Apoptosis Of Hippocampal Neurons Research Articles

Visualization of Unconjugated Bilirubin In Vivo with a Novel Approach Using Chemical Exchange Saturation Transfer Magnetic Resonance Imaging in a Rat Model.

Unconjugated bilirubin (UCB) visualization is valuable for early bilirubin encephalopathy (BE) diagnosis and management. UCB neurotoxicity is a challenge, necessitating improved imaging modalities for precise localization and characterization. This study developed a noninvasive method for UCB imaging in the brain using chemical exchange saturation transfer (CEST) magnetic resonance imaging, which visualizes UCB distribution through amide-bulk water proton exchange, a process termed bilirubin CEST (Bil-CEST) imaging. Bil-CEST imaging parameters were initially optimized; the exchange rate of the amide protons of UCB was calculated. Bil-CEST imaging characteristics and specificity were assessed using in vitro images of UCB solutions under different conditions and images of other brain metabolites. Bil-CEST maps of the rat brain were collected at the baseline and dynamically, postinjection of the UCB solution or vehicle into lateral ventricles of Sprague-Dawley rats. The model was validated using a water maze and pathological staining. In vitro, the Bil-CEST effect was observed at approximately 5.5 ppm downfield from bulk water. This effect was proportional to the UCB concentration and B1 amplitude. In vivo, Bil-CEST imaging revealed a progressive enhancement following a lateral ventricular UCB injection. Conversely, no significant imaging changes were observed in the vehicle group. Compared with the vehicle group, the UCB group had more hippocampal neuronal apoptosis and worse cognitive function. These findings highlight the utility of Bil-CEST in direct UCB imaging, indicating its potential as a clinically valuable biomarker for BE diagnosis and management.

Electroacupuncture pretreatment alleviates post-stroke spasticity in rats by inhibiting NF-κB/NLRP3 signaling pathway-mediated inflammation and neuronal apoptosis

To explore the mechanism of electroacupuncture pretreatment (EP) for relieving post-stroke spasticity in rats. Eighteen rats were randomized equally into sham-operated group, middle cerebral artery occlusion (MCAO) group, and MCAO+EP group. In MCAO+EP group, the rats received electroacupuncture at the acupoints Qubin and Baihui for 3 consecutive days prior to MCAO. Neurological deficits and cognitive function of the rats were evaluated, and pathologies in the hippocampus were examined using HE, Nissl, and TUNEL staining. The expressions of IL-4, IL-6, TNF-α, and TMAO in the brain tissues were detected with ELISA, and the mRNA and protein expression levels of NF-κB p65, NLRP3, caspase-3, and caspase-9 were determined with qRT-PCR, Western blotting, and immunohistochemistry. The rats receiving MCAO had significantly increased neurological deficit scores and showed increased muscle tension, number of apoptotic neurons, and expressions of IL-6, TNF-α, NF-κB p65, NLRP3, caspase-3 and caspase-9 in the hippocampus and significantly reduced length of time for new object recognition. Microscopically, the cells in the hippocampus of the MCAO rats showed uneven and loosened arrangement and unclear cell boundaries. In contrast, the rats in I/R+EP group showed significantly lowered neurological deficit scores and dystonia rating scores, reduced cell apoptosis, lowered hippocampal expressions of IL-6, TNF-α, caspase-3, caspase-9, and NF-κB p65, increased time for new object recognition, tightly arranged and uniformly stained hippocampal cells with clear boundaries, with also an increased number of active neurons and enhanced expression of IL-4 in the hippocampus. EP alleviates post-stroke spasticity in rats by inhibiting inflammatory responses and hippocampal neuronal apoptosis mediated by the NF-κB/NLRP3 signaling pathway.

Tibetan golden acupuncture inhibits JNK/caspase-3 signaling pathway to alleviate neuronal apoptosis in cerebral ischemia-reperfusion injury

BackgroundApoptosis induced by cerebral ischemia-reperfusion is one of the key pathological processes of nerve injury. Tibetan golden acupuncture (GA) is a common treatment for ischemic brain injury in Tibetan. The aim of this study was to explore whether GA prevents cerebral ischemia-reperfusion-induced apoptosis in mice by blocking the JNK/caspase-3 pathway. MethodsIn experiment I, 36 mice were randomly divided into a Sham group, CI/RI group, CI/RI + GA group. Morris water maze tests, TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining and flow cytometry (FCM) were used to evaluate the effect of the GA intervention on CI/RI. In experiment II, 30 mice were randomly divided into a Sham group, CI/RI group, CI/RI + GA group, CI/RI + SP group and CI/RI + SP + EA group. Western blotting was used to detect protein expression of key factors in the JNK signaling pathway in the hippocampus. ResultsAfter 7 and 14 interventions, behavioral evaluations in CI/RI + GA group was significantly different from those in CI/RI groups (p < 0.01), pathological injury and apoptosis were significantly reduced (p < 0.01). Compared with CI/RI group, the expression of P-JNK/JNK, Cleaved caspase-3/caspase-3, Bax, and Bad proteins in CI/RI + GA group, CI/RI + SP and CI/RI + SP + GA groups were significantly decreased (p < 0.01). The expression of B-cell lymphoma 2 (Bcl-2) was significantly increased (p < 0.01, p < 0.05). ConclusionsGA can restore neurological dysfunction and inhibit hippocampal neuronal apoptosis in CI/RI mice, at least partially through inhibition of the JNK/Caspase-3 signaling pathway and regulation of apoptosis signals.

Effect of remimazolam toluene sulfonate on the cognitive function of juveniles and its mechanism of action

Remimazolam is a new benzodiazepine. Currently, it remains unclear how repeated exposure to remimazolam affects the cognitive function of the developing brain. In the present study, the equivalent doses of the two sedatives were derived from S-shaped dose–response curves, and the ED95 of remimazolam was 45 mg/kg (95% CI 37.579–79.280), and for midazolam, it was 77 mg/kg (95% CI 63.751–127.21) using probability analysis. Then, we evaluated the effects of remimazolam and midazolam on cognitive function in juvenile mice (C57BL/6) through Y-maze and MWM. TUNEL staining was used to observe the apoptosis of neurons in hippocampus, western blotting was used to detect the expression changes of related proteins, and the changes of LTP were observed by recording the activity of neurons through electrical stimulation. We found that there was no significant difference in the behavior of mice in MWM. However, the short-term memory of developing mice was impaired in Y-maze after repeated exposure to remimazolam and midazolam. Furthermore, our data demonstrated that the short-term memory damage caused by remimazolam is lighter than midazolam. Concurrently, the extent of caspase-3 upregulation, the number of neuronal apoptosis in CA1 and CA3 regions, a downward trend of PSD95 and BDNF in the hippocampus, and the inhibition of LTP were highly consistent with the behavior of short-term memory impairment. These results indicate that the degree of memory impairment caused by remimazolam is milder than that caused by midazolam, making it a potential replacement for midazolam in repeated medication and long-term sedation in children.

(+)-Borneol inhibits neuroinflammation and M1 phenotype polarization of microglia in epileptogenesis through the TLR4-NFκB signaling pathway.

To investigate the effect of (+)-borneol on neuroinflammation and microglia phenotype polarization in epileptogenesis and its possible mechanism. Based on mouse models of status epilepticus (SE) induced by pilocarpine, and treated with 15 mg/kg (+)-borneol, western-blot was used to detect the expressions of NeuN, Iba-1, TLR4, p65 and p-p65 in the hippocampus. Immunofluorescence was used to detect the expression of apoptosis-related proteins Bax and Bcl-2. To explore the effect of (+)-borneol on microglia in vitro, we used the kainic acid-induced microglia model and the concentration of (+)-borneol was 25 μM according to CCK-8 results. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-10 (IL-10) in the supernatant of each group was detected by ELISA. The nitric oxide (NO) content in the supernatant was detected by Griess method. The expressions of Iba-1 and TLR4-NFκB signaling pathway-related proteins (TLR4, p65, p-p65) were detected by Western-Blot. Immunofluorescence was used to detect microglia's M1 and M2 phenotype polarization and the expression of Iba-1 and TLR4. (+)-borneol reduced hippocampal neuronal injury, apoptosis, and microglia activation by inhibiting the TLR-NFκB signaling pathway in SE mice. TLR4 agonist LPS partially reversed the neuroprotective effect of (+)-borneol. In the KA-induced microglia model, (+)-borneol inhibited microglia activation, M1 phenotype polarization, and secretion of pro-inflammatory cytokines through the TLR4-NFκB signaling pathway. LPS treatment inhibited the therapeutic effects of (+)-borneol. (+)-borneol inhibits microglial neuroinflammation and M1 phenotype polarization through TLR4-NFκB signaling pathway and reduces neuronal damage and apoptosis in SE mice. Therefore, (+)-borneol may be a potential drug for epilepsy modification therapy.

