Concentraciones de oxígeno intermitentes tienen impacto en el desarrollo postnatal temprano de ratas Sprague-Dawley: efectos en CA1 del hipocampo / Intermittent oxygen concentrations have an impact on the early postnatal development of Sprague-Dawley rats: effects on hippocampal CA1

El periodo postnatal temprano se caracteriza por rápido crecimiento cerebral, posiblemente relacionado con variaciones del oxígeno tisular. Esto ha motivado el estudio de protocolos que suministran diferentes concentraciones de oxígeno intermitentes, para observar sus efectos morfológicos y cerebrales. Se utilizaron 52 crías de ratas Sprague Dawley, distribuidas en igual número a cuatro grupos experimentales, Control (C, 21 %O2), Hipoxia Intermitente (HI, 11 %O2), Hiperoxia Intermitente (HOI, 30 %O2) e Hipoxia Hiperoxia Intermitente (HHI, 11 % -30 %O2). Los protocolos consideraron 5 ciclos de 5 minutos de dosificación, durante 50 minutos diarios. Se realizó en una cámara semihermética entre los días 5 al 11 postnatales. Las evaluaciones de crecimiento corporal y cuantificación neuronal, se realizaron en las crías macho, en el día 28 postnatal. El peso corporal en el grupo hipoxia intermitente mostró diferencias significativas respecto al grupo hiperoxia intermitente (HI vs HOI, p<0,01) y al grupo hipoxia-hiperoxia Intermitente (HI vs HHI, p< 0,001). La talla corporal disminuyó en el grupo hipoxia-hiperoxia intermitente con diferencias significativas respecto del grupo control (C vs HHI, p<0,05) y respecto del grupo hipoxia intermitente (HHI vs HI, p< 0,01). El conteo neuronal en el área CA1 del hipocampo aumentó en el grupo hipoxia intermitente con diferencias significativas respecto a los grupos control (C vs HI; p<0,05), al grupo hiperoxia intermitente (HI vs HOI; p<0,001) y al grupo hipoxia-hiperoxia intermitente (HI vs HHI; p<0,001). Finalmente, el grupo hipoxia- hiperoxia Intermitente disminuyó significativamente en la cantidad de neuronas en comparación al grupo hiperoxia intermitente (HHI vs HOI; p<0,001). La hipoxia intermitente mostró resultados beneficiosos en el crecimiento corporal y cantidad de neuronas en el área CA1 del hipocampo, en contraste, la hipoxia hiperoxia intermitente experimentó resultados adversos con disminución de estas variables, en el periodo postnatal temprano de la rata.

SUMMARY: The early postnatal period is characterized by rapid brain growth, possibly related to variations in tissue oxygen. This has motivated the study of protocols that supply different intermittent oxygen concentrations, to observe their morphological and cerebral effects. Fifty-two pups Sprague-Dawley rats were distributed in equal numbers into four experimental groups, Control (C, 21 %O), Intermittent Hypoxia (HI, 11 %O), Intermittent Hyperoxia (HOI, 30 %O2) and Intermittent Hypoxia Hyperoxia (HHI, 11 % - 30 %O2). The protocols considered 5 cycles of 5 min of dosing, for 50 min diary. It was performed in a semi- hermetic chamber between 5 to 11postnatal days. The evaluations of body growth and neuronal quantification were analyzed in male pups, on postnatal day 28. Body weight in the intermittent hypoxia group showed significant differences compared to the intermittent hyperoxia group (HI vs HOI, p<0.01) and the intermittent hypoxia- hyperoxia group (HI vs HHI, p<0.001). Body size decreased in the Intermittent hypoxia-hyperoxia group with significant differences compared to the control group (C vs HHI, p<0.05) and with respect to the intermittent hypoxia group (HHI vs HI, p<0.01). The neuronal count in the area CA1 of the hippocampus increased in the intermittent hypoxia group with significant differences compared to the control groups (C vs HI; p<0.05), to the intermittent hyperoxia group (HI vs HOI; p< 0.001) and the intermittent hypoxia-hyperoxia group (HI vs HHI; p<0.001). Finally, the intermittent hypoxia- hyperoxia group decreased significantly in the number of neurons compared with the intermittent hyperoxia group (HHI vs HOI; p<0.001). Intermittent hypoxia showed beneficial results in body growth and the number of neurons in the CA1 area of the hippocampus, in contrast, intermittent hypoxia-hyperoxia experienced adverse results with a decrease in these variables, in the early postnatal period of the rat.

