Changes in polyamine levels and spectrin degradation following kainate-induced seizure activity: Effect of difluoromethylornithine

The induction of ornithine decarboxylase (ODC) in adult CNS and the resulting changes in polyamine levels are often observed under conditions associated with activation of NMDA receptors, calpain stimulation and spectrin degradation. The present study was directed at evaluating the links between these two sets of events. We measured the effects of an acute treatment of adult rats with difluoromethylornithine (DFMO), an irreversible inhibitor of ODC, on biochemical alterations following kainate-induced seizure activity. Beside ODC activity and polyamine levels, we assayed the in situ spectrin degradation and the in vitro binding of 3H-Ro5-4864, a ligand for the peripheral benzodiazepine binding sites which is a good marker of glial proliferation, at various time intervals following systemic kainic acid (KA) injection. Kainate-induced seizure activity was followed by a transient increase in ODC activity, a long-lasting increase in putrescine levels and spectrin degradation, and a delayed increase in 3H-Ro5-4864 binding, mainly in hippocampus and piriform cortex. Treatment of the animals with DFMO markedly reduced the increase in putrescine levels up to 7 days after KA injection. It also reduced the increase in spectrin breakdown observed at 16 h but not at 4 and 7 days after KA injection. Finally, it did not modify the increase in 3H-Ro5-4864 binding measured 4 and 7 days after KA injection. The levels of putrescine were positively correlated with the extent of spectrin proteolysis in KA-treated animals whether or not they were treated with DFMO, at 16 h but not at 7 days after KA injection. The results indicate that the extent of spectrin breakdown observed shortly after KA-induced seizure activity is causally related to the changes in ODC activity and putrescine levels. Although the data are consistent with the idea that putrescine could be a marker for acute pathology, they do not support a role for polyamines in delayed neurotoxicity.     

Regional distribution and time-course of calpain activation following kainate-induced seizure activity in adult rat brain

Systemic injection of kainic acid (KA) in adult rat elicits a pattern of neuronal pathology which exhibits several features of human temporal lobe epilepsy. KA-induced seizure activity is accompanied by the activation of the calcium-dependent protease calpain in limbic structures. In the present study, we evaluated the spatio-temporal activation of calpain after the onset of seizure activity by immunohistochemistry using an antibody for the spectrin breakdown product (sbdp) generated by calpain-mediated spectrin proteolysis. In addition, we compared the changes in sbdp immunoreactivity with those in immunoreactivity to subunits of the Glu/AMPA receptors (GluR₁ andGluR₂₃). One hour after seizure onset, sbdp accumulation was observed in selected interneurons in stratum oriens and in the hilus of the dentate gyrus. By 4 h, sbdp immunoreactivity was prominent in dendritic fields of the hippocampus as well as in neurons in thalamus and piriform cortex. By 8 h, sbdp immunoreactivity had disappeared from interneurons but was localized in pyramidal cell bodies in hippocampus. Intense labeling of cell bodies and dendritic fields persisted until 5 days following KA treatment. Changes in GