GABA Receptor Activity Suppresses the Transition from Inter-ictal to Ictal Epileptiform Discharges in Juvenile Mouse Hippocampus / 神经科学通报·英文版

Exploring the transition from inter-ictal to ictal epileptiform discharges (IDs) and how GABA receptor-mediated action affects the onset of IDs will enrich our understanding of epileptogenesis and epilepsy treatment. We used Mg-free artificial cerebrospinal fluid (ACSF) to induce epileptiform discharges in juvenile mouse hippocampal slices and used a micro-electrode array to record the discharges. After the slices were exposed to Mg-free ACSF for 10 min-20 min, synchronous recurrent seizure-like events were recorded across the slices, and each event evolved from inter-ictal epileptiform discharges (IIDs) to pre-ictal epileptiform discharges (PIDs), and then to IDs. During the transition from IIDs to PIDs, the duration of discharges increased and the inter-discharge interval decreased. After adding 3 μmol/L of the GABA receptor agonist muscimol, PIDs and IDs disappeared, and IIDs remained. Further, the application of 10 μmol/L muscimol abolished all the epileptiform discharges. When the GABA receptor antagonist bicuculline was applied at 10 μmol/L, IIDs and PIDs disappeared, and IDs remained at decreased intervals. These results indicated that there are dynamic changes in the hippocampal network preceding the onset of IDs, and GABA receptor activity suppresses the transition from IIDs to IDs in juvenile mouse hippocampus.

Oxygen/Glucose Deprivation and Reperfusion Cause Modifications of Postsynaptic Morphology and Activity in the CA3 Area of Organotypic Hippocampal Slice Cultures

Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.

Effects of ginkgolide B on neuronal discharges in rat hippocampal CA1 area / 神经解剖学杂志

Extracellular single-unit discharge recording technique was used to examine the effects of Ginkgolide B (BN52021) on the discharges of neurons in CAI area of hippocampal slices and to elucidate the mechanisms involved.The results showed that:(1) In response to the application of ginkgolide B (0.1,1,10 βμmol/L; n =43) into the perfusate for 2 rain,the spontaneous discharge rates (SDR) of 42/43 (97.67%) neurons were significantly decreased in a dose-dependent manner; (2) Pretreatment with L-glutamate (L-Glu,0.2mmol/L) led to a marked increase in the SDR of all 10 (100%) neurons in an epileptiform pattern.The increased discharges were suppressed significantly after ginkgolide B (1 μmol/L) was applied into the perfusate for 2 rain; (3) In 8 neurons,perfusion of the selective L-type calcium channel agonist,Bay K 8644 (0.1 μmol/L),induced a significant increase in the discharge rate of 8/8 (100%) neurons.Ginkgolide B (1 μmoL/L) applied into the perfusate inhibited the discharges of 7/8 (87.5%) slices; (4) In 8 neurons,the broad potassium channels blocker,tetraethylammonium (TEA,1 mmol/L) completely blocked the inhibitory effect of ginkgolide B (1 μmol/L).These results suggest that ginkgolide B can inhibit the electrical activity of CAI neurons.The inhibitory effect may be related to the blockade of L-type voltage-activated calcium channel and may be concerned with delayed rectifier potassium channel (KDR),which indicated that ginkgolide B play a protective role on the central neurons.

Effect of growth hormone on neuronal death in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation / 소아과

PURPOSE: To investigate whether growth hormone (GH) has a protective effect on neurons in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation (OGD). METHODS: Cultured hippocampal slices of 7-day-old rats were exposed to OGD for 60 min. Then, the slices were immediately treated with three doses of GH (5, 50, or 500 micrometer) in media. The relative fluorescent densities of propidium iodide (PI) uptake in the slices and relative lactate dehydrogenase (LDH) activities in the media were determined and compared between each GH-treated group of slices and untreated slices (control) at 12 and 24 h after OGD. Immunofluorescent staining for caspase-3 and TUNEL staining were performed to observe the effect of GH on apoptotic neuronal death. RESULTS: The relative fluorescent densities of PI uptake in CA1 and dentate gyrus (DG) of the hippocampal slices in each GH-treated group were not significantly different from those in the untreated slices at 12 and 24 h after OGD (P>0.05). Treatment with GH could reduce the relative LDH activities in the media of the GH-treated groups only at 12 h after OGD (P<0.05). Expression of caspase-3 and TUNEL positivity in CA1 and DG of the slices treated with 50-iM GH were not different from those of the untreated slices at 12 and 24 h after OGD. CONCLUSION: Treatment of hippocampal slice cultures with GH after OGD does not show a definitive protective effect on neuronal death but can reduce the LDH efflux of the slices in media at 12 h after OGD.

Effect of growth hormone on neuronal death in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation / 소아과

PURPOSE: To investigate whether growth hormone (GH) has a protective effect on neurons in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation (OGD). METHODS: Cultured hippocampal slices of 7-day-old rats were exposed to OGD for 60 min. Then, the slices were immediately treated with three doses of GH (5, 50, or 500 micrometer) in media. The relative fluorescent densities of propidium iodide (PI) uptake in the slices and relative lactate dehydrogenase (LDH) activities in the media were determined and compared between each GH-treated group of slices and untreated slices (control) at 12 and 24 h after OGD. Immunofluorescent staining for caspase-3 and TUNEL staining were performed to observe the effect of GH on apoptotic neuronal death. RESULTS: The relative fluorescent densities of PI uptake in CA1 and dentate gyrus (DG) of the hippocampal slices in each GH-treated group were not significantly different from those in the untreated slices at 12 and 24 h after OGD (P>0.05). Treatment with GH could reduce the relative LDH activities in the media of the GH-treated groups only at 12 h after OGD (P<0.05). Expression of caspase-3 and TUNEL positivity in CA1 and DG of the slices treated with 50-iM GH were not different from those of the untreated slices at 12 and 24 h after OGD. CONCLUSION: Treatment of hippocampal slice cultures with GH after OGD does not show a definitive protective effect on neuronal death but can reduce the LDH efflux of the slices in media at 12 h after OGD.

An improved method of making oxygen-glucose deprivation model of neonatal rats hippocampal slice in vitro / 重庆医科大学学报

Objective:To introduce an economical and pragmatic method of establishing oxygen-glucose deprivation model for hippocampal slice of neonatal rats in vitro. Methods: Hippocampal slices(400?m) from 8~10-day-old rats were transferred into an incubator with insert of Millicell membrance and incubated for 7d,14d,20d and 30d respectively.Then they were observed under convened microscope to evaluate their growing state,and detected their ability to absorb propidiumiodide(PI) under fluorescent microscope after they had been stained by PI , The state of the hippocampal slices was observed at different time after aerating Nitrogen gas. Results:(1)No PI labelled cells were found after 7d and 14d.However,15% PI positive cells were found after 30d.(2)The longer in Nitrogen gas ,the more apoptosis cells.(3)Intensive fluorescence was observed in the CA1, CA3 and DG areas of the hippocampal slice after aerating Nitrogen gas for 1.5h.Conclusion:The hippocampal slice can be alive for about 30 days.Stable oxygen-glucose deprivation model of the hippocampal slice in vitro was successfully established after aerating Nitrogen gas for 1.5h.

