Novel Object Recognition Test Research Articles

Protective effects of geraniol in a male rat model of Alzheimer's disease: A behavioral, biochemical, and histological study.

Alzheimer's disease (AD) as a neurodegenerative disease can cause behavioral impairments due to oxidative stress. Aging and oxidative conditions are some AD risk factors. We assessed the influence of geraniol (GR), an acyclic monoterpene alcohol, on behavioral functions, hippocampal oxidative status, and histological alterations in AD rats induced by amyloid-β (Aβ). Male Wistar rats (n = 70) were randomly allocated to the control, sham, AD, control-GR (100 mg/kg; per oral: P.O.), AD-GR (100 mg/kg; P.O.; treatment), GR-AD (100 mg/kg; P.O.; pretreatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment + treatment) groups. GR administration was done for four continuous weeks. After treatments, novel object recognition (NOR) and Morris water maze (MWM) tests assessed the animals' behavior. Then, hippocampal specimens were collected for biochemical assessment. Finally, the number of intact neurons was identified in the hippocampus using hematoxylin and eosin staining. Aβ microinjection increased learning and memory deficits in both NOR and MWM tests, oxidative stress status, and neuronal loss. Oral GR administration improved behavioral deficits and reduced oxidative stress status and neuronal loss in the Aβ-infused animals. GR ameliorates behavioral impairments through a decrease in neuronal degeneration and oxidative stress.

Mechanism of Pyroptosis in Postoperative Cognitive Dysfunction Rats and α7-nicotinic Receptor Agonist Regulating NLRP3 Inflammasome Activation

Background: This study investigates the efficacy of α7-nicotinic acetylcholine receptor (α7nAChR) agonists in mitigating postoperative cognitive dysfunction (POCD) in a rat model. This investigation aimed to elucidate the therapeutic potential of α7nAChR agonists in modulating neuroinflammatory pathways to improve cognitive outcomes post-surgery. Objective: Serum levels of pro-inflammatory cytokines IL-1β and IL-18 were measured as markers of systemic inflammation, while the expression levels of NLRP3 mRNA were quantified to evaluate pyroptosis and NLRP3 inflammasome activation. Methods: Adult male Sprague-Dawley rats were divided into control (no surgery), POCD (surgeryinduced), and POCD treated with an α7nAChR agonist. Cognitive function was assessed using the Morris Water Maze (MWM) and Novel Object Recognition (NOR) tests. Results: The results showed a notable cognitive impairment in the group with POCD, as shown by increased escape latency noted in the MWM test and decreased discrimination index in the NOR test, while controls had no change. However, treatment with the α7nAChR agonist led to a significant improvement in cognitive performance among the POCD rats such that it closely matched those of the controls. Furthermore, the POCD group exhibited elevated serum levels of IL-1β and IL-18 and increased expression of pyroptosis-related markers, indicating enhanced neuroinflammation and inflammasome activation. Conclusion: These findings highlighted the therapeutic efficacy of α7nAChR agonists in mitigating neuroinflammation and improving cognitive outcomes post-surgery. Our study supports the potential of targeting the cholinergic anti-inflammatory pathway, emphasizing clinical evaluation of α7nAChR agonists in postoperative patients.

Sex differences in the role of AKAP12 in behavioral function of middle-aged mice

A-kinase anchoring protein 12 (AKAP12) is a key scaffolding protein that regulates cellular signaling by anchoring protein kinase A (PKA) and other signaling molecules. While recent studies suggest an important role for AKAP12 in the brain, including cognitive functions, its role in middle-aged mice and potential sex differences are not fully understood. Therefore, this study investigated the effects of AKAP12 on cognitive and exploratory behavior in middle-aged mice, focusing on sex differences. Cognitive function was assessed using the spontaneous Y-maze test and the novel object recognition test (NORT). No significant sex differences in cognitive function were found in middle-aged C57BL/6J mice; however, female mice showed greater exploratory behavior during the NORT. In addition, both middle-aged male and female Akap12 knockout (KO) mice performed similarly to wild-type (WT) mice in the Y-maze test, but had lower discrimination indices in the NORT, suggesting a potential role for AKAP12 in short-term memory. Notably, exploratory behavior was suppressed in female Akap12 KO mice compared to WT mice, whereas male Akap12 KO mice did not show this effect. There were no significant differences in movement distance and velocity during the Y-maze test and NORT between WT and KO mice of either sex. These results indicate that AKAP12 affects cognitive function and exploratory behavior in middle-aged mice and that these effects differ between sexes.

Targeted TGF-βR2 Silencing in the Retrotrapezoid Nucleus Mitigates Respiratory Dysfunction and Cognitive Decline in a Mouse Model of Cerebral Amyloid Angiopathy with and without Stroke.