Mitochondrial transplantation following cardiopulmonary resuscitation improves neurological function in rats by inducing M2-type MG/MΦ polarization

AimExplore the effects of mitochondrial transplantation (MT) after cardiopulmonary resuscitation (CPR) on the polarization of microglia/macrophages (MG/MΦ) and neurological function.MethodsSeventy-five Sprague-Dawley rats were randomly divided into five groups: sham, normal saline (NS), vehicle, mitochondria (Mito), and non-functional mitochondria (N-Mito) group. Rats in sham group underwent surgical procedures without cardiac arrest, while the other four groups underwent cardiac arrest and CPR, and then received NS, respiration buffer, mitochondrial suspension or non-functional mitochondria, immediately after the restoration of spontaneous circulation (ROSC). The number of mitochondria in the hippocampus, the morphology and structure of mitochondria in MG/MΦ, the phenotype of MG/MΦ, and hippocampal tissue injury, neuroinflammation, and neuronal apoptosis were detected on days 1 and 3 after ROSC. Neurodeficit score (NDS) was performed on days 1, 3, 7, 15 and 30 after ROSC.ResultsCompared with other groups, the number of mitochondria in the hippocampus was increased, and the morphology and structure of mitochondria in MG/MΦ were significantly improved in the Mito group. Our results show higher expression of M2-type markers in MG/MΦ and decreased hippocampal tissue damage in the Mito group. Levels of NSE and S100β in serum, and TNF-α, IL-6 in the hippocampus were decreased, while the levels of TGF-β and IL-10 were increased in the Mito group. Apoptosis rate of neurons in the Mito group was decreased and the NDS of the Mito group was higher than the other groups.ConclusionsExogenous MT can improve neurological function after CPR by promoting the polarization of MG/MΦ to M2-type cells, and this could be a potential method for brain protection after CPR.

The involvement of lidocaine in amyloid-β1-42-dependent mitochondrial dysfunction and apoptosis in hippocampal neurons via nerve growth factor-protein kinase B pathway.

This project is conceived to reveal the role of lidocaine in the process of Alzheimer's disease (AD) and its possible downstream targets. After the employment of AD cell model in mice hippocampal neuronal HT-22 cells in the presence of amyloid-β1-42 (Aβ1-42), Cell Counting Kit-8 method investigated cell viability. Oxidative damage was assayed based on a dichloro-dihydro-fluorescein diacetate fluorescent probe and commercially available kits. The 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide fluorescent probe estimated mitochondrial function. Terminal-deoxynucleotidyl transferase mediated nick end labeling, western blotting, and immunofluorescence appraised the apoptotic level. Western blot also ascertained the alternations of nerve growth factors (NGF)-protein kinase B (Akt) pathway-related proteins. Aβ1-42 concentration dependently triggered the viability loss, oxidative damage, and apoptosis in HT-22 cells. Lidocaine promoted the viability and reduced the mitochondrial impairment and mitochondria-dependent apoptosis in Aβ1-42-treated HT-22 cells in a concentration-dependent manner. Besides, lidocaine activated the NGF-Akt pathway and NGF absence blocked NGF-Akt pathway, aggravated mitochondrial dysfunction as well as mitochondria-dependent apoptosis in lidocaine-administrated HT-22 cells in response to Aβ1-42. Altogether, these observations concluded that lidocaine might stimulate NGF-Akt pathway to confer protection against mitochondrial impairment and apoptosis in Aβ1-42-mediated cellular model of AD.

Yeast Extract Peptides Alleviate Depression in Chronic Restraint Stress Rats by Alleviating Hippocampal Neuronal Apoptosis and Dysbiosis of the Gut Microbiota.

Depression as a global neurological disorder, and hippocampal neuronal apoptosis and disorders of the gut microbiota are closely related to it. This study aims to expose the ameliorative effect of enzyme peptides (AP) from brewer's yeast on depressive behavior caused by chronic restraint stress (CRS) in rats. After 4 weeks of AP intervention, a significant alleviation of depressive behavior in the sucrose preference test (SPT), forced swim test (FST), and light-dark test (LDT) is observed in depressed rats. AP ameliorates neuronal damage with increased the expression of the key CREB/BDNF/TrkB/Akt signaling pathway, which increases the levels of the monoamine neurotransmitters 5-hydroxytryptamine (5-HT) and norepinephrine (NE) in the hippocampus, buffering hyperactivity of the hypothalamo-pituitary-adrenal axis (HPA), and decreasing the serum cortisol (CORT) and adrenocorticotropic hormone (ACTH) levels in rats. In addition, AP modulates the disruption of the rat gut microbiota by chronic restraint stress (CRS), and the changes in the abundance of Lactobacillus animalis and Lactobacillus johnsonii are probably the key for AP performing antidepressant benefits. A strong correlation is found between gut microbiota and biochemical markers of depression. AP, as a natural and safe active substance, has a positive effect in the treatment of depression.

HINT1 promotes neuronal apoptosis and triggers schizophrenia-like behavior in rats

This study aims to investigate the mechanism by which Histidine triad nucleotide-binding protein 1 (HINT1) promotes hippocampal neuronal apoptosis, triggering schizophrenia (SZ)-like behavior in rats. By establishing a rat SZ-like model, we assessed learning, memory, emotional response, and cognitive function through the Morris Water Maze, auditory startle response, and open field tests. HINT1 expression in the hippocampus was analyzed via RT-PCR and Western blot. We also created a HINT1 overexpression model in hippocampal neuronal cells to analyze its effects on cell proliferation and apoptosis. This analysis was conducted using the CCK-8 assay and flow cytometry, along with the quantification of apoptosis-related proteins and neurotrophic factors. Our findings indicated that the SZ-like model rats exhibited diminished learning and memory abilities, altered emotional reactions, and impaired cognitive functions, alongside a notable increase in HINT1 mRNA and protein levels. HINT1 overexpression was observed to inhibit hippocampal neuronal cell proliferation and promote apoptosis, with an increase in the expression of pro-apoptotic proteins and a decrease in neurotrophic factors. These results suggest HINT1's role in the onset and development of SZ-like behavior through its upregulation and induction of apoptosis in hippocampal neuronal cells, underlining its potential as a therapeutic target.

Relation of telomere length and apoptosis in the hippocampus of Alzheimer’s male rats after twelve weeks of combined exercise

Background. Apoptosis of the nerve tissue, especially the hippocampus, has been introduced as one of the potential causes of neurological diseases such as Alzheimer’s disease, and it may be related to telomere length. In addition, exercise affects various aspects of nerve cell activity and may prevent their death. Based on this, the aim of this study was to investigate the relationship between telomere length and apoptosis of hippocampal neurons after 12 weeks of combined exercise in Alzheimer's rats. Methods. Overall, 35 male Wistar rats (weight 174±22g) were divided into control, Alzheimer’s, aerobic, resistance, and combined groups, each including 7 animals. Alzheimer’s was induced, and 8 mg/kg of trimethyltin was injected intraperitoneally. The groups of training were implemented for 12 weeks/5 days a week. After anesthetizing and perfusing the rats, the hippocampal tissue was isolated, and a real-time polymerase chain reaction was used to measure gene expression using the Master-mix Ampliqon and Synaclon DNA synthesis kit. Differences were determined by a one-way analysis of variance, and groups were compared by using Tukey’s post hoc test (P≤0.05). Results. Overall, 35 male Wistar rats (weight 174±22g) were divided into control, Alzheimer’s, aerobic, resistance, and combined groups, each including 7 animals. Alzheimer’s was induced, and 8 mg/kg of trimethyltin was injected intraperitoneally. The groups of training were implemented for 12 weeks/5 days a week. After anesthetizing and perfusing the rats, the hippocampal tissue was isolated, and a real-time polymerase chain reaction was used to measure gene expression using the Master-mix Ampliqon and Synaclon DNA synthesis kit. Differences were determined by a one-way analysis of variance, and groups were compared by using Tukey’s post hoc test (P&lt;0.05). Conclusion. It seems that performing combined exercise (swimming and resistance) is effective in improving the telomere length and decreasing the apoptosis of Alzheimer’s rats’ hippocampus. Practical Implications. Performing combined sports activities (aerobic and strength) effectively improves telomeres while reducing neuron apoptosis.

Low-frequency rTMS Plays a Neuroprotective role in Pilocarpine-induced Status Epilepticus Rat Models Through the AMPAR GluA1-STIM-Ca2+ Pathway.

