Apparatus design and behavioural testing protocol for the evaluation of spatial working memory in mice through the spontaneous alternation T-maze

Deep neural networks and stochastic methods for cognitive modeling of rat behavioral dynamics in T -mazes

Modeling animal decision-making requires mathematical rigor and computational analysis to capture underlying cognitive mechanisms. This study presents a cognitive model for rat decision-making behavior in T -mazes by combining stochastic methods with deep neural architectures. The model adapts Wyckoff's stochastic framework, originally grounded in Bush's discrimination learning theory, to describe probabilistic transitions between directional choices under reinforcement contingencies. The existence and uniqueness of solutions are demonstrated via fixed-point theorems, ensuring the formulation is well-posed. The asymptotic properties of the system are examined under boundary conditions to understand the convergence behavior of decision probabilities across trials. Empirical validation is performed using Monte Carlo simulations to compare expected trajectories with the model's predictive output. The dataset comprises spatial trajectory recordings of rats navigating toward food rewards under controlled experimental protocols. Trajectories are preprocessed through statistical filtering, augmented to address data imbalance, and embedded using t-SNE to visualize separability across behavioral states. A hybrid convolutional-recurrent neural network (CNN-LSTM) is trained on these representations and achieves a classification accuracy of 82.24%, outperforming conventional machine learning models, including support vector machines and random forests. In addition to discrete choice prediction, the network reconstructs continuous paths, enabling full behavioral sequence modeling from partial observations. The integration of stochastic dynamics and deep learning develops a computational basis for analyzing spatial decision-making in animal behavior. The proposed approach contributes to computational models of cognition by linking observable behavior to internal processes in navigational tasks.

Effects of maternal drinking patterns and epigallocatechin-3-gallate treatment on behavioural and molecular outcomes in a mouse model of fetal alcohol spectrum disorders

Prenatal alcohol exposure (PAE) impairs fetal development leading to fetal alcohol spectrum disorders (FASD). Antioxidants like epigallocatechin-3-gallate (EGCG) may mitigate alcohol-induced oxidative stress, a major contributor to FASD. This study assessed the effects of PAE on cognition and behaviour under two drinking patterns and the role of postnatal EGCG therapy in a FASD-like mouse model. C57BL/6J mice were divided into five groups: control, moderate drinking (Mod), binge drinking (Bin), Mod+EGCG, and Bin+EGCG. Cognitive and behavioural performance were assessed using Rotarod test, T-Maze, and Morris Water Maze (MWM). Western blot analyses evaluated brain and cerebellum biomarkers related to neuronal plasticity, maturation, differentiation, transport, and proliferation. PAE impaired motor coordination, significantly reducing rotarod walking time in both drinking patterns. Spatial learning and memory were also disrupted, decreasing T-maze success rate. It also decreased time in the platform area and distance travelled in MWM. Both drinking patterns affected neuronal plasticity (BDNF, DYRK1A) and maturation (NeuN), astrocyte differentiation (GFAP, s100β), neuronal transport (MBP) and proliferation (GDNF, Wnt-3) via oxidative stress (Nrf2). Our results show how EGCG treatment significantly improved behavioural tests results and restored most brain and cerebellum biomarkers, reaching levels similar to control. These findings highlight the impact of PAE on cognition and behaviour and how EGCG may counteract its effects by reducing oxidative stress and enhancing brain plasticity. Our findings open the door to future studies on the mechanism of action of this antioxidant in order to use it as a therapeutic tool in this vulnerable population.

Physiological and behavioral pharmacology of ethanol in honey bees

Ethanol has been consumed by humans since the dawn of civilization and, over the course of millennia, a wide variety of ethanol-rich drinks have been produced across cultures. Traditionally, it was believed that only humans voluntarily consume ethanol and become inebriated by it. However, a growing amount of evidence is showing that several non-human animal species spontaneously consume ethanol in nature. Among these, there is the honey bee (Apis mellifera), which can find ethanol in decaying fruits and in the fermented nectar of flowers. Importantly, honey bees represent a useful animal model of ethanol consumption as, like humans, they voluntarily consume ethanol, they show acute dose-dependent motor and postural signs of inebriation, they display ethanol-induced disruption of cognitive functions and social behavior, and they develop ethanol dependence. Moreover, they are small, easy to acquire and easy to maintain in the laboratory. Finally, we possess a vast database of information on their natural history, physiology, genetics and behavior, with their ethogram comprising a wide variety of basic to complex behaviors, including the capacity to self-administer large quantities of ethanol. The present article reviews what is currently known about the physiological and behavioral pharmacology of ethanol in honey bees. The topics covered include the effect of ethanol on gene expression, epigenetic changes of DNA, neuronal stress, posture, locomotion, learning (comprising classical and operant conditioning), communication, social feeding (trophallaxis), aggression and foraging-related decision-making in honey bees.

Chitosan-coated nanostructured lipid carriers for intranasal delivery of sinapic acid in Aβ1-42 induced C57BL/6 mice for Alzheimer's disease treatment

Sinapic acid (SA) is a plant-derived antioxidant that exhibits neuroprotective activity. However, its poor bioavailability in the brain limits its therapeutic application in treating Alzheimer's disease (AD). Therefore, the present study hypothesizes that coating nanostructured lipid carriers (NLCs) with a biological macromolecule like chitosan (CH-SA-NLCs) could enhance the delivery of SA for AD treatment. The CH-SA-NLCs were spherical with sizes below 200 nm, confirmed by AFM, SEM, and TEM and achieved a sustained drug release of 76.5 % in pH 6.5 simulated nasal fluid over 24 h. Moreover, the histopathology study confirmed the safety of CH-SA-NLCs, validating its suitability for intranasal administration. Not only the in vitro sustained drug release closely correlated with in vivo pharmacokinetics of CH-SA-NLCs (i.n.), demonstrating a 1.7-fold increase in SA's half-life compared to plain SA (i.v.) in plasma but also CH-SA-NLCs (i.n.) achieved a superior AUC0-∞ of 7676.32 ± 2738.55 ng/g*h with a 2.6-fold improved drug targeting efficiency of SA in the brain of BALB/c mice. These improvements resulted in significant neuroprotective effects and decreased oxidative stress and inflammatory levels in Aβ1-42-induced mice. Overall, the study highlights safe and effective intranasal delivery of SA via chitosan-coated nanocarrier as a promising AD treatment strategy.

A Gut Microbial Metabolite Alleviates Stress-Induced Neurobehavioral Dysfunction in an Alzheimer's Disease Model

Chronic psychological stress is a known risk factor for neurodegenerative disorders like Alzheimer's disease (AD), but its role in AD neuropathology remains unclear. Using the water-avoidance stress model in the APP/PS1 preclinical mouse model of AD, we investigate how chronic stress exacerbates neurobehavioral dysfunction and cognitive impairment and explore the neuroprotective potential of indole-3-propionate (IPA), a microbiome-derived metabolite, in mitigating these effects. Our findings show that psychological stress leads to depression- and anxiety-like behaviors, as indicated by reduced grooming and exploration behaviors; however, these effects are ameliorated by IPA supplementation. Stress also disrupts the gut microbiome and promotes intestinal inflammation. While IPA does not significantly alter microbiome composition, it mitigates inflammation by normalizing IL-17a and TGF-β gene expression and reducing TNF-⍺ and IL-6 protein levels. Although stress has a limited effect on hippocampal inflammation, IPA suppresses low-grade neuroinflammation by downregulating IL-1β, TNF-⍺, IL-6, and MCP-1 protein levels. Additionally, IPA treatment tends to reduce hippocampal amyloid-β plaques. These findings highlight the detrimental effects of chronic psychosocial stress on AD pathology and suggest that IPA may confer neuroprotection through the gut-immune-brain axis, supporting the therapeutic potential of microbial metabolites in mitigating cognitive decline.

Chlorella vulgaris Supplementation Attenuates Lead Accumulation, Oxidative Stress, and Memory Impairment in Rats

Lead is a harmful heavy metal known to alter the environment and affect human health. Several industries have contributed to the increase in lead contamination, making it a major global concern. Thus, remediation strategies are necessary to prevent lead bioaccumulation and deleterious health effects. The aim of this study was to determine the capacity of the green microalga Chlorella vulgaris (C. vulgaris or CV) to remove lead in an animal model and prevent the accumulation of this heavy metal in the principal organs (brain, liver, and kidney) and blood. Forty male Wistar rats were randomly assigned to four groups (n = 10): control group (CT); C. vulgaris supplementation group, 5% of the diet (CV); lead acetate administration group, 500 ppm (Pb); and C. vulgaris supplementation group, 5% of the diet plus lead acetate administration group, 500 ppm (CV-Pb). After 4 weeks of exposure, we measured lead accumulation, memory function, oxidative stress, and antioxidant activity (SOD and GSH). Lead exposure altered memory function, increased oxidative stress in the brain and kidney, and increased SOD activity in the brain. Supplementation with C. vulgaris restored memory function to control levels; reduced oxidative stress in the brain and kidney; and decreased the accumulation of lead in the liver, kidney, and blood of rats exposed to lead. Based on our results, C. vulgaris is a lead chelating and antioxidant agent in animal models.

Social subordination is associated with better cognitive performance and higher theta coherence of the mPFC-vHPC circuit in male rats

Social dominance hierarchy is considered an influential factor on cognitive performance. The spatial working memory (SWM) is inversely related to dominance status after the formation of social hierarchy. However, their neural underpinings are poorly understood. The medial prefrontal cortex (mPFC) and ventral hippocampus (vHPC) play pivotal roles in social hierarchy and SWM. To investigate the associations between social hierarchy and SWM and their neural circuit (mPFC-vHPC), we used twenty one natal male Wistar rats after weaning (3 rats per cage, 7 cages in total). In the 9th postnatal week, the tube test was started to determine the relative social rank in each cage (dominant, middle-ranked, subordinate). One month after living in the hierarchy, we implanted electrodes in mPFC and vHPC. One week following recovery, the SWM test was performed using T-maze with two difficulty levels (30s and 5min delays between trials) while recording the local field potentials. The percentage of correct responses showed no significant difference among three different social groups. However, subordinates demonstrated significantly lower latency in reaching the goal arm, while middle-ranked rats exhibited the longest latency in 30s delay. Electrophysiological data revealed significantly higher theta correlation and coherence of the mPFC-vHPC circuit in subordinates. Although theta rhythm synchronization was reduced in all social ranks by increasing task difficulty, the subordinates maintained better task performance and less reduction of theta coherence. These findings underscore the association between social hierarchy and working memory performance within the mPFC-vHPC circuit, highlighting the influence of social rank on implicated circuit.

Acute Administration of Edaravone Improves Cognitive Impairment in a Mouse Model of mPFC Ischemia: Crosstalk Between Necroptosis, Neuroinflammation, and Antioxidant Defense

Edaravone (Eda), a well-known free radical scavenger, has been reported as a possible therapeutic agent for ischemic stroke patients' recovery. This study aimed to investigate the effects of time-dependent treatment with Eda on medial prefrontal cortex (mPFC) ischemia. Mice were randomly allocated into six groups: control, sham, normal saline, Eda-I, Eda-II, and Eda-III. After induction of a photothrombotic ischemia in the mPFC region, Eda-I, Eda-II, and Eda-III groups received 3 mg/kg Eda intraperitoneally at the times of 0, 2, and 6 h post-surgery. After 1 day of recovery, the mice underwent behavioral tests (open field, novel object recognition, and T-maze). Next, necroptosis, NOD-like receptor protein 3 (NLRP3), and nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related protein levels were measured in the lesioned area using western blot analysis. For double confirmation, IL-1β and IL-18 were also assessed by immunofluorescence in the area. Further, histological evaluations were performed to measure tissue damage. The results showed that mPFC ischemia impaired recognition and spatial working memory without affecting locomotor activity, while immediate Eda administration improved cognitive impairments. Furthermore, acute Eda treatment reduced RIP1, RIP3, and MLKL levels, inhibited NLRP3 inflammasome proteins (NLRP3, ASC, and Cas1), decreased IL-1β and IL-18, upregulated Nrf2 and its targets (NQO-1 and HO-1), and diminished tissue damage. Our results highlighted the effects of acute administration of Eda post-stroke on improving cognitive impairments by suppressing necroptosis and NLRP3 inflammasome pathways and activating the Nrf2 antioxidant defense mechanism.

Early postural adjustments in cats during a reaching task reflect strategies to predict the forthcoming target location

Many types of voluntary movement depend on appropriate postural adjustments. In most situations, such postural adjustments are influenced by learning and are therefore subject to prediction strategies developed through learning. To address how these prediction strategies affect early postural adjustments (EPAs) that occur several hundred milliseconds before movement, we trained two cats in a reaching task where the location of the target was predictable through learning. At the beginning of each trial, the cat stood still with each paw on a force plate for several hundred milliseconds. A target then appeared on either side of a horizontal touch panel, prompting the cat to lift a forepaw. A food reward followed upon holding the target with the forepaw. Target location was alternated every three rewarded trials: one SWITCH followed by two STAY trials. In both cats, EPAs prior to target onset in STAY trials were significantly dependent on the predetermined target location, indicating that they anticipated the target location as a part of their strategy. In SWITCH trials, EPAs aligned with the subsequent STAY trials in both switch directions for one cat, but only in one direction for the other, suggesting that they developed different strategies to handle target location switches.

Mild Zika Virus Infection in Mice Without Motor Impairments Induces Working Memory Deficits, Anxiety-like Behaviors, and Dysregulation of Immunity and Synaptic Vesicle Pathways

BACKGROUND

The Zika virus (ZIKV) is an arbovirus linked to "Congenital Zika Syndrome" and a range of neurodevelopmental disorders (NDDs), with microcephaly as the most severe manifestation. Milder NDDs, such as autism spectrum disorders and delays in neuropsychomotor and language development, often go unnoticed in neonates, resulting in long-term social and academic difficulties. Murine models of ZIKV infection can be used to mimic part of the spectrum of motor and cognitive deficits observed in humans. These can be evaluated through behavioral tests, enabling comparison with gene expression profiles and aiding in the characterization of ZIKV-induced NDDs.

OBJECTIVES

This study aimed to identify genes associated with behavioral changes following a subtle ZIKV infection in juvenile BALB/c mice.

METHODS

Neonatal mice were subcutaneously inoculated with ZIKV (MH544701.2) on postnatal day 1 (DPN) at a dose of 6.8 × 103 PFU. Viral presence in the cerebellum and cortex was quantified at 10- and 30-days post-infection (DPI) using RT-qPCR. Neurobehavioral deficits were assessed at 30 DPI through T-maze, rotarod, and open field tests. Next-Generation Sequencing (NGS) was performed to identify differentially expressed genes (DEGs), which were analyzed through Gene Ontology (GO) and KEGG enrichment. Gene interaction networks were then constructed to explore gene interactions in the most enriched biological categories.

RESULTS

A ZIKV infection model was successfully established, enabling brain infection while allowing survival beyond 30 DPI. The infection induced mild cognitive behavioral changes, though motor and motivational functions remained unaffected. These cognitive changes were linked to the functional repression of synaptic vesicles and alterations in neuronal structure, suggesting potential disruptions in neuronal plasticity.

CONCLUSIONS

Moderate ZIKV infection with circulating strains from the 2016 epidemic may cause dysregulation of genes related to immune response, alterations in cytoskeletal organization, and modifications in cellular transport mediated by vesicles. Despite viral control, neurocognitive effects persisted, including memory deficits and anxiety-like behaviors, highlighting the long-term neurological consequences of ZIKV infection in models that show no apparent malformations.

Changes in cerebral cortex redox status and cognitive performance in short- and long-term high-sucrose diet fed rats

Rising evidence suggests that Metabolic Syndrome (MetS) would be correlated with the development of neurodegenerative diseases. Although this has emerged as a relevant area of research, it has not been fully explored. It is not clear if a greater impairment of the metabolic peripheral environment is accompanied by a greater impairment of the central nervous system. We have previously shown that feeding rats with a high-sucrose diet (HSD) represents an animal model that resembles the human MetS phenotype. The aim of the present work was to assess in rats fed a HSD for a short (3 weeks-wk) or a long (15 weeks-wk) term, whether the worsening of the peripheral metabolic and hormonal profile that occur as the time of HSD consumption increases, is also accompanied by a worsening of oxidative stress in the cerebral cortex and/or cognitive behavior. Male Wistar rats received a HSD or a control diet during 3 wk or 15 wk. We found an increase in reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), advanced glycation end products (AGEs) and glutathione peroxidase (GPx) and glutathione reductase (GR) enzyme activities in the cerebral cortex of 3 wk HSD-fed rats. All of these parameters, except for the GPx, were also increased in the 15 wk HSD-fed group and values were similar to those observed at 3 wk. Glutathione reduced form (GSH), catalase (CAT) activity and brain-to-body weight ratio were reduced in 15 wk HSD-fed animals. Glutathione S- transferase (GST) was similar in all dietary groups. A poor performance in novel object recognition test and T-maze memory tasks was observed in 3 wk and 15 wk HSD-fed rats in a similar magnitude. Our results add new evidence related to the association between an adverse peripheral metabolic environment and brain/cognitive dysfunction.

Lurcher Mouse as a Model of Cerebellar Syndromes

Cerebellar extinction lesions can manifest themselves with cerebellar motor and cerebellar cognitive affective syndromes. For investigation of the functions of the cerebellum and the pathogenesis of cerebellar diseases, particularly hereditary neurodegenerative cerebellar ataxias, various cerebellar mutant mice are used. The Lurcher mouse is a model of selective olivocerebellar degeneration with early onset and rapid progress. These mice show both motor deficits as well as cognitive and behavioral changes i.e., pathological phenotype in the functional domains affected in cerebellar patients. Therefore, Lurcher mice might be considered as a tool to investigate the mechanisms of functional impairments caused by cerebellar degenerative diseases. There are, however, limitations due to the particular features of the neurodegenerative process and a lack of possibilities to examine some processes in mice. The main advantage of Lurcher mice would be the expected absence of significant neuropathologies outside the olivocerebellar system that modify the complex behavioral phenotype in less selective models. However, detailed examinations and further thorough validation of the model are needed to verify this assumption.

The first rodent behavioral study (1822) and the diffusion of human-bred albino rats and mice in the 19th century

Rodents, in particular rats and mice, are currently the most widely employed animal models in psychology and behavioral neuroscience. Nevertheless, an interesting historical question is: when was the first rodent behavioral study performed and by whom? The current article presents the first rodent behavioral study in the history of science: a case of interspecies social bonding between a rat and a dog, observed in 1822 by the British chemist Samuel Moss (1794-1868) and subsequently described by the same in a scientific article in 1836. In the present article, after a biographical sketch of Samuel Moss, I examine in detail the notable case of interspecies bonding observed by Moss. This case is notable under several points of view. First, Moss's rat was an albino, a variety which at that time was extremely rare. Moreover, at that time, in the Western world rats were mostly seen as pest animals or baits for rat-catching sports, and were not kept as pets. The color of the rat played a key role in its fate, being the reason for which it was originally brought to Moss and for which Moss decided to keep it under his care. Third, the relationship that arose between the rat and the dog is even more surprising if we consider that the dog was a trained rat-catcher. Importantly, this rat-dog bonding case, which showcased the tameness of Moss's albino rat in both lay and scientific publications, represented the first popularization of the docility of albino rats. After having outlined Moss's case, considering the importance of albino rats in our current society, both in scientific research (where the albino rat has become the prototype of the laboratory rat) and as pets, I provide an historical contextualization regarding albino rodents, starting from the 17th century, and I then trace the history of the post-Moss diffusion of human-bred albino rats and mice in the 19th century.

Beyond the blur: Scopolamine's utility and limits in modeling cognitive disorders across sexes - Narrative review

Scopolamine, widely regarded as the gold standard in preclinical studies of memory impairments, acts as a non-selective antagonist of central and peripheral muscarinic receptors. While its application in modeling dementia primarily involves antagonism at the M1 receptor, its non-selective peripheral actions may introduce adverse effects that influence behavioral test outcomes. This review analyzes preclinical findings to consolidate knowledge on scopolamine's use and elucidate potential mechanisms responsible for its amnestic effects. We focused on recognition, spatial, and emotional memory processes, alongside executive functions such as attention, cognitive flexibility, and working memory. The cognitive effects of scopolamine are highly dose-dependent, influenced by factors such as species, age, and sex of subjects. Notably, scopolamine rapidly induces observable memory impairments across species, from fish to rodents and primates, often with deficits that can persist for days. However, the compound's broad action on muscarinic receptors and its peripheral side effects, including pupil dilation and reduced salivation, complicates result interpretation, particularly in tasks requiring visual discrimination or food intake. The review also highlights scopolamine's translational value in modeling dementia and Alzheimer's disease, emphasizing the importance of considering individual factors and task-specific designs. Despite its widespread use, scopolamine's limited specificity for cholinergic dysfunction and inability to fully mimic the complex pathophysiology of cognitive disorders like Alzheimer's and Parkinson's disease point to the need for complementary models. This review aims to guide researchers in using scopolamine for modeling cognitive impairments, ensuring attention to factors impacting experimental outcomes.

Varenicline Attenuates Memory Impairment in Amyloid-Beta-Induced Rat Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder characterized by cognitive decline. Despite extensive research, therapeutic options remain limited. Varenicline, an α4β2 nicotinic acetylcholine receptor agonist, shows promise in enhancing cognitive function. This study aimed to evaluate varenicline's effect on memory and hippocampal activity in rat model of AD. Forty-eight adult male Wistar rats were randomly assigned to control, sham, AD, and varenicline (0.1, 1, and 3 mg/kg/po for 14 days) groups. AD was induced by intracerebroventricular (i.c.v.) injection of 4 µl amyloid-beta (Aβ)1-42 (1 µg/µl). Spatial learning and memory, hippocampal synaptic function, and CA1 electrophysiological activity were evaluated using appropriate methods. Barnes maze and T-maze behavioral tests revealed that varenicline, particularly at 1 mg/kg, significantly improved spatial memory compared to the AD group. Western blot analysis showed varenicline's ability to upregulate synaptic proteins PSD-95, synaptophysin, and GAP-43 in the hippocampus, with the most significant effects observed at 1 mg/kg. Electrophysiological recordings demonstrated that varenicline at 1 mg/kg enhanced hippocampal long-term potentiation (LTP), indicating improved synaptic plasticity. Single-unit recordings showed an increase in spike count with varenicline administration. These findings suggest that varenicline, particularly at 1 mg/kg, ameliorates memory deficits in AD rats possibly through modulation of synaptic proteins and enhancement of hippocampal LTP and electrical activity. Further investigations are warranted to elucidate varenicline's precise mechanisms of action in alleviating AD-induced cognitive deficits and its potential as a therapeutic intervention for AD-related cognitive impairment.

Blockade of A2AR improved brain perfusion and cognitive function in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder that affects more than 6.2 million Americans aged 65 and older, particularly women. Along with AD's main hallmarks (formation of β-amyloid plaques and tau neurofibrillary tangles), there are vascular alterations that occurs in AD pathology. Adenosine A2 receptor (A2AR) is one of the key factors of brain vascular autoregulation and is overexpressed in AD patients. Our previous findings suggest that protein arginine methyltransferase 4 (PRMT4) is overexpressed in AD, which leads to decrease in cerebral blood flow in aged female 3xTg mice. We aimed to investigate the mechanism behind A2AR signaling in the regulation of brain perfusion and blood-brain barrier integrity in age and sex-dependent 3xTg mice, and if it is related to PRMT4. Istradefylline, a highly selective A2AR antagonist, was used to modulate A2AR signaling. Aged female 3xTg and C57BL/6 J mice were evaluated for brain perfusion (via laser speckle) and cognitive function (via open field, T-maze and novel object recognition). Our results suggest that modulation of A2AR signaling in aged female 3xTg increased cerebral perfusion by decreasing PRMT4 expression, restored the levels of APP and tau, maintained blood-brain barrier integrity by maintaining the expression of tight junction proteins, and preserved functional learning/memory.

Challenges and insights of transferring animal maze studies principles to human spatial learning research

Maze tasks, originally developed in animal research, have become a popular method for studying human cognition, particularly with the advent of virtual reality. However, these experiments frequently rely on simplified environments and tasks, which may not accurately reflect the complexity of real-world situations. Our pilot study aims to transfer a multi-alternative maze with a complex task structure, previously demonstrated to be useful in studying animal cognition, to studying human spatial cognition. The challenges to be resolved at this stage included developing a virtual maze and selecting an appropriate instruction that will elicit processes similar to those observed in animal models. A virtual maze was developed, and two types of instructions were provided to the participants: (1) to collect coins; (2) to interact with the maze in order to draw its structure after the game. The results indicate that a more structured instruction with a clear attainable goal ("collect") prompted more in-depth exploration and engagement with the key elements of the maze, eliciting processes similar to those of animals. While the maze demonstrates promise as a tool for comparative studies, it also has the potential to uncover different aspects of human cognition.

Prosapip1 in the dorsal hippocampus mediates synaptic protein composition, long-term potentiation, and spatial memory

Prosapip1 is a brain-specific protein localized to the postsynaptic density, where it promotes dendritic spine maturation in primary hippocampal neurons. However, nothing is known about the role of Prosapip1 in vivo. To examine this, we utilized the Cre-loxP system to develop a Prosapip1 neuronal knockout mouse. We found that Prosapip1 controls the synaptic localization of its binding partner SPAR, along with PSD-95 and the GluN2B subunit of the NMDA receptor (NMDAR) in the dorsal hippocampus (dHP). We next sought to identify the potential contribution of Prosapip1 to the activity and function of the NMDAR and found that Prosapip1 plays an important role in NMDAR-mediated transmission and long-term potentiation (LTP) in the CA1 region of the dHP. As LTP is the cellular hallmark of learning and memory, we examined the consequences of neuronal knockout of Prosapip1 on dHP-dependent memory. We found that global or dHP-specific neuronal knockout of Prosapip1 caused a deficit in learning and memory whereas developmental, locomotor, and anxiety phenotypes were normal. Taken together, Prosapip1 in the dHP promotes the proper localization of synaptic proteins which, in turn, facilitates LTP driving recognition, social, and spatial learning and memory.

Rearing in an envy-like environment increases anxiety-like behaviour in mice

Interest in the societal and psychological harm caused by widespread envy and social comparison is increasing. Envy is associated with anxiety and depression, though the mechanism by which envy affects neuropsychiatric disorders, such as depression, remains unclear. Clarifying the neurobiological basis of envy's effects on behaviour and emotion regulation in experimental mice is essential for developing disease-prevention and treatment strategies. As mice recognize other mice in neighbouring cages, this study investigated whether they recognize neighbouring cages housed in environmentally enriched cages and suffer psychological stress due to envy. After being raised in an envy-like environment for 3 weeks, we revealed changes in the behaviour of the mice through a series of behavioural experiments. Mice raised in an envious environment showed increased body weight and anxiety-like behaviour but decreased social behaviour and serum corticosterone levels compared to control mice. Thus, mice recognize their neighbouring cages and experience psychological stress due to envy. This study revealed a part of the scientific basis for why envy increased anxiety. Using this novel experimental breeding environment, it may be possible to create an experimental animal model of anxiety disorders.

Research on Alzheimer's Disease (AD) Involving the Use of In vivo and In vitro Models and Mechanisms

BACKGROUND

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by the progressive formation of extracellular amyloid plaques, intracellular neurofibrillary tangles, inflammation, and impaired antioxidant systems. Early detection and intervention are vital for managing AD effectively.

OBJECTIVES

This review scrutinizes both in-vivo and in-vitro screening models employed in Alzheimer's disease research. in-vivo models, including transgenic mice expressing AD-related mutations, offer profound insights into disease progression and potential therapeutic targets. A thorough understanding of these models and mechanisms will facilitate the development of novel therapies and interventions for Alzheimer's disease. This review aims to provide an overview of the current experimental models in AD research, assess their strengths and weaknesses as model systems, and underscore the future prospects of experimental AD modeling.

METHODS

We conducted a systematic literature search across multiple databases, such as Pub- Med, Bentham Science, Elsevier, Springer Nature, Wiley, and Research Gate. The search strategy incorporated pertinent keywords related to Alzheimer's disease, in-vivo models, in-vitro models, and screening mechanisms. Inclusion criteria were established to identify studies focused on in-vivo and in-vitro screening models and their mechanisms in Alzheimer's disease research. Studies not meeting the predefined criteria were excluded from the review.

RESULTS

A well-structured experimental animal model can yield significant insights into the neurobiology of AD, enhancing our comprehension of its pathogenesis and the potential for cutting-edge therapeutic strategies. Given the limited efficacy of current AD medications, there is a pressing need for the development of experimental models that can mimic the disease, particularly in pre-symptomatic stages, to investigate prevention and treatment approaches. To address this requirement, numerous experimental models replicating human AD pathology have been established, serving as invaluable tools for assessing potential treatments.

CONCLUSION

In summary, this comprehensive review underscores the pivotal role of in-vivo and in-vitro screening models in advancing our understanding of Alzheimer's disease. These models offer invaluable insights into disease progression, pathological mechanisms, and potential therapeutic targets. By conducting a rigorous investigation and evaluation of these models and mechanisms, effective screening and treatment methods for Alzheimer's disease can be devised. The review also outlines future research directions and areas for enhancing AD screening models.

A bespoke water T-maze apparatus and protocol: an optimized, reliable, and repeatable method for screening learning, memory, and executive functioning in laboratory mice

The Morris Water Maze (MWM) is the most commonly used assay for evaluating learning and memory in laboratory mice. Despite its widespread use, contemporary reviews have highlighted substantial methodological variation in experimental protocols and that the associated testing procedures are acutely (each trial) and chronically (testing across days) stressful; stress impairs attention, memory consolidation and the retrieval of learned information. Moreover, the interpretation of behavior within the MWM is often difficult because of wall hugging, non-spatial swim strategies, floating, and jumping off the escape platform. Together, these issues may compromise the reproducibility, generalizability, and predictability of experimental results, as well as animal welfare. To address these issues, and as an initial proof-of-principle, we first narrowed the spatial dimensions of the MWM by using a T-insert, which constrained and reduced the overall length of time/distance that the animal must swim in order to navigate to the escape platform, thus reducing stress and off-task behavior. Given the robust performance observed across spatial acquisition (learning and memory) as well as during reversal learning (executive function), we further reduced (by 43%) the overall distance and time that the animal must swim in order to find the escape platform in a bespoke standalone Water T-Maze (WTM). We show, across five experiments, procedural refinements to our protocol and demonstrate robust, reliable and reproducible indicators of learning, memory and executive functioning in a task that is also significantly more efficient (3 days of testing within the WTM vs. 11 days of testing within the MWM). Taken together, our WTM apparatus and protocol are a significant improvement over other water-based apparatuses and protocols for evaluating learning, memory, and executive functioning in laboratory mice.

Astrocytic Ca2+ activation by chemogenetics mitigates the effect of kainic acid-induced excitotoxicity on the hippocampus

Astrocytes play a multifaceted role regulating brain glucose metabolism, ion homeostasis, neurotransmitters clearance, and water dynamics being essential in supporting synaptic function. Under different pathological conditions such as brain stroke, epilepsy, and neurodegenerative disorders, excitotoxicity plays a crucial role, however, the contribution of astrocytic activity in protecting neurons from excitotoxicity-induced damage is yet to be fully understood. In this work, we evaluated the effect of astrocytic activation by Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) on brain glucose metabolism in wild-type (WT) mice, and we investigated the effects of sustained astrocyte activation following an insult induced by intrahippocampal (iHPC) kainic acid (KA) injection using 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) positron emission tomography (PET) imaging, along with behavioral test, nuclear magnetic resonance (NMR) spectroscopy and histochemistry. Astrocytic Ca2+ activation increased the 18F-FDG uptake, but this effect was not found when the study was performed in knock out mice for type-2 inositol 1,4,5-trisphosphate receptor (Ip3r2-/-) nor in floxed mice to abolish glucose transporter 1 (GLUT1) expression in hippocampal astrocytes (GLUT1ΔGFAP). Sustained astrocyte activation after KA injection reversed the brain glucose hypometabolism, restored hippocampal function, prevented neuronal death, and increased hippocampal GABA levels. The findings of our study indicate that astrocytic GLUT1 function is crucial for regulating brain glucose metabolism. Astrocytic Ca2+ activation has been shown to promote adaptive changes that significantly contribute to mitigating the effects of KA-induced damage. This evidence suggests a protective role of activated astrocytes against KA-induced excitotoxicity.

Chrysophanol attenuates cognitive impairment, neuroinflammation, and oxidative stress by TLR4/NFκB-Nrf2/HO-1 and BDNF/VEGF signaling in stress-intensified PTZ induced epilepsy in mice

Background

Stress is among the most common comorbid conditions with epilepsy and a strong factor in the pathophysiology of seizures. An imbalance in neuronal circuits causes recurrent unprovoked seizures in epilepsy. Dysregulation of BDNF/VEGF expression, oxidative stress, increased levels of neuroinflammatory cytokines, and increased expression of apoptotic genes contribute to the underlying cause of the seizure.

Objectives

Chrysophanol, an anthraquinone, has broad-spectrum therapeutic potential. This study evaluated the neuroprotective effect of chrysophanol with underlying pathways in PTZ-induced epilepsy with stress as a comorbid condition.

Methods

Male mice were given 35 mg/kg of PTZ every other day to induce seizures. In addition, they were exposed to 120 min of daily restraint stress for 21 days to induce stress. Chrysophanol (0.1, 1, 10 mg/kg) was administered to the mice 30 min before the PTZ in the acute study. The most effective dose (10 mg/kg) was proceeded for the chronic epilepsy model. Following this, various tests were conducted, including behavioral assessments for memory impairment and stress, analysis of antioxidant levels, histopathological and immunohistochemistry examinations, measurement of cortisol levels using ELISA, and gene expression analysis using RT-PCR.

Results

Chrysophanol demonstrated a notable decrease in both the intensity and frequency of seizures. Additionally, it effectively boosted the levels of important antioxidants such as GSH, GST, and CAT, while simultaneously reducing the levels of MDA and Nitric oxide. The histopathological analysis also showed improvement in overall morphology and survival of neurons. Chrysophanol treatment effectively showed an increase in the expression of BCL-2, and Nrf-2 with a decrease in BAX expression confirmed by immunohistochemistry. Dysregulation of vascular permeability factor, production of inflammatory cytokines, and apoptotic gene expression was successfully reversed after chrysophanol treatment analyzed through RT-PCR. Cortisol concentration was decreased in treatment groups analyzed through Enzyme-linked immunoassay. Molecular docking of chrysophanol with different proteins declared the binding affinity of the ligands with the target sites of proteins.

Conclusion

In conclusion, chrysophanol demonstrated remarkable neuroprotective and antiepileptic effects at a dose of 10 mg/kg in stress-exacerbated PTZ-induced epilepsy following the TLR4/NFκB -Nrf2/HO-1 and BDNF/VEGF pathways.