Effects of electroacupuncture with different courses on the synaptic structure and synaptic function-related proteins in mice with radiation-induced brain injury / 生理学报

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.

Effects of Beta; 1-adrenoceptors in the Basolateral Amygdala on Spatial Memory, Passive Avoidance, Long-term Potentiation and Neuronal Arborization in the Hippocampal CA1 Region in Response to Unavoidable Stress

Abstract Norepinephrine in the basolateral amygdala (BLA) plays a pivotal role in mediating the effects of stress on memory functions in the hippocampus, however, the functional contribution of β1-adrenergic receptors on the BLA inputs to the CA1 region of hippocampus and memory function are not well understood. In the present study the role of β1-adrenoreceptor in the BLA on memory, neuronal arborization and long-term potentiation (LTP) in the CA1 region of hippocampus was examined by infusion the β1-adrenoreceptor agonist (Dobutamine; 0.5µl/side) or antagonist (Atenolol; 0.25µL/side) bilaterally into the BLA before foot-shock stress. Passive avoidance test results showed that Step-through latency time was significantly decreased in the stress group rats one, four and seven days after the stress, which intra-BLA injection of Atenolol or Dobutamine before stress couldn't attenuate this reduction. Barnes-maze results revealed that infusion of Dobutamine and Atenolol significantly reduced spatial memory indicators such as increased latency time, the number of errors and the distance traveling to achieve the target hole in the stress group. These learning impairments in stress rats correlated with a reduction of LTP in hippocampal CA1 synapses in-vivo, which infusion of Dobutamine and Atenolol couldn't attenuate the population spike amplitude and mean-field excitatory postsynaptic potentials (fEPSP) slope reduction induced by stress. Also, the Golgi-Cox staining demonstrated that infusion of Atenolol attenuated stress decreased CA1 region dendritic and axonal arborization. These results suggest that β1-adrenergic receptors activation or block seem to exacerbate stress-induced hippocampal memory deficits and this effect is independent of CA1 LTP modulation.

Transduced Tat-aldose Reductase Protects Hippocampal Neuronal Cells against Oxidative Stress-induced Damage

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.

Research on network pharmacology of Acori Tatarinowii Rhizoma combined with Curcumae Radix in treating epilepsy / 中国中药杂志

The chemical constituents and action targets of Acori Tatarinowii Rhizoma and Curcumae Radix were screened by network pharmacological method,and the mechanism of the combination of Acori Tatarinowii Rhizoma and Curcumae Radix in the treatment of epilepsy was analyzed. All chemical constituents of Acori Tatarinowii Rhizoma and Curcumae Radix were retrieved by TCMSP,and their action targets were screened. Component target PPI network was constructed. Epilepsy-related genes were retrieved from PharmGkb database,and PPI networks of disease targets were drawn by Cytoscape software. Cytoscape software was used to merge the network,screen the core network,and further analyze the gene GO function and KEGG pathway enrichment,which was verified by experimental research. One hundred and five chemical constituents of Acori Tatarinowii Rhizoma and 222 chemical constituents of Curcumae Radix were retrieved. Nineteen compounds were selected as candidate compounds according to OB and DL values. Among them,4 chemical constituents of Acori Tatarinowii Rhizoma and 15 chemical constituents of Curcumae Radix were found. A total of 88 target proteins were retrieved by retrieving TCMSP data,and PPI network was constructed. Through PharmGkb database,29 epilepsy-related genes were retrieved and disease target network was established. Cytoscape software and plug-ins were used for network merging and core network screening,and 69 genes were screened out. Through GO function analysis and KEGG pathway analysis,the mechanism of anti-epilepsy is related to prolactin signaling pathway,HTLV-Ⅰ infection signaling pathway,MAPK signaling pathway and herpes simplex infection signaling pathway. Further experimental verification showed that the serum prolactin level in epileptic rats was significantly increased. The neurons in hippocampal CA1 area degenerated,necrotized and lost 24 hours after epileptic seizure,and some neuron interstitial edema occurred. The possible mechanism of compatibility of Acori Tatarinowii Rhizoma and Curcumae Radix is related to serum prolactin level,MAPK signaling pathway,HTLV-Ⅰ infection and herpes simplex infection. The analysis may be related to viral encephalitis caused by HTLV-Ⅰ virus and herpes simplex infection,which damages nerve cells and causes seizures.