Effects of Ascorbic and Dehydroascorbic Acids on Apoptotic Cell Death in Hippocampal Slice Culture

Ascorbic acid (AA) and dehydroascorbic acid (DHA) are known to have protective effects in experimental central nerve system disorder models such as stroke, ischemia, and epileptic seizures. The present study was conducted to examine the protective effect of AA and DHA on kainic acid (KA) neurotoxicity using organotypic hippocampal slice cultures (OHSC). Protective effects of AA and DHA on KA-induced cell death were evaluated by analyzing caspase-3. In addition, to determine if the prooxidant effect of AA is related to iron, the effect of AA on cell death was examined using desferrioxamine (DFO), an iron chelator. After 12h-KA treatment, significant delayed neuronal death was detected in CA3 region, but not in CA1. The AA (500 micrometer) and DHA (100 and 500 micrometer) pretreatments significantly prevented cell death by inhibiting caspase-3 activation in CA3 region. In the concentration of 1,000 micrometer, however, AA pretreatment might have prooxidant effect, but AA-induced oxidative reaction is mainly not related to transition metal ions. These data showed that the pretreatments of intermediate-dose AA and DHA protected KA-induced neuronal damage in OHSCs and co-pretreatment of AA and DFO did not affect cell death except for a few cases. These data suggest that both AA and DHA pretreatment have antioxidant or prooxidant effect depending on doses treated on KA-induced neuronal injury and the possible prooxidant effect of AA may not depend on the Fenton reaction.

An improved method of making oxygen-glucose deprivation model of hippocampal slice in vitro in neonatal rats / 重庆医科大学学报

Objective:To introduce an economical and pragmatic method of establishing oxygen-glucose deprivation model of hippocampal slice in neonatal rats in vitro,Methods:Hippocampal slices(400?m)from 8~10-day-old rats are transferred into an incubator with insert of Millicell membrance and incubated for 7 d,14 d,20 d and 30 d,respectively.The growing state of the hippocampal slices were observed under the convened microscope,and its ability to absorb propidiumiodide (PI) was detected under fluorescent microscope after the hippocampal slice was stained by PI,and the state of the hippocampal slices at different time after aerating Nitrogen gas was observed. Results: ① No PI labelled cells were found after 7 d and 14 d. However,15% PI positive cells were found after 30 d. ②The longer in Nitrogen gas,the more apoptosis cells. ③Intensive fluorescence was observed in the CA1,CA3 and DG areas of the hippocampal slice after aerating Nitrogen gas for 1.5h. Conclusion:The hippocampal slice can be alive for about 30 days.Stable oxygen-glucose deprivation model of the hippocampl slice in vitro was successfully established after aerating Nitrogen gas for 1.5 h.

Estrogen Pretreatment of Organotypic Hippocampal Slices Protects Neurons against Oxygen-Glucose Deprivation with Akt Activation

In several experimental models, estrogens protect neurons against ischemic insults. However, the recent clinical studies of hormone replacement showed negative results to prevent stroke. Therefore, optimal models to study estrogen replacement for neuroprotection are needed before its clinical application. Organotypic hippocampal slice under oxygen-glucose deprivation (OGD) has been established as a model of cerebral ischemia and has advantages to study drug effects. We investigated whether estrogen protected CA1 neurons and affected activation of Akt (pAkt) in CA1 region under OGD. Thus, rat hippocampal slices on day 7 of culture were treated with 17-beta estradiol (E, 1 nM) for 7 days before 30 min OGD, and cell death of CA1 neurons was quantified by propidium iodide (PI) staining and expression of pAkt was studied by Western blot and immunofluorescence. PI intensity in slices treated with E was significantly reduced 72 hour after OGD compared to that of non-treated slices (p<0.05). E pretreatment also increased the expression of pAkt 72 hour after OGD compared to that of no treatment (p<0.01). These data suggest that estrogen pretreatment may rescue neurons from ischemic insults through the activation of Akt and also indicate that our model would be a useful alternative method to study the mechanisms and effects of estrogen replacement treatment for neuroprotection.

Effects of electromagnetic stimulation on neurogenesis and neuronal proliferation in rat hippocampal slice culture / 소아과

PURPOSE: Transcranial electromagnetic stimulation(TMS) is a noninvasive method which stimulates the central nervous system through pulsed magnetic fields without direct effect on the neurons. Although the neurobiologic mechanisms of magnetic stimulation are unknown, the effects on the brain are variable according to the diverse stimulation protocols. This study aims to observe the effect of the magnetic stimulation with two different stimulation methods on the cultured hippocampal slices. METHODS: We obtained brains from 8-days-old Spague-Dawley rats and dissected the hippocampal tissue under the microscope. Then we chopped the tissue into 450 micrometer thickness slices and cultured the hippocampal tissue by Stoppini's method. We divided the inserts, which contained five healthy cultured hippocampal slices respectively, into magnetic stimulation groups and a control group. To compare the different effects according to the frequency of magnetic stimulation, stimulation was done every three days from five days in vitro at 0.67 Hz in the low stimulation group and at 50 Hz in the high stimulation group. After N-methyl-D-aspartate exposure to the hippocampal slices at 14 days in vitro, magnetic stimulation was done every three days in one and was not done in another group. To evaluate the neuronal activity after magnetic stimulation, the NeuN/beta-actin ratio was calculated after western blotting in each group. RESULTS: The expression of NeuN in the magnetic stimulation group was stronger than that of the control group, especially in the high frequency stimulation group. After N-methyl-D-aspartate exposure to hippocampal slices, the expression of NeuN in the magnetic stimulation group was similar to that of the control group, whereas the expression in the magnetic non-stimulation group was lower than that of the control group. CONCLUSION: We suggest that magnetic stimulation increases the neuronal activity in cultured hippocamal slices, in proportion to the stimulating frequency, and has a neuroprotective effect on neuronal damage.

Effect of TrkA and p75NTR on the Survival of Neurons in the Cultured Organotypic Hippocampal Slice

BACKGROUND: Nerve growth factor (NGF) promotes the survival and differentiation of vertebrate neurons, and their actions are mediated by two classes of cell surface receptors: tyrosine kinase A receptor (TrkA) and p75 neurotrophic receptor (p75NTR). We evaluated the role of NGF receptors in neuronal survival and the physical interactions between them. METHODS: Organotypic hippocampal slices were obtained from 5 to 7-day-old rat pups and were grown for 14 days in vitro. The expression of the TrkA and p75NTR was evaluated by the western blot and immunohistochemical methods. The neuroprotective effect of NGF on the blocking of antibody-induced neuronal cell death was tested by the application of NGF (0, 50 and 150 ng/ml) to the culture media in the presence of 200 ng/ml of blocking antibodies against TrkA and p75NTR. Functional interactions between the two receptors were examined using the immunoprecipitation method. RESULTS: TrkA and p75NTR were co-expressed in the principal neurons of the hippocampal slice culture, and the expression level was increased time dependently until 14 days of culture. The blocking antibody against each receptor induced neuronal damage in time and dose-dependent manners. NFG delayed or prevented the blocking antibody from inducing neuronal damage. Results from the immunoprecipitation experiment showed physical interactions between the two NGF receptors. CONCLUSIONS: Our results indicate that the co-expressed NGF receptors, TrkA and p75NTR, might have protective roles in the survival of neuronal cells through the cooperative interactions between them.

A study for morphology and the reactivity of rats hippocampal slice in vitro culture / 重庆医科大学学报

Objective:To explore the method of culturing rat hippocampal slice in vitro and to observe the changes of neurons' morphology and reactivity in cultured slice.Methods:Organotypic hippocampal slices were prepared by taking brains from 6-9 day old wistar rats.After the hippocampi was isolated and chopped into 400?m thickness,slices were transferred to Millipore inserts and placed in six-well trays in CO_2 incubators at 37℃.Then the cultured hippocampal slices were observed for the changes of morphology by macroscopic observation and using inverted phase contrast microscope;Expression of Fos protein in cultured hippocampal slice was detected by immunocytochemistry for observation of the internal response of hippocampal neurons to the damage;The electrophysiological activity of hippocampal neurons were detected by using patch clamp technique. Results:(1)The number of neurons in cultured hippocampal slices was increased,and the thickness of cultured hippocampal slices was decreased markedly along with the culturing period in vitro.After being cultured for 4 weeks,the thickness of hippocampal slices was decreased to about 150?m.(2)With the treatment of pilocarpine to induce seizure-like activity,the number of neurons which expressing Fos protein was increased in CA1 area of the cultured hippocampal slice.(3)With the application of pathch clamp technique,the changes of the ion currents of pyramidal neurons in CA1 area were recorded by the whole-cell recording after culturing for 1 week,2 weeks,3 weeks and 4 weeks respectively.Conclusion:Cultured hippocampal slice in vitro could retain satisfactory liveness and function for at least 4 weeks.

