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To explore the roles of astrocytes in the epileptogenesis, astrocytes and neurons were isolated, purified and cultured in vitro from cerebral cortex of rats. The astrocytes were activated by ciliary neurotrophic factor (CNTF) and astrocytic conditioned medium (ACM) was collected to treat neurons for 4, 8 and 12 h. By using Western blot, the expression of calmodulin dependent protein kinase II (CaMK II), inducible nitric oxide synthase (iNOS) and adenylate cyclase (AC) was detected in neurons. The results showed that the expression of CaMK II, iNOS and AC was increased significantly in the neurons treated with ACM from 4 h to 12 h (P<0.05), and that of iNOS and AC peaked at 8 h and 12 h respectively. It was suggested that there might be some epileptogenic factors in the ACM and such signal pathways as NOS-NO-cGMP, Ca2+/CaM-CaMK II and AC-cAMP-PKA might take part in the signal transduction of epileptogenesis.
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To explore the roles of astrocytes in the epileptogenesis, astrocytes and neurons were isolated, purified and cultured in vitro from cerebral cortex of rats. The astrocytes were activated by ciliary neurotrophic factor (CNTF) and astrocytic conditioned medium (ACM) was collected to treat neurons for 4, 8 and 12 h. By using Western blot, the expression of calmodulin dependent protein kinase Ⅱ (CaMK Ⅱ), inducible nitric oxide synthase (iNOS) and adenylate cyclase (AC) was detected in neurons. The results showed that the expression of CaMK Ⅱ, iNOS and AC was increased significantly in the neurons treated with ACM from 4 h to 12 h (P＜0.05), and that of iNOS and AC peaked at 8 h and 12 h respectively. It was suggested that there might be some epileptogenic factors in the ACM and such signal pathways as NOS-NO-cGMP, Ca2+/CaM-CaMK Ⅱ and AC-cAMP-PKA might take part in the signal transduction of epileptogenesis.
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To explore the effect of coriaria lactone (CL)-activated astrocyte-conditioned medium on the cerebral TNF-alpha of normal rats, the CL-activated astrocyte-conditioned medium (ACM) was injected into the lateral ventricle of SD rats. The rats were observed for behavioral changes, and the changes of the expression of TNF-alpha in the cerebral cortex and hippocampus were immunohistochemically examined by employing SP method. TNF-alpha level was assessed by means of radioimmunoassay in homogenate of cerebral cortex and hippocampus as well as cerebrospinal fluid. Seizure episodes were observed in ACM group 30 min after the ACM injection, but they were not observed in the control group. Immunohistochemical detection showed that the immunoreaction of TNF-alpha in hippocampus and cerebral cortex of rats were stronger than that of the control group 4 h after the ACM injection (P<0. 05). In this group, the concentrations of TNF-alpha in homogenate of cerebral cortex and hippocampus and cerebrospinal fluid were higher than those of the control group (P<0.05). It is suggested that the ACM activated by CL can enhance the expression of TNF-alpha in normal rats, and is related to epileptogenesis.
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To explore the effect of coriaria lactone (CL)-activated astrocyte-conditioned medium on the cerebral TNF-α of normal rats, the CL-activated astrocyte-conditioned medium (ACM) was injected into the lateral ventricle of SD rats. The rats were observed for behavioral changes, and the changes of the expression of TNF-α in the cerebral cortex and hippocampus were immunohistochemically examined by employing SP method. TNF-α level was assessed by means of radioimmunoassay in homogenate of cerebral cortex and hippocampus as well as cerebrospinal fluid. Seizure episodes were observed in ACM group 30 min after the ACM injection, but they were not observed in the control group.Immunohistochemical detection showed that the immunoreaction of TNF-α in hippocampus and cerebral cortex of rats were stronger than that of the control group 4 h after the ACM injection (P＜0.05). In this group, the concentrations of TNF-α in homogenate of cerebral cortex and hippocampus and cerebrospinal fluid were higher than those of the control group (P＜0.05). Itis suggested that the ACM activated by CL can enhance the expression of TNF-α in normal rats,and is related to epileptogenesis.