Low-frequency repetitive transcranial magnetic stimulation (rTMS) refers to the stimulation of the brain using repetitive magnetic field pulses at a low frequency (≤ 1Hz) to reduce seizures. Currently, the mechanism is not well understood.Male Sprague-Dawley rats underwent pilocarpine-induced status epilepticus (SE) and were then stimulated with low-frequency rTMS. An epilepsy cell model was then established by incubating rat hippocampal neurons with Mg2+-free extracellular fluids. The effects of the low-frequency rTMS on epileptogenesis and hippocampal neuron injury were evaluated using a video electroencephalogram (vEEG) and Nissl staining, and the expression of AMPAR GluA1 and STIM in the hippocampus and hippocampal neurons was assessed using western blot and immunofluorescence. Additionally, the intracellular Ca2+ concentration and reactive oxygen species (ROS) were measured using flow cytometry.Low-frequency rTMS attenuated spontaneous recurrent seizures in rats with epilepsy, with the SE group exhibiting a higher incidence (100%) and frequency (3.00 ± 0.18 times/day) than the SE + 0.3 (50% incidence, 0.06 ± 0.03 times/day), SE + 0.5 (0.20 ± 0.02 times/day) and SE + 1Hz (1.02 ± 0.05 times/day) groups. Additionally, rTMS reduced the damage and apoptosis of hippocampal pyramidal neurons, increasing their numbers in the CA1 and CA3 regions. Furthermore, AMPAR GluA1 and STIM expression were upregulated in the hippocampus when using rTMS, reversing the downregulation caused by seizures. Immunofluorescence verified the increased fluorescence intensity of AMPAR GluA1 and STIM. Moreover, rTMS inhibited Ca2+ overload and ROS in epileptic neuron models.Low-frequency rTMS may exert neuroprotective effects through the AMPAR GluA1-STIM-Ca2+ pathway.

Glycyrrhizic Acid Inhibits Hippocampal Neuron Apoptosis by Activating the PI3K/ AKT Signaling Pathway.

Glycyrrhizic acid (GA), one of the main active substances in Glycyrrhiza, has anti-inflammatory, anti-viral, and neuroprotective effects. GA can significantly reduce cerebral infarction size in middle cerebral artery occlusion (MCAO) rats and suppress inflammatory responses. However, the underlying mechanism by which GA protects the neuronal system remains poorly understood. Cell proliferation and viability were tested using CCK-8 and Edu assays. The effects of GA on apoptosis were detected using flow cytometry and Tunel assays. Western blotting was performed to assess protein expression. Behavioral experiments were conducted using the Morris water maze and rotation tests. Infarct size was observed using TTC staining. We report that GA protects neurons by inhibiting apoptosis, mainly through the PI3K/AKT pathway in oxygen-glucose deprivation/reoxygenation (OGD/R) and MCAO rat models. GA increases the viability and proliferation of oxygen- and glucose-deprived hippocampal neurons. Hippocampal neuron apoptosis decreased after GA treatment in vitro and in vivo. Furthermore, we determined that GA treatment increased the active state of PI3K and its downstream protein p-AKT, whereas when using a specific inhibitor of PI3K, Y294002, the levels of p-PI3K and p-AKT decreased. Finally, we showed that GA treatment improved spatial memory and motor coordination in MCAO rats, while TTC staining showed that GA decreased cerebral infarct size in MCAO rats. We reveal that GA protects hippocampal neurons by inhibiting their apoptosis, mainly through the PI3K/AKT signaling pathway.

Gynosaponin ameliorates sevoflurane anesthesia-induced cognitive dysfunction and neuronal apoptosis in rats through modulation of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway.

Anesthetic sevoflurane (Sev) causes cognitive dysfunction and neuronal death when used as an anesthetic during surgical procedures. Gynosaponin (GpS) was studied for its effects on brain morphology and cognitive behaviors in Sevanesthetized rats. The present study investigated whether GpS has an effect on Sev anesthesia-induced abnormalities in brain morphology and cognitive behaviors, as well as on apoptosis and inflammation of neurons in rats, and delved into the molecular mechanisms. Male Sprague-Dawley rats were induced by 3% Sev anesthesia, and GpS was injected into the rats via the tail vein. The in vitro model of Sev anesthesia was constructed by treating primary rat hippocampal neurons with 4.1% Sev in the presence of GpS (5, 10, and 20 μM). The neuroprotective effects of GpS against Sev-induced cognitive deficits in rats were evaluated using the open field and Morris water maze tests. The apoptosis of hippocampal neurons was observed using hematoxylin-eosin (HE staining and TUNEL assay. Cleaved caspase-3 expression and reactive oxygen species production in rat hippocampal tissue were measured by immunofluorescence. Apoptosis-related proteins and the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway were determined via Western blot. Pro-inflammatory factors tumor necrosis factor-α and interleukin-6 were measured via ELISA. Levels of malondialdehyde, superoxide dismutase and glutathione were assayed by commercial kits. Viability and apoptosis of hippocampal neurons were detected by Cell Counting Kit-8 and flow cytometry. Expression of cleaved caspase-3, B-cell leukemia/lymphoma 2 protein (Bcl-2) Bcl-2-associated protein (Bax) was determined by Western blot. GpS significantly reduced Sev-induced decline in short-term memory, learning and cognitive abilities, as well as neuronal degeneration apoptosis and inflammatory responses, GpS also lessened oxidative stress damage, and activated the PI3K/Akt/mTOR pathway (p<0.05). GpS therapy enhanced learning and memory abilities in rats suffering from Sev-induced cognitive deficits. The PI3K/Akt/mTOR pathway inhibitor LY294002 reversed the ameliorative effects of high-dose GpS on cognitive deficits and cell damage in primary hippocampal neurons in Sev anesthetized rats (p<0.05). We conclude that GpS ameliorates Sev-induced neurotoxicity and cognitive dysfunction by modulating the PI3K/Akt/mTOR pathway and alleviating neuronal apoptosis and oxidative stress.