Nanoformulated fisetin ameliorates Alzheimer's disease via reducing proinflammatory cytokines and activating the NRF2/HO-1 pathway

Aim: The study aimed to evaluate the neuroprotective effect of a chitosan-coated fisetin nanoformulation in an experimental Alzheimer's disease (AD) model, focusing on improving fisetin's pharmacokinetics and exploring its impact on both brain and colon pathology.Materials & methods: AD was induced in mice by intracerebroventricular administration of Aβ1-42. Mice were treated with either fisetin or a fisetin nanoformulation (5 mg/kg/day, orally) for 21 days. Behavioural assessments were conducted to evaluate memory impairment, motor deficits, and depression-like behaviour. Oxidative stress markers and pro-inflammatory cytokines were measured in the cortex, hippocampus and colon. The changes in cortical and hippocampal AChE levels were also recorded. Histological studies were performed on the cortex, hippocampus (dentate gyrus), and proximal colon.Results: The fisetin nanoformulation significantly improved neurobehavioral outcomes, reducing memory impairment, motor deficits and depression-like symptoms induced by Aβ1-42. It also decreased oxidative and nitrosative stress, along with pro-inflammatory cytokine levels in the cortex, hippocampus and colon. Histological analyses revealed improved brain and colon tissue architecture after treatment with the nanoformulation.Conclusion: The chitosan-coated fisetin nanoformulation enhanced the neuroprotective effects of fisetin in an AD model, likely by improving its pharmacokinetic profile. The findings also suggest a potential link between colon health and Aβ-induced AD pathology, underscoring the therapeutic potential of fisetin nanoformulations in AD management.

Impaired exploration induced by type 1 diabetes is related to locomotor activity rather than a reduction in motivation

Type 1 diabetes mellitus (T1D) is associated with cognitive impairments in humans. A well-established animal model of T1D is induced through the administration of streptozotocin (STZ), a glucose analog that induces pancreatic β-cell death, resulting in hyperglycemia and cognitive impairment linked to neuroinflammation and oxidative stress. Tumor necrosis factor (TNF)-α, a key inflammatory mediator, is elevated in the central nervous system (CNS) of diabetic animals. In this study, we utilized TNFR1 knockout mice to investigate the role of TNFR1 signaling in short-term T1D-related cognitive impairment. Our findings showed that diabetic animals did not develop cognitive damage within the first 2 weeks of T1D but exhibited reduced exploration in all behavioral tests. Our findings suggest that this reduction in exploration was attributable to motor impairment, as there was no reduction in motivated novelty-seeking behavior. Additionally, deletion of TNFR1 signaling attenuated gait speed impairment in diabetic mice, but did not affect other motor-related or exploratory behaviors.

Endothelial Piezo1 channel mediates mechano-feedback control of brain blood flow

Hyperemia in response to neural activity is essential for brain health. A hyperemic response delivers O2 and nutrients, clears metabolic waste, and concomitantly exposes cerebrovascular endothelial cells to hemodynamic forces. While neurovascular research has primarily centered on the front end of hyperemia-neuronal activity-to-vascular response-the mechanical consequences of hyperemia have gone largely unexplored. Piezo1 is an endothelial mechanosensor that senses hyperemia-associated forces. Using genetic mouse models and pharmacologic approaches to manipulate endothelial Piezo1 function, we evaluated its role in blood flow control and whether it impacts cognition. We provide evidence of a built-in brake system that sculpts hyperemia, and specifically show that Piezo1 activation triggers a mechano-feedback system that promotes blood flow recovery to baseline. Further, genetic Piezo1 modification led to deficits in complementary memory tasks. Collectively, our findings establish a role for endothelial Piezo1 in cerebral blood flow regulation and a role in its behavioral sequelae.

Impact of Lyophilized Milk Kefir-Based Self-Nanoemulsifying System on Cognitive Enhancement via the Microbiota-Gut-Brain Axis

Chronic inflammatory bowel disorders (IBDs) are characterized by altered intestinal permeability, prompting inflammatory, oxidative stress, and immunological factors. Gut microbiota disorders impact brain function via the bidirectional gut-brain axis, influencing behavior through inflammatory cascades, oxidative stress, and neurotransmitter levels. This study highlights the potential effect of integrating lyophilized milk kefir alone and lyophilized milk kefir as solid carriers loaded with a self-nanoemulsifying self-nanosuspension (SNESNS) of licorice extract on an induced chronic IBD-like model in rats. Licorice-SNESNS was prepared by the homogenization of 30 mg of licorice extract in 1 g of the selected SNEDDS (30% Caraway oil, 60% Tween 20, and 10% propylene glycol (w/w)). Licorice-SNESNS was mixed with milk kefir and then freeze-dried. Dynamic TEM images and the bimodal particle size curve confirmed the formation of the biphasic nanosystems after dilution (nanoemulsion and nanosuspension). Daily oral administration of lyophilized milk kefir (100 mg/kg) loaded with SNESNS (10 mg/kg Caraway oil and 1 mg/kg licorice) restored normal body weight and intestinal mucosa while significantly reducing submucosal inflammatory cell infiltration in induced rats. Importantly, this treatment demonstrated superior efficacy compared to lyophilized milk kefir alone by leading to a more significant alleviation of neurotransmitter levels and improved memory functions, thereby addressing gut-brain axis disorders. Additionally, it normalized fecal microbiome constituents, inflammatory cytokine levels, and oxidative stress in examined tissues and serum. Moreover, daily administration of kefir-loaded SNESNS normalized the disease activity index, alleviated histopathological changes induced by IBD induction, and partially restored the normal gut microbiota. These alterations are associated with improved cognitive functions, attributed to the maintenance of normal neurotransmitter levels and the alleviation of triggered inflammatory factors and oxidative stress levels.

Aprepitant's roles in abating seizures, behavioral, and cognitive deficits in mice model of epilepsy

BACKGROUND

Aprepitant (APR), a neurokinin 1 receptor antagonist, is an approved drug for treating chemotherapy-induced nausea and vomiting.

OBJECTIVES

Investigate the beneficial roles of APR alone or in combination with sodium valproate (VPA) against lithium pilocarpine [li-pilo]-induced seizures, behavioral changes, and cognitive deficits.

METHODS

Thirty male mice were divided into five groups, each containing 6. "Vehicle Group I," "Control Group II "li-pilo, " Valproate (VPA) group III (400 mg/kg/i.p.), "APR group IV, " and "Combination Group V." Videos of mice were recorded, and they were watched for episodes of spontaneous recurring seizures (SRS). Behavioral Tests were performed. At the end of the study, animal brains were taken for biochemical assays and gene expression studies.

RESULTS

APR partially protected against SRS with partial restoration of average behavioral and standard cognitive skills associated with a significant increase in brain SOD activity and a significant decrease in MDA, IL-1β, NF-КB, and SP-3 levels in relation to the control group. Interestingly, a combination of APR with VPA in epileptic mice showed complete protection against li-pilo-induced behavioral changes and cognitive deficits, a significant increase in brain SOD activity, and a considerable decrease in MDA, IL-1β, NF-ΚB, and SP levels to normal.

CONCLUSION

Using APR as an adjuvant to VPA is more effective in protecting against li-pilo-induced seizures, behavioral changes, and cognitive deficits due to its antioxidant, anti-inflammatory, and NK1 antagonist effects than using APR alone as drug therapy.

Timed fetal inflammation and postnatal hypoxia cause cortical white matter injury, interneuron imbalances, and behavioral deficits in a double-hit rat model of encephalopathy of prematurity

Extreme preterm birth-associated adversities are a major risk factor for aberrant brain development, known as encephalopathy of prematurity (EoP), which can lead to long-term neurodevelopmental impairments. Although progress in clinical care for preterm infants has markedly improved perinatal outcomes, there are currently no curative treatment options available to combat EoP. EoP has a multifactorial etiology, including but not limited to pre- or postnatal immune activation and oxygen fluctuations. Elucidating the underlying mechanisms of EoP and determining the efficacy of potential therapies relies on valid, clinically translatable experimental models that reflect the neurodevelopmental and pathophysiological hallmarks of EoP. Here, we expand on our double-hit rat model that can be used to study EoP disease mechanisms and therapeutic options in a preclinical setting. Pregnant Wistar dams were intraperitoneally injected with 10 μg/kg LPS on embryonic day (E)20 and offspring was subjected to hypoxia (140 min, 8% O2) at postnatal day 4. Rats exposed to fetal inflammation and postnatal hypoxia (FIPH) showed neurodevelopmental impairments, such as reduced nest-seeking ability, ultrasonic vocalizations, social engagement, and working memory, and increased anxiety and sensitivity. Impairments in myelination, oligodendrocyte maturation and interneuron development were examined as hallmarks for EoP, in different layers and coordinates of the cortex using histological and molecular techniques. Myelin density and complexity was decreased in the cortex, which partially coincided with a decrease in mature oligodendrocytes. Furthermore, interneuron populations (GAD67+ and PVALB+) were affected. To determine if the timing of inducing fetal inflammation affected the severity of EoP hallmarks in the cortex, multiple timepoints of fetal inflammation were compared. Inflammation at E20 combined with postnatal hypoxia gave the most severe EoP phenotype in the cortex. In conclusion, we present a double-hit rat model which displays various behavioral, anatomical and molecular hallmarks of EoP, including diffuse white matter injury. This double-hit model can be used to investigate pathophysiological mechanisms and potential therapies for EoP.

