OBJECTIVE: To observe the effect of Huayu Tongluo moxibustion on the NOD-like receptor protein 3 (NLRP3)/cysteine-aspartic acid protease-1 (Caspase-1)/gasdermin D (GSDMD) signaling pathway in rats with vascular dementia (VD), and to explore its mechanism in improving learning and memory ability and alleviating neuronal injury in the hippocampal CA1 region. METHODS: A total of 80 SPF-grade male Wistar rats were included. Three rats were excluded based on the Morris water maze test. From the remaining rats, 12 were randomly selected as the sham operation group. The rest were used to establish VD models via modified bilateral common carotid artery ligation. Thirty-six successfully modeled rats were randomly divided into a model group, a medication group, and a moxibustion group, with 12 rats in each group. The medication group was treated with nimodipine solution (12 mg/kg) via gavage. The moxibustion group was treated with Huayu Tongluo moxibustion. The suspended moxibustion was applied at Shenting (GV24) and Dazhui (GV14), and aconite cake-separated moxibustion was applied at Baihui (GV20), with each acupoint treated for 20 min. All treatments were administered once daily for 21 consecutive days. Before and after modeling, and after intervention, the Morris water maze test was used to assess cognitive function. After intervention, the activation and morphology of microglia in the hippocampal CA1 region were observed by immunofluorescence. Ultrastructure of hippocampal CA1 neurons was examined by transmission electron microscopy. Western blot was used to detect protein expression of NLRP3, apoptosis-associated speck-like protein (ASC), Caspase-1, GSDMD, and interleukin-1β (IL-1β) in the hippocampal CA1 region. ELISA was used to detect the content of IL-6, IL-8, and tumor necrosis factor-α (TNF-α) in the hippocampal CA1 region. RESULTS: Compared with the sham operation group, the model group showed longer mean escape latency (P<0.01) and fewer platform crossings (P<0.01); the microglial processes in the hippocampal CA1 region were thickened, cytoplasm was hypertrophic, and relative fluorescence intensity of ionized calcium-binding adapter molecule 1 (IBA-1) was increased (P<0.05); the neuronal ultrastructure in the CA1 region was severely damaged, rough endoplasmic reticulum was swollen, mitochondria were deformed and swollen, some cristae were ruptured or dissolved, showing vacuolar changes; the protein expression of NLRP3, ASC, Caspase-1, GSDMD, and IL-1β, as well as levels of IL-6, IL-8, and TNF-α were significantly elevated (P<0.001). Compared with the model group, both the medication group and the moxibustion group showed shortened mean escape latency (P<0.01) and increased platform crossings (P<0.01); the microglial processes were thinner, and IBA-1 fluorescence intensity was decreased (P<0.05); the neuronal ultrastructure in the CA1 region was partially improved; the protein expression of NLRP3, ASC, Caspase-1, GSDMD, and IL-1β, and levels of IL-6, IL-8, and TNF-α were significantly reduced (P<0.001). Compared with the medication group, the moxibustion group showed shortened mean escape latency (P<0.05) and more platform crossings (P<0.05); the IBA-1 fluorescence intensity was decreased (P<0.05); the neuronal ultrastructure in the CA1 region was improved; the protein expression of NLRP3, ASC, Caspase-1, GSDMD, and IL-1β, as well as levels of IL-6, IL-8, and TNF-α, were significantly lower (P<0.001). CONCLUSION The Huayu Tongluo moxibustion could enhance learning and memory abilities in VD rats, inhibit excessive activation of microglia, and alleviate neuronal injury in the hippocampal CA1 region. Its mechanism may involve modulation of the NLRP3/Caspase-1/GSDMD signaling pathway, reduction of inflammatory responses.
Animals ; Male ; Dementia, Vascular/physiopathology* ; Rats ; Signal Transduction ; Moxibustion ; Rats, Wistar ; CA1 Region, Hippocampal/injuries* ; NLR Family, Pyrin Domain-Containing 3 Protein/genetics* ; Caspase 1/genetics* ; Memory ; Humans ; Neurons/metabolism* ; Learning