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid-beta peptides within cerebral blood vessels, leading to neurovascular complications. Ischemic strokes result from acute disruptions in cerebral blood flow, triggering metabolic disturbances and neurodegeneration. Both conditions often co-occur and are associated with respiratory dysfunctions. The retrotrapezoid nucleus (RTN), which is crucial for CO2 sensing and breathing regulation in the brainstem, may play a key role in breathing disorders seen in these conditions. This study aims to investigate the role of Transforming Growth Factor Beta (TGF-β) signaling in the RTN on respiratory and cognitive functions in CAA, both with and without concurrent ischemic stroke.Adult male Tg-SwDI (CAA model) mice and C57BL/6 wild-type controls underwent stereotaxic injections of lentivirus targeting TGF-βR2 in the RTN. Stroke was induced by middle cerebral artery occlusion using a monofilament. Respiratory functions were assessed using whole-body plethysmography, while cognitive functions were evaluated through the Barnes Maze and Novel Object Recognition Test (NORT). Immunohistochemical analysis was conducted to measure TGF-βR2 and GFAP expressions in the RTN.CAA mice exhibited significant respiratory dysfunctions, including reduced respiratory rates and increased apnea frequency, as well as impaired cognitive performance. TGF-βR2 silencing in the RTN improved respiratory functions and cognitive outcomes in CAA mice. In CAA mice with concurrent stroke, TGF-βR2 silencing similarly enhanced respiratory and cognitive functions. Immunohistochemistry confirmed reduced TGF-βR2 and GFAP expressions in the RTN following silencing.Our findings demonstrate that increased TGF-β signaling and gliosis in the RTN contribute to respiratory and cognitive dysfunctions in CAA and CAA with stroke. Targeting TGF-βR2 signaling in the RTN offers a promising therapeutic strategy to mitigate these impairments. This study is the first to report a causal link between brainstem gliosis and both respiratory and cognitive dysfunctions in CAA and stroke models.

Lactobacillus Helveticus Improves Controlled Cortical Impact Injury-Generated Neurological Aberrations by Remodeling of Gut-Brain Axis Mediators.

Considerable studies augured the potential of gut microbiota-based interventions in brain injury-associated complications. Based on our earlier study results, we envisaged the sex-specific neuroprotective effect of Lactobacillus helveticus by remodeling of gut-brain axis. In this study, we investigated the effect of L. helveticus on neurological complications in a mouse model of controlled cortical impact (CCI). Adult, male and female, C57BL/6 mice underwent CCI surgery and received L. helveticus treatment for six weeks. Sensorimotor function was evaluated via neurological severity score and rotarod test. Long-term effects on anxiety-like behavior and cognition were assessed using the elevated-zero maze (EZM) and novel object recognition test (NORT). Brain perilesional area, blood, colon, and fecal samples were collected post-CCI for molecular biology analysis. CCI-operated mice displayed significant neurological impairments at 1-, 3-, 5-, and 7-days post-injury (dpi) and exhibited altered behavior in EZM and NORT compared to sham-operated mice. However, these behavioral changes were ameliorated in mice receiving L. helveticus. GFAP, Iba-1, TNF-α, and IL-1β expressions and corticotrophin-releasing hormone (CRH) levels were elevated in the perilesional cortex of CCI-operated male/female mice. These elevated biomarkers and decreased BDNF levels in both male/female mice were modified by L. helveticus treatment. Additionally, L. helveticus treatment restored altered short-chain fatty acids (SCFAs) levels in fecal samples and improved intestinal integrity but did not affect decreased plasma levels of progesterone and testosterone in CCI mice. These results indicate that L. helveticus exerts beneficial effects in the CCI mouse model by mitigating inflammation and remodeling of gut microbiota-brain mediators.

NCOG-26. THERAPEUTIC POTENTIAL OF FECAL MICROBIOME TRANSPLANT TO IMPROVE COGNITIVE DYSFUNCTION INDUCED BY CRANIAL IRRADIATION IN MICE

Abstract Radiation therapy (RT) is a crucial treatment for brain tumors, but radiation-induced cognitive dysfunction (RICD) affects 50-90% of patients, significantly impacting their quality of life. Evidence suggests that gut microbiome dysfunction may contribute to progressive cognitive dysfunction (CD). Prior studies in aging and stroke models show that fecal microbiome transplants (FMT) from healthy hosts can promote recovery and improve cognition. To investigate the link between RICD and the gut microbiome, we subjected mice to Sham/9Gy/15Gy cranial irradiation, followed by cognitive tests using the Y-maze and Novel Object Recognition Test (NORT) at various time points. Both 9Gy and 15Gy irradiation resulted in significant cognitive dysfunction, as indicated by altered performance in both tests at 7 and 30 days post-irradiation. Fecal samples were collected before irradiation and at 10 and 30 days post-RT. Microbial DNA was extracted, and the 16S rRNA gene was sequenced and analyzed using the bioinformatics visualization toolkit, ATIMA. Significant gut dysbiosis was observed in both 9Gy and 15Gy irradiated mice compared to pre-irradiation samples, with the 15Gy group showing more pronounced and consistent changes in fecal microbiome diversity, particularly at 30 days post-RT. We hypothesized that FMT from healthy hosts (non-radiated mice) could prevent or ameliorate RICD by modulating microbial, metabolomic, and immunologic profiles. To test this, a separate cohort of mice received 15Gy cranial irradiation and FMT via oral gavage. After a 20-day post-irradiation period, cognitive and gut permeability tests were conducted. The FMT group exhibited significantly improved gut permeability and cognitive performance compared to controls. Our findings suggest that gut dysbiosis plays a crucial role in RICD and that FMT may be a potential strategy to mitigate RICD and improve the quality of life in brain tumor patients undergoing cranial RT.