Protective effects of calpain inhibitor calpeptin on hypoxia/glucose deprivation injury in rat hippocampal slices / 中国药理学通报

Aim To investigate effects of calpain inhibitor calpeptin against hypoxia/glucose deprivation injury in rat hippocampal slices.Methods Forty hippocampal slices were randomly divided into two groups:Control group and calpeptin group.Calpeptin group then divided again into 1 ?mol?L-1 group,10 ?mol?L-1 group,100 ?mol?L-1 group and 200 ?mol?L-1 group according to the concentration of calpeptin in ACSF_ OGD(n=8 per group).By using electrophysiology method,changes of OPS and HIP during hypoxia/glucose deprivation process and effects of different concentration of calpeptin on it were observed.We also observed the neuronal apoptosis in hippocampal CA1 region after hypoxia/glucose deprivation and effects of different concentration of calpeptin on it.Results The HIP appearance rate and neuronal apoptosis in hippocampal CA1 region of 10 ?mol?L-1 group,100 ?mol?L-1 group and 200?mol?L-1 group significantly reduced,the OPS recovery amplitude and OPS recovery rate significantly increased,and every index among 10 ?mol?L-1 group,100 ?mol?L-1 group and 200 ?mol?L-1 group had no significant difference.Conclusion(10～200)?mol?L-1 calpeptin improved the hypoxia/glucose deprivation induced brain injury of rat hippocampal slices and the mechanism might be related to the inhibition of the neuronal apoptosis by calpeptin.

The Protective Effect of Preconditioning Ischemia on Subsequent Cerebral Ischemic Insults

A brief period of cerebral ischemia produces neuronal damage in the vulnerable regions of the brain, such as the CA1 area of the hippocampus. However, mild ischemic episodes may limit damage from subsequent ischemic insults, the phenomenon known as ischemic tolerance or preconditioning. We used hippocampal slices as an experimental model to investigate the possible utilization of ischemic tolerance, and to determine the effects of various drugs acting on glutamate and adenosine receptors following a conditioned ischemic insult. Preconditioning ischemic insult was induced in hippocampal slices of 450nm thickness for 60-70 seconds. Glutamate and adenosine receptors were pretreated 1 hour later with D,L-2-amino-5-phosphonovaleric acid(AP-5, 50nM), propentofylline(PPF, 200nM), 6-cyano-7-nitroquinoxaline-2,3-dione(CNQX, 10nM), 8-cyclopentyl-3,7-dihydro-1,3-dipropyl-1H-purine-2,6-dione(DPCPX, 1, 10nM) and 2-chloro-N6-cyclopentyl-adenosine (CCPA, 1, 10, 50nM). The slices were reoxygenated for 3 hours, after then a second ischemic insult was induced by substituting 95% O2, 5% CO2 and glucose for 95% N2, 5% CO2 and sucrose for 10 minutes. Population spikes(PS) were estimated from extracellular electrophysiological recordings of the hippocampal CA3-CA1 synaptic conduction 1 hour following the second ischemic insult. The PS(mV) was 2.69+/-0.06 in the normal hippocampal slice, while it was reduced to 1.21+/-0.05 in the hippocampal slice induced with 10 minutes of ischemia. The effects of the A1 selective agonist CPPA revealed a reduction of PS to 0.98+/-0.06 with low concentration(1nM), similar PS as the control group with a concentration of 10nM, and an increase in ischemic tolerance of 1.78+/-0.05 at a higher concentration(50nM). The selective A1 antagonist DPCPX(1nM) showed minimal reduction in PS of 1.10+/-0.04, while the NMDA antagonist AP-5(5nM) had a more profound weakening effect(1.05+/-0.04). The adenosine uptake inhibitor profentophylline(200nM) augmented the PS to 1.56+/-0.06; this effect was not influenced by 1nM DPCPX(1.60+/-0.07), but was abolished by a higher concentration of 10nM(1.36+/-0.05). These results confirmed ischemic tolerance in the hippocampal experimental model. We conclude that adenosine plays an important role in ischemic tolerance as activation of adenosine receptors or adenosine uptake inhibition enhances ischemic tolerance.

