CA1 Region Research Articles

Therapeutic effects of pentoxifylline in propionic acid‐induced autism symptoms in rat models: A behavioral, biochemical, and histopathological study

AbstractObjectiveThe role of propionic acid (PPA) in eliciting behaviors analogous to autism in rat models is a documented phenomenon. This study examines the therapeutic implications of pentoxifylline—an agent traditionally used for peripheral vascular diseases—on these autism‐like behaviors by modulating brain proteins and reducing pro‐inflammatory cytokines like tumor necrosis factor‐α (TNF‐α) in a rat model.MethodsThis research involved 30 male Wistar albino rats, which were divided into three distinct groups: a baseline control set, a PPA‐treated cluster receiving a 250 mg/kg/day dose of PPA via intraperitoneal injection for a span of five days followed by saline orally, and a PPA group administered an oral dose of pentoxifylline at 300 mg/kg/day over 15 days. Subsequent to the treatment phase, euthanasia was carried out for the extraction of brain and blood samples, which were then analyzed for histopathological and biochemical markers.ResultsThe pentoxifylline‐treated subjects demonstrated a significant mitigation in the manifestation of autistic‐like behaviors, as assessed through a triad of social interaction tests. A noteworthy decline in TNF‐α levels was observed, alongside a significant rise in the concentration of adenosine triphosphate and nerve growth factor in brain tissue (p < 0.05). Histopathological analysis underscored a reduction in oxidative stress and a significant preservation of neuronal cell types, specifically pyramidal neurons in the hippocampal CA1 and CA3 regions and Purkinje cells in the cerebellum (p < 0.001).ConclusionPentoxifylline treatment has been found to effectively reduce the behavioral symptoms associated with autism, as well as biochemical and histopathological disruptions induced by PPA in rat models, highlighting its potential as a neurotherapeutic agent.

The ameliorative potential of platelet-rich plasma and exosome on renal ischemia/reperfusion-induced uremic encephalopathy in rats.

Uremic Encephalopathy results from the elevation of toxins and blood-brain barrier (BBB) disruption. Renal Ischemia/Reperfusion (I/R) injury is the principal cause of acute kidney injury and brain tissue injury. The present study was crafted to estimate the restorative impact of platelet-rich plasma (PRP) and exosome injection before the reperfusion phase on the kidney following renal I/R injury and its influence on brain tissue by tracking the histopathological, biochemical, and Doppler ultrasonography alternations in both kidney and brain tissue. Forty mature male rats were divided into five groups as follows: control, I/R, PRP, exosome, and Exosome + PRP. Renal Doppler ultrasonography was traced for all rats. Serum kidney functions and acetylcholine esterase enzyme (AchE) were evaluated. Both Gamma-aminobutyric acid (GABA) and glutamate were assessed in brain tissues. The oxidative stress (malondialdehyde), anti-oxidative (glutathione and catalase), and pro-inflammatory (Tumor necrosis factor- α and interleukin-6) markers were estimated in renal tissues. Additionally, morphometric histological examination was performed in both renal and brain tissues. Both PRP and exosome-received rats exhibited a significant improvement in both serum kidney functions and AchE compared to I/R rats. There was a 3.39-fold increase in GABA and a 2.27-fold decrease in glutamate levels in the brain tissue of PRP rats compared to the I/R rats. A significant elevation (P ≤ 0.0001) of glutathione and catalase besides a significant reduction in the expression of TNF-α and IL-6 was observed in renal tissue compared to I/R rats. A significant severe reduction (P < 0.0001) in the number of Purkinje cells, pyramidal cells in the cerebellar cortex, and the CA1 region in the hippocampus was observed in I/R rats which was significantly alleviated by both PRP and exosome. Furthermore, there was a significant improvement in Doppler parameters. PRP exerted a significant superior impact on the restoration of kidney functions and repairing uremic-induced damage in brain tissue.

Augmentation of Endogenous 2-Arachidonoylglycerol Mitigates Autistic Behaviors of BTBR Mice.

