Neurons In Hippocampal CA1 Region Research Articles

Impaired synaptic plasticity and decreased glutamatergic neuron excitability induced by SIRT1/BDNF downregulation in the hippocampal CA1 region are involved in postoperative cognitive dysfunction

BackgroundPostoperative cognitive dysfunction (POCD) is a common complication after anesthesia/surgery, especially among elderly patients, and poses a significant threat to their postoperative quality of life and overall well-being. While it is widely accepted that elderly patients may experience POCD following anesthesia/surgery, the exact mechanism behind this phenomenon remains unclear. Several studies have indicated that the interaction between silent mating type information regulation 2 homologue 1 (SIRT1) and brain-derived neurotrophic factor (BDNF) is crucial in controlling cognitive function and is strongly linked to neurodegenerative disorders. Hence, this research aims to explore how SIRT1/BDNF impacts cognitive decline caused by anesthesia/surgery in aged mice.MethodsOpen field test (OFT) was used to determine whether anesthesia/surgery affected the motor ability of mice, while the postoperative cognitive function of 18 months old mice was evaluated with Novel object recognition test (NORT), Object location test (OLT) and Fear condition test (FC). The expressions of SIRT1 and other molecules were analyzed by western blot and immunofluorescence staining. The hippocampal synaptic plasticity was detected by Golgi staining and Long-term potentiation (LTP). The effects of SIRT1 and BDNF overexpression as well as chemogenetic activation of glutamatergic neurons in hippocampal CA1 region of 18 months old vesicular glutamate transporter 1 (VGLUT1) mice on POCD were further investigated.ResultsThe research results revealed that older mice exhibited cognitive impairment following intramedullary fixation of tibial fracture. Additionally, a notable decrease in the expression of SIRT1/BDNF and neuronal excitability in hippocampal CA1 glutamatergic neurons was observed. By increasing levels of SIRT1/BDNF or enhancing glutamatergic neuron excitability in the CA1 region, it was possible to effectively mitigate synaptic plasticity impairment and ameliorate postoperative cognitive dysfunction.ConclusionsThe decline in SIRT1/BDNF levels leading to changes in synaptic plasticity and neuronal excitability in older mice could be a significant factor contributing to cognitive impairment after anesthesia/surgery.Graphical

Effect of electroacupuncture on behavior and hippocampal inflammatory factors in rats with chronic fatigue syndrome.

To observe the effect of electroacupuncture (EA) on the changes of behavior and hippocampal inflammatory factors in rats with chronic fatigue syndrome (CFS), so as to explore its possible mechanisms in the treatment of CFS. Twenty-seven SD rats were randomly divided into control, model and electroacupuncture (EA) groups (n=9 rats in each group). The CFS model was established by multi-factor compound stress stimulation method. Rats of the EA group received EA (10 Hz) at "Shenting" (GV24) penetrating "Baihui" (GV20), "Dazhui" (GV14) for 15 min, twice a day for 14 days. The general conditions, Morris water maze test, open field test, the exhausted running platform were conducted for determining the rats' locomotor and learning-memory activities. H.E. staining was used to observe the morphological structure of neurons in hippocampal CA1 region. The contents of interleukin (IL)-10, IL-17 and transforming growth factor (TGF) β1 in hippocampus and serum of rats were detected by ELISA, and the positive expressions of IL-10, IL-17 and TGF-β1 in hippocampal CA1 region were detected by immunofluorescence staining. Compared with the control group, the score of general condition was increased (P<0.05), the escape latency was prolonged (P<0.05), the number of crossing the original platform was decreased (P<0.05), the numbers of crossing the grid and entering the central area were increased (P<0.05), and the exhaustive treadmill time was shortened (P<0.05) in the model group. The contents of IL-10 in the hippocampus and serum were decreased (P<0.05), while IL-17 and TGF-β1 contents were increased (P<0.05). The immunofluorescence intensity of IL-10 in the hippocampus was decreased (P<0.05), while the intensity of IL-17 and TGF-β1 were increased (P<0.05). After treatment, compared with the model group, the score of general condition was decreased (P<0.05), the escape latency was shortened (P<0.05), the number of crossing the original platform was increased (P<0.05), the numbers of crossing the grid and entering the central area were decreased (P<0.05), and the exhaustive treadmill time was prolonged (P<0.05) in the EA group. The contents of IL-10 in the hippocampus and serum were increased (P<0.05), while IL-17 and TGF-β1 levels were decreased (P<0.05). The immunofluorescence intensity of IL-10 in the hippocampus was increased (P<0.05), while the intensity of IL-17 and TGF-β1 were decreased (P<0.05). H.E. staining showed that in the model group, the number of neurons in the hippocampus decreased, with disordered arrangement and loose structure, and a small numbers of neuronal nuclei were missing. The degree of tissue damage of the EA group was milder than that of the model group. EA can alleviate fatigue and spatial learning and memory impairment in CFS rats, which may be related to the regulation of peripheral and central inflammation.