Acute depletion of complement C3 with cobra venom factor attenuates memory deficits induced by status epilepticus.

Status epilepticus (SE) significantly increases the risk for the development of unprovoked seizures, memory loss, and temporal lobe epilepsy. Our prior studies showed that SE increases complement C3 signaling in the hippocampus, which parallels memory deficits. Additionally, C3 knockout (KO) mice were protected against SE-induced memory impairments, suggesting a mechanistic role for C3 in this pathophysiology. In this study, we utilized cobra venom factor (CVF), a structural analog of C3 that results in its depletion, to investigate the protective effects of post-SE C3 ablation on memory deficits that develop during epileptogenesis. SE was induced in male rats using the chemoconvulsant pilocarpine. Two weeks later, control (C) and SE rats were treated with either vehicle (V) or CVF. Recognition memory was assessed using the novel object recognition (NOR) test in four groups (C + V, C + CVF, SE + V, and SE + CVF). Immunoblotting was used to measure hippocampal protein levels of C3 along with synaptic, astrocyte, and blood-brain barrier (BBB) stability markers, Psd95, GFAP, and albumin, respectively. In the NOR test, rats in the C + V and C + CVF groups spent more time exploring the novel object. SE + V rats explored both objects equally, while SE + CVF rats spent significantly more on the novel object, suggesting a rescue of cognitive performance by CVF. While CVF-mediated C3 depletion did not restore normal protein levels of Psd95 or GFAP in hippocampi of SE + CVF rats, CVF treatment attenuated SE-induced extravasation of albumin, suggesting potential rescue of BBB stability. Our findings indicate that acute C3 depletion with CVF can attenuate memory deficits that develop during SE-induced epileptogenesis. This finding further suggests that targeting C3 could hold promise in addressing cognitive comorbidities associated with SE and acquired epilepsy. A long-lasting seizure, known as status epilepticus (SE), can raise the chance of having more seizures in the future and can lead to memory problems. While the exact reasons for these issues are not completely known, it is believed that brain inflammation might be involved. In this study, we show that the activation of the body's immune response, especially a part called the C3 component, plays a role in the memory problems that occur after an episode of SE.

Hippocampal cannabinoid type 2 receptor alleviates chronic neuropathic pain-induced cognitive impairment via microglial DUSP6 pathway in rats.

Approximately 50% of patients with chronic neuropathic pain experience cognitive impairment, which negatively impacts their quality of life. The cannabinoid type 2 receptor (CB2R) may be involved in hippocampal cognitive processes. However, its role in chronic neuropathic pain-induced cognitive impairment remains elusive. Spared nerve injury (SNI) was used to induce chronic neuropathic pain in rats, while the novel-object recognition test and the Y-maze test were employed to assess cognitive function. Immunofluorescence, western blotting, and stereotaxic hippocampal microinjection were utilized to elucidate the potential mechanisms. We observed a reduction in mechanical pain threshold and cognitive impairment in SNI rats. This was accompanied by a tendency for hippocampal microglia to adopt pro-inflammatory functions. Notably, no changes were detected in CB2R expression. However, downregulation of the endogenous ligands AEA and 2-AG was evident. Hippocampal microinjection of a CB2R agonist mitigated cognitive impairment in SNI rats, which correlated with a tendency for microglia to adopt anti-inflammatory functions. Additionally, SNI-induced activation of the p-ERK/NFκB pathway in the hippocampus. Activation of CB2R reversed this process by upregulating DUSP6 expression in microglia. The effects elicited by CB2R activation could be inhibited through the downregulation of microglial DUSP6 via hippocampal adeno-associated virus (AAV) microinjection. Conversely, overexpression of hippocampal DUSP6 using AAV ameliorated the cognitive deficits observed in SNI rats, which remained unaffected by the administration of a CB2R antagonist. Our findings demonstrate that activation of hippocampal CB2R can mitigate chronic neuropathic pain-induced cognitive impairment through the modulation of the DUSP6/ERK/NFκB pathway.