The lipid-based endocannabinoid (eCB) system regulates a host of developmental, physiological, and pathological processes in the mammalian brain, and recent studies have suggested that dysfunction of eCB system may contribute to the neuropathology of autism spectrum disorder (ASD). However, specific contributions to ASD-related developmental, cognitive, and behavioral phenotypes remain largely unexplored. The current study was designed to investigate if enhancing eCB signaling by blocking 2-arachidonoylglycerol (2-AG) hydrolase can mitigate ASD-like behaviors in a mouse model, and if such effects are associated with suppression of inflammatory signaling, oxidative stress, or neuronal apoptosis. Intraperitoneal injection of the 2-AG hydrolase monoacylglycerol lipase (MAGL) JZL184 (4, 16, or 40mg/kg) elevated 2-AG and reversed eCB system metabolic enzymes and receptors expression deficits in BTBR T + ltpr3tf/J (BTBR) mouse model of ASD. Moreover, the hyperactivity, excessive stereotypy, impaired social behavior, and cognitive deficits characteristic of this animal model were significantly improved by JZL184. Concomitantly, JZL184 administration reversed the abnormal pro- and anti-inflammatory cytokine concentrations measured in the hippocampus of BTBR mice. In addition, JZL184 reversed the observed overexpression of pro-apoptotic Bax and underexpression of anti-apoptotic Bcl-2 in BTBR mice and enhanced neuronal numbers in hippocampal CA1 and CA3 regions. We also found that the behavioral test battery influenced eCB concentrations independently of JZL184 treatment. Collectively, these findings suggest that augmenting eCB signaling can mitigate ASD-related phenotypes by suppressing neuroinflammation and neuronal apoptosis.

Distinct catecholaminergic pathways projecting to hippocampal CA1 transmit contrasting signals during navigation in familiar and novel environments.

Neuromodulatory inputs to the hippocampus play pivotal roles in modulating synaptic plasticity, shaping neuronal activity, and influencing learning and memory. Recently, it has been shown that the main sources of catecholamines to the hippocampus, ventral tegmental area (VTA) and locus coeruleus (LC), may have overlapping release of neurotransmitters and effects on the hippocampus. Therefore, to dissect the impacts of both VTA and LC circuits on hippocampal function, a thorough examination of how these pathways might differentially operate during behavior and learning is necessary. We therefore utilized two-photon microscopy to functionally image the activity of VTA and LC axons within the CA1 region of the dorsal hippocampus in head-fixed male mice navigating linear paths within virtual reality (VR) environments. We found that within familiar environments some VTA axons and the vast majority of LC axons showed a correlation with the animals' running speed. However, as mice approached previously learned rewarded locations, a large majority of VTA axons exhibited a gradual ramping-up of activity, peaking at the reward location. In contrast, LC axons displayed a pre-movement signal predictive of the animal's transition from immobility to movement. Interestingly, a marked divergence emerged following a switch from the familiar to novel VR environments. Many LC axons showed large increases in activity that remained elevated for over a minute, while the previously observed VTA axon ramping-to-reward dynamics disappeared during the same period. In conclusion, these findings highlight distinct roles of VTA and LC catecholaminergic inputs in the dorsal CA1 hippocampal region. These inputs encode unique information, with reward information in VTA inputs and novelty and kinematic information in LC inputs, likely contributing to differential modulation of hippocampal activity during behavior and learning.

Distinct catecholaminergic pathways projecting to hippocampal CA1 transmit contrasting signals during navigation in familiar and novel environments

Neuromodulatory inputs to the hippocampus play pivotal roles in modulating synaptic plasticity, shaping neuronal activity, and influencing learning and memory. Recently, it has been shown that the main sources of catecholamines to the hippocampus, ventral tegmental area (VTA) and locus coeruleus (LC), may have overlapping release of neurotransmitters and effects on the hippocampus. Therefore, to dissect the impacts of both VTA and LC circuits on hippocampal function, a thorough examination of how these pathways might differentially operate during behavior and learning is necessary. We therefore utilized two-photon microscopy to functionally image the activity of VTA and LC axons within the CA1 region of the dorsal hippocampus in head-fixed male mice navigating linear paths within virtual reality (VR) environments. We found that within familiar environments some VTA axons and the vast majority of LC axons showed a correlation with the animals’ running speed. However, as mice approached previously learned rewarded locations, a large majority of VTA axons exhibited a gradual ramping-up of activity, peaking at the reward location. In contrast, LC axons displayed a pre-movement signal predictive of the animal’s transition from immobility to movement. Interestingly, a marked divergence emerged following a switch from the familiar to novel VR environments. Many LC axons showed large increases in activity that remained elevated for over a minute, while the previously observed VTA axon ramping-to-reward dynamics disappeared during the same period. In conclusion, these findings highlight distinct roles of VTA and LC catecholaminergic inputs in the dorsal CA1 hippocampal region. These inputs encode unique information, with reward information in VTA inputs and novelty and kinematic information in LC inputs, likely contributing to differential modulation of hippocampal activity during behavior and learning.