Effects of aerobic exercise on depression-like behavior and TLR4/NLRP3 pathway in hippocampus CA1 region of CUMS-depressed mice

Background and purposeThe paper observes regulation of the expression levels of NLRP3 and TLR4 in hippocampal CA1 neurons in CUMS mice by aerobic exercise with constructing CUMS depression mouse model, in order to explore the neuroprotective mechanism of aerobic exercise on the hippocampus of depressed mice. Study design and method24 healthy male 8-week-old C57BL/6 mice were randomly divided into CG, MG and ME. Thirteen stress-stimulating factors were randomly formulated into a CUMS stress-stimulating program. The mice were underwent 28 days of CUMS depression model, referenced clinical means for experimental research. The study was approved by the Ethics Committee of Yichun University (YCUEC IRB number LSK NO.2022.18). After model preparation, ME mice were subjected to moderate-intensity treadmill exercise training for 8 weeks. TST, FST and SPT were used to detect the depression-like behaviors of the mice in each group. Nissl staining was used to compare the cell morphology in the CA1 region of the mouse hippocampus. Immunohistochemical staining and western blot were used to detect the changes in the expression levels of NLRP3, TLR4 and other proteins in the CA1 region of the mouse hippocampus. ResultsThe results of neurobehavioral assessment showed that, the immobility time of TST and FST were significantly increased, and SPT index was significantly decreased of MG mice. Compared with MG, ME mice significantly improved depression-like behaviors such as TST, FST and SPT index. Nissl staining showed that the morphology of neurons in CA1 region of hippocampus of MG mice were mostly vacuolar-like, with severe nuclear pyknosis. Abnormal morphological changes such as vacuolar-like and pyknotic pyknosis of neurons in the hippocampal CA1 region of ME mice were significantly reduced. Protein expression test showed that the number of NLRP3, TLR4, IL-1β and IL-10 positive neurons in hippocampal CA1 region of MG mice increased significantly compared with CG, and the proportion of positive cells increased significantly, while NLRP3 and TLR4 positive neurons in the hippocampal CA1 region of ME mice were significantly reduced, the proportion of TLR4 positive cells was significantly reduced. ConclusionSystematic moderate-intensity exercise can effectively improve the depression-like behavior of CUMS depressed mice through the expression of TLR4/NLRP3 inflammatory signaling pathway, and provide an effective experimental basis for the clinical rehabilitation treatment of depression.

Effect of transcutaneous electrical acupoint stimulation on learning and memory ability of chronic fatigue syndrome rats and its mechanisms

To observe the effect of transcutaneous electrical acupoint stimulation (TEAS) on the histomorphological manifestations of hippocampal CA1 region and the expression of extracellular regulatory protein kinase (ERK), cyclic adenosine response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in chronic fatigue syndrome (CFS) rats, so as to explore the mechanisms of TEAS in improving the learning and memory abilities of CFS rats. Forty male Wistar rats were randomly divided into normal group (10 rats) and modeling group (30 rats); then after modeling, they were selected and randomly divided into model group (10 rats) and TEAS group (10 rats). CFS rats model was prepared by sleep deprivation combined with weight-bearing swimming. Rats in the TEAS group were stimulated with Han's acupoint nerve stimulator at bilateral "Zusanli" (ST36) and "Shenshu" (BL23) (2 Hz/15 Hz, 1-2 mA), 20 min each time, once a day for 4 weeks with 1 d rest every 6 d. The score of general conditions of rats was evaluated. The learning and memory ability was tested with Morris water maze. The morphology and ultrastructure of hippocampal CA1 region were observed by HE staining and transmission electron microscopy. The expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were detected by real time quantitative PCR and Western blot, respectively. Compared with the normal group, the score of general condition was increased (P<0.01); the escape latency was prolonged (P<0.05, P<0.01) and the times of crossing the original platform was decreased (P<0.05); the expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were decreased (P<0.05, P<0.01) in the model group. Compared with the model group, the scores of general condition on the 42nd and 49th day were decreased (P<0.05, P<0.01); the escape latency was shortened (P<0.01, P<0.05)and the times of crossing the original platform were increased (P<0.05); the expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were increased (P<0.01, P<0.05) in the TEAS group. The morphology of neurons in hippocampal CA1 region was normal in the normal group. In the model group, the number of neurons in hippocampal CA1 region decreased, the arrangement of nerve cells was scattered, the number of apoptotic cells increased, some nuclear structures disappeared, nuclear heterochromatin increased, the cell membrane wrinkled, the chromatin appeared empty bright area, and the crista was incomplete. Compared with the model group, the nerve cells morphology in hippocampal CA1 region was more regular, the number of apoptotic cells decreased, the chromatin and the cytoplasm were uniformly distributed, and the crista was relatively intact in the TEAS group. TEAS can improve the learning and memory ability of CFS rats, the mechanisms may be related to improving the neural structure of hippocampal CA1 region and up-regulating the expression levels of ERK/CREB/BDNF.

LONG NONCODING RNA UPREGULATES ADAPTER SHCA PROTEIN EXPRESSION TO PROMOTE COGNITIVE IMPAIRMENT AFTER CARDIAC ARREST AND RESUSCITATION.

Aim: More patients are resuscitated from cardiac arrest and cardiopulmonary resuscitation (CA/CPR) due to advances in medical care. However, the burden now lies with post-cardiac arrest cognitive impairment in CA/CPR survivors. Based on our previous study, we aimed to further confirm the correlation between the long noncoding RNA-promoting ShcA (lncRNA-PS)/Src homology and collagen A (ShcA) axis and CA/CPR-induced cognitive impairment in molecular, cellular, and tissue levels. Methods and Results: The in vivo experiments were based on a mouse model of CA/CPR, while oxygen-glucose deprivation and reoxygenation was used as a cell model in vitro. Conditional ShcA suppression in neurons of the hippocampal CA1 region was achieved by cyclization recombinase of bacteriophage P1 recognizing DNA fragment locus of x-over P1 site (Cre/LoxP recombination system). Genetic manipulation of HT22 was achieved by lentivirus targeting lncRNA-PS and ShcA. Neurological function score was remarkably decreased, and cognitive function was affected after restoration of spontaneous circulation. LncRNA-PS and ShcA overexpression after CA/CPR, mainly happened in neurons of hippocampal CA1 region, was observed by in situ hybridization and immunofluorescence. Neuronal ShcA knockdown in hippocampal CA1 region before CA/CPR attenuated cognitive impairment after CA/CPR. ShcA deficiency protected HT22 cell line against oxygen-glucose deprivation and reoxygenation by inhibiting inflammation and apoptosis. In vitro upregulation of lncRNA-PS elevated ShcA expression, which was reversed by knockdown of ShcA. Conclusions: This study revealed that lncRNA-PS/ShcA axis is critically involved in the pathogenesis of cognitive impairment after CA/CPR. By inhibiting ShcA expression in neurons of the hippocampal CA1 region could improve the survival outcomes in mice after CA/CPR.

Oxytocin protects neurons from hypoxic-ischemic brain injury by enhancing inhibitory neurotransmission in neonatal rats

Purpose: To study the protective effect of oxytocin on hypoxic-ischemic brain neuron injury in neonatal rats, and the mechanism of action involved.Methods: Hippocampal slices from neonatal SD rats were cultured in oxygen/glucose-deprived (OGD) solution, leading to establishment of hypoxic-ischemic model of hippocampal slices in vitro. The slices were assigned to 3 groups: control (ACSF solution), model (OGD solution), and oxytocin (OGD solution + 1 μM oxytocin). The effect of oxytocin on vertebral neurons in hippocampal CA1 region of HIBD rats was determined using TOPRO-3 staining, while the effects of oxytocin on hypoxic depolarization (AD) and inhibitory postsynaptic currents (iPSCs) were measured by cell patch clamp technique.Results: The fluorescence intensity of vertebral lamina in hippocampal CA1 area of model group was significantly higher than that of control group, while the corresponding value for oxytocin group was significantly lower than that of model group (p &lt; 0.05). The time lapse before occurrence of AD in hippocampal CA1 area was significantly longer in oxytocin group than in model group, while the time lapse before neuronal AD in oxytocin receptor antagonist group was lower than that in oxytocin group. The frequency and amplitude of iPSCs in oxytocin group were markedly higher than the corresponding control values.Conclusion: Oxytocin exerts protective effect against hypoxic-ischemic brain neuronal damage in neonatal rats by regulating the activation of oxytocin receptor and GABA receptor, and inhibiting nerve transmission. These findings may be of benefit in the development of a suitable therapy for HIBD.