Effect of adenosine on the release of (3H)-5-hydroxytryptamine during glucose/oxygen deprivation from rat hippocampal slices

The effects of adenosine, adenosine A1 receptor antagonist (DPCPX), or NMDA receptor antagonist (APV) on the spontaneous release of (3H)-5-hydroxytryptamine ((3H)-5-HT) during normoxic/normoglycemic or hypoxic/hypoglycemic period were studied in the rat hippocampal slices. The hippocampus was obtained from the rat brain and sliced 400 mum thickness with the tissue slicer. After 30 min's preincubation in the normal buffer, the slices were incubated for 30 min in a buffer containing (3H)-5-HT (0.1 muM, 74 muCi/8 ml) for uptake, and washed. To measure the release of (3H)-5-HT into the buffer, the incubation medium was drained off and refilled every ten minutes through sequence of 14 tubes. Induction of glucose/oxygen deprivation (GOD; medium depleting glucose and gassed with 95% N2/5% CO2) was done in 6th and 7th tube. The radioactivities in each buffer and the tissue were counted using liquid scintillation counter and the results were expressed as a percentage of the total radioactivities. When slices were exposed to GOD for 20 mins, the spontaneous release of (3H)-5-HT was markedly increased and this increase of (3H)-5-HT release was blocked by adenosine (10 muM) or DL-2-amino-5-phosphonovaleric acid (APV; 30 muM). Adenosine A1 receptor specific antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) exacerbate GOD-induced increase of spontaneous release of (3H)-5-HT. These results suggest that Adenosine may play a role in the GOD-induced spontaneous release of (3H)-5-HT through adenosine A1 receptor activity.

Effects of K+ channel modulators on extracellular K+ accumulation during ischemia in the rat hippocampal slice

Loss of synaptic transmission and accumulation of extracellular K+((K+)o) are the key features in ischemic brain damage. Here, we examined the effects of several K+ channel modulators on the early ischemic changes in population spike (PS) and (K+)o in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in 3.3 +/- 0.22 min (mean +/- SEM, n = 40). The hypoxic injury potential (HIP), a transient recovery of PS appeared at 6.0 +/- 0.25 min (n = 40) in most slices during AA and lasted for 3.3 +/- 0.43 min. (K+)o increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among K+ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 (0.3 ~ 10 muM), niflumic acid (0.1 mM), glibenclamide (40 muM), tolbutamide (300 muM) and pinacidil (100 muM), only 4-aminopyridine (0.3 mM) induced slight increase of (K+)o during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in (K+)o in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive K+ channels, large conductance Ca2+/-activated K+ channels and ATP-sensitive K+ channels may not be the major contributors to the sudden increase of (K+)o during the early stage of brain ischemia, suggesting the presence of other routes of K+ efflux during brain ischemia.