Convection-enhanced delivery of [177Lu]Lu-labeled gold nanoparticles combined with anti-PD1 checkpoint immunotherapy improves the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors

IntroductionOur objective was to study convection enhanced delivery (CED) of 177Lu-labeled metal chelating polymer (MCP) conjugated to gold nanoparticles ([177Lu]Lu-MCP-AuNP) alone or combined with anti-PD1 immune checkpoint inhibition (ICI) for improving the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors. MethodsC57BL/6J mice with GL261 tumors were treated with [177Lu]Lu-MCP-AuNP (0.8 or 2.7 MBq; 4 × 1011 AuNP) alone or combined with anti-PD1 antibodies (200 μg i.p. every 2 d × 3 doses). Control mice received normal saline, non-radioactive MCP-AuNP or anti-PD1 antibodies. Kaplan-Meier median survival was estimated. T-cell infiltration into the brain was probed by flow cytometry. Toxicity was assessed by monitoring body weight and cognitive function tests [Object Location Test (OLT) and Novel Object Recognition Test (NORT)] and T2-weighted MRI of the brain, overall health and ex vivo histopathological examination of the brain. ResultsTreatment with [177Lu]Lu-MCP-AuNP (0.8 MBq) significantly increased median survival compared to MCP-AuNP (29 vs. 25 d; P = 0.007) or normal saline-treated mice (24 d; P < 0.001). Combining [177Lu]Lu-MCP-AuNP (0.8 MBq) with anti-PD1 antibodies increased median survival to 32 d (P < 0.0001 vs. normal saline). Increasing the mean amount of [177Lu]Lu-MCP-AuNP to 2.7 MBq and combining with anti-PD1 antibodies extended survival to at least 218 d in 5/9 mice. Increased CD8+ cytotoxic T-cells and decreased CD4+ helper T-cells were found in the brain vs. normal saline-treated mice. No weight loss (>20 %) was observed for treated or control mice. There was no change in cognitive function in mice treated with [177Lu]Lu-MCP-AuNP (0.8 MBq) alone or combined with anti-PD1 antibodies assessed by the OLT or NORT. T2-weighted MRI in mice treated with 2.7 MBq [177Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies revealed edema, gliosis and ex vacuo dilatation of the ventricle proximal to the site of infusion. Histopathological examination of the brain revealed dilatation of the ventricle and gliosis proximal to the site of infusion but no radiation necrosis. MRI and histological analysis did not reveal tumor in the brain of these mice. Mice treated with 2.7 MBq [177Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies did not demonstrate overall deleterious health effects. ConclusionsWe conclude that CED of [177Lu]Lu-MCP-AuNP combined with anti-PD1 checkpoint immunotherapy improved the survival of immunocompetent C67BL/6J mice with GL261 glioma tumors in the brain. Higher administered amounts of [177Lu]Lu-MCP-AuNP (2.7 MBq vs. 0.8 MBq) were most effective and yielded long-term survival. Advances in knowledge and implications for patient careThis study demonstrates that combining a locally-infused radiation nanomedicine, [177Lu]Lu-MCP-AuNP and anti-PD1 checkpoint immunotherapy improved the survival of mice with glioma tumors in the brain. In the future, this treatment may be useful to treat residual tumor at the surgical margins in patients with GBM to prevent local recurrence and improve survival.

Effects of Prenatal Methcathinone Exposure on the Neurological Behavior of Adult Offspring.

Our previous research has shown that prenatal methcathinone exposure affects the neurodevelopment and neurobehavior of adolescent offspring, but the study on whether these findings continue into adulthood is limited. This study aims to explore the effects of prenatal methcathinone exposure on anxiety-like behavior, learning and memory abilities, as well as serum 5-hydroxytryptamine and dopamine concentrations in adult offspring. Pregnant rats were injected daily with methcathinone between the 7th and 20th days of gestation. The neurobehavioral performance of both male and female adult offspring rats was evaluated by neurobehavioral tests, including open-field tests, Morris water maze (MWM) tests, and novel object recognition (NOR) tests. The levels of 5-hydroxytryptamine and dopamine concentration in rat serum were detected by ELISA. Significant differences were found in the length of center distance and time of center duration in the open-field test, as well as the times of crossing the platform in the MWM test, between the prenatal methcathinone exposure group and the control group. Results of the NOR test showed that adult offspring rats exposed to methcathinone need more time to discriminate the novel object. No gender differences were detected in the neurobehavioral tests. The serum concentrations of 5-hydroxytryptamine and dopamine in rats exposed to methcathinone prenatally were lower than that in the control group, and the serum dopamine concentration was independent of gender in each group. Prenatal methcathinone exposure affects the neurological behavior in adult offspring, and 5-hydroxytryptamine and dopamine might be involved in the process.

Impact of feeding age on cognitive impairment in mice with Disrupted-In-Schizophrenia 1 (Disc1) mutation under a high sucrose diet

A combination of genetic predisposition and environmental factors contributes to the development of psychiatric disorders such as schizophrenia, bipolar disorder and major depressive disorder. Previous studies using mouse models suggested that prolonged high sucrose intake during puberty can serve as an environmental risk factor for the onset of psychiatric disorders. However, the impact of both the duration and timing of high sucrose consumption during different developmental stages on pathogenesis remains poorly defined. We therefore investigated the effects of a long-term high sucrose diet on cognitive deficit, a core symptom of psychiatric disorders, using Disrupted-in-Schizophrenia 1 locus-impairment heterozygous mutant (Disc1het) mice as a model for genetic predisposition. First, Disc1het mice and their littermate control (WT) were fed either a high sucrose diet or a control starch diet for nine weeks starting at weaning (postnatal day 24), and tested for cognitive performance in the object location test (OLT) and the novel object recognition test (NORT) (assessing spatial and recognition memory, respectively). Only Disc1het mice on a high sucrose diet displayed deficits in OLT (p < 0.0001), demonstrating impaired hippocampus-dependent spatial memory. This behavioral abnormality was accompanied by a decreased proportion of the high parvalbumin-expressing interneurons (High-PV neurons) in the ventral hippocampus, a cell type that regulates neural activity and a variety of learning and memory processes such as spatial and working memory. We further explored the critical developmental period for high sucrose intake to cause cognitive deficits in adulthood by comparing specific feeding periods during puberty (P24-P65) and post-puberty (P65-P90). Compared to those on a standard chow diet, high sucrose intake caused deficits in spatial memory in both WT and Disc1het mice, with more pronounced effects in Disc1het mice. In particular, Disc1het mice on a sucrose diet during adolescence showed more pronounced cognitive deficit than those fed after adolescence. Our results suggest that adolescence is particularly vulnerable to nutritional environmental risk factors, and that high sucrose consumption may cause hippocampus-dependent memory deficits via decreased High-PV interneuron function when combined with Disc1-related genetic predisposition.

8734 Absent FSH Signaling Rescues Spatial and Recognition Memory Impairments in Female 3xTg Mice

Abstract Disclosure: S. Sims: None. F. Sen: None. F. Sultana: None. A. Liu: None. V. Laurencin: None. A. Gumerova: None. O. Barak: None. S. Rojekar: None. A.R. Pallapati: None. L. Cullen: None. R. Chen: None. K. Goosens: None. V. Ryu: None. T. Yuen: None. M. Zaidi: None. T. Frolinger: None. F. Korkmaz: None. Alzheimer’s disease (AD) is a major progressive neurodegenerative disorder of the aging population, accounting for more than 60-80% of dementia cases. High serum level of the pituitary gonadotropin, follicle-stimulating hormone (FSH), is strongly associated with the onset of AD. We recently showed that FSH activates hippocampal Fshr to drive AD–like pathology and cognitive impairment in AD mice, that FSH blockade in these mice abrogates the AD-like phenotype by inhibiting the neuronal C/EBPβ–δ-secretase pathway, and that FSH and ApoE4, the most prevalent genetic risk factor of AD, jointly trigger AD-like pathogenesis by activating C/EBPβ-δ-secretase signaling. To further confirm the role of FSH in AD cognitive decline, we used female 3xTg;Fshr+/+, 3xTg;Fshr+/– and 3xTg;Fshr–/– mice that underwent sham surgery or ovariectomy (OVX) at 8 weeks of age. Sham-operated 3xTg;Fshr–/– mice were implanted with 17β-estradiol pellets to normalize E2 levels. Morris Water Maze (MWM) and Novel object recognition (NOR) tests were perform in these mice to assess spatial and recognition memory, respectively. 3xTg;Fshr+/+ mice displayed impaired spatial memory at 5-month of age in the MWM test. This impairment, in both the learning and retrieval phases, is significantly ameliorated in 3xTg;Fshr–/– mice and to a lesser extent in 3xTg;Fshr+/– mice, suggesting that Fshr expression has a negative impact on memory. At 5 and 10 months of age, sham-operated 3xTg;Fshr–/– mice show better memory performance in the MWM test during the learning phase when compared to their wild-type littermates, suggesting a rescue of spatial memory and progression with age. However, this rescue was not seen when mice were ovariectomized. At 5 months of age, sham-operated 3xTg;Fshr–/– mice displayed better memory retrieval compared with 3xTg;Fshr+/+ mice. This effect was not observed when the mice were 10-month-old, suggesting that the beneficial effect of the absence of FSH signaling on memory consolidation could be masked by disease severity and older age. OVX 3xTg;Fshr+/+, 3xTg;Fshr+/– mice displayed a decline in memory consolidation at 10-months of age compared with 5-month of age, while the 3xTg;Fshr–/– mice showed a significantly slower decline. Using the NOR test, we found impaired recognition memory in 10-month-old sham-operated or OVX 3xTg;Fshr+/+ and 3xTg;Fshr+/– mice; this effect was prevented in OVX 3xTg;Fshr–/– mice. Finally, 3xTg;Fshr–/– mice displayed lower Aβ40 and Aβ42 levels in the brain (ELISA). Altogether, our results confirm a protective effect of absent Fshr signaling on spatial learning, consolidation, memory retrieval, recognition memory and reduction of brain Aβ40 and Aβ42. Presentation: 6/1/2024