OBJECTIVES: To investigate the neural mechanisms of rhythmic activity in the hippocampal CA1 region and orbitofrontal cortex (OFC) during a spatial goal-directed task. METHODS: Four long-Evans rats were trained to perform a spatial goal-directed task in a land-based water maze (Cheese-board maze). The task was divided into 5 periods: Pre-test, Pre-sleep, Learning, Post-sleep, and Post-test. During the Learning phase, the task was split into two goal navigation and two reward acquisition processes with a total of 8 learning stages. Local field potentials (LFP) from the CA1 and the OFC were recorded, and power spectral density analysis was performed on Theta (6-12 Hz), Beta (15-30 Hz), Low gamma (30-60 Hz), and High gamma (60-90 Hz) bands. Coherence, phase-locking value (PLV), and phase-amplitude cross coupling (PAC) were used to assess the interactions between the CA1 and the OFC during learning and memory. RESULTS: During the task training, the rats showed consistent rhythms of OFC neural activity across the task states (P>0.05) while exhibiting significant changes in Beta and High gamma rhythms in the CA1 region (P<0.05). Coherence and PLV between the CA1 and the OFC were higher during goal navigation, especially in the stable learning phase (Stage 8 vs Stage 1, P<0.01). The rats showed stronger cross-frequency coupling between CA1-Theta and OFC-Low gamma in the Post-test phase than in the Pre-test phase (P<0.05). CONCLUSIONS Learning and memory consolidation in goal-directed tasks involve synchronized activity between the CA1 region and the OFC, and cross-frequency coupling plays a key role in maintaining short-term memory of reward locations in rats.
Animals ; Rats ; Rats, Long-Evans ; CA1 Region, Hippocampal/physiology* ; Memory Consolidation/physiology* ; Prefrontal Cortex/physiology* ; Maze Learning/physiology* ; Goals ; Male ; Memory/physiology* ; Learning/physiology*

Early-life stress (ES) leads to cognitive dysfunction in female adolescents, but the underlying neural mechanisms remain elusive. Recent evidence suggests that the cell adhesion molecules NECTIN1 and NECTIN3 play a role in cognition and ES-related cognitive deficits in male rodents. In this study, we aimed to investigate whether and how nectins contribute to ES-induced cognitive dysfunction in female adolescents. Applying the well-established limited bedding and nesting material paradigm, we found that ES impairs recognition memory, suppresses prefrontal NECTIN1 and hippocampal NECTIN3 expression, and upregulates corticotropin-releasing hormone (Crh) and its receptor 1 (Crhr1) mRNA levels in the hippocampus of adolescent female mice. Genetic experiments revealed that the reduction of dorsal CA1 (dCA1) NECTIN3 mediates ES-induced object recognition memory deficits, as knocking down dCA1 NECTIN3 impaired animals' performance in the novel object recognition task, while overexpression of dCA1 NECTIN3 successfully reversed the ES-induced deficits. Notably, prefrontal NECTIN1 knockdown did not result in significant cognitive impairments. Furthermore, acute systemic administration of antalarmin, a CRHR1 antagonist, upregulated hippocampal NECTIN3 levels and rescued object and spatial memory deficits in stressed mice. Our findings underscore the critical role of dCA1 NECTIN3 in mediating ES-induced object recognition memory deficits in adolescent female mice, highlighting it as a potential therapeutic target for stress-related psychiatric disorders in women.
Animals ; Female ; Mice ; CA1 Region, Hippocampal/metabolism* ; Cell Adhesion Molecules/metabolism* ; CRF Receptor, Type 1/metabolism* ; Memory Disorders/etiology* ; Mice, Inbred C57BL ; Nectins/genetics* ; Receptors, Corticotropin-Releasing Hormone/antagonists & inhibitors* ; Recognition, Psychology/physiology* ; Stress, Psychological/complications*