Remimazolam ameliorates postoperative cognitive dysfunction after deep hypothermic circulatory arrest through HMGB1-TLR4-NF-κB pathway

BackgroundPostoperative cognitive dysfunction (POCD) is a complication of deep hypothermic circulatory arrest (DHCA). Various amounts of neurologic dysfunctions have been shown after DHCA, which has often been attributed to systemic inflammatory response syndrome and cerebral ischemia/reperfusion injury. Remimazolam is one of the commonly used anesthetic drugs with protective actions against inflammatory diseases, such as sepsis and cerebral ischemia/reperfusion injury. Here, we determined the protective effect and potential mechanism of action of remimazolam against neuronal damage after DHCA. MethodsA rat model of DHCA was established, and a gradient dosage of remimazolam was administered during cardiopulmonary bypass (CPB). The cognitive function of rats was evaluated by Morris water maze. Hematoxylin and eosin and TUNEL staining were performed to assess hippocampus tissue injury and neuronal apoptosis. Inflammatory cytokines concentration were analyzed by enzyme-linked immunosorbent assay. The protein expression was analyzed using automated electrophoresis western analysis and immunohistochemical analysis. ResultsThe appropriate dosage of remimazolam reduced histologic injury, neuronal apoptosis, microglia activation, and secondary inflammatory cascades, as well as the downregulation of the expression of the HMGB1-TLR4-NF-κB pathway after DHCA, improved the memory and learning abilities in DHCA rats. Further, administration of a TLR4 antagonist TAK-242 had a similar effect to remimazolam, while the TLR4 agonist LPS attenuated the effect of remimazolam. ConclusionsRemimazolam could ameliorate POCD after DHCA through the HMGB1-TLR4-NF-κB signaling pathway.

Impaired learning and memory in male mice induced by sodium arsenite was associated with MMP-2/MMP-9-mediated blood-brain barrier disruption and neuronal apoptosis

Arsenic is a widespread environmental contaminant known to accumulate in the brain, leading to cognitive impairment. However, the exact mechanisms by which arsenic causes cognitive deficits remain unclear. The present study aims to discover whether the destruction of the blood-brain barrier (BBB) mediated by matrix metalloproteinases 2 and matrix metalloproteinases 9 (MMP-2 and MMP-9) and subsequent neuronal apoptosis are involved in arsenic-induced cognitive impairment. Ninety male mice were given 0, 25, and 50 mg/L NaAsO2 in drinking water and 30 mg/kg doxycycline hyclate (DOX, an inhibitor of MMPs) gavage for 12 weeks to observe the alterations in learning and memory of mice, the morphology of hippocampal neurons, as well as the BBB permeability and ultrastructure, the localization and expression of tight junction proteins, MMP-2, and MMP-9. Our findings indicated that arsenic exposure induced learning and memory impairment in mice, accompanied by neuronal loss and apoptosis. Furthermore, arsenic exposure increased hematogenous IgG leakage into the brain, disrupted the tight junctions, reduced the expression of Claudin5, Occludin, and ZO1 in the endothelial cells, and increased the expression of MMP-2 and MMP-9 in the endothelial cells and astrocytes. Finally, DOX intervention preserved BBB integrity, alleviated hippocampal neuronal apoptosis, and improved cognitive impairment in mice caused by arsenic exposure. Our research demonstrates that cognitive disfunction in mice induced by arsenic exposure is associated with MMP-2 and MMP-9-mediated BBB destruction and neuronal apoptosis. The current investigation provides new insights into mechanisms of arsenic neurotoxicity and suggests that MMP-2 and MMP-9 may serve as potential therapeutic targets for treating arsenic-induced cognitive dysfunction in the future.