A Simple Tube Escape Assay to Test Learning and Memory in Zebrafish with Minimized Habituation

Various methods have been used in rodents to evaluate learning and memory. Although much less frequently used, the zebrafish emerges as an alternative model organism in this context. For example, it allows assessing potential behavioral deficits because of neurodevelopmental disorders or environmental neurotoxins. A variety of learning tasks have been employed in previous studies that required extensive habituation and training sessions. Here, we introduce a simpler and faster method to evaluate learning and memory of zebrafish with minimum habituation. A new apparatus, a transparent L-shaped tube, was developed in which we trained each zebrafish to swim through a long arm and measured the time to swim through this arm. We demonstrate that in this task, zebrafish could acquire both short-term (1 h) and long-term memory (4 days). We also studied learning and memory of a gene knockout (KO) zebrafish that showed social impairments related to autism. We found KO mutant zebrafish to show a quantitative impairment in habituation, learning, and memory performance compared with wild-type control fish. In conclusion, we established a novel learning apparatus and sensitive paradigm that allowed us to evaluate learning and memory of adult zebrafish that required only a brief habituation period and minimal training.

Photoperiod, food restriction and memory for objects and places in mice

The suprachiasmatic nucleus (SCN) contains a population of cell-autonomous circadian oscillators essential for entrainment to daily light-dark (LD) cycles. Synchrony among SCN oscillators is modified by photoperiod and determines functional properties of SCN clock cycling, including its amplitude, phase angle of entrainment, and free running periodicity (τ). For many species, encoding of daylength in SCN output is critical for seasonal regulation of metabolism and reproduction. C57BL/6 mice do not show seasonality in these functions, yet do show photoperiodic modulation of SCN clock output. The significance of this for brain systems and functions downstream from the SCN in these species is largely unexplored. C57BL/6 mice housed in a long-day photoperiod have been reported to perform better on tests of object, spatial and fear memory compared to mice in a standard 12 h photoperiod. We previously reported that encoding of photoperiod in SCN output, evident in τ in constant dark (DD), can be blocked by limiting food access to a 4 h mealtime in the light period. To determine whether this might also block the effect of long days on memory, mice entrained to 18 h:6 h (L18) or 6 h:18 h (L6) LD cycles were tested for 24 h object memory (novel object preference, NOP) and spatial working memory (Y-maze spontaneous alternation, SA), at 4 times of day, first with food available ad libitum and then during weeks 5-8 of daytime restricted feeding. Photoperiod modified τ as expected, but did not affect performance on the NOP and SA tests, either before or during restricted feeding. NOP performance did improve in the restricted feeding condition in both photoperiods, eliminating a weak time of day effect evident with food available ad-libitum. These results highlight benefits of restricted feeding on cognitive function, and suggest a dose-response relationship between photoperiod and memory, with no benefits at daylengths up to 18 h.

FOS mapping reveals two complementary circuits for spatial navigation in mouse

Here, we show that during continuous navigation in a dynamic external environment, mice are capable of developing a foraging strategy based exclusively on changing distal (allothetic) information and that this process may involve two alternative components of the spatial memory circuit: the hippocampus and retrosplenial cortex. To this end, we designed a novel custom apparatus and implemented a behavioral protocol based on the figure-8-maze paradigm with two goal locations associated with distinct contexts. We assessed whether mice are able to learn to retrieve a sequence of rewards guided exclusively by the changing context. We found out that training mice in the apparatus leads to change in strategy from the internal tendency to alternate into navigation based exclusively on visual information. This effect could be achieved using two different training protocols: prolonged alternation training, or a flexible protocol with unpredictable turn succession. Based on the c-FOS mapping we also provide evidence of opposing levels of engagement of hippocampus and retrosplenial cortex after training of mice in these two different regimens. This supports the hypothesis of the existence of parallel circuits guiding spatial navigation, one based on the well-described hippocampal representation, and another, RSC-dependent.

An Enteric Bacterial Infection Triggers Neuroinflammation and Neurobehavioral Impairment in 3xTg-AD Transgenic Mice

BACKGROUND

Klebsiella pneumoniae is infamous for hospital-acquired infections and sepsis, which have also been linked to Alzheimer disease (AD)-related neuroinflammatory and neurodegenerative impairment. However, its causative and mechanistic role in AD pathology remains unstudied.

METHODS

A preclinical model of K. pneumoniae enteric infection and colonization is developed in an AD model (3xTg-AD mice) to investigate whether and how K. pneumoniae pathogenesis exacerbates neuropathogenesis via the gut-blood-brain axis.

RESULTS

K. pneumoniae, particularly under antibiotic-induced dysbiosis, was able to translocate from the gut to the bloodstream by penetrating the gut epithelial barrier. Subsequently, K. pneumoniae infiltrated the brain by breaching the blood-brain barrier. Significant neuroinflammatory phenotype was observed in mice with K. pneumoniae brain infection. K. pneumoniae-infected mice also exhibited impaired neurobehavioral function and elevated total tau levels in the brain. Metagenomic analyses revealed an inverse correlation of K. pneumoniae with gut biome diversity and commensal bacteria, highlighting how antibiotic-induced dysbiosis triggers an enteroseptic "pathobiome" signature implicated in gut-brain perturbations.

CONCLUSIONS

The findings demonstrate how infectious agents following hospital-acquired infections and consequent antibiotic regimen may induce gut dysbiosis and pathobiome and increase the risk of sepsis, thereby increasing the predisposition to neuroinflammatory and neurobehavioral impairments via breaching the gut-blood-brain barrier.

Interhemispheric CA1 projections support spatial cognition and are affected in a mouse model of the 22q11.2 deletion syndrome

Untangling the hippocampus connectivity is critical for understanding the mechanisms supporting learning and memory. However, the function of interhemispheric connections between hippocampal formations is still poorly understood. So far, two major hippocampal commissural projections have been characterized in rodents. Mossy cells from the hilus of the dentate gyrus project to the inner molecular layer of the contralateral dentate gyrus and CA3 and CA2 pyramidal neuron axonal collaterals to contralateral CA3, CA2 and CA1. In contrary, little is known about commissural projection from the CA1 region. Here, we show that CA1 pyramidal neurons from the dorsal hippocampus project to contralateral dorsal CA1 as well as dorsal subiculum. We further demonstrate that the interhemispheric projection from CA1 to dorsal subiculum supports spatial memory and spatial working memory in WT mice, two cognitive functions impaired in male mice from the Df16(A) +/- model of 22q11.2 deletion syndrome (22q11.2DS) associated with schizophrenia. Investigation of the CA1 interhemispheric projections in Df16(A) +/- mice revealed that these projections are disrupted with male mutants showing stronger anatomical defects compared to females. Overall, our results characterize a novel interhemispheric projection from dCA1 to dorsal subiculum and suggest that dysregulation of this projection may contribute to the cognitive deficits associated with the 22q11.2DS.

Long-term adaptation of prefrontal circuits in a mouse model of NMDAR hypofunction

Pharmacological approaches to induce N-methyl-d-aspartate receptor (NMDAR) hypofunction have been intensively used to understand the aetiology and pathophysiology of schizophrenia. Yet, the precise cellular and molecular mechanisms that relate to brain network dysfunction remain largely unknown. Here, we used a set of complementary approaches to assess the functional network abnormalities present in male mice that underwent a 7-day subchronic phencyclidine (PCP 10 mg/kg, subcutaneously, once daily) treatment. Our data revealed that pharmacological intervention with PCP affected cognitive performance and auditory evoked gamma oscillations in the prefrontal cortex (PFC) mimicking endophenotypes of some schizophrenia patients. We further assessed PFC cellular function and identified altered neuronal intrinsic membrane properties, reduced parvalbumin (PV) immunostaining and diminished inhibition onto L5 PFC pyramidal cells. A decrease in the strength of optogenetically-evoked glutamatergic current at the ventral hippocampus to PFC synapse was also demonstrated, along with a weaker shunt of excitatory transmission by local PFC interneurons. On a macrocircuit level, functional ultrasound measurements indicated compromised functional connectivity within several brain regions particularly involving PFC and frontostriatal circuits. Herein, we reproduced a panel of schizophrenia endophenotypes induced by subchronic PCP application in mice. We further recapitulated electrophysiological signatures associated with schizophrenia and provided an anatomical reference to critical elements in the brain circuitry. Together, our findings contribute to a better understanding of the physiological underpinnings of deficits induced by subchronic NMDAR antagonist regimes and provide a test system for characterization of pharmacological compounds.

Membrane remodeling by FAM92A1 during brain development regulates neuronal morphology, synaptic function, and cognition

The Bin/Amphiphysin/Rvs (BAR) domain protein FAM92A1 is a multifunctional protein engaged in regulating mitochondrial ultrastructure and ciliogenesis, but its physiological role in the brain remains unclear. Here, we show that FAM92A1 is expressed in neurons starting from embryonic development. FAM92A1 knockout in mice results in altered brain morphology and age-associated cognitive deficits, potentially due to neuronal degeneration and disrupted synaptic plasticity. Specifically, FAM92A1 deficiency impairs diverse neuronal membrane morphology, including the mitochondrial inner membrane, myelin sheath, and synapses, indicating its roles in membrane remodeling and maintenance. By determining the crystal structure of the FAM92A1 BAR domain, combined with atomistic molecular dynamics simulations, we uncover that FAM92A1 interacts with phosphoinositide- and cardiolipin-containing membranes to induce lipid-clustering and membrane curvature. Altogether, these findings reveal the physiological role of FAM92A1 in the brain, highlighting its impact on synaptic plasticity and neural function through the regulation of membrane remodeling and endocytic processes.