Gather your neurons and model together: Community times ahead.

Bottom-up, data-driven, large-scale models provide a mechanistic understanding of neuronal functions. A new study in PLOS Biology builds a biologically realistic model of the rodent CA1 region that aims to become an accessible tool for the whole hippocampal community.

Community-based reconstruction and simulation of a full-scale model of the rat hippocampus CA1 region.

The CA1 region of the hippocampus is one of the most studied regions of the rodent brain, thought to play an important role in cognitive functions such as memory and spatial navigation. Despite a wealth of experimental data on its structure and function, it has been challenging to integrate information obtained from diverse experimental approaches. To address this challenge, we present a community-based, full-scale in silico model of the rat CA1 that integrates a broad range of experimental data, from synapse to network, including the reconstruction of its principal afferents, the Schaffer collaterals, and a model of the effects that acetylcholine has on the system. We tested and validated each model component and the final network model, and made input data, assumptions, and strategies explicit and transparent. The unique flexibility of the model allows scientists to potentially address a range of scientific questions. In this article, we describe the methods used to set up simulations to reproduce in vitro and in vivo experiments. Among several applications in the article, we focus on theta rhythm, a prominent hippocampal oscillation associated with various behavioral correlates and use our computer model to reproduce experimental findings. Finally, we make data, code, and model available through the hippocampushub.eu portal, which also provides an extensive set of analyses of the model and a user-friendly interface to facilitate adoption and usage. This community-based model represents a valuable tool for integrating diverse experimental data and provides a foundation for further research into the complex workings of the hippocampal CA1 region.

The protective effect of DMI on hippocampus EEG, behavioral and biochemical parameters in hypoxia-induced seizure on neonatal period.

Hypoxia-Induced Neonatal Seizure (HINS) is a prevalent type of seizure in infants caused by hypoxic conditions, which can lead to an increased risk of epilepsy, learning disabilities, and cognitive impairments later in life. This study focuses on examining the effects of dimethyl itaconate (DMI) on cognition, motor coordination, and anxiety-like behavior in male rats that have experienced HINS. 42 male Wistar newborn rats (PND10) were randomly divided into six groups (n = 7). 1) Control (Vehicle only); received DMI solvent (0.1ml) without applying hypoxia. 2-3) DMI; receiving (20 and 50 mg/kg; i.p). 4) HINS; they were placed in a hypoxia chamber with 7% oxygen and 93% nitrogen concentration for 15 minutes. 5-6) DMI+HINS; received DMI (20 and 50 mg/kg; i.p) 24h before hypoxia. Behavioral tests including; Novel object recognition test, Rotarod, Parallel bar, Open field and elevated plus maze (EPM); started at age 45 after birth. After behavioral tests, the hippocampal CA1 region local EEG was recorded in all groups. Then the brain hippocampus tissue was isolated and the amount of MDA, SOD, NO, and Thiol was measured by ELISA method. Data showed that the administration of DMI improved motor symptoms, anxiety-like behaviors, and cognition in HINS rats (p<0.05). EEG power in the HINS group decreased significantly compared to other experimental groups (p<0.05). Biochemical observations showed that DMI significantly reduced oxidative stress and inflammation in the hippocampal tissue of HINS rats (p<0.05). Increased hippocampal oxidative stress and inflammation can be effective in the occurrence of behavioral disorders observed in HINS rats. While DMI improved these behavioral impairments by reducing oxidative stress and inflammation.