Enriched environment alleviates post-stroke cognitive impairment through enhancing α7-nAChR expression in rats

Enriched environment (EE) is a simple and effective intervention to improve cognitive function in post-stroke cognitive impairment (PSCI), partly due to the rebalancing of the cholinergic signaling pathway in the hippocampus. α7-nicotinic acetylcholine receptor (α7-nAChR) is a cholinergic receptor whose activation inhibits inflammation and promotes the recovery of neurological function in PSCI patients. However, it is still unclear whether EE can regulate α7-nAChR and activate the cholinergic anti-inflammatory pathway (CAP) in PSCI. To investigate the effects of EE on cognitive impairment, and the role of α7-nAChR in PSCI. A PSCI rat model was induced by middle cerebral artery occlusion and reperfusion (MCAO/R) and were reared in standard environment (SE) or EE for 28d, control group with sham surgery. Cognitive function was determined by Morris water maze test. The long-term potentiation (LTP) was assessed by Electrophysiology. Histopathological methods were used to determine infarct volume, α7-nAChR expression and the cytokines and cholinergic proteins expression. Compared with SE group, rats in EE group had better cognitive function, higher expression of α7-nAChR positive neurons in hippocampal CA1 region. In addition, EE attenuated unfavorable changes induced by MCAO/R in cytokines and cholinergic proteins, and also enhanced LTP promoted by nicotine and attenuated by α-BGT; but showed no significantly difference in infarct volume. EE markedly improves cognitive impairment and enhances neuroplasticity in PSCI rats, which may be closely related to enhancement of α7-nAChR expression.

Modulation of behavioral responses and CA1 neuronal death by nitric oxide in the neonatal rat's hypoxia model.

IntroductionNeonatal hypoxia leads to cognitive and movement impairments that might persist throughout life. Hypoxia impairs hippocampal blood circulation and metabolism. The exact mechanisms underlying hypoxia‐induced memory impairment are not fully understood. Nitric oxide (NO) is a key neuromodulator that regulates cerebral blood flow. In this study, we aimed to evaluate the possible role of NO on behavioral and histomorphometric changes in the hippocampus following hypoxia in neonate rats.Material and methodsNeonate male rats (n = 28) were randomly divided into 4 groups: control, hypoxia, hypoxia plus L‐NAME (20 mg/kg), and hypoxia plus L‐arginine (200 mg/kg). Drugs were injected intraperitoneally for seven consecutive days. Hypoxia was induced by keeping rats in a hypoxic chamber (7% oxygen and 93% nitrogen intensity). Ten to 14 days after hypoxia, behavioral changes were measured using a shuttle box, a rotarod, and an open field test. The histological changes in the hippocampus were measured using H&E and Nissl staining methods.ResultsFindings showed that hypoxia caused significant atrophy in the hippocampus. Furthermore, the administration of L‐NAME decreased the atrophy of the hippocampus in comparison with the hypoxic group. Behavioral results showed that hypoxia impaired memory performance and motor activity responses. Additionally, the administration of L‐NAME improved behavioral performance in a significant manner compared with the hypoxic group.ConclusionsHypoxia damaged the neurons of hippocampal CA1 region and induced memory impairment. The NOS inhibitor, L‐NAME, significantly attenuated the negative effects of hypoxia on behavior and observed changes in the hippocampus.

Environmental enrichment rescues cognitive impairment with suppression of TLR4-p38MAPK signaling pathway in vascular dementia rats

Increasing evidence demonstrated the promising effects of environmental enrichment (EE) on brain recovery and cognitive performance in animal models of various diseases. However, the effect and molecular mechanisms of EE on vascular dementia (VD) remain to be studied. The aim of this study was to explore the effect of EE on cognitive decline and its mechanism. Sprague-Dawley rats underwent 2-vessel occlusion (2-VO) surgery or sham operation. Subsequently, rats were kept in EE for 4 weeks. In Morris water maze (MWM) test, we demonstrated that EE significantly improved cognitive function in rats with VD. HE staining exhibited morphological changes of neurons and quantitative analysis of TUNEL showed increased apoptotic neurons in hippocampal CA1 region following 2-VO. Results from RT-qPCR showed up-regulation of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) after 2-VO. Western blotting analysis revealed enhanced toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MYD88) and phosphorylated p38 mitogen-activated protein kinase (p-p38MAPK) in 2-VO rats. Whereas administration of EE reduced apoptotic neurons, down-regulated inflammatory factors. Moreover, EE suppressed protein expression of TLR4-p38MAPK pathway. Spearman correlation analysis showed that improved cognitive function was associated with decreased expression of TLR4 and p-p38MAPK proteins. Thus, our study proved that EE has a prominent effect on cognitive impairment and neuronal damage following 2-VO by attenuating inflammation and apoptosis, which may be realized via inhibiting the TLR4-P38MAPK signaling pathway.