Proinflammatory factors inhibition and fish oil treatment: A promising therapy for neonatal seizures

Brain injury is one of the most important causes of infant mortality and chronic neurological disabilities. Hypoxia is an acute brain injury which led to various cognitive, behavioral, and memory disorders throughout life. Previous studies reported neuroprotective possibilities for fish oil (FO) in brain-injured situations. In this study, we evaluated the effect of the FO diet during the lactation period on seizure activity, behavioral performance, histomorphometry, and inflammatory changes in the brains of hypoxia rats. Male Wistar rats were randomly divided in to 4 groups: Sham (intact rats), hypoxia, FO and FO+hypoxia groups. Hypoxia was induced by keeping neonate rats at PND12 in a hypoxic chamber (7 % oxygen and 93 % nitrogen intensity) for 15 minutes. In the FO groups, rats received oral FO (1 ml/day) for 12 days during the lactation period. Seizure activity was assessed by measuring the number of tonic-clonic seizures and seizure thresholds. Novel object recognition tests (NORT), rotarod, and open field tests were used to measure behavioral performances. A Histological study was performed to evaluate histomorphometric changes in the hippocampus and cerebellum. The gene expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) was measured using RT-PCR. Findings showed that the number of tonic-clonic seizures, atrophy, and cell death in the hippocampus and cerebellum, the gene expression of TNF-α and IL-1β in the hippocampus, and behavioral disorders were significantly increased in the hypoxia rats compared to the sham group. Administration of FO in the hypoxia groups significantly decreased the gene expression of TNF-α and IL-1β, the number of tonic-clonic seizures, and neuronal cell death in the hippocampus and cerebellum compared to the hypoxia groups. Furthermore, it can improve behavioral tasks and cognitions.

Automated analysis of a novel object recognition test in mice using image processing and machine learning

The novel object recognition test (NORT) is one of the most commonly employed behavioral tests in experimental animals designed to evaluate an animal's interest in and recognition of novelty. However, manual procedures, which rely on researchers’ observations, prevent high throughput analysis. In this study, we developed an automated analysis method for NORT utilizing machine learning-assisted exploratory behavior detection. We recorded the exploratory behavior of the mice using a video camera. The coordinates of the mouse nose and tail base in recorded video files were detected using a pre-trained machine learning model, DeepLabCut. Each video was then segmented into frame images, which were categorized into "exploratory,” or "non-exploratory" frames based on manual observation. Mouse feature vectors were calculated as vectors from the nose to the vertices of the object and were utilized for SVM training. The trained SVM effectively detected exploratory behaviors, showing a strong correlation with human observer assessments. Upon application to NORT, the duration of mouse exploratory behavior towards objects predicted by the SVM exhibited a significant correlation with the assessments made by human observers. The novelty discrimination index derived from the SVM predictions also aligned well with that from human observations.

Personality may modulate learning and memory differences in two taxa of the African striped mouse genus Rhabdomys

AbstractDifferent environments place different cognitive demands on constituent taxa. Learning and memory involve cognitive processes with associated costs, and it is expected that different levels of learning will occur in taxa from different environments. Greater memory loads linked to increased environmental complexity require greater learning and memory capacities. We investigated the variation in learning and memory in sister taxa of striped mice (genus Rhabdomys). We studied two populations each of the mesic grassland‐occurring R. d. chakae and the mostly arid‐occurring R. pumilio. We conducted two sets of experiments. (1) In a novel object recognition (NOR) test, we assessed memory by recording the duration of exploration of similar and novel objects by test mice. (2) In an associative learning task, we assessed whether mice could associate specific scents with or without a food incentive or with different quantities of the food incentive in previous training phases. We measured the latency of mice to contact scents in a two‐sample choice in the test phase. In the NOR test, R. pumilio spent less time investigating similar objects in a training trial than R. d. chakae but increased absolute exploration of the novel object when presented with a novel and a familiar object in the retention trial, suggesting a sensitization to the novel object by R. pumilio. In the associative learning experiments, R. pumilio approached the stimuli faster than R. d. chakae, whereas mice from both taxa preferred scents associated with a seed versus no seed and scents associated with 5 seeds versus 1 seed. The data provide evidence of taxon‐level differences in learning and memory, likely related to environmentally modulated personality differences between the taxa.