Deciphering the Protective Role of HIF-1α Downregulation on HIBD through the MALAT1/miR-140-5p/TGFBR1/NF-κB Signaling Pathway.

Hypoxic-ischemic brain damage (HIBD) in neonates is a substantial cause of mortality and neurodevelopmental impairment, with the exact molecular mechanisms still being elucidated. The involvement of HIF-1α, MALAT1, miR-140-5p, TGFBR1, and the NF-κB signaling pathway in such injury cascades is of increasing research interest due to their pivotal roles in cellular and pathological processes. This study aimed to explore how HIF-1α regulates the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis to participate in the molecular mechanisms of HIBD in neonatal rats. Utilizing bioinformatic analyses and a suite of experimental approaches, the study delineated interactions and regulatory relationships among the molecules. Knockdown of HIF-1α was shown to mitigate brain tissue damage in a neonatal HIBD rat model through the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis, revealing a protective effect achieved by inhibiting hippocampal neuron apoptosis and potentially guiding the way toward therapeutic interventions in HIBD. This study implicates the HIF-1α mediated regulation of the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis in the pathological development of HIBD, offering insights into novel potential interventional strategies.

Berberine Alleviates Sevoflurane Anesthesia-Induced Cognitive Dysfunction in Neonatal Mice via Regulating CREB1.

Sevoflurane has been shown to stimulate neurotoxicity and lead to cognitive impairment. Berberine is known for its role in regulating nervous system diseases, including cognitive dysfunction. This study aimed to investigate the effects of berberine on cognitive dysfunction induced by sevoflurane anesthesia and its potential mechanisms. In the in vivo study, neonatal mice were subjected to sevoflurane anesthesia to induce cognitive dysfunction. The cognitive function of the neonatal mice was evaluated using the Morris water maze test, open field test, and tail suspension test. Enzyme-linked immunosorbent assay (ELISA) was utilized to assess the levels of inflammatory factors. Immunohistochemistry (IHC) was conducted to detect ionized calcium-binding adaptor molecule 1 (IBA-1)-positive cells and cleaved caspase-3-positive cells in the hippocampus of the neonatal mice. Western blotting was used to measure the levels of cyclic adenosine monophosphate (cAMP) response element-binding protein 1 (CREB1) in hippocampal tissues and neurons. Hippocampal neurons were isolated from the hippocampus of neonatal mice. These neurons were treated with berberine or subjected to cell transfection. The cell counting kit-8 (CCK-8) assay and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay were conducted to measure cell viability and apoptosis of hippocampal neurons in vitro. Berberine significantly attenuated sevoflurane-induced cognitive impairment and inflammation in neonatal mice (p < 0.05 or p < 0.01). Additionally, berberine reduced sevoflurane-triggered neuronal apoptosis in the hippocampus of neonatal mice (p < 0.01). Sevoflurane markedly decreased CREB1 expression in the hippocampus of neonatal mice (p < 0.01), which was elevated by berberine treatment (p < 0.01). Mechanistically, sevoflurane significantly suppressed cell viability and promoted cell apoptosis of hippocampal neurons (p < 0.0001 or p < 0.01), which were mitigated by berberine (p < 0.05, p < 0.01, or p < 0.001). Furthermore, berberine significantly elevated CREB1 expression in sevoflurane-treated hippocampal neurons (p < 0.01). The beneficial effects of berberine on cell viability and apoptosis in sevoflurane-treated hippocampal neurons were blocked by CREB1 depletion (p < 0.001). Our results demonstrated that CREB1 was significantly decreased in the hippocampus of sevoflurane-treated neonatal mice in vivo and in sevoflurane-treated hippocampal neurons in vitro. This decrease was mitigated by berberine treatment. Moreover, berberine improved sevoflurane anesthesia-induced cognitive impairment in neonatal mice by attenuating neuronal inflammation and apoptosis in vivo. The inhibitory effects of berberine on sevoflurane-induced cell apoptosis were reversed by CREB1 downregulation. These findings indicate that berberine protects against sevoflurane anesthesia-induced cognitive impairment by reducing apoptosis of hippocampal neurons, partially through increasing CREB1 expression.

Genetic patterning in hippocampus of rat undergoing impaired spatial memory induced by long-term heat stress

The organism's normal physiological function is greatly impacted in a febrile environment, leading to the manifestation of pathological conditions including elevated body temperature, dehydration, gastric bleeding, and spermatogenic dysfunction. Numerous lines of evidence indicate that heat stress significantly impacts the brain's structure and function. Previous studies have demonstrated that both animals and humans experience cognitive impairment as a result of exposure to high temperatures. However, there is a lack of research on the effects of prolonged exposure to high-temperature environments on learning and memory function, as well as the underlying molecular regulatory mechanisms. In this study, we examined the impact of long-term heat stress exposure on spatial memory function in rats and conducted transcriptome sequencing analysis of rat hippocampal tissues to identify the crucial molecular targets affected by prolonged heat stress exposure. It was found that the long-term heat stress impaired rats' spatial memory function due to the pathological damages and apoptosis of hippocampal neurons at the CA3 region, which is accompanied with the decrease of growth hormone level in peripheral blood. RNA sequencing analysis revealed the signaling pathways related to positive regulation of external stimulation response and innate immune response were dramatically affected by heat stress. Among the verified differentially expressed genes, the knockdown of Arhgap36 in neuronal cell line HT22 significantly enhances the cell apoptosis, suggesting the impaired spatial memory induced by long-term heat stress may at least partially be mediated by the dysregulation of Arhgap36 in hippocampal neurons. The uncovered relationship between molecular changes in the hippocampus and behavioral alterations induced by long-term heat stress may offer valuable insights for the development of therapeutic targets and protective drugs to enhance memory function in heat-exposed individuals.

The impact of dexmedetomidine on ketamine-induced neurotoxicity and cognitive impairment in young mice.

The potential neuroprotective effects of dexmedetomidine against ketamine-induced neurotoxicity remain inconclusive. This study aims to investigate the influence of dexmedetomidine on ketamine-induced neuronal apoptosis and neurodevelopmental toxicity. In vitro experiments employed concentrations of 0.1uM for dexmedetomidine and 50 uM for ketamine individually as well as their combination. Changes in apoptotic proteins and dendritic development in neurons were assessed after a 6-h exposure to the drugs with evaluations conducted 24hs' post-treatment. In vivo experiments entailed intraperitoneal administration starting from postnatal Day 7 (P7) continuously for 3days (P7-P9) using dosages of 100 mg/kg for ketamine and 1mg/kg for dexmedetomidine alone or combined. Learning, memory and motor coordination abilities were evaluated via rotary rod tests and shuttle box experiments at P30 and P60, respectively. Dexmedetomidine effectively mitigated ketamine-induced apoptosis in hippocampal neurons but did not alleviate associated dendritic developmental abnormalities. Although causing reduced motor coordination in mice, no improvement was observed with regard to this effect or reaction speed when treated with dexmedetomidine alongside ketamine. This study demonstrates that while dexmedetomidine can mitigate ketamine-induced neuronal apoptosis, it has limited impact on its associated neurodevelopmental toxicities.

Diosmin ameliorates inflammation, apoptosis and activates PI3K/AKT pathway in Alzheimer's disease rats.

Alzheimer's disease (AD), a prevalent cognitive disorder among the elderly, is frequently linked to the abnormal accumulation of myloid-β (Aβ), which is mainly as a result of neuronal death and inflammation. Diosmin, a flavonoid, is considered a potential drug for the treatment of AD. Our study aimed to uncover the molecular mechanism of diosmin in AD therapy. Here, rats were randomly divided into three groups: control, Aβ25-35, and Aβ25-35 + diosmin groups. AD model rats were induced by Aβ25-35 intraventricular injection, meanwhile 50mg/kg diosmin was orally administered for 6-week intervention. Morris water maze test assessed learning and memory abilities. Hippocampal neuronal damage was determined by HE, Nissl, and TUNEL staining. These assays indicate that diosmin improves cognitive dysfunction and reduces hippocampal neuronal loss and apoptosis. Western blot showed that diosmin reduced Bax (1.21 ± 0.12) and cleaved caspase-3 (1.27 ± 0.12) expression, and increased Bcl-2 (0.70 ± 0.06), p-PI3K (0.71 ± 0.08), and p-AKT (0.96 ± 0.10) in the hippocampus. ELISA indicated diosmin reduces IL-1β, IL-6, and TNF-α levels, suggesting anti-inflammation effect. These results suggest that diosmin inhibits neuronal apoptosis and neuroinflammatory responses to improve cognitive dysfunction in AD rats, possibly related to upregulation of the PI3K/AKT pathway, providing a scientific basis for its use in AD treatment.