Gyrophoric Acid, a Secondary Metabolite of Lichens, Exhibits Antidepressant and Anxiolytic Activity In Vivo in Wistar Rats

Gyrophoric acid (GA) is a secondary metabolite of various lichens. It exhibits various biological activities in vitro, but only one study has been carried out in vivo. Because our previous study showed that GA stimulates neurogenesis in healthy rats, the current study aimed to explore the potential of GA during stress-induced depressive-like states in male Wistar rats. In the experiment, pregnant females were used. In the last week of pregnancy, females were subjected to restraint stress. After birth, progeny aged 60 days were stressed repeatedly. The males were divided into three groups: control animals (CTR; n = 10), males with a depression-like state (DEP; n = 10), and GA-treated animals (GA; n = 10). GA males were treated with GA (per os 10 mg/kg) daily for one month, starting from the 60th postnatal day. Our results indicate that GA acts as an antioxidant, as shown by a lowered ROS level in leukocytes (p &lt; 0.01). Moreover, it prolonged the time spent in open arms in the elevated plus maze (p &lt; 0.001). Concomitantly, the stimulation of proliferative activity in hippocampal regions was seen (hilus p &lt; 0.01; subgranular zone p &lt; 0.001) when compared with DEP males. Additionally, the number of mature neurons in the CA1 region of the hippocampus increased markedly (p &lt; 0.01), indicating the role of GA in the maturation process of neurons. Thus, our study points to the potential anxiolytic/antidepressant activity of GA. However, future studies are needed in this complex area.

Neuronal ACE1 knockout disrupts the hippocampal renin angiotensin system leading to memory impairment and vascular loss in normal aging

Angiotensin I converting enzyme (ACE1) maintains blood pressure homeostasis by converting angiotensin I into angiotensin II in the renin-angiotensin system (RAS). ACE1 is expressed in the brain, where an intrinsic RAS regulates complex cognitive functions including learning and memory. ACE1 has been implicated in neurodegenerative disorders including Alzheimer's disease and Parkinson's disease, but the mechanisms remain incompletely understood. Here, we performed single-nucleus RNA sequencing to characterize the expression of RAS genes in the hippocampus and discovered that Ace is mostly expressed in CA1 region excitatory neurons. To gain a deeper understanding of the function of neuronal ACE1, we generated ACE1 conditional knockout (cKO) mice lacking ACE1 expression specifically in hippocampal and cortical excitatory neurons. Interestingly, ACE1 cKO mice exhibited hippocampus-dependent memory impairment in the Morris water maze, y-maze, and fear conditioning tests. Total ACE1 level was significantly reduced in the cortex and hippocampus of ACE1 cKO mice showing that excitatory neurons are the predominant cell type expressing ACE1 in the forebrain. Despite similar reductions in total ACE1 level in both the hippocampus and cortex, the RAS pathway was dysregulated in the hippocampus only. Importantly, ACE1 cKO mice exhibited age-related capillary loss selectively in the hippocampus. Here, we show selective vulnerability of the hippocampal microvasculature and RAS pathway to neuronal ACE1 knockout. Our results provide important insights into the function of ACE1 in the brain and demonstrate a connection between neuronal ACE1 and cerebrovascular function in the hippocampus.

Effects of JAL-TA9 on cognitive deficits in Alzheimer's disease model mouse

Many studies have been conducted to find an effective drug for Alzheimer's disease (AD) treatment. However, no effective drug applicable for clinical use has been developed. Recently, the FDA approved Lecanemab, an antibody drug that acts as an aggregation inhibitor against Amyloid-beta (Aβ), for AD treatment. However, there are still no fundamental drugs for AD. In this study, we present a strategy for AD treatment that removes Aβ by cleavage reaction using one of the Catalytides, JAL-TA9 (YKGSGFRMI). A single dose of JAL-TA9 administered into the CA1 region of the hippocampus and the intraventricular space improved the deficits in short-term memory of APP-knock-in mice. It also improved the memory of Aβ25-35-induced model mice, as evaluated by the Y-maze and objective recognition tests. These data strongly suggest that JAL-TA9 could be effective in treating AD. However, these administration methods are difficult to apply clinically due to their high invasiveness. Thus, we tested the improvement effects of dementia by administering JAL-TA9 nasally. It is very interesting and exciting that the dementia of Aβ25-35 induced AD model mice was improved by four applications once every three days. These results strongly suggest that JAL-TA9 is the best candidate for AD treatment because it is effective even in the late stage of AD.