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To explore the mechanism of epilepsy induced by IL-1beta and IL-6, the changes of glutamic acid (Glu) and GABA immunoreaction in the cerebral cortex and hippocampus of rats with seizure induced by IL-1beta or IL-6 were studied. Rats were randomly divided into 3 groups: control group (intracerebroventricular injection (icv) of NS), IL-1beta group (icv injection of IL-1beta) and IL-6 group (i. c. v. injection of IL-6). 120 min after the icv injection of reagents of IL-1beta or IL-6, behavioral changes were observed and Glu and GABA in the cerebral cortex and hippocampus were examined by means of immunohistochemistry. Our results showed that no seizure developed in the control group, while moderate seizure was observed in IL-1beta group and IL-6 group. Compared with the controls, the immunoreaction of Glu was significantly increased, while GABA was obviously decreased in IL-1beta group and IL-6 group after 120 min. Our study suggested that the IL-1beta and II-6 might promote and induce epilepsy by increasing Glu and decreasing GABA in the cerebral cortex and hippocampus.
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Comportamento Animal , Córtex Cerebral/metabolismo , Epilepsia/metabolismo , Ácido Glutâmico/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Epilepsia/induzido quimicamente , Hipocampo/metabolismo , Imuno-Histoquímica , Interleucina-1 , Interleucina-6 , Masculino , Distribuição Aleatória , Ratos , Ratos Sprague-DawleyRESUMO
Summary: To explore the mechanism of epilepsy induced by IL-1β and IL-6, the changes of glutamic acid (Glu) and GABA immunoreaction in the cerebral cortex and hippocampus of rats with seizure induced by IL-1β or IL-6 were studied. Rats were randomly divided into 3 groups: control group (intracerebroventricular injection (icv) of NS), IL-1β group (icv injection of IL-1β) and IL-6 group (i.c.v. injection of IL-6). 120 min after the icv injection of reagents of IL-1β or IL-6, behavioral changes were observed and Glu and GABA in the cerebral cortex and hippocampus were examined by means of immunohistochemistry. Our results showed that no seizure developed in the control group, while moderate seizure was observed in IL-1β group and IL-6 group. Compared with the controls, the immunoreaction of Glu was significantly increased, while GABA was obviously decreased in IL-1β group and IL-6 group after 120 min. Our study suggested that the IL-1β and IL-6 might promote and induce epilepsy by increasing Glu and decreasing GABA in the cerebral cortex and hippocampus.
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The effects of chloroquine on glial fibrillary acidic protein (GFAP), proliferation cell nuclear antigen (PCNA) and Cyclin D1 in hippocampus and cerebral cortex of rats with seizures induced by pentylenetetrazole (PTZ) were observed in the present study. Forty-eight male adult Sprague-Dawley (SD) rats were randomly divided into control group, chloroquine intervening group, and PTZ group. The behavior and electroencephalogram (EEG) were observed and recor ded. GFAP and PCNA were examined with immunohistochemistry. The content of Cyclin D1 in hippocampus and cerebral cortex was inspected with Western blot. The results showed no seizure activity in the control group, severe seizure activity in the PTZ group (Ⅳ-Ⅴ degree), and slight seizure activity ( Ⅰ - Ⅲ degree) in the chloroquine intervening group (P＜0. 05). EEG recordings showed no epileptic spikes in the control group, high amplitude with fast frequency in the PTZ group, low-amplitude and slow frequency in the chloroquine intervening group. The expression of GFAP and the positive index of PCNA in the PTZ group were higher than those of control group (P ＜0.05 and P＜0.01, respectively). No differences in GFAP expression and PCNA index were observed between chloroquine intervening and control groups (P＞0.05). The content of Cyclin D1 in hippocampus and cerebral cortex was significantly higher in the PTZ group than in control and chloroquine intervening groups (P＜ 0.05). Therefore, it is considered that chloroquine, by inhibiting the functions and proliferation of glial cells in the hippocampus and cerebral cortex, can alleviate the seizure activities. These results suggest that chloroquine may be an ideal anticonvulsant in preventing and treating epilepsy.