Chrysophanol improves memory ability of d-galactose and Aβ25-35 treated rat correlating with inhibiting tau hyperphosphorylation and the CaM-CaMKIV signal pathway in hippocampus.

This study was aimed to investigate the effect of Chrysophanol (CHR) on Alzheimer's disease. We also attempted to understand the potential mechanisms. An Alzheimer's disease rat model was established using an intraperitoneal injection of d-galactose combined with an intracerebral injection of amyloid-β peptide (25-35), and the effect of CHR on the learning and memory ability, the hippocampal neurons change, the ultrastructure of the hippocampal CA1 region, the protein levels of CaM, CaMKK, CaMKIV, p-CaMKIV and p-tau in the hippocampus of rats were studied. The results showed that CHR significantly improved the cognitive deficits, alleviated hippocampal neurons damage, prevented the ultrastructure alteration of neurons in hippocampal CA1 region, and reduced the protein levels of CaM, CaMKK, p-CaMKIV and p-tau in the hippocampus of AD rats. These results suggested that Chrysophanol could improve memory ability of Alzheimer's disease rat by inhibiting tau hyperphosphorylation and the CaM-CaMKIV signal pathway.

Transplantation of NSCs Promotes the Recovery of Cognitive Functions by Regulating Neurotransmitters in Rats with Traumatic Brain Injury.

Transplantation of neural stem cells (NSCs) may be a potential strategy for traumatic brain injury treatment (TBI) due to their intrinsic advantages, such as cell replacement, secretion of neurotrophins and formation of functional synapses with host. However the underlying effects of transplanted NSCs on host micro-environment still need to be further elucidated. In this manuscript the effects of NSCs on release of neurotransmitter, survival of hippocampal neurons, reactivity of astrocytes and recovery of cognitive function after TBI were observed. The NSCs were isolated from cortex of neonatal Sprague-Dawley rat and then transplanted into injured brain regions caused by free-weight drop. The proliferation of astrocytes around injured sites were examined by GFAP immunofluorescent staining on 3, 7, 14days after injury. The survival of neurons at CA1 regions of hippocampus toward contused regions was observed by HE staining on 3 and 14days post-injury. The content of glutamic acid (Glu) and GABA in hippocampal tissues was examined on 1, 3, 7, 14, 28days after injury by ELISA. On third day post-injury, hippocampal-dependent spatial memory was measured for 5days without intermittent. NSCs in culture have the ability to proliferate and differentiate into different phenotypes of neural cells. After transplantation of NSCs, the proliferation of astrocytes around injured site was significantly inhibited compared to the injured group. At the same time the survival of neurons in hippocampal CA1 region were much more than those in injured group on 14days post-injury. Meanwhile, the cognitive functions in NSC transplanted group was remarkably improved compared with injured group (p < 0.05). Furthermore, NSCs transplantation dramatically inhibited the release of Glu and maintained the content of GABA in injured hippocampal tissues on 1, 3, 7, 14, 28days post-injury, which was of difference in statistics (p < 0.05). NSCs transplantation can effectively alleviate the formation of glial scar, enhance the survival of hippocampal neurons and improve cognitive function defects in rats with TBI. The underlying mechanism may be related to their effects on inhibiting the release of Glu and maintaining the content of GABA, so as to down-regulate excitotoxicity of neurotransmitter and improve the micro-environment in injured sites.

Trans-Himalayan Phytococktail Confers Protection Against Hypobaric Hypoxia-Induced Hippocampal Neurodegeneration and Memory Impairment in Male Sprague Dawley Rats.