Changes of 5-hydroxytryptamine release by different glucose concentration from hippocampal slices exposed to hypoxia

We have previously reported that the spontaneous release of [3H]5-hydroxytryptamine(5-HT) was markedly decreased by hypoxic insult in rat hippocampal slices. In the present study, the effect of glucose on 5-HT release was examined. Fractional release of [3H]5-HT was measured from an incubation medium exchanged every 10 min for 140 min and after stabilization of [3H]5-HT release, 10 or 20 min period of hypoxia was induced by exchanging the media which have been previously saturated by 95% N2/5% CO2 gas. In the media containing 1, 2, 5, 10 or 20 mM glucose, [3H]5-HT release was stabilized after 40 min of incubation. Exposure to hypoxia decreased [3H]5-HT release up to 60% of the control level in a glucose concentration-dependent manner and recovered gradually after hypoxic periods. However, in the media containing no glucose, the spontaneous release of [3H] 5-HT increased continuously during incubation. Moreover, when hippocampal slices were exposed to hypoxia, the [3H]5-HT release increased up to 150% of the control level and recovered gradually to the control level after hypoxic periods. These results demonstrate that hypoxia inhibits or enhances 5-HT release in the presence or absence of extracellular glucose respectively and suggest that the availability of extracellular glucose is a key factor to determine the direction of 5-HT release under hypoxic condition.

Effect of active fraction of Tiaoxin Recipe on long-term potentiation inhibited by corticosterone in area CA1 of rat hippocampal slices / 中草药

Objective To investigate the effect of active fraction A (TXR-A) extracted from Tiaoxin Recipe (TXR) on inhibition of corticosterone on long-term potentiation (LTP) induced by high frequency stimulation (HFS) in rat hippocampal slices. Methods The slices were divided into control, corticosterone, corticosterone+TXR, and corticosterone+different concentration of TXR-A groups, then were incubated with artificial cerebrospinal fluid (ACSF) added by drugs for 1 h before recording and were perfused with the same ACSF during recording. Population spike (PS) was recorded from stratum pyramidale of area CA1 using extracellular recording following stimulation of Schaffer collaterals in rat hippocampal slices. Then a 100 Hz, 100 pulses HFS was used to induce LTP. Results PS amplitude was decreased significantly vs that in the control group, when the slices were pre-incubated in ACSF added by corticosterone (2 ?mol/L) over 1.5 h, meaning that LTP was inhibited by corticosterone. However, PS amplitude of the slices pre-incubated in ACSF added by corticosterone (2 ?mol/L) and high concentration TXR-A was increased significantly vs that of corticosterone pre-treating slices, meaning that high concentration TXR-A enhanced LTP inhibited by corticosterone. Furthermore, increased LTP amplitude in high concentration TXR-A was much more than that in TXR. Conclusion TXR-A is one of main TXR active ingredients which facilitate LTP inhibited by corticosterone in area CA1 of rat hippocampal slices. The antagonist (effect) on corticosterone inhibition on LTP is one of the mechanisms to benefit the intelligence.

Study on the protective effect of Acathopanax Senticosus to the neuron by toxicity of Glu / 临床神经病学杂志

Objective To study the protective effect of Acathopanax Senticosus(AS) to the neuron by toxicity of Glu.Methods With hippocampal slice in rats and histography technique,we observed the effect in OPS of ischemic hippocampal slice by Glu between AS group and no AS group,and the changes of ultrastructure in the two groups were also observed.Results In AS group OPS was decreased and disappeared after slice with Glu for 5 min,the recovery rate of OPS was 16.6%,the degree was 41.5%.There was significant difference in the two groups( P

EFFECTS OF GLUCOCORTICOID ON ELECTRICAL ACTIVITIES OF HIPPOCAMPAL NEURONS OF RATS IN VITRO / 第二军医大学学报

IntraccUular recording of the rat hippocampal slices was established and used to analyse the effects of glucocorticoid on resting membrane potential as well as input resistance of the cells in CA1 and CA2 of hippocampal slices.The results indicate that the steroid hyperpolarized some of the hippocampal neurons with a tendency of increasing the cells'input resistance within 1-2 min, suggesting that glucocorticoid can influence the function of central neurons in a non-genomic pattern, and the underlying mechanism involves the change of resting membrane potential.