Growth arrest DNA damage-inducible protein 45 β (GADD45B) has been reported to be a regulatory factor for active DNA demethylation and is implicated in the modulation of synaptic plasticity and chronic stress-related psychopathological processes. However, its precise role and mechanism of action in stress susceptibility remain elusive. In this study, we found a significant reduction in GADD45B expression specifically in the ventral, but not the dorsal hippocampal CA1 (dCA1) of stress-susceptible mice. Furthermore, we demonstrated that GADD45B negatively regulates susceptibility to social stress and NMDA receptor-dependent long-term potentiation (LTP) in the ventral hippocampal CA1 (vCA1). Importantly, through pharmacological inhibition using the NMDA receptor antagonist MK801, we provided further evidence supporting the hypothesis that GADD45B potentially modulates susceptibility to social stress by influencing NMDA receptor-mediated LTP. Collectively, these results suggested that modulation of NMDA receptor-mediated synaptic plasticity is a pivotal mechanism underlying the regulation of susceptibility to social stress by GADD45B.
Animals ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; CA1 Region, Hippocampal/drug effects* ; Male ; Stress, Psychological/physiopathology* ; Mice ; Neuronal Plasticity/drug effects* ; Long-Term Potentiation/drug effects* ; Mice, Inbred C57BL ; Antigens, Differentiation/metabolism* ; Dizocilpine Maleate/pharmacology* ; Excitatory Amino Acid Antagonists/pharmacology* ; GADD45 Proteins

Learning-associated functional plasticity at hippocampal synapses remains largely unexplored. Here, in a single session of reward-based trace conditioning, we examine learning-induced synaptic plasticity in the dorsal CA1 hippocampus (dCA1). Local field-potential recording combined with selective optogenetic inhibition first revealed an increase of dCA1 synaptic responses to the conditioned stimulus (CS) induced during conditioning at both Schaffer collaterals to the stratum radiatum (Rad) and temporoammonic input to the lacunosum moleculare (LMol). At these dCA1 inputs, synaptic potentiation of CS-responding excitatory synapses was further demonstrated by locally blocking NMDA receptors during conditioning and whole-cell recording sensory-evoked synaptic responses in dCA1 neurons from naive animals. An overall similar time course of the induction of synaptic potentiation was found in the Rad and LMol by multiple-site recording; this emerged later and saturated earlier than conditioned behavioral responses. Our experiments demonstrate a cued memory-associated dCA1 synaptic plasticity induced at both Schaffer collaterals and temporoammonic pathways.
Animals ; CA1 Region, Hippocampal/physiology* ; Male ; Association Learning/physiology* ; Neuronal Plasticity/physiology* ; Cues ; Memory/physiology* ; Synapses/physiology* ; Conditioning, Classical/physiology* ; Excitatory Postsynaptic Potentials/physiology* ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; Rats ; Optogenetics

Neuropathic pain is frequently comorbidity with cognitive deficits. Neuralized1 (Neurl1)-mediated ubiquitination of CPEB3 in the hippocampus is critical in learning and memory. However, the role of Neurl1 in the cognitive impairment in neuropathic pain remains elusive. Herein, we found that lumbar 5 spinal nerve ligation (SNL) in male rat-induced neuropathic pain was followed by learning and memory deficits and LTP impairment in the hippocampus. The Neurl1 expression in the hippocampal CA1 was decreased after SNL. And this decrease paralleled the reduction of ubiquitinated-CPEB3 level and reduced production of GluA1 and GluA2. Overexpression of Neurl1 in the CA1 rescued cognitive deficits and LTP impairment, and reversed the reduction of ubiquitinated-CPEB3 level and the decrease of GluA1 and GluA2 production following SNL. Specific knockdown of Neurl1 or CPEB3 in bilateral hippocampal CA1 in naïve rats resulted in cognitive deficits and impairment of synaptic plasticity. The rescued cognitive function and synaptic plasticity by the treatment of overexpression of Neurl1 before SNL were counteracted by the knockdown of CPEB3 in the CA1. Collectively, the above results suggest that the downregulation of Neurl1 through reducing CPEB3 ubiquitination and, in turn, repressing GluA1 and GluA2 production and mediating synaptic plasticity impairment in hippocampal CA1 leads to the genesis of cognitive deficits in neuropathic pain.
Animals ; Male ; Neuralgia/metabolism* ; Rats ; Down-Regulation/physiology* ; Ubiquitination/physiology* ; Neuronal Plasticity/physiology* ; Rats, Sprague-Dawley ; CA1 Region, Hippocampal/metabolism* ; Cognitive Dysfunction/metabolism* ; RNA-Binding Proteins/metabolism* ; Receptors, AMPA/metabolism*