Pretreatment of Populus tomentiglandulosa protects hippocampal CA1 pyramidal neurons from ischemia-reperfusion injury in gerbils via increasing SODs expressions and maintaining BDNF and IGF-I expressions / 中国天然药物

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.

Improved effects of saponins from Panax japonicus on decline of cognitive function in natural aging rats via NLRP3 inflammasome pathway / 中国中药杂志

The aim of this paper was to investigate the effect of total saponins from Panax japonicus( SPJ) on cognitive decline of natural aging rats and its mechanism. Thirty male SD rats of eighteen month old were randomly divided into three groups: aged group,10 mg·kg~(-1) SPJ-treated group and 30 mg·kg~(-1) SPJ-treated group. The SPJ-treated groups were given SPJ at the dosages of 10 mg·kg~(-1) and 30 mg·kg~(-1),respectively,from the age of 18 to 24 months. Aged group were lavaged the same amount of saline,10 six-month-old rats were used as control group,with 10 rats in each group. The open field test,novel object recognition and Morris water maze were performed to detect the changes of cognitive function in each group. The changes of synaptic transmission of long-term potentiation( LTP) in hippocampal CA1 region were detected by field potential recording. Western blot was used to detect the protein levels of NLRP3,ASC,caspase-1 and the changes of Glu A1,Glu A2,CAMKⅡ,CREB and phosphorylation of CAMKⅡ,CREB in each group.The results showed that SPJ could improve the decline of cognitive function in aging rats,reduce the damage of LTP in the hippocampal CA1 region of aged rats,and decrease the expression of NLRP3,ASC,caspase-1 in aging rats. At the same time,SPJ could enhance the membrane expression of AMPA receptor( Glu A1 and Glu A2),and increase the expression of p-CAMKⅡand p-CREB in aging rats.SPJ could improve cognitive decline of natural aging rats,and its mechanism may be related to regulating NLRP3 inflammasome,thus regulating the membrane expression of AMPA receptor,and enhancing the expression phosphorylation of CAMKⅡ and CREB.

G protein-coupled estrogen receptor alleviates cerebral ischemia-reperfusion injury through inhibiting endoplasmic reticulum stress / 生理学报

The aim of this study was to investigate whether G protein-coupled estrogen receptor (GPER) could alleviate hippocampal neuron injury under cerebral ischemia-reperfusion injury (CIRI) by acting on endoplasmic reticulum stress (ERS). The CIRI animal model was established by middle cerebral artery occlusion (MCAO). Female ovariectomized (OVX) Sprague-Dawley (SD) female rats were randomly divided into 4 groups: control, ischemia-reperfusion injury (MCAO), vehicle (MCAO+DMSO), and GPER-specific agonist G1 (MCAO+G1) groups. The neurobehavioral score was assessed by the Longa score method, the morphological changes of the neurons were observed by the Nissl staining, the cerebral infarction was detected by the TTC staining, and the neural apoptosis in the hippocampal CA1 region was detected by TUNEL staining. The distribution and expression of GRP78 (78 kDa glucose-regulated protein 78) in the hippocampal CA1 region were observed by immunofluorescent staining. The protein expression levels of GRP78, Caspase-12, CHOP and Caspase-3 were detected by Western blot, and the mRNA expression levels of GRP78, Caspase-12, and CHOP were detected by the real-time PCR. The results showed that the neurobehavioral score, cerebral infarct volume, cellular apoptosis index, as well as GRP78, Caspase-12 and CHOP protein and mRNA expression levels in the MCAO group were significantly higher than those of control group. And G1 reversed the above-mentioned changes in the MCAO+G1 group. These results suggest that the activation of GPER can decrease the apoptosis of hippocampal neurons and relieve CIRI, and its mechanism may involve the inhibition of ERS.

A design of raster plot for illustrating dynamic neuronal activity during deep brain stimulation / 生物医学工程学杂志

Deep brain stimulation (DBS), which usually utilizes high frequency stimulation (HFS) of electrical pulses, is effective for treating many brain disorders in clinic. Studying the dynamic response of downstream neurons to HFS and its time relationship with stimulus pulses can reveal important mechanisms of DBS and advance the development of new stimulation modes (e.g., closed-loop DBS). To exhibit the dynamic neuronal firing and its relationship with stimuli, we designed a two-dimensional raster plot to visualize neuronal activity during HFS (especially in the initial stage of HFS). Additionally, the influence of plot resolution on the visualization effect was investigated. The method was then validated by investigating the neuronal responses to the axonal HFS in the hippocampal CA1 region of rats. Results show that the new design of raster plot is able to illustrate the dynamics of indexes (such as phase-locked relationship and latency) of single unit activity (i.e., spikes) during periodic pulse stimulations. Furthermore, the plots can intuitively show changes of neuronal firing from the baseline before stimulation to the onset dynamics during stimulation, as well as other information including the silent period of spikes immediately following the end of HFS. In addition, by adjusting resolution, the raster plot can be adapted to a large range of firing rates for clear illustration of neuronal activity. The new raster plot can illustrate more information with a clearer image than a regular raster plot, and thereby provides a useful tool for studying neuronal behaviors during high-frequency stimulations in brain.

Transient forebrain ischemia induces impairment in cognitive performance prior to extensive neuronal cell death in Mongolian gerbil (Meriones unguiculatus)

In Mongolian gerbils, bilateral common carotid artery occlusion (BCCAO) for several minutes induces ischemia, due to an incomplete circle of Willis, resulting in delayed neuronal cell death in the Cornet d'Ammon 1 (CA1) region of the hippocampus. Neuronal cell death in the hippocampus and changes in behavior were examined after BCCAO was performed for 5 min in the gerbils. One day after BCCAO, the pyramidal neurons of the CA1 region of the hippocampus showed degenerative changes (clumped chromatin in nuclei). At 5 and 10 days after BCCAO, extensive neuronal cell death was observed in the hippocampal CA1 region. Cognitive performance was evaluated by using the radial maze and passive avoidance tests. In the radial maze test, which examines win-stay performance, the number of errors was significantly higher in ischemic gerbils than in sham-operated gerbils on days 1 and 2 post-operation. In the passive avoidance test, the latency and freezing times were significantly shorter in ischemic gerbils than in sham-operated gerbils on the days 1, 2, and 4–6 post-operation. These results indicate that transient forebrain ischemia impairs cognitive performance, even immediately after the ischemic insult when there are only subtle signs of neuronal cell death.

Effect of Neuronal Excitability in Hippocampal CA1 Area on Auditory Pathway in a Rat Model of Tinnitus / 中华医学杂志(英文版)

Background@#Tinnitus is a common disorder that causes significant morbidity; however, the neurophysiological mechanism is not yet fully understood. A relationship between tinnitus and limbic system has been reported. As a significant component of the limbic system, the hippocampus plays an important role in various pathological processes, such as emotional disturbance, decreased learning ability, and deterioration of memory. This study was aimed to explore the role of the hippocampus in the generation of tinnitus by electrophysiological technology.@*Methods@#A tinnitus model was established in rats through intraperitoneal injection of salicylate (SA). Subsequently, the spontaneous firing rate (SFR) of neurons in the hippocampal CA1 area was recorded with in vivo multichannel recording technology to assess changes in excitability induced by SA. To investigate the effect of excitability changes of hippocampus on the auditory pathway, the hippocampus was electrically stimulated and neural excitability in the auditory cortex (AC) was monitored.@*Results@#Totally 65 neurons in the hippocampal CA1 area were recorded, 45 from the SA group (n = 5), and 20 from the saline group (n = 5). Two hours after treatment, mean SFR of neurons in the hippocampal CA1 area had significantly increased from 3.06 ± 0.36 Hz to 9.18 ± 1.30 Hz in the SA group (t = -4.521, P 0.05). In the AC, 79.3% (157/198) of recorded neurons showed responses to electrical stimulation of the hippocampal CA1 area. Presumed pyramidal neurons were excited, while intermediate neurons were inhibited after electrical stimulation of the hippocampus.@*Conclusions@#The study shows that the hippocampus is excited in SA-induced tinnitus, and stimulation of hippocampus could modulate neuronal excitability of the AC. The hippocampus is involved in tinnitus and may also have a regulatory effect on the neural center.

Neuroprotective Effect of Duloxetine on Chronic Cerebral Hypoperfusion-Induced Hippocampal Neuronal Damage

Chronic cerebral hypoperfusion (CCH), which is associated with onset of vascular dementia, causes cognitive impairment and neuropathological alterations in the brain. In the present study, we examined the neuroprotective effect of duloxetine (DXT), a potent and balanced serotonin/norepinephrine reuptake inhibitor, on CCH-induced neuronal damage in the hippocampal CA1 region using a rat model of permanent bilateral common carotid arteries occlusion. We found that treatment with 20 mg/kg DXT could attenuate the neuronal damage, the reduction of phosphorylations of mTOR and p70S6K as well as the elevations of TNF-α and IL-1β levels in the hippocampal CA1 region at 28 days following CCH. These results indicate that DXT displays the neuroprotective effect against CCH-induced hippocampal neuronal death, and that neuroprotective effect of DXT may be closely related with the attenuations of CCH-induced decrease of mTOR/p70S6K signaling pathway as well as CCH-induced neuroinflammatory process.

Temporal changes in mammalian target of rapamycin (mTOR) and phosphorylated-mTOR expressions in the hippocampal CA1 region of rat with vascular dementia

Mammalian target of rapamycin (mTOR) has an important role in various biological processes in cells. In the present study, we investigated temporal changes in mTOR and phosphorylated-mTOR (p-mTOR) expressions in the rat hippocampal CA1 region following chronic cerebral hypoperfusion (CCH) induced by permanent bilateral common carotid arteries occlusion (2VO). The mTOR immunoreactivity in the pyramidal neurons and mTOR protein level in the hippocampal CA1 region were markedly decreased at 21 and 28 days after 2VO surgery. However, p-mTOR protein expression was significantly increased at 7 days following CCH but then decreased with time. The results indicate that mTOR and p-mTOR expressions change in the hippocampal CA1 region after 2VO surgery and that reduced expressions of mTOR and p-mTOR may be closely related to the CCH-induced neuronal damage in the hippocampal CA1 region.

Age-dependent differences in myelin basic protein expression in the hippocampus of young, adult and aged gerbils / 한국실험동물학회지

Myelin degeneration is one of the characteristics of aging and degenerative diseases. This study investigated age-related alterations in expression of myelin basic protein (MBP) in the hippocampal subregions (dentate gyrus, CA2/3 and CA1 areas) of gerbils of various ages; young (1 month), adult (6 months) and aged (24 months), using western blot and immunohistochemistry. Western blot results showed tendencies of age-related reductions of MBP levels. MBP immunoreactivity was significantly decreased with age in synaptic sites of trisynaptic loops, perforant paths, mossy fibers, and Schaffer collaterals. In particular, MBP immunoreactive fibers in the dentate molecular cell layer (perforant path) was significantly reduced in adult and aged subjects. In addition, MBP immunoreactive mossy fibers in the dentate polymorphic layer and in the CA3 striatum radiatum was significantly decreased in the aged group. Furthermore, we observed similar age-related alterations in the CA1 stratum radiatum (Schaffer collaterals). However, the density of MBP immunoreactive fibers in the dentate granular cell layer and CA stratum pyramidale was decreased with aging. These findings indicate that expression of MBP is age-dependent and tissue specific according to hippocampal layers.

Neuroprotection of Dexmedetomidine against Cerebral Ischemia-Reperfusion Injury in Rats: Involved in Inhibition of NF-κB and Inflammation Response

Dexmedetomidine is an α2-adrenergic receptor agonist that exhibits a protective effect on ischemia-reperfusion injury of the heart, kidney, and other organs. In the present study, we examined the neuroprotective action and potential mechanisms of dexmedetomidine against ischemia-reperfusion induced cerebral injury. Transient focal cerebral ischemia-reperfusion injury was induced in Sprague-Dawley rats by middle cerebral artery occlusion. After the ischemic insult, animals then received intravenous dexmedetomidine of 1 μg/kg load dose, followed by 0.05 μg/kg/min infusion for 2 h. After 24 h of reperfusion, neurological function, brain edema, and the morphology of the hippocampal CA1 region were evaluated. The levels and mRNA expressions of interleukin-1β, interleukin-6 and tumor nevrosis factor-α as well as the protein expression of inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-κBp65, inhibitor of κBα and phosphorylated of κBα in hippocampus were assessed. We found that dexmedetomidine reduced focal cerebral ischemia-reperfusion injury in rats by inhibiting the expression and release of inflammatory cytokines and mediators. Inhibition of the nuclear factor-κB pathway may be a mechanism underlying the neuroprotective action of dexmedetomidine against focal cerebral I/R injury.

Neuroprotection of Dexmedetomidine against Cerebral Ischemia-Reperfusion Injury in Rats: Involved in Inhibition of NF-κB and Inflammation Response

Dexmedetomidine is an α2-adrenergic receptor agonist that exhibits a protective effect on ischemia-reperfusion injury of the heart, kidney, and other organs. In the present study, we examined the neuroprotective action and potential mechanisms of dexmedetomidine against ischemia-reperfusion induced cerebral injury. Transient focal cerebral ischemia-reperfusion injury was induced in Sprague-Dawley rats by middle cerebral artery occlusion. After the ischemic insult, animals then received intravenous dexmedetomidine of 1 μg/kg load dose, followed by 0.05 μg/kg/min infusion for 2 h. After 24 h of reperfusion, neurological function, brain edema, and the morphology of the hippocampal CA1 region were evaluated. The levels and mRNA expressions of interleukin-1β, interleukin-6 and tumor nevrosis factor-α as well as the protein expression of inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-κBp65, inhibitor of κBα and phosphorylated of κBα in hippocampus were assessed. We found that dexmedetomidine reduced focal cerebral ischemia-reperfusion injury in rats by inhibiting the expression and release of inflammatory cytokines and mediators. Inhibition of the nuclear factor-κB pathway may be a mechanism underlying the neuroprotective action of dexmedetomidine against focal cerebral I/R injury.

Effects of low frequency stimulation on spontaneous inhibitory and excitatory post-synaptic currents in hippocampal CA1 pyramidal cells of kindled rats

Objective: Low-frequency stimulation [LFS] exerts suppressive effects in kindled animals. It is believed that overstimulated glutamatergic and decreased GABAergic transmission have long been associated with seizure activity. In this study, we investigated the effect of electrical LFS on different parameters of spontaneous excitatory and inhibitory post-synaptic currents [sEPSCs and sIPSCs] in hippocampal CA1 pyramidal cells in kindled animals

Materials and Methods: In this experimental study, rats were kindled by electrical stimulation of the hippocampal CA1 area in a semi-rapid manner [12 stimulations/day]. The animals were considered fully kindled when they showed stage 5 seizures on three consecutive days. One group of animals received LFS 4 times at 30 seconds, 6 hours, 18 and 24 hours following the last kindling stimulation. Each LFS consisted of 4 packages at 5 minutes intervals. Each package of LFS consisted of 200 pulses at 1 Hz and each monophasic square wave pulse duration was 0.1 millisecond. At 2-3 hours post-LFS, acute hippocampal slices were prepared and a whole cell patch clamp recording was performed in all animals to measure the different parameters of sEPSCs and sIPSCs

Results: In kindled animals, the inter-event interval [as an index of occurrence] of sEPSCs decreased, whereas sIPSC increased. In addition, the decay time constant of sIPSCs as an index of the duration of its activity decreased compared to the control group. There was no significant difference in other parameters between the kindled and control groups. Application of LFS in kindled animals prevented the observed changes. There was no significant difference between the measured parameters in kindled+LFS and control groups