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To explore the mechanism of interleukin-1beta (IL-1beta) in the onset of seizure and the effect of IL-1beta on the expression of adenylyl cyclase (AC) in rats with seizure induced by L-glutamate. Experimental rats were first injected with IL-1beta and then L-glutamate (a dose under the threshold) was injected into the right lateral ventricle. The rats were sacrificed 4 h after the onset of epileptic activity and examined for changes in behavior, immunohistochemistry and compared with those with seizure induced by L-glutamate alone. It was found that the expression of AC in hippocampal and neocortex of rats with seizure induced by IL-1beta and L-glutamate were stronger than that of control group (P<0.05), without significant difference found between the L-glutamate group and IL-1beta plus L-glutamate group in the expression of AC, the latent period and the severity of seizure. When IL-ra were given (i.c.v.) first, there was no epileptic activity and the expression of AC did not increase. There were no differences in the expression of AC of rats with IL-1ra and that of control rats. But when 2-methyl-2-(carboxycyclopropyl) glycine (MCCG) was given (i.c.v.) first, the strongest expression of AC, the shortest latent period and the the most serious seizure activities were observed. The results indicated that IL-1beta could facilitate the onset of epilepsy induced by L-glutamate through IL-1R, metabotropic glutamate receptors might work with IL-1R and the increased expression of AC might be involved in the process.
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Animais , Masculino , Ratos , Adenilil Ciclases , Genética , Ácido Glutâmico , Hipocampo , Metabolismo , Interleucina-1 , Farmacologia , Neocórtex , Metabolismo , ConvulsõesRESUMO
Objective To explore the effects of astrocytes on the N-ethylmaleimide-sensitive fusion protin,(NSF) and AMPA receptor of the neurons as well as their function in epileptogenesis. Methods ACM was injected into lateral ventricle of SD rats and the behaviour changes were observed; Immunohistochemical method was used to assess the changes of the expression of NSF in the cerebral cortex and hippocampus; The cultured neurons were divided into control group, ACM group and CNQX+ACM group at random, immunocytochemistry was used to assess the changes of the expression of NSF, Western blotting was used to assess the changes of the content of NSF of the cultured neurons. Results Seizure was observed in ACM group 30 min after injecting ACM. the immunoreaction of NSF in hippocampus and cerebral cortex of rats were depressed than those of the control group 2h, 4h after injecting ACM (P
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Twenty cDNA differential fragments were isolated from the hippocampus of rats in epileptic state using mRNA differential display technique. Four fragments were sequenced and compared with the known sequences in the Genebank, which showed that ERG8, ERG11, ERG12had no significant identity to any known sequences; ERG14 had 64%-69% identity to microtubulin-associated protein of the rat. Because the differential expression of these genes was caused by epilepsy inducer coriaria lactone (CL) and anti-epilepsy drug MK-801 and ERG8 might be a novel candidate epilepsy gene; ERG11 and ERG12 might be novel candidate anti-epilepsy genes.Since the microtubulin-associated protein is closely associated with the collateral sprouting of mossy fibers in the hippocampus of seizured rat, the high expression of ERG14 in the early stage of epilepsy might predict the growth of axon and formation of synapse.
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To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (Iasp) in rat hippocampal CAI neurons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (Iasp) at a holding potential (VH) of -40mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50,Hill coefficient as well as maximal-effect concentration and reversal potential of Iasp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]I of neurons by acting on Gly site, thereby inducing epilepsy.
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In order to explore the roles of different neurotransmitters in epileptic pathogenesis,the synaptic connections between glutamic acid (Glu) neurons and GABA neurons in normal rat hippocampus were studied by pre-embedding double labeling immunoelectron microscopy. The GABA immunoreaction was first demonstrated by chromogen DAB, then the Glu immunoreaction was demonstrated by molybdic acid-TMB method. After being stabilized by DAB-cobalt chloride,the sections were processed for electron microscopic embedding. Under electron microscope, there were many Glu immunoreaction-positive neurons in the pyramidal layer of hippocampal CA1 area and some GABA immunoreaction-positive neurons with pyramidal or polygonal perikarya in the pyramidal, polymorphic and radiant layer of CA1 area. There were also symmetric dendro-axonic synapses formed by GABA-positive dendrites and Glu-positive axons in the polymorphic layer and symmetric axo-dendritic synapses formed by GABA-positive axons and Glu-positive dendrites in the radiant layer. In addition, there were symmetric autoregulatory axo-dendritic synapses between Glu-positive axons and dendrites and autoregulatory axo-axonic synapses (both symmetric and asymmetric) between GABA-positive axons. Above mentioned results, for the first time,showed that there were complex synaptic regulatory relationships between excitatory Glu neurons and inhibitory GABA neurons in the hippocampal CA1 area, thereby, providing ultrastructural evidence for different neurotransmitters participating in epileptic pathogenesis.
