur in peripheral inflammatory diseases, whereas the influences of peripheral leukocytes on the brain after peripheral trauma remain largely unclear. In this study, we found that leukocytes, largely macrophages, transiently invaded the brain of zebrafish larvae after peripheral trauma through vasculature-independent migration, which was a part of the systemic inflammation and was mediated by interleukin-1b (il1b). Notably, myeloid cells in the brain that consist of microglia and invading macrophages were implicated in posttraumatic anxiety-like behaviors, such as hyperactivity (restlessness) and thigmotaxis (avoidance), while a reduction in systemic inflammation or myeloid cells can rescue these behaviors. In addition, invading leukocytes together with microglia were found to be responsible for the clearance of apoptotic cells in the brain; however, they also removed the nonapoptotic cells, which suggested that phagocytes have dual roles in the brain after peripheral trauma. More importantly, a category of conserved proteins between zebrafish and humans or rodents that has been featured in systemic inflammation and neurological disorders was determined in the zebrafish brain after peripheral trauma, which supported that zebrafish is a translational model of posttraumatic neurological disorders. These findings depicted leukocyte invasion of the brain during systemic inflammation after peripheral trauma and its influences on the brain through il1b-dependent mechanisms.

Sevoflurane Induces Neurotoxicity in the Animal Model with Alzheimer's Disease Neuropathology via Modulating Glutamate Transporter and Neuronal Apoptosis.

Perioperative neurocognitive disorders are frequently observed in postoperative patients and previous reports have shown that pre-existing mild cognitive impairment with accumulated neuropathology may be a risk factor. Sevoflurane is a general anesthetic agent which is commonly used in clinical practice. However, the effects of sevoflurane in postoperative subjects are still controversial, as both neurotoxic or neuroprotective effects were reported. The purpose of this study is to investigate the effects of sevoflurane in 3 × Tg mice, a specific animal model with pre-existing Alzheimer's disease neuropathology. 3 × Tg mice and wild-type mice were exposed to 2 h of sevoflurane respectively. Cognitive function, glutamate transporter expression, MAPK kinase pathways, and neuronal apoptosis were accessed on day 7 post-exposure. Our findings indicate that sevoflurane-induced cognitive deterioration in 3 × Tg mice, which was accompanied with the modulation of glutamate transporter, MAPK signaling, and neuronal apoptosis in the cortical and hippocampal regions. Meanwhile, no significant impact was observed in wild-type mice. Our results demonstrated that prolonged inhaled sevoflurane results in the exacerbation of neuronal and cognitive dysfunction which depends on the neuropathology background.

Prehabilitative resistance exercise reduces neuroinflammation and improves mitochondrial health in aged mice with perioperative neurocognitive disorders.

BACKGROUND: Postoperative neurocognitive dysfunction remains a significant problem in vulnerable groups such as the elderly. While experimental data regarding its possible pathogenic mechanisms accumulate, therapeutic options for this disorder are limited. In this study, we evaluated the neuroprotective effect of a period of preconditioning resistant training on aged mice undergoing abdominal surgery. Further, we examined the underlying mechanisms from the perspective of neuroinflammatory state and synaptic plasticity in the hippocampus. METHODS: 18-month-old C57BL/6N mice were trained for 5 weeks using a ladder-climbing protocol with progressively increasing weight loading. Preoperative baseline body parameters, cognitive performance and neuroinflammatory states were assessed and compared between sedentary and trained groups of 9-month-old and 18-month-old mice. To access the neuroprotective effect of resistance training on postoperative aged mice, both sedentary and trained mice were subjected to a laparotomy under 3% sevoflurane anesthesia. Cognitive performance on postoperative day 14, hippocampal neuroinflammation, mitochondrial dysfunction and synaptic plasticity were examined and compared during groups. RESULTS: 18-month-old mice have increased body weight, higher peripheral and central inflammatory status, reduction in muscle strength and cognitive performance compared with middle-aged 9-month-old mice, which were improved by resistance exercise. In the laparotomy group, prehabilitative resistant exercise improved cognitive performance and synaptic plasticity, reduced inflammatory factors and glial cells activation after surgery. Furthermore, resistance exercise activated hippocampal PGC-1α/BDNF/Akt/GSK-3ß signaling and improved mitochondrial biogenesis, as well as ameliorated mitochondrial dynamics in postoperative-aged mice. CONCLUSIONS: Resistance exercise reduced risk factors for perioperative neurocognitive disorders such as increased body weight, elevated inflammatory markers, and pre-existing cognitive impairment. Accordantly, preoperative resistance exercise improved surgery-induced adverse effects including cognitive impairment, synaptic deficit and neuroinflammation, possibly by facilitate mitochondrial health through the PGC1-a/BDNF pathway.

Investigating key factors underlying neurodegeneration linked to alpha-synuclein spread.

AIMS: It has long been considered that accumulation of pathological alpha-synuclein (aSyn) leads to synaptic/neuronal loss which then results in behavioural and cognitive dysfunction. To investigate this claim, we investigated effects downstream of aSyn preformed fibrils (PFFs) and 6-hydroxydopamine (6-OHDA), because aSyn PFFs induce spreading/accumulation of aSyn, and 6-OHDA rapidly causes local neuronal loss. METHODS: We injected mouse aSyn PFFs into the medial forebrain bundle (MFB) of Sprague-Dawley rats. We investigated spread of pathological aSyn, phosphorylation of aSyn and tau, oxidative stress, synaptic/neuronal loss and cognitive dysfunction 60, 90 and 120 days after injection. Similarly, we injected 6-OHDA into the MFB and examined the same parameters 1 and 3 weeks after injection. RESULTS: Following aSyn PFF injection, phosphorylated aSyn was found distant from the injection site in the hippocampus and frontal cortex. However, despite neuron loss being evident close to the site of injection in the substantia nigra at 120 days post injection, there were no other neurodegeneration-associated features associated with aSyn including synaptic loss. In contrast, 6-OHDA caused severe neuronal loss in the substantia nigra at 3 weeks post injection that was accompanied by phosphorylation of aSyn and tau, oxidative stress, loss of synaptic proteins, cognitive and motor dysfunction. CONCLUSIONS: Our results demonstrate that spread/replication and slow accumulation of pathological aSyn may not be sufficient to induce neurodegenerative changes. In contrast, oxidative stress responses in addition to aSyn accumulation were associated with other Parkinson's disease (PD)-associated abnormalities and cognitive dysfunction. Our results may be important when considering why only some PD patients develop dementia.