Background: Exposure to hypobaric hypoxia (HH) has been reported to cause neurodegeneration and memory impairment. Hippophae rhamnoides, Prunus armeniaca, and Rhodiola imbricata, the indigenous plants of Indian Trans-Himalaya are widely used in traditional Tibetan and Amchi system of medicine. These are rich sources of diverse bioactive metabolites having prophylactic and therapeutic uses against a wide array of neurodegenerative diseases. The objective of this study was to elucidate the prophylactic and neuroprotective efficacy of formulated phytococktail (PC) against simulated HH-induced neurodegeneration in male Sprague Dawley (SD) rats. Materials and Methods: A PC containing H. rhamnoides fruit pulp, P. armeniaca fruit pulp, and R. imbricata dry root extract (100:50:1) was formulated. The neuroprotective efficacy of PC was evaluated in male SD rats following exposure to 7 day HH at simulated altitude (25,000 ft, 282 mm Hg). Rats were divided into four groups viz., normoxia group (NOR), normoxic group treated with PC (NORPC), 7 day hypoxic group treated with vehicle (7DH), and 7 day hypoxic group treated with PC (7DHPC). Memory impairment and neuromorphological alterations were measured. Targeted protein expression was analyzed by immunoblotting study. Results: PC supplementation significantly reduced the oxidative stress markers during exposure to HH. Spatial memory impairment by HH was significantly ameliorated by PC. HH-induced augmented pyknosis, decreased dendritic arborization, and increased Hoechst-positive neurons in hippocampal CA3 region were significantly ameliorated by PC. Immunoblotting study showed upregulation of BDNF and TrkB expression by PC. PC also prevented the hippocampal neurodegeneration by activating the PI3K/AKT signaling pathway, which leads to GSK-3β inactivation by its phosphorylation and alleviation of hippocampal Caspase3 expression leading to inhibition of apoptotic neuronal cell death. Conclusion: The present study advocates the potential role of PC as an effective neuroprotective supplement in preventing HH-induced neurodegeneration. Activation of the PI3K/Akt pathway through BDNF/TrkB interaction following PC supplementation after exposure to HH inhibits hippocampal neuronal apoptosis and memory impairment.

A study on the protective effects of protein transduction domain 4-Cu, Zn superoxide dismutase fusion protein aganist global cerebral ischemia/reperfusion injury in rats

Objective To investigate the protective effects of protein transduction domain 4-Cu, Zn superoxide dismutase fusion protein (PTD4-Cu, Zn-SOD) against cerebral ischemia/reperfusion injury (CI/RI) in rats. Methods A total of 120 adult male rats were randomly divided into four groups (n=30): sham group (group SH), ischemia/reperfusion group(group I/R), superoxide dismutase group (group SOD), PTD4-Cu, Zn-SOD group (group PTD4-SOD). For group I/R, SH and PTD4-SOD, their bilateral carotid arteries were temporarily occluded over 6 min after electrocoagulation of bilateral vertebral arteries for 24 h to establish a CI/RI model. Before reperfusion, rats in group SOD and PTD4-SOD were injected with 6 mg/kg SOD or 6 mg/kg PTD4-SOD via the tail vein, respectively, while those in group SH and group I/R received the same volume of phosphate buffer saline(PBS) via the tail vein. Then the brain tissue samples were harvested 2, 6, 12, 24, 72 h after reperfusion(n=6). The pathological changes of the hippocampus were observed by hematoxylin-eosin (H-E) staining. The activity of SOD in the hippocampus was detected by xanthine oxidase method. The apoptosis rate of hippocampal cells was examined by flow cytomrtry. Results H-E stain: the neurons in hippocampal CA1 region of group SH were tightly arranged, where the cytoplasm was reddish and the nuclear was stained blue, with the clear nucleus. The neurons of group I/R were arranged in a disordered manner and idioblast counts were increased. The cytoplasm and nucleolus obviously shrunk, where the nucleolus disappeared or dissolved. Compared with group I/R, group PTD4-SOD presented tightly arranged neurons in hippocampal CA1 region, with little sparse idioblasts. The changes in group SOD was between group PTD4-SOD and group I/R. SOD activity test: compare with group SH, remarkable difference was found in groups I/R, SOD and PTD4-SPD 12, 24 and 72 h after perfusion (P<0.05). Compared with group PTD4-SOD, remarkable difference were found in group I/R and group SOD at each time point (P<0.05). The cell apoptosis rate of hippocampus: compared with group SH, there were marked differences in the apoptosis rate in group I/R, group SOD, group PTD4-SOD at each time point (P<0.05). Compared with group PTD4-SOD, remarkable difference were found in group I/R and group SOD at each time point (P<0.05). Conclusions PTD4-Cu, Zn-SOD can relieve CI/RI, which may be associated with enhanced SOD activity and free radical scavenging. Key words: Ischemia-reperfusion injury; Free radicals; Protein transduction domain-superoxide dismutase fusion protein

Sevoflurane reduces cerebral injuries in rats resuscitated from cardiac arrest through down-regulating the expression of Bax and Bak