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Twenty cDNA differential fragments were isolated from the hippocampus of rats in epileptic state using mRNA differential display technique. Four fragments were sequenced and compared with the known sequences in the Genebank, which showed that ERG8, ERG11, ERG12had no significant identity to any known sequences; ERG14 had 64%-69% identity to microtubulin-associated protein of the rat. Because the differential expression of these genes was caused by epilepsy inducer coriaria lactone (CL) and anti-epilepsy drug MK-801 and ERG8 might be a novel candidate epilepsy gene; ERG11 and ERG12 might be novel candidate anti-epilepsy genes.Since the microtubulin-associated protein is closely associated with the collateral sprouting of mossy fibers in the hippocampus of seizured rat, the high expression of ERG14 in the early stage of epilepsy might predict the growth of axon and formation of synapse.
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To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (Iasp) in rat hippocampal CAI neurons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (Iasp) at a holding potential (VH) of -40mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50,Hill coefficient as well as maximal-effect concentration and reversal potential of Iasp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]I of neurons by acting on Gly site, thereby inducing epilepsy.
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In order to explore the roles of different neurotransmitters in epileptic pathogenesis,the synaptic connections between glutamic acid (Glu) neurons and GABA neurons in normal rat hippocampus were studied by pre-embedding double labeling immunoelectron microscopy. The GABA immunoreaction was first demonstrated by chromogen DAB, then the Glu immunoreaction was demonstrated by molybdic acid-TMB method. After being stabilized by DAB-cobalt chloride,the sections were processed for electron microscopic embedding. Under electron microscope, there were many Glu immunoreaction-positive neurons in the pyramidal layer of hippocampal CA1 area and some GABA immunoreaction-positive neurons with pyramidal or polygonal perikarya in the pyramidal, polymorphic and radiant layer of CA1 area. There were also symmetric dendro-axonic synapses formed by GABA-positive dendrites and Glu-positive axons in the polymorphic layer and symmetric axo-dendritic synapses formed by GABA-positive axons and Glu-positive dendrites in the radiant layer. In addition, there were symmetric autoregulatory axo-dendritic synapses between Glu-positive axons and dendrites and autoregulatory axo-axonic synapses (both symmetric and asymmetric) between GABA-positive axons. Above mentioned results, for the first time,showed that there were complex synaptic regulatory relationships between excitatory Glu neurons and inhibitory GABA neurons in the hippocampal CA1 area, thereby, providing ultrastructural evidence for different neurotransmitters participating in epileptic pathogenesis.
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The relationship between CCK-and VP-neurons in the rat retrochiasmatic area was studied at ultrastructural level by means of pre-embedding(PAP) double immunoelectron microscopic labeling technique. First, the VP-immunoreactivity was demonstrated by DAB method. After thoroughly washing, the CCK-immuno- reactivity was revealed by ammonium molybdate-TMB method. Being stabili- zed by DAB-cobalt chloride, the sections were embedded in Epon 812. Under ele- ctron microscope, it was observed that in the retrochiasmatic area, the VP-LI products distributed diffusely as high electron dense granular or flocculent depo- sits, whereas the CCK-LI products distributed sparsely as needle-or mass-like deposits. VP-LI perikarya were small in size with oval shape and CCK-LI peri- karya were medium in size with polygonal shape. CCK-LI perikarya and dendri- tes received afferent synapses from non-CCK- and non-VP-axonal terminals VP- LI axons received afferent synapses from VP and non-VP-axonal terminals It was interesting that the VP-LI axonal terminals formed efferent axoaxonic syna- pses with CCK-LI axonal endings and, vice versa, the CCK-LI axonal terminals established also efferent axoaxonic synapses with VP-LI axonal endings. The above mentioned results identified for the first time that in the rat retrochiasma- tic area not only there were CCK- and VP-neurons, but also there were reciprocal synaptic regulations between above two kinds of peptidergic neuron, providing new ultrastructural basis for the regulatory mechanism of the neuroendocrine in hypothalamus.