Conclusion: LFS application may prevent seizure-induced increase in the occurrence of sEPSCs and seizure-induced decrease in occurrence and activity duration of sIPSCs

Isoflurane provides neuroprotection in neonatal hypoxic ischemic brain injury by suppressing apoptosis / Isoflurano fornece neuroproteção em lesão cerebral hipóxico-isquêmica neonatal por inibição da apoptose

Abstract Background and objectives: Isoflurane is halogenated volatile ether used for inhalational anesthesia. It is widely used in clinics as an inhalational anesthetic. Neonatal hypoxic ischemia injury ensues in the immature brain that results in delayed cell death via excitotoxicity and oxidative stress. Isoflurane has shown neuroprotective properties that make a beneficial basis of using isoflurane in both cell culture and animal models, including various models of brain injury. We aimed to determine the neuroprotective effect of isoflurane on hypoxic brain injury and elucidated the underlying mechanism. Methods: A hippocampal slice, in artificial cerebrospinal fluid with glucose and oxygen deprivation, was used as an in vitro model for brain hypoxia. The orthodromic population spike and hypoxic injury potential were recorded in the CA1 and CA3 regions. Amino acid neurotransmitters concentration in perfusion solution of hippocampal slices was measured. Results: Isoflurane treatment caused delayed elimination of population spike and improved the recovery of population spike; decreased frequency of hypoxic injury potential, postponed the onset of hypoxic injury potential and increased the duration of hypoxic injury potential. Isoflurane treatment also decreased the hypoxia-induced release of amino acid neurotransmitters such as aspartate, glutamate and glycine induced by hypoxia, but the levels of γ-aminobutyric acid were elevated. Morphological studies showed that isoflurane treatment attenuated edema of pyramid neurons in the CA1 region. It also reduced apoptosis as evident by lowered expression of caspase-3 and PARP genes. Conclusions: Isoflurane showed a neuro-protective effect on hippocampal neuron injury induced by hypoxia through suppression of apoptosis.

Resumo Justificativa e objetivos: Isoflurano é um éter volátil halogenado usado para anestesia por via inalatória. É amplamente usado na clínica como um anestésico para inalação. A lesão hipóxico-isquêmica neonatal ocorre no cérebro imaturo e resulta em morte celular tardia via excitotoxicidade e estresse oxidativo. Isoflurano mostrou ter propriedades neuroprotetoras que formam uma base benéfica para o seu uso tanto em cultura de células quanto em modelos animais, incluindo vários modelos de lesão cerebral. Nosso objetivo foi determinar o efeito neuroprotetor de isoflurano em hipóxia cerebral e elucidar o mecanismo subjacente. Métodos: Fatias de hipocampo, em fluido cerebrospinal artificial (CSFA) com glicose e privação de oxigênio, foram usadas como um modelo in vitro de hipóxia cerebral. O pico de população ortodrômica (PPO) e o potencial de lesão hipóxica (PLH) foram registrados nas regiões CA1 e CA3. A concentração de neurotransmissores de aminoácidos na solução de perfusão das fatias de hipocampo foi medida. Resultados: O tratamento com isoflurano retardou a eliminação do PPO e melhorou a recuperação do PPO; diminuiu a frequência do PLH, retardou o início do PLH e aumentou a duração do PLH. O tratamento com isoflurano também diminuiu a liberação de neurotransmissores de aminoácidos induzida pela hipóxia, como aspartato, glutamato e glicina, mas os níveis de ácido γ-aminobutírico (GABA) estavam elevados. Estudos morfológicos mostram que o tratamento de edema com isoflurano atenuou o edema de neurônios piramidais na região CA1. Também reduziu a apoptose, como mostrado pela expressão reduzida da caspase-3 e genes PARP. Conclusões: Isoflurano mostrou um efeito neuroprotetor na lesão neuronal no hipocampo induzida por hipóxia através da supressão de apoptose.