The retrosplenial cortex has been implicated in processing sensory information and spatial learning, with abnormal neural activity reported in association with psychedelics and in mouse and non-human primate models of autism spectrum disorders (ASDs). The direct role of the retrosplenial cortex in regulating social behaviors remains unclear. In this work, we reveal that neural activity in the retrosplenial agranular cortex (RSA), a subregion of the retrosplenial cortex, is initially activated, then quickly suppressed upon social contact. This up-down phase of RSA neurons is crucial for normal social behaviors. Parvalbumin-positive GABAergic neurons in the hippocampal CA1 region were found to send inhibitory projections to the RSA. Blocking these CA1-RSA inhibitory inputs significantly impaired social behavior. Notably, enhancing the CA1-RSA inhibitory input rescued the social behavior defects in an ASD mouse model. This work suggests a neural mechanism for the salience processing of social behavior and identifies a potential target for ASD intervention using neural modulation approaches.
Animals ; Social Behavior ; CA1 Region, Hippocampal/physiology* ; Mice ; Male ; Autism Spectrum Disorder/physiopathology* ; Mice, Inbred C57BL ; GABAergic Neurons/drug effects* ; Neural Inhibition/drug effects* ; Parvalbumins/metabolism* ; Neural Pathways/physiology* ; Cerebral Cortex/physiology*

The aim of the present study was to investigate the effects of different courses of electroacupuncture on synaptic structure and synaptic function-related proteins expression in the hippocampal CA1 region of radiation-induced brain injury mice. Sixty C57BL/6J male mice were randomly divided into control group, radiation-induced brain injury model group, 1-week electroacupuncture group (EA1), 2-week electroacupuncture group (EA2), 3-week electroacupuncture group (EA3), and electroacupuncture-control (EA-Ctrl) group. The mice in model group were exposed to X-ray irradiation (8 Gy, 10 min) to establish radiation-induced brain injury model. The mice in EA groups were acupunctured at electroacupuncture points (Baihui, Fengfu and bilateral Shenshu) for 1 week, 2 weeks and 3 weeks respectively after radiation. Immunohistochemistry was used to observe synaptic structure in hippocampal CA1 region. The expressions of brain-derived neurotrophic factor (BDNF), synapsin-1 and postsynaptic density 95 (PSD95) in the hippocampal CA1 region of each group were detected by RT-PCR and Western blotting. The results showed that the nuclear gap in model and EA-Ctrl groups was significantly decreased compared to control group, however nucleus to cytoplasm ratio was significantly increased. The synaptic cleft, postsynaptic density (PSD) thickness, the mitochondrial surface density, volume density and specific surface area were significantly reduced. Compared with model group, the nucleus to cytoplasm ratio of EA2 group was significantly decreased, the PSD thickness and mitochondrial volume density were significantly increased; the nuclear gap of EA3 group was significantly increased, nucleus to cytoplasm ratio was significantly decreased, synaptic cleft and PSD thickness were significantly increased, and the mitochondrial surface density and specific surface area were all increased significantly. In addition, compared with the control group, the gene and protein expressions of BDNF, synapsin-1 and PSD95 in the hippocampal CA1 region of the model group and EA-Ctrl group were significantly decreased. However, compared with the model group, the gene expression of synapsin-1 in EA groups was significantly up-regulated, the gene expression of BDNF in EA1 and EA2 groups was significantly up-regulated, and the gene expression of PSD95 in EA2 group was significantly up-regulated. Moreover, the protein expressions of BDNF, synapsin-1 and PSD95 of EA groups were significantly up-regulated compared with the model group. These results indicate that the synaptic structure and the expression of synaptic function-related proteins in hippocampal CA1 region were injured by radiation exposure, whereas electroacupuncture intervention can significantly improve the synaptic structure and function damage caused by radiation.
Animals ; Brain Injuries ; CA1 Region, Hippocampal ; Electroacupuncture ; Hippocampus ; Male ; Mice ; Mice, Inbred C57BL