RECORD, a high-throughput, customizable system that unveils behavioral strategies leveraged by rodents during foraging-like decision-making

Translational studies benefit from experimental designs where laboratory organisms use human-relevant behaviors. One such behavior is decision-making, however studying complex decision-making in rodents is labor-intensive and typically restricted to two levels of cost/reward. We design a fully automated, inexpensive, high-throughput framework to study decision-making across multiple levels of rewards and costs: the REward-COst in Rodent Decision-making (RECORD) system. RECORD integrates three components: 1) 3D-printed arenas, 2) custom electronic hardware, and 3) software. We validated four behavioral protocols without employing any food or water restriction, highlighting the versatility of our system. RECORD data exposes heterogeneity in decision-making both within and across individuals that is quantifiably constrained. Using oxycodone self-administration and alcohol-consumption as test cases, we reveal how analytic approaches that incorporate behavioral heterogeneity are sensitive to detecting perturbations in decision-making. RECORD is a powerful approach to studying decision-making in rodents, with features that facilitate translational studies of decision-making in psychiatric disorders.

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.

Formulation and Characterization of Silibinin Entrapped Nano-Liquid Crystals for Activity against Aβ1-42 Neurotoxicity in In-Vivo Model

Silibinin (SIL) Encapsulated Nanoliquid Crystalline (SIL-NLCs) particles were prepared to study neuroprotective effect against amyloid beta (Aβ1-42) neurotoxicity in Balb/c mice model. Theses NLCs were prepared through hot emulsification and probe sonication technique. The pharmacodynamics was investigatigated on Aβ1-42 intracerebroventricular (ICV) injected Balb/c mice. The particle size, zeta potential and drug loading were optimized to be 153 ± 2.5 nm, -21 mV, and 8.2%, respectively. Small angle X-ray (SAXS) and electron microscopy revealed to crystalline shape of SIL-NLCs. Thioflavin T (ThT) fluroscence and circular dichroism (CD) technique were employed to understand monomer inhibition effect of SIL-NLCs on Aβ1-4. In neurobehavioral studies, SIL-NLCs exhibited enhanced mitigation of memory impairment induced on by Aβ1-42 in T-maze and new object recognition test (NORT). Whereas biochemical and histopathological estimation of brain samples showed reduction in level of Aβ1-42 aggregate, acetylcholine esterase (ACHE) and reactive oxygen species (ROS). SIL-NLCs treated animal group showed higher protection against Aβ1-42 toxicity compared to free SIL and Donopezil (DPZ). Therefore SIL-NLCs promises great prospect in neurodegenerative diseases such as Alzheimer's disease.

Impacts of age and environment on postnatal microglial activity: Consequences for cognitive function following early life adversity

Early life adversity (ELA) increases the likelihood of later-life neuropsychiatric disorders and cognitive dysfunction. Importantly, ELA, neuropsychiatric disorders, and cognitive deficits all involve aberrant immune signaling. Microglia are the primary neuroimmune cells and regulate brain development. Microglia are particularly sensitive to early life insults, which can program their responses to future challenges. ELA in the form of maternal separation (MS) in rats alters later-life microglial morphology and the inflammatory profile of the prefrontal cortex, a region important for cognition. However, the role of microglial responses during MS in the development of later cognition is not known. Therefore, here we aimed to determine whether the presence of microglia during MS mediates long-term impacts on adult working memory. Clodronate liposomes were used to transiently deplete microglia from the brain, while empty liposomes were used as a control. We hypothesized that if microglia mediate the long-term impacts of ELA on working memory in adulthood, then depleting microglia during MS would prevent these deficits. Importantly, microglial function shifts throughout the neonatal period, so an exploratory investigation assessed whether depletion during the early versus late neonatal period had different effects on adult working memory. Surprisingly, empty liposome treatment during the early, but not late, postnatal period induced microglial activity changes that compounded with MS to impair working memory in females. In contrast, microglial depletion later in infancy impaired later life working memory in females, suggesting that microglial function during late infancy plays an important role in the development of cognitive function. Together, these findings suggest that microglia shift their sensitivity to early life insults across development. Our findings also highlight the potential for MS to impact some developmental processes only when compounded with additional neuroimmune challenges in a sex-dependent manner.

Behaviour Hallmarks in Alzheimer's Disease 5xFAD Mouse Model

The 5xFAD transgenic mouse model widely used in Alzheimer's disease (AD) research recapitulates many AD-related phenotypes with a relatively early onset and aggressive age-dependent progression. Besides developing amyloid peptide deposits alongside neuroinflammation by the age of 2 months, as well as exhibiting neuronal decline by the age of 4 months that intensifies by the age of 9 months, these mice manifest a broad spectrum of behavioural impairments. In this review, we present the extensive repertoire of behavioural dysfunctions in 5xFAD mice, organised into four categories: motor skills, sensory function, learning and memory abilities, and neuropsychiatric-like symptoms. The motor problems, associated with agility and reflex movements, as well as balance and coordination, and skeletal muscle function, typically arise by the time mice reach 9 months of age. The sensory function (such as taste, smell, hearing, and vision) starts to deteriorate when amyloid peptide buildups and neuroinflammation spread into related anatomical structures. The cognitive functions, encompassing learning and memory abilities, such as visual recognition, associative, spatial working, reference learning, and memory show signs of decline from 4 to 6 months of age. Concerning neuropsychiatric-like symptoms, comprising apathy, anxiety and depression, and the willingness for exploratory behaviour, it is believed that motivational changes emerge by approximately 6 months of age. Unfortunately, numerous studies from different laboratories are often contradictory on the conclusions drawn and the identification of onset age, making preclinical studies in rodent models not easily translatable to humans. This variability is likely due to a range of factors associated with animals themselves, housing and husbandry conditions, and experimental settings. In the forthcoming studies, greater clarity in experimental details when conducting behavioural testing in 5xFAD transgenic mice could minimise the inconsistencies and could ensure the reliability and the reproducibility of the results.

Immunotherapy-related cognitive impairment after CAR T cell therapy in mice

Persistent central nervous system (CNS) immune dysregulation and consequent dysfunction of multiple neural cell types is central to the neurobiological underpinnings of a cognitive impairment syndrome that can occur following traditional cancer therapies or certain infections. Immunotherapies have revolutionized cancer care for many tumor types, but the potential long-term cognitive sequelae are incompletely understood. Here, we demonstrate in mouse models that chimeric antigen receptor (CAR) T cell therapy for both CNS and non-CNS cancers can impair cognitive function and induce a persistent CNS immune response characterized by white matter microglial reactivity and elevated cerebrospinal fluid (CSF) cytokines and chemokines. Consequently, oligodendroglial homeostasis and hippocampal neurogenesis are disrupted. Microglial depletion rescues oligodendroglial deficits and cognitive performance in a behavioral test of attention and short-term memory function. Taken together, these findings illustrate similar mechanisms underlying immunotherapy-related cognitive impairment (IRCI) and cognitive impairment following traditional cancer therapies and other immune challenges.

Liraglutide versus pramlintide in protecting against cognitive function impairment through affecting PI3K/AKT/GSK-3β/TTBK1 pathway and decreasing Tau hyperphosphorylation in high-fat diet- streptozocin rat model

The American Diabetes Association guidelines (2021) confirmed the importance of raising public awareness of diabetes-induced cognitive impairment, highlighting the links between poor glycemic control and cognitive impairment. The characteristic brain lesions of cognitive dysfunction are neurofibrillary tangles (NFT) and senile plaques formed of amyloid-β deposition, glycogen synthase kinase 3 beta (GSK3β), and highly homologous kinase tau tubulin kinase 1 (TTBK1) can phosphorylate Tau proteins at different sites, overexpression of these enzymes produces extensive phosphorylation of Tau proteins making them insoluble and enhance NFT formation, which impairs cognitive functions. The current study aimed to investigate the potential contribution of liraglutide and pramlintide in the prevention of diabetes-induced cognitive dysfunction and their effect on the PI3K/AKT/GSK-3β/TTBK1 pathway in type 2 diabetic (T2D) rat model. T2D was induced by administration of a high-fat diet for 10 weeks, then injection of a single dose of streptozotocin (STZ); treatment was started with either pramlintide (200 μg/kg/day sc) or liraglutide (0.6 mg/kg/day sc) for 6 weeks in addition to the HFD. At the end of the study, cognitive functions were assessed by novel object recognition and T-maze tests. Then, rats were sacrificed for biochemical and histological assessment of the hippocampal tissue. Both pramlintide and liraglutide treatment revealed equally adequate control of diabetes, prevented the decline in memory function, and increased PI3K/AKT expression while decreasing GSK-3β/TTBK1 expression; however, liraglutide significantly decreased the number of Tau positive cells better than pramlintide did. This study confirmed that pramlintide and liraglutide are promising antidiabetic medications that could prevent associated cognitive disorders in different mechanisms.