Fasudil Alleviates Postoperative Neurocognitive Disorders in Mice by Downregulating the Surface Expression of α5GABAAR in Hippocampus.

Postoperative neurocognitive disorder (PND) refers to the cognitive impairment experienced by patients after surgery. As a target of sevoflurane, a kind of inhalation anesthetic, the balance of the GABAergic system can be disrupted during the perioperative period. In this study, we explored the promoting effect of abnormal elevation of the α5 subtype of γ-aminobutyric acid type A (GABAA) receptors caused by sevoflurane and surgical trauma on PND, as well as the therapeutic effect of fasudil on PND. Eight-week-old mice were pretreated with fasudil, and after 10 days, sevoflurane-induced femoral fracture surgery was performed to establish an animal model of PND. The Morris water maze and fear conditioning tests were used to evaluate PND induced by this model. Biochemical and electrophysiological analyses were conducted to assess the protective effect of fasudil on the GABAergic system. Following artificial fracture, the hippocampus-dependent memory was damaged in these mice. Fasudil pretreatment, however, ameliorated cognitive function impairment in mice induced by sevoflurane and surgery. Mechanistically, fasudil was found to restore the increased hippocampus expression and function of α5GABAARs in mice with PND. In addition, pretreatment with Fasudil inhibited the enhancement in the calcium ion concentration and phosphorylation of Camk2, as well as the activation of the Radixin pathway which led to increased phosphorylation of the ERM family in the hippocampal CA1 region of the PND model. Preadministration of fasudil improved postoperative cognitive function in PND mice by inhibiting the activation of Camk2 and Radixin pathways and finally downregulating the surface expression of α5GABAAR in hippocampus neurons.

High-Salt Diet Accelerates Neuron Loss and Anxiety in APP/PS1 Mice Through Serpina3n

High salt (HS) consumption is an independent risk factor for neurodegenerative diseases such as dementia, stroke, and cerebral small vessel disease related to cognitive decline. Recently, Alzheimer’s disease-like pathology changes have been reported as consequences of a HS diet in wild-type (wt) mice. However, it has not been revealed how HS diets accelerate the progress of Alzheimer’s disease (AD) in APP/PS1 mice. Here, we fed APP/PS1 mice a HS diet or normal diet (ND) for six months; the effects of the HS/ND on wt mice were also observed. The results of our behavior test reveal that the HS diet exacerbates anxiety, β-amyloid overload, neuron loss, and synapse damage in the hippocampi of APP/PS1 mice; this was not observed in HS-treated wt mice. RNA sequencing shows that nearly all serpin family members were increased in the hippocampus of HS-treated APP/PS1 mice. Gene function analysis showed that a HS diet induces neurodegeneration, including axon dysfunction and neuro-ligand-based dysfunction, and regulates serine protein inhibitor activities. The mRNA and protein levels of Serpina3n were dramatically increased. Upregulated Serpina3n may be the key for β-amyloid aggregation and neuronal loss in the hippocampus of HS-treated APP/PS1 mice. Serpina3n inhibition attenuated the anxiety and increased the number of neurons in the hippocampal CA1(cornu ammonis) region of APP/PS1 mice. Our study provides novel insights into the mechanisms by which excessive HS diet deteriorates anxiety in AD mice. Therefore, decreasing daily dietary salt consumption constitutes a pivotal public health intervention for mitigating the progression of neuropathology, especially for old patients and those with neurodegenerative disease.

Unraveling Neurotoxicity Discrepancies: Comparative In vitro and In vivo Analysis of Colistin and Polymyxin B and the Underlying Mechanisms.

Polymyxins, including colistin and polymyxin B, are the final resort against Gram-negative bacterial infections. However, its clinical application is restricted due to concerns related to neurotoxicity. Despite the similar antibacterial spectrum and mode of action shared between colistin and polymyxin B, there is still a lack of definitive evidence to support the idea that their neurotoxicity profiles are identical. To comprehensively compare the neurotoxicity between colistin and polymyxin B both in vivo and in vitro and establish a theoretical foundation to guide the rational use of polymyxins within clinical settings. in vitro experiments simulated nerve damage by exposing N2a and RSC96 cells to colistin and polymyxin B. The evaluation of nerve injury included assessments of cell viability and apoptosis. To discern the variance in the mechanisms of nerve injury between colistin and polymyxin B, oxidative stress levels were examined, such as SOD, CAT, GSH, and malondialdehyde (MDA). In in vivo experiments, a rat nerve injury model was created by intraventricular injections of colistin and polymyxin B, respectively. The impact of these drugs on brain injury in rats, particularly within the hippocampus and medulla oblongata, was measured using HE and Nissl staining. The potential influence of polymyxins on the ferroptosis pathway was evaluated by assessing LPO and Fe2+ levels and the degree of mitochondrial impairment. At equivalent doses, colistin demonstrated a reduced level of neurotoxicity compared to polymyxin B, both in vitro and in vivo. in vitro experiments revealed greater cell viability and a lower apoptosis rate after colistin treatment than after polymyxin B treatment. This variance in outcomes could be attributed to the comparatively lower levels of oxidative stress associated with colistin administration.In a rat model, nerve injury resulted in observable damage to both the hippocampus and the medulla oblongata. A comprehensive assessment of the extent of damage in the CA1 to CA4 regions of the hippocampus, and the solitary tract nucleus of the medulla oblongata underscored that the neurotoxic effects of colistin remained milder compared to those elicited by polymyxin B. Even when evaluated at equivalent multiples of clinically recommended doses, colistin exhibited lower neurotoxicity in vivo than polymyxin B. For the first time, this study demonstrated the role of ferroptosis in polymyxin B-induced nerve damage. The activation levels observed within the ferroptosis pathway due to polymyxin B exceeded those triggered by colistin. Colistin exhibited a marked reduction in neurotoxicity compared to polymyxin B, evident in both the equivalent and clinically recommended doses. These findings suggest that, from the perspective of neurotoxicity, colistin presents a more favorable option for clinical use.

LncRNA MSTRG.13,871/miR155-5p/Grip1 network involved in the post-cardiac arrest brain injury

Post-cardiac arrest brain (PCABI) is a severe medical condition characterized by a significant risk of neurological impairment and death. Nevertheless, the specific process and essential molecules responsible for its development are not fully understood. Profiling based on competing endogenous RNAs (ceRNA) has been implicated in the onset and progression of neurological disorders, yet its role in PCABI remains unclear. In this study, we performed RNA transcriptome sequencing analysis to identify differentially expressed genes in the rat model for cardiac arrest and cardiopulmonary resuscitation (CA/CPR). A hub ceRNA regulatory network was constructed using miRWalk 2.0 and Cytohubba plug-in in Cytoscape. Subsequently, real-time quantitative reverse transcription-polymerase chain reaction and dual-luciferase activity assays validated MSTRG.13,871, miR-155-5p, and Grip1 as differentially expressed in CA/CPR group, with MSTRG.13,871 capable of targeting both miR-155-5p and Grip1. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed the ceRNA network enrichment in immunoregulation mechanisms such as mitochondrion, apoptotic process, and negative regulation cell death. Our research highlights the mechanism of PCABI by revealing a critical regulatory axis involving MSTRG.13,871-miR-155-5p-Grip1 in the hippocampus CA1 region after CA/CPR in rats, proposing a feasible controlled mechanism, which may serve as a theoretical basis for designing innovative therapies.