Remimazolam attenuates lipopolysaccharide-induced neuroinflammation and cognitive dysfunction

ObjectiveRemimazolam, a novel benzodiazepine, is widely used as an anesthetic in endoscopic procedures; however, its effects on cognitive function remain unclear, limiting its broader application in general anaesthesia. Neuroinflammation is a well-established key factor in the etiology and progression of cognitive dysfunction, including conditions such as Alzheimer's disease, Parkinson's disease, postoperative delirium, and postoperative cognitive dysfunction. Preclinical studies have demonstrated that remimazolam exerts anti-inflammatory and neuroprotective effects, and clinical reports indicate a reduced incidence of postoperative delirium in patients treated with remimazolam. Nevertheless, whether remimazolam improves cognitive function through its anti-inflammatory properties remains uncertain. This study aimed to investigate the neuroprotective effects of remimazolam and its underlying mechanism in a lipopolysaccharide (LPS)-induced model of neuroinflammation, neuronal injury, and cognitive dysfunction MethodsC57BL/6 J male mice were administered LPS intraperitoneally to establish a model of neuroinflammation-induced cognitive impairment. A subset of mice received remimazolam via intraperitoneal injection 30 minutes prior to LPS administration. Cognitive performance was evaluated using behavioural tests, including the Morris Water Maze (MWM), Novel Object Recognition (NOR) test, and Open Field Test (OFT). Hippocampal tissues were analyzed by haematoxylin-eosin (HE) staining to assess structural changes. Inflammatory markers, including Interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, were quantified using enzyme-linked immunosorbent assay (ELISA) and real-time quantitative PCR. Immunofluorescence was used to detect translocator protein (TSPO) and markers of microglia activation (IBA-1, CD16/32, and CD206). Results(1) Remimazolam reversed LPS-induced cognitive deficits, as evidenced by shorter spatial exploration latency and increased platform crossings in the MWM, and an elevated recognition index in the NOR test. (2) Remimazolam improved hippocampal morphology, reducing LPS-induced neuronal damage. (3) Remimazolam significantly decreased levels of hippocampal inflammatory cytokines, inhibited microglial activation, promoted M2-type microglia polarization, and increased TSPO expression. ConclusionRemimazolam demonstrated neuroprotective and anti-neuroinflammatory effects in a mouse model of LPS-induced cognitive impairment. These effects are likely mediated through the regulation of TSPO, which inhibits microglial activation and promotes the polarization of microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype.

Therapeutic effects of alpha lipoic acid and/or caffeine-loaded chitosan nanoparticles on memory impairment and neurochemical changes in high-fat diet-induced obese rats

The therapeutic effects of alpha lipoic acid (LA) and/or caffeine-loaded chitosan nanoparticles (CCNPs) on obesity-induced memory impairment were evaluated in the present study. Rats were divided into control rats, obese rats induced by high fat diet (HFD) and obese rats treated with LA and/or CCNPs. Obesity was confirmed by measuring the body mass index (BMI). Memory and cognitive functions were evaluated by novel object recognition test (NORT). The levels of serotonin (5-HT), dopamine (DA), norepinephrine (NE), lipid peroxidation (MDA), nitric oxide (NO), reduced glutathione (GSH), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), leptin (LEP) and ghrelin (GHR) and the activities of monoamine oxidase (MAO), acetylcholinesterase (AchE) and Na+,K+,ATPase were determined in the cortex and hippocampus. The cerebral histopathological alterations were examined in obese rats.Obese rats showed impaired memory and exhibited significant neurochemical changes, including decreased levels of 5-HT, DA, GSH, GHR, and Na+,K+-ATPase activity, as well as an increase in AchE, MAO, MDA, NO, IL-1β, TNF-α, and LEP. LA and/or CCNPs treatment reduced BMI and improved memory. LA or CCNPs alleviated the cortical and hippocampal neurochemical changes and histopathological changes induced by obesity. Furthermore, LA and CCNPs exhibited antioxidant and anti-inflammatory properties, which likely contributed to their effects. However, no synergistic effect was observed between LA and CCNPs. These findings suggest that LA or CCNPs may be a potential therapy against obesity and its adverse effects on memory, mediated by their ability to restore monoamine levels and exhibit antioxidant and anti-inflammatory properties.

GLT-1 downregulation in hippocampal astrocytes induced by type 2 diabetes contributes to postoperative cognitive dysfunction in adult mice.