GDI2 deletion alleviates neurodegeneration and memory loss in the 5xFAD mice model of Alzheimer's disease

Accumulation of insoluble deposits of amyloid β-peptide (Aβ), derived from amyloid precursor protein (APP) processing, represents one of the major pathological hallmarks of Alzheimer's disease (AD). Perturbations in APP transport and hydrolysis could lead to increased Aβ production. However, the precise mechanisms underlying APP transport remain elusive. The GDP dissociation inhibitor2 (GDI2), a crucial regulator of Rab GTPase activity and intracellular vesicle and membrane trafficking, was investigated for its impact on AD pathogenesis through neuron-specific knockout of GDI2 in 5xFAD mice. Notably, deficiency of GDI2 significantly ameliorated cognitive impairment, prevented neuronal loss in the subiculum and cortical layer V, reduced senile plaques as well as astrocyte activation in 5xFAD mice. Conversely, increased activated microglia and phagocytosis were observed in GDI2 ko mice. Further investigation revealed that GDI2 knockout led to more APP co-localized with the ER rather than the Golgi apparatus and endosomes in SH-SY5Y cells, resulting in decreased Aβ production. Collectively, these findings suggest that GDI2 may regulate Aβ production by modulating APP intracellular transport and localization dynamics. In summary, our study identifies GDI2 as a pivotal regulator governing APP transport and process implicated in AD pathology; thus highlighting its potential as an attractive pharmacological target for future drug development against AD.

Neuroprotective effects of gemfibrozil in neurological disorders: Focus on inflammation and molecular mechanisms

BACKGROUND

Gemfibrozil (Gem) is a drug that has been shown to activate PPAR-α, a nuclear receptor that plays a key role in regulating lipid metabolism. Gem is used to lower the levels of triglycerides and reduce the risk of coronary heart disease in patients. Experimental studies in vitro and in vivo have shown that Gem can prevent or slow the progression of neurological disorders (NDs), including cerebral ischemia (CI), Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Neuroinflammation is known to play a significant role in these disorders.

METHOD

The literature review for this study was conducted by searching Scopus, Science Direct, PubMed, and Google Scholar databases.

RESULT

The results of this study show that Gem has neuroprotective effects through several cellular and molecular mechanisms such as: (1) Gem has the ability to upregulate pro-survival factors (PGC-1α and TFAM), promoting the survival and function of mitochondria in the brain, (2) Gem strongly inhibits the activation of NF-κB, AP-1, and C/EBPβ in cytokine-stimulated astroglial cells, which are known to increase the expression of iNOS and the production of NO in response to proinflammatory cytokines, (3) Gem protects dopamine neurons in the MPTP mouse model of PD by increasing the expression of PPARα, which in turn stimulates the production of GDNF in astrocytes, (4) Gem reduces amyloid plaque pathology, reduces the activity of glial cells, and improves memory, (5) Gem increases myelin genes expression (MBP and CNPase) via PPAR-β, and (6) Gem increases hippocampal BDNF to counteract depression.

CONCLUSION

According to the study, Gem was investigated for its potential therapeutic effect in NDs. Further research is needed to fully understand the therapeutic potential of Gem in NDs.

Maternal aerobic exercise decreases the effects of a perinatal Western diet on the short and long-term memory of CD1 mouse progeny

Maternal nutrition and physical activity during pregnancy and lactation can modify offspring development. Here, we investigated the effects of maternal aerobic exercise (AE) and Western diet (WD) on brain development, cognitive flexibility, and memory of progenies. Sixteen adult female mice were assigned to AE or sedentary groups (SED) and fed a balanced diet (BD) or WD. Offspring were categorized into four groups: WD + AE, WD + SED, BD + AE, and BD + SED. The AE group showed enhanced spontaneous alternation in the T-maze test, suggesting an improvement in working memory and tasks related to cognitive flexibility. The novel object recognition (NOR) test showed that the BD + AE pups improved their absolute discrimination and discrimination index at 24 h, which suggests a delay in memory consolidation without affecting evocation. WD + SED showed poorer discrimination and recognition memory. The pups of AE mothers had better efficiency in short-term memory, whereas WD offspring showed low performance in long-term memory. Interestingly, exercise improved tasks related to cognitive flexibility, regardless of the diet. These findings indicate that maternal diet and physical activity modify offspring development and suggest that maternal AE during pregnancy could be a beneficial intervention to counteract the adverse effects of WD by improving spatial memory and cognitive flexibility in offspring.

Resistant starches from dietary pulses improve neurocognitive health via gut-microbiome-brain axis in aged mice

Introduction

Cognitive decline is a common consequence of aging. Dietary patterns that lack fibers and are high in saturated fats worsen cognitive impairment by triggering pro-inflammatory pathways and metabolic dysfunctions. Emerging evidence highlights the neurocognitive benefits of fiber-rich diets and the crucial role of gut-microbiome-brain signaling. However, the mechanisms of this diet-microbiome-brain regulation remain largely unclear.

Methods

Accordingly, we herein investigated the unexplored neuroprotective mechanisms of dietary pulses-derived resistant starch (RS) in improving aging-associated neurocognitive function in an aged (60-weeks old) murine model carrying a human microbiome.

Results and discussion

Following 20-weeks dietary regimen which included a western-style diet without (control; CTL) or with 5% w/w fortification with RS from pinto beans (PTB), black-eyed-peas (BEP), lentils (LEN), chickpeas (CKP), or inulin fiber (INU), we find that RS, particularly from LEN, ameliorate the cognitive impairments induced by western diet. Mechanistically, RS-mediated improvements in neurocognitive assessments are attributed to positive remodeling of the gut microbiome-metabolome arrays, which include increased short-chain fatty acids and reduced branched-chain amino acids levels. This microbiome-metabolite-brain signaling cascade represses neuroinflammation, cellular senescence, and serum leptin/insulin levels, while enhancing lipid metabolism through improved hepatic function. Altogether, the data demonstrate the prebiotic effects of RS in improving neurocognitive function via modulating the gut-brain axis.

A modified Mediterranean-style diet enhances brain function via specific gut-microbiome-brain mechanisms

Alzheimer's disease (AD) is a debilitating brain disorder with rapidly mounting prevalence worldwide, yet no proven AD cure has been discovered. Using a multi-omics approach in a transgenic AD mouse model, the current study demonstrated the efficacy of a modified Mediterranean-ketogenic diet (MkD) on AD-related neurocognitive pathophysiology and underlying mechanisms related to the gut-microbiome-brain axis. The findings revealed that MkD induces profound shifts in the gut microbiome community and microbial metabolites. Most notably, MkD promoted growth of the Lactobacillus population, resulting in increased bacteria-derived lactate production. We discovered elevated levels of microbiome- and diet-derived metabolites in the serum as well, signaling their influence on the brain. Importantly, these changes in serum metabolites upregulated specific receptors that have neuroprotective effects and induced alternations in neuroinflammatory-associated pathway profiles in hippocampus. Additionally, these metabolites displayed strong favorable co-regulation relationship with gut-brain integrity and inflammatory markers, as well as neurobehavioral outcomes. The findings underscore the ameliorative effects of MkD on AD-related neurological function and the underlying gut-brain communication via modulation of the gut microbiome-metabolome arrays.

3-N-butylphthalide attenuates neuroinflammation in rotenone-induced Parkinson's disease models via the cGAS-STING pathway

Neuroinflammation is crucial in the onset and progression of dopaminergic neuron loss in Parkinson's disease (PD). We aimed to determine whether 3-N-Butylphthalide (NBP) can protect against PD by inhibiting the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and the inflammatory response of microglia. MitoSOX/MitoTracker/Hoechst staining was used to detect the levels of mitochondrial reactive oxygen species (ROS) in BV2 cells. Quantitative Real-Time Polymerase Chain Reaction was used to measure the levels of free cytoplasmic mitochondrial DNA (mtDNA) in BV2 cells and mouse brain tissues. Behavioral impairments were assessed using rotarod, T-maze, and balance beam tests. Dopaminergic neurons and microglia were observed using immunohistochemical staining. Expression levels of cGAS, STING, nuclear factor kappa-B (NfκB), phospho- NfκB (p-NfκB), inhibitor of NfκBα (IκBα), and phospho-IκBα (p-IκBα) proteins in the substantia nigra and striatum were detected using Western Blot. NBP decreased mitochondrial ROS levels in rotenone-treated BV2 cells. NBP alleviated behavioral impairments and protected against rotenone-induced microgliosis and damage to dopaminergic neurons in the substantia nigra and striatum of rotenone-induced PD mice. NBP decreased rotenone-induced mtDNA leakage and mitigated neuroinflammation by inhibiting cGAS-STING pathway activation. NBP exhibited a protective effect in rotenone-induced PD models by significantly inhibiting the cGAS-STING pathway. Moreover, NBP can alleviate neuroinflammation, and is a potential therapeutic drug for alleviating clinical symptoms and delaying the progression of PD. This study provided insights for the potential role of NBP in PD therapy, potentially mitigating neurodegeneration, and consequently improving the quality of life and lifespan of patients with PD. The limitations are that we have not confirmed the exact mechanism by which NBP decreases mtDNA leakage, and this study was unable to observe the actual clinical therapeutic effect, so further cohort studies are required for validation.