Neuroprotective effects of Daphnetin on hippocampal neurons and blood-brain barrier integrity in a mouse model of cerebral ischemia

The purpose of this research was to assess the impact of different doses of Daphnetin (DAP, a natural compound derived from coumarin) on hippocampus neuronal injury, neurobehavioral function, blood-brain barrier (BBB) integrity, expression of claudin-5, brain-derived neurotrophic factor (BDNF), superoxide dismutase (SOD), and inflammatory markers in a mouse model of cerebral ischemia. Cerebral ischemia was induced in mice through 30 minutes of bilateral common carotid occlusion (BCCAO), followed by 48 hours of reperfusion. The viability of hippocampal neurons was assessed using Cresyl violet staining and BBB function was determined by measuring Evans blue (E.B) dye leakage. Spatial memory was tested using the Radial Arm Water Maze (RAWM) task. Claudin-5 and BDNF were measured by immunofluorescence, while SOD, interleukin-1 beta (IL-1β), and nuclear factor-κB (NF-κB) expression were determined through western blotting. Administering DAP significantly increased neuron survival in the hippocampus CA1, CA3, and dentate gyrus (DG) regions and improved spatial memory dose-dependently (P<0.0001). Treatment with DAP (40 mg/kg IP) significantly reduced E.B leakage and brain water content (P<0.001). Furthermore, it increased the claudin-5, BDNF, and SOD levels and diminished NF-κB and IL-1β expression (P<0.0001). The research found that DAP protected neurons in the CA1, CA3, and DG areas of the hippocampus, enhanced behavioral functions, and preserved BBB integrity in a cerebral ischemia model. This positive impact is achieved by increasing the expression of claudin-5, BDNF, and SOD and diminishing neuroinflammation. Further research is required to clarify the mechanisms and possible clinical uses.

Ultrastructural characterization of hippocampal inhibitory synapses under resting and stimulated conditions.

The present study uses electron microscopy to document ultrastructural characteristics of hippocampal GABAergic inhibitory synapses under resting and stimulated conditions in three experimental systems. Synaptic profiles were sampled from stratum pyramidale and radiatum of the CA1 region from (1) perfusion fixed mouse brains, (2) immersion fixed rat organotypic slice cultures, and from (3) rat dissociated hippocampal cultures of mixed cell types. Synapses were stimulated in the brain by a 5min delay in perfusion fixation to trigger an ischemia-like excitatory condition, and by treating the two culture systems with 90 mM high K+ for 2-3min to depolarize the neurons. Upon such stimulation conditions, the presynaptic terminals of the inhibitory synapses exhibited similar structural changes to those seen in glutamatergic excitatory synapses, with depletion of synaptic vesicles, increase of clathrin-coated vesicles and appearance of synaptic spinules. However, in contrast to excitatory synapses, no structural differences were detected in the postsynaptic compartment of the inhibitory synapses upon stimulation. There were no changes in the appearance of material associated with the postsynaptic membrane or the length and curvature of the membrane. Also no change was detected in the labeling density of gephyrin, a GABAergic synaptic marker, lining the postsynaptic membrane. Furthermore, virtually all inhibitory synaptic clefts remained rigidly apposed, unlike in the case of excitatory synapses where ~ 20-30% of cleft edges were open upon stimulation, presumably to facilitate the clearance of neurotransmitters from the cleft. The fact that no open clefts were induced in inhibitory synapses upon stimulation suggests that inhibitory input may not need to be toned down under these conditions. On the other hand, similar to excitatory synapse, EGTA (a calcium chelator) induced open clefts in ~ 18% of inhibitory synaptic cleft edges, presumably disrupting similar calcium-dependent trans-synaptic bridges in both types of synapses.

The administration of a phentolamine infusion into the basolateral amygdala enhances long-term memory and diminishes anxiety-like behavior in stressed rats.