Objective To investigate the neuroprotective mechanism of sevoflurane in rats resuscitated from cardiac arrest (CA). Methods A ventricular fibrillation-induced CA model was established. Forty Wistar rats were randomly divided into the sham group, sevoflurane group and control group. Apoptosis-related proteins were measured by Western blot at 24 h after restoration of spontaneous circulation (ROSC). The status of mitochondrial permeability transition pore (MPTP) were measured using a spectrophotometer, and the mitochondrial membrane potential (MMP) were measured with JC-1 fluorescent probe. At 72 h after ROSC, the apoptotic index of neurons in hippocampal CA1 region was counted by TUNEL staining. Results The protein expression of Bax, Bak, cleaved-caspase 9, cleaved-caspase 3 and cytosolic cytochrome c were lower in the sevoflurane group (all P<0.05), the protein expression of Bcl-2 was higher in the sevoflurane group compared with the control group (P<0.05). The sevoflurane group had a less opening status of MPTP and a higher MMP compared with the control group (all P<0.05). The sevoflurane group had less apoptotic neurons compared with the control group (P<0.05). Conclusion By up-regulating the expression of Bcl-2, down-regulating Bax and Bak, sevoflurane could reduce the apoptosis of neurons and decrease the opening of MPTP, eventually reduce cerebral injuries. Key words: Cardiac arrest; Sevoflurane; Apoptosis; Mitochondrial permeability transition pore; Bax; Bak

An Evaluation of the Effect of Deprivation of Maternal Care on LTP Induction in Neurons of Hippocampal CA1 Region in Morphine-Dependent Rats

An Evaluation of the Effect of Deprivation of Maternal Care on LTP Induction in Neurons of Hippocampal CA1 Region in Morphine-Dependent Rats

Effect of bupivacaine on mEPSCs and mIPSCs of neurons in hippocampal CA1 region of rats

Objective To evaluate the effect of bupivacaine on miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs) of neurons in hippocampal CA1 region of rats. Methods Twenty SPF healthy male Sprague-Dawley rats, aged 4-6 weeks, weighing 300-350 g, were divided into control group (C group, n=10) and bupivacaine model group (BPV group, n=10) using a random number table method.The central nervous system toxicity model was established by infusing 0.75% bupivacaine at a rate of 1 mg·kg-1·min-1 via the tail vein in BPV group, while normal saline was infused for 7.5 min at a rate of 1 mg·kg-1·min-1 via the tail vein in C group.Rats were sacrificed at 6 h after successful establishment of the model, the brains was removed and hippocampal slices were prepared.The whole-cell patch-clamp technique was used to record the frequency and amplitude of mEPSCs and mIPSCs. Results Compared with C group, the frequency of mIPSCs was significantly decreased (P 0.05). Conclusion The mechanism of bupivacaine-induced central nervous system toxicity is related to decreasing the frequency of mIPSCs in hippocampal neurons of rats. Key words: Bupivacaine; Drug toxicity; Central nervous system; Hippocampus; Neurons; Electrophysiology; Synaptic transmission

Pathology of nNOS-Expressing GABAergic Neurons in Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common form of dementia that is often accompanied by mood and emotional disturbances and seizures. There is growing body of evidence that neurons expressing γ-aminobutyric acid (GABA) play an important role in regulation of cognition, mood, and emotion as well as seizure susceptibility, but participation of GABAergic neuronal pathology in Alzheimer’s disease (AD) is not understood well at present. Here, we report that transgenic mice expressing human amyloid precursor protein Swedish–Dutch–Iowa mutant (APPSweDI) exhibit early loss of neurons expressing GAD67, a GABA-synthesizing enzyme, in advance of the loss of pyramidal neurons in hippocampal CA1 region. The loss of GAD67+ neurons in APPSweDI mice accompanied with decreased spatial cognition as well as increased anxiety-like behaviors and kainic acid-induced seizure susceptibility at early phase. In the hippocampal CA1 region, GAD67+ neurons expressed high basal levels of neuronal nitric oxide synthase (nNOS) and nitrosative stress (nitrotyrosine). Similarly, GAD67+ neurons in primary cortical and hippocampal neuron cultures also expressed high basal levels of nNOS and degenerated in response to lower Aβ concentrations due to their high basal levels of nitrosative stress. Given the role of GABAergic neurons in cognitive and neuropsychiatric functions, this study reports the role of nNOS-mediated nitrosative stress in dysfunction of GABAergic neurons and its potential participation in early development of cognitive and neuropsychiatric symptoms in AD.