Type 2 diabetes mellitus (T2DM) is related to an increased risk of postoperative cognitive dysfunction (POCD), which may be caused by neuronal hyperexcitability. Astrocyte glutamate transporter 1 (GLT-1) plays a crucial role in regulating neuron excitability. We investigated if T2DM would magnify the increased neuronal excitability induced by anesthesia/surgery (A/S) and lead to POCD in young adult mice, and if so, determined whether these effects were associated with GLT-1 expression. T2DM model was induced by high fat diet (HFD) and injecting STZ. Then, we evaluated the spatial learning and memory of T2DM mice after A/S with the novel object recognition test (NORT) and object location test (OLT). Western blotting and immunofluorescence were used to analyze the expression levels of GLT-1 and neuronal excitability. Oxidative stress reaction and neuronal apoptosis were detected with SOD2 expression, MMP level, and Tunel staining. Hippocampal functional synaptic plasticity was assessed with long-term potentiation (LTP). In the intervention study, we overexpressed hippocampal astrocyte GLT-1 in GFAP-Cre mice. Besides, AAV-Camkllα-hM4Di-mCherry was injected to inhibit neuronal hyperexcitability in CA1 region. Our study found T2DM but not A/S reduced GLT-1 expression in hippocampal astrocytes. Interestingly, GLT-1 deficiency alone couldn't lead to cognitive decline, but the downregulation of GLT-1 in T2DM mice obviously enhanced increased hippocampal glutamatergic neuron excitability induced by A/S. The hyperexcitability caused neuronal apoptosis and cognitive impairment. Overexpression of GLT-1 rescued postoperative cognitive dysfunction, glutamatergic neuron hyperexcitability, oxidative stress reaction, and apoptosis in hippocampus. Moreover, chemogenetic inhibition of hippocampal glutamatergic neurons reduced oxidative stress and apoptosis and alleviated postoperative cognitive dysfunction. These findings suggest that the adult mice with type 2 diabetes are at an increased risk of developing POCD, perhaps due to the downregulation of GLT-1 in hippocampal astrocytes, which enhances increased glutamatergic neuron excitability induced by A/S and leads to oxidative stress reaction, and neuronal apoptosis.

Feasibility and effectiveness of transcutaneous auricular vagus nerve stimulation (taVNS) in awake mice.

Transcutaneous auricular vagus nerve stimulation (taVNS) is widely used to treat a variety of disorders because it is noninvasive, safe, and well tolerated by awake patients. However, long-term and repetitive taVNS is difficult to achieve in awake mice. Therefore, developing a new taVNS method that fully mimics the method used in clinical settings and is well-tolerated by awake mice is greatly important for generalizing research findings related to the effects of taVNS. The study aimed to develop a new taVNS device for use in awake mice and to test its reliability and effectiveness. We demonstrated the reliability of this taVNS device through retrograde neurotropic pseudorabies virus (PRV) tracing and evaluated its effectiveness through morphological analysis. After 3 weeks of taVNS application, the open field test (OFT) and elevated plus maze (EPM) were used to evaluate anxiety-like behaviors, and the Y-maze test and novel object recognition test (NORT) were used to evaluate recognition memory behaviors, respectively. We found that repetitive taVNS was well tolerated by awake mice, had no effect on anxiety-like behaviors, and significantly improved memory. Our findings suggest that this new taVNS device for repetitive stimulation of awake mice is safe, tolerable, and effective.

Molecular and immunohistochemical alterations in fluoride-induced neurological impediment in adult rats

SummaryThis study highlights the potential neurotoxic and impaired behavioral effects associated with high fluoride concentrations in drinking water. PurposeFluoride is known to cause neurotoxicity, evinced by lower I.Q. levels in children from high-fluoride regions as compared to those in low-fluoride regions. Thus, the present study was designed to investigate the molecular mechanism behind the neurological and behavioural changes induced by sodium fluoride in Wistar rats. Material and methodsA total of 24 female Wistar rats, aged six weeks and weighing approximately 150–220 g, were randomly divided into three groups: Group I (control) received reverse osmosis (R.O.) water, Group II received Sodium Fluoride (NaF) at 10 ppm, and Group III received NaF at 50 ppm in their drinking water for 60 days. The animals underwent behavioural tests including the Forced Swim Test (F.S.T.), Open Field Test (OFT), and Novel Object Recognition Test (N.O.R.T.), to assess any alterations in behaviour. After 60 days, the animals were euthanized, and their blood and brain samples were analysed to evaluate biochemical changes by Western Blot/I.H.C. analysis of B.A.X., Bcl2, LC3B, TLR4, PARP1, p53, Caspase, α-Synuclein, PARKIN, NeuN, KI67, DNM-1, and M.F.N. for assessing molecular pathways for toxicity. ResultsImpaired locomotion, memory impairment, and behaviour resembling depression in the animals were evinced by reduced mobility index in the F.S.T., discrimination index in the N.O.R.T., and reduced locomotor activity in the open field test results. Additionally, alterations in antioxidant levels and oxidative stress parameters were observed in the brain. The expression levels of various apoptotic and inflammatory biomarkers (B.A.X., Bcl2, TLR4, PARP1, p53, and Caspase) showed apoptosis in neurons. The confocal studies showed increased expression of inflammatory (α-Synuclein, PARKIN), apoptotic (LC3B, B.A.X., p53, KI67), and mitochondrial dysfunction (NeuN, DNM-1, M.F.N.) markers in fluoride-treated animals. Toxicity was more prominent in 50 ppm of fluoride-treated animals. ConclusionFluoride showed potent neuronal toxicity as evidenced by alterations of various molecular markers.