The basolateral amygdala (BLA) contains adrenergic receptors, which are known to be involved in stress, anxiety, and memory. The objective of this study was to explore whether inhibition of α-adrenergic receptors (by phentolamine, an α-adrenergic receptor antagonist) in the BLA can reduce foot-shock stress-induced anxiety-like behavior, memory deficits, and long-term potentiation (LTP) deficits within the CA1 region of the rat hippocampus. Forty male Wistar rats were assigned to the intact, control, stress (Str), Phent (phentolamine), and Phent + Str groups. Animals were subjected to six shocks on 4 consecutive days, and phentolamine was injected into BLA 20 min before the animals were placed in the foot-shock stress apparatus. Results from the elevated plus maze test (EPM) revealed a reduction in anxiety-like behaviors (by an increased number of entries into the open arm, percentage of time spent in the open arm, and rearing and freezing) among stressed animals upon receiving injections of phentolamine into the BLA. The open-field test results (increased rearing, grooming, and freezing behaviors) were consistent with the EPM test results. Phentolamine infusion into the BLA enhanced spatial memory, reducing errors in finding the target hole and decreasing latency time in the Barnes maze test for stress and nonstress conditions. Injecting phentolamine into the BLA on both sides effectively prevented LTP impairment in hippocampal CA1 neurons after being subjected to foot-shock stress. It has been suggested that phentolamine in the BLA can effectively improve anxiety-like behaviors and memory deficits induced by foot-shock stress.

Harmful Effects on the Hippocampal Morpho-Histology and on Learning and Memory in the Offspring of Rats with Streptozotocin-Induced Diabetes

Learning alterations in the child population may be linked to gestational diabetes as a causal factor, though this remains an open and highly controversial question. In that sense, it has been reported that maternal hyperglycemia generates a threatening condition that affects hippocampal development in offspring. The pyramidal cells of the CA3 subfield, a key structure in learning and memory processes, are particularly important in cognitive deficiencies. We evaluate the effect of the hyperglycemic intrauterine environment on hippocampal histomorphometry in offspring, correlating it with spatial learning and memory, as well as the morphology of dendrites and spines in 30-day-old pups (P30). The maternal hyperglycemia affected the body weight, height, and brain size of fetuses at 21 days of gestation (F21), newborn pups (P0) and P30 pups from diabetic rats, which were smaller compared to the control group. Consequently, this resulted in a decrease in hippocampal size, lower neuronal density and cytoarchitectural disorganization in the CA3 region of the hippocampus in the offspring at the three ages studied. The behavioral tests performed showed a direct relationship between morpho-histological alterations and deficiencies in learning and memory, as well as alterations in the morphology of the dendrites and spines. Therefore, knowing the harmful effects caused by gestational diabetes can be of great help to establish therapeutic and educational strategies that can help to improve learning and memory in children.

PFKFB3 ameliorates ischemia-induced neuronal damage by reducing reactive oxygen species and inhibiting nuclear translocation of Cdk5.

The enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB) plays an essential role in glycolysis and in the antioxidant pathway associated with glutathione. Therefore, we investigated the effects of PFKFB3 on oxidative and ischemic damage. We synthesized a fusion protein of transactivator of transcription (Tat)-PFKFB3 to facilitate its passage into the intracellular space and examine its effects against oxidative stress induced by hydrogen peroxide (H2O2) treatment and ischemic damage caused by occlusion of the common carotid arteries for 5min in gerbils. The Tat-PFKFB3 protein was efficiently delivered into HT22 cells in a concentration- and time-dependent manner, with higher levels observed 18h after treatment. Furthermore, treatment with 6 µM Tat-PFKFB3 demonstrated intracellular delivery into HT22 cells, as analyzed through immunocytochemical staining. Moreover, it significantly ameliorated the reduction of cell viability induced by 200 µM H2O2 treatment. Tat-PFKFB3 treatment also alleviated H2O2-induced DNA fragmentation and reactive oxygen species formation in HT22 cells. In gerbils, the intraperitoneal administration of 2mg/kg Tat-PFKFB3 efficiently delivered the substance to all hippocampal areas, including the hippocampal CA1 region. This administration significantly mitigated ischemia-induced hyperlocomotion, long-term memory deficits, and ischemic neuronal death in the hippocampal CA1 region after ischemia. Additionally, treatment with 2mg/kg Tat-PFKFB3 significantly ameliorated the translocation of Cdk5 from the cytosol to the nucleus in the hippocampal CA1 region 24h after ischemia, but not in other regions. The treatment also significantly reduced reactive oxygen species formation in the CA1 region. These findings suggest that Tat-PFKFB3 reduces neuronal damage in the hippocampal CA1 region after ischemia through the reduction of Cdk5 signaling and reactive oxygen species formation. Therefore, Tat-PFKFB3 may have potential applications in reducing ischemic damage.