Inosine improves cognitive function and decreases aging-induced oxidative stress and neuroinflammation in aged female rats

In the present study, the effect of inosine was evaluated on learning and memory of 18months old aged female rats. Inosine (50, 100 and 200mg/kg; i.p.) was administered to separate groups of rats for 15 successive days. Donepezil (1mg/kg; i.p.), an acetylcholinesterase inhibitor, was used as a standard drug. Behavioral models such as Morris water maze and elevated plus maze were used to evaluate the effect of drugs on learning and memory of rats. After behavioral studies, animals were killed and their brain was isolated and further processed for estimation of various biochemical parameters such as acetylcholinesterase activity, oxidative stress markers, proinflammatory marker and histological examinations. Inosine (100 and 200mg/kg) significantly improved learning and memory of aged rats. Further, inosine significantly reduced lipid peroxidation and nitrite, and increased the levels of reduced glutathione and superoxide dismutase. However, no significant difference in AChEs activity was observed in inosine-treated rats as compared to aged control rats. TNF-α level was found to be ameliorated in aged rats by inosine. Histopathological evaluation showed that inosine-treated aged rats have less number of pyknotic neurons in hippocampal CA1 region as compared to aged control rats. In conclusion, inosine significantly improved learning and memory of aged female rats possibly through its antioxidant as well as anti-inflammatory effect and improvement of neuronal survival in the hippocampal CA1 region. However, additional studies are required to further explore the downstream signaling pathways involved in the neuroprotective effect of inosine in aged animals.

Pathophysiological functions of gas mediators in neurodegeneration

Since the discovery of nitric oxide (NO) as gaseous signaling molecule, two other gaseous mediators, carbon monoxide (CO) and hydrogen sulfide (H2S) have been found to be also involved in many physiological and pathophysiological functions. This review will briefly summarize our recent progress in the pathophysiology of NO and H2S. In the photoreceptor cells, the level of intracellular Ca2+ is kept relatively low by H2S. Intraperitoneal injection of H2S donor to mice protected photoreceptor cells from light-induced retinal degeneration caused by oxidative stress and elevation of intracellular Ca2+. Another gaseous mediator NO induces Ca2+ release from the endoplasmic reticulum via S-nitrosylated type 1 ryanodine receptor (RyR1) Ca2+ release channel. NO-induced Ca2+ release (NICR) was abolished in primary cultured neurons from the knock-in mice, in which the S-nitrosylation site Cys-3636 of RyR1 was replaced by Ala (Ryr1C3636A). The neurons in hippocampal CA3 region of Ryr1C3636A mice were protected against seizure-induced neuronal cell death. The result indicates that NICR is critical for status epilepticus-induced neurodegeneration. The developments in the pathophysiology of gaseous mediators in the central nervous system will provide a better pharmacological advances for the treatment of neurodegenerative diseases.

Necrostatin-1 protects hippocampal neurons against ischemia/reperfusion injury via the RIP3/DAXX signaling pathway in rats

Global cerebral ischemia/reperfusion (I/R) induces selective neuronal injury in CA1 region of hippocampus, leading to severe impairment in behavior, learning and memory functions. However, the molecular mechanism underlying the processes was not elucidated clearly. RIP3 is a key molecular switch connecting apoptosis, necrosis and necroptosis. DAXX, as a novel substrate of RIP3, plays a vital role in ischemia-induced neuronal death. The aim of this study is to investigate the role and mechanism of RIP3/DAXX signaling pathway on neurons in CA1 region of the rat hippocampus after cerebral I/R. Global cerebral ischemia was induced by the method of four-vessel occlusion. RIP1 specific inhibitor Necrostatin-1 was administered by intracerebroventricular injection 1h before ischemia. Open-field, closed-field, and Morris water maze tests were performed respectively to examine the anxiety and cognitive behavior in each group. Hematoxylin and eosinstaining was used to examine the survival of hippocampal CA1 pyramidal neurons. Western blot or immunoprecipitation were carried to detect protein expression, phosphorylation, and interaction. We found that pre-treatment with Nec-1 protected locomotive ability, relieved anxiety behavior, and improved cognitive ability in the rats subjected to cerebral I/R. In addition Moreover, Nec-1 decreased significantly the dead rate of neurons in hippocampal CA1 region after cerebral I/R through suppressing RIP1-RIP3 interaction and RIP3 activation along with RIP3-DAXX interaction, and then blocked DAXX translocation from nucleaus to cytoplasm, which resulted in the inactiviation of DAXX. We concluded that pre-treatment with Nec-1 can protect neurons in the hippocampal CA1 region against ischemic damage through the RIP3-DAXX signaling pathway.