Aldose reductase (AR) protein, a member of the NADPH-dependent aldo-keto reductase family, reduces a wide range of aldehydes and enhances cell survival by inhibition of oxidative stress. Oxidative stress is known as one of the major pathological factor in ischemia. Since the precise function of AR protein in ischemic injury is fully unclear, we examined the function of AR protein in hippocampal neuronal (HT-22) cells and in an animal model of ischemia in this study. Cell permeable Tat-AR protein was produced by fusion of protein transduction domain in Tat for delivery into the cells. Tat-AR protein transduced into HT-22 cells and significantly inhibited cell death and regulated the mitogen-activate protein kinases (MAPKs), Bcl-2, Bax, and Caspase-3 under oxidative stress condition. In an ischemic animal model, Tat-AR protein transduced into the brain tissues through the blood-brain barrier (BBB) and drastically decreased neuronal cell death in hippocampal CA1 region. These results indicate that transduced Tat-AR protein has protective effects against oxidative stress-induced neuronal cell death in vitro and in vivo, suggesting that Tat-AR protein could be used as potential therapeutic agent in ischemic injury.
Aldehyde Reductase ; Aldehydes ; Blood-Brain Barrier ; Brain ; CA1 Region, Hippocampal ; Caspase 3 ; Cell Death ; Cell Survival ; Humans ; In Vitro Techniques ; Ischemia ; Models, Animal ; Neurons ; Oxidative Stress ; Oxidoreductases ; Protein Kinases

To examine the effects of Populus tomentiglandulosa (PT) extract on the expressions of antioxidant enzymes and neurotrophic factors in the cornu ammonis 1 (CA1) region of the hippocampus at 5 min after inducing transient global cerebral ischemia (TGCI) in gerbils, TGCI was induced by occlusion of common carotid arteries for 5 min. Before ischemic surgery, 200 mg·kg PT extract was orally administrated once daily for 7 d. We performed neuronal nuclear antigen immunohistochemistry and Fluoro-Jade B staining. Furthermore, we determined in situ production of superoxide anion radical, expression levels of SOD1 and SOD2 as antioxidant enzymes and brain-derived neurotrophic factor (BDNF) and insulin-like growth factor I (IGF-I) as neurotrophic factors. Pretreatment with 200 mg·kg PT extract prevented neuronal death (loss). Furthermore, pretreatment with 200 mg·kg PT extract significantly inhibited the production of superoxide anion radical, increased expressions of SODs and maintained expressions of BDNF and IGF-I. Such increased expressions of SODs were maintained in the neurons after IRI. In summary, pretreated PT extract can significantly increase levels of SODs and protect the neurons against TGCI, suggesting that PT can be a useful natural agent to protect against TGCI.
Animals ; Brain-Derived Neurotrophic Factor ; genetics ; metabolism ; CA1 Region, Hippocampal ; drug effects ; metabolism ; Gerbillinae ; Humans ; Insulin-Like Growth Factor I ; genetics ; metabolism ; Male ; Neuroprotective Agents ; administration & dosage ; Plant Extracts ; administration & dosage ; Populus ; chemistry ; Pyramidal Cells ; drug effects ; metabolism ; Reperfusion Injury ; drug therapy ; genetics ; metabolism ; Superoxide Dismutase ; genetics ; metabolism ; Up-Regulation ; drug effects