Effect of Qidan Granule on PMC Derived Peptide Content and Structure of Hippocampal CA1 Region in Microwave Radiated Rats / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the protection of high intensity microwave radiation on hypothalamo-pituitary-adrenal axis (HPAA) activity and hippocampal CA1 structure in rats and the protectiveeffect of Qindan Granule (QG) on radiation injured rats.</p><p><b>METHODS</b>Totally 48 Wistar rats were randomlydivided into 8 groups, i.e., the normal control group, post-radiation day 1, 7, and 10 groups, 7 and 10days prevention groups, day 7 and 10 treatment groups, 6 in each group. Rats in prevention groups wererespectively administered with QG liquid (1 mL/100 g, 4. 75 g crude drugs) for 7 days and 10 days bygastrogavage and then microwave radiation. Then preventive effect for radiation injury was statisticallycalculated with the normal control group and the post-radiation day 1 group. Rats in treatment groupswere firstly irradiated, and then administered with QG liquid (1 mL/100 g, 4.75 g crude drugs). Finally preventive effect for radiation injury was statistically calculated with the normal control group, post-radiation day 7 and 10 groups. Contents of corticotrophin releasing hormone (CRH), beta endorphin (beta-EP), adrenocorticotropic hormone (ACTH), and heat shock protein 70 (HSP70) were detected. Morphological changes and structure of hippocampal CA1 region were observed under light microscope.</p><p><b>RESULTS</b>Compared with the normal control group, contents of CRH and beta-EP significantly decreased in each radiation group. Serum contents of ACTH and beta-EP significantly increased in post-radiation day 1 and 7 groups (P < 0.05). Compared with radiation groups, beta-EP content in serum and pituitary significantly increased, and serum ACTH content significantly decreased in prevention groups (P < 0.05). Pituitary contents of CRH and beta-EP significantly increased in prevention groups. Serum contents of ACTH, beta-EP, and HSP70 were significantly lower in day 7 treatment group than post-radiation day 7 group (P < 0.05). Morphological results showed that pyramidal neurons in the hippocampal CA1 region arranged in disorder, with swollen cells, shrunken and condensed nucleus, dark dyeing cytoplasm, unclear structure. Vessels in partial regions were dilated with static blood; tissues were swollen and sparse. In prevention and treatment groups pathological damage of hippocampal CA1 region was obviously attenuated; neurons were arranged more regularly; swollen, pycnotic, or deleted neuron number were decreased; vascular dilatation and congestion was lessened.</p><p><b>CONCLUSION</b>QG could affect HPAA function and activity of high intensity microwave radiated rats, showing certain preventive and therapeutic effects of microwave radiated rats by adjusting synthesis and release of partial bioactive peptides and hormones in HPAA, improving pathological injury in hippocampal CA1 region.</p>

Effect of Yangxue Qingnao Granule on the Expression of CD11b in CA1 Region of Hippocampus of Vascular Dementia Rats / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effect of Yangxue Qingnao Granule (YQG) on the expression of CD11b in CA1 region of hippocampus of vascular dementia rats, and to explore its regulation on microglias.</p><p><b>METHODS</b>Totally 144 SD rats were randomly divided into the sham-operation group, the vascular dementia model group (model), and the YQG treated group (treated). The vascular dementia rat model was prepared by modified Pulsinelli's four-vessel occlusion. Rats in the sham-operation group and the model group were administered with normal saline -(at the daily dose of 10 mL/kg) by gastrogavage, while those in the treated group were administered with YQG (0.32 g/mL, at the daily dose of 10 mL/kg) by gastrogavage. All administration was performed once per day for 8 successive weeks. The expression of CD11b in CA1 region of hippocampus of vascular dementia rats was detected at week 1, 2, 4, and 8, respectively.</p><p><b>RESULTS</b>Compared with the sham-operation group, the expression of CD11b in CA1 region of hippocampus of vascular dementia rats were significantly enhanced in the model group at each time point (P < 0.01). Compared with the model group, the expression of CD11b in CA1 region of hippocampus of vascular dementia rats significantly decreased in the treated group at each time point (P < 0.01), especially at week 2.</p><p><b>CONCLUSION</b>Obvious activation and proliferation of microglias could be seen in CA1 region of hippocampus of vascular dementia rats, and YQG could inhibit activation and proliferation of microglias.</p>