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The chemical nature of spinal ganglionic neurons, the peripheral processes of which project divergently to the somatic and visceral areas, has been identified by means of tri-labeling method of combining fluorescein tracing and immunocytochemistry. Ten rats were used. First, 2?l of 2% fast blue (FB) were injected into the left coeliac ganglion. Two days later, 2% nuclear yellow (NY) was injected into left 9-11th intercostal nerves(l?l for each). On the 4th day, animal was perfused with 10% formalin in 0.1mol/L phosphate buffer.The left Th9-11 spinal ganglia were removed and cut into sections by cryostat. The sections were observed under fluorescence microscope and photographed. The results showed that there were three kinds of neurons in the spinal ganglia: (1) single FB labeled cells with blue fluorescent cytoplasm accounted for 38.8% of total labeled cells; (2) single NY labeled cells with yellow fluorescent nuclei accounted for 52,7%; (3) FB and NY double labeled cells accounted for 8.5% and mostly were small or medium in size. Then, the double labeled cells-containing sections were further processed by substance P-demonstrating PAP immunocytochemical staining. The immunostain and fluorescent photographs in the same section were compared and identified each other. We have found that the labeling ratio of SP/NY was 1.4%; SP/FB was 7% and SP/NY+FB was 28.8%. Present study has not only identified the convergence of somato-vesceral sensation in spinal ganglia but also detected the chemical nature of these neurons(substance P) for the first time. In addition, this result has provided a morphological basis for the mechanisma of referred pain and somato-visceral reflection.
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Somatostatin-containing neurons and nerve fibers in the commissural subnucleus of the nucleus tractus solitarii(NTS) of the rat were studied by means of munoelectron microscopy. The results showed that somatostatin-like immunoreactive positive neurons are medium or small cells, fusiform or elliptical. Somatostatin- like immunoreactive positive axons are unmyelinated,and mainly form passage or terminal synapses. Somatostatin-positive cell bodies themselves have not been obser- ved to form synapses with somatostatin-positive fibers,but their dendrites may receive innervation from immunoreactive-negative fibers by axo-dendritic synapses.
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6-OHDA was injected into the third cerebroventricle of rats.24 hours later,thanimals were sacrificed and the degeneration of catecholaminergic (CA) nerve term-inals were studied by electron microscopic cytochemical method.The results showedthat there were a number of degenerated nerve terminals in the arcuate nucleus.Thecharacteristics of these terminals were as follows:enhanced axoplasmic electron opa-sity,destroyed mitochondria and synaptic vesicles and the formation of dense bodies.The multilocular forms were commonly encountered.Most of degenerated terminalswere surrouded by processes of glial cells.The degnerated perikarya of the neuronsin arcuate nucleus with decreased RER,destroyed mitochondria and dense bodieswere also observed.Based on the characteristics of degenerated features the authorsbelieved that these damaged terminals should mainly belong to DA fibers.Theymight regulate or control the function of the arcuate nucleus by means of differentkinds of synaptic mechanisms.The source of DA nerve fibers may originate from A_(12)A_(14) or A_(15) cell groups of the hypothalamus.
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Objective To investigate the distribution of interleukin\|2 receptor (IL\|2R) and glucocorticoid receptor(GR) and identify coexistence of IL\|2R and GR in the rat brain. Methods The double labeling immunocytochemical technique(PAP method combined with ABC method), DAB and BDHC were used in the double labeling immunocytochemical method as the chromogens respectively. The reactive products of former was brown or yellow and later was black blue. Results IL\|2R and GR positive neurons were widely distributed in the cerebral cortex, hippocampus, thalamus, many motor and sense nuclei in the brain stem. The immunoreactive products of IL\|2R were found to be located on cell membrane and GR in nucleus and cytoplasm. There were a lot of positive double labeling neurons in the rat brain. The rate of double labeled cells in the total number of positive cells varied in different regions of brain, such as, 50 percent in cerebral cortex and 30 percent in nucleus of abducent nerve. Conclusion Immunogical cytokines and hormone could regulate the neuronal function through their corresponding receptors which coexisted in the same brain neurons. The present study might provide morphological evidence in the level of receptor for the immuno\|neuro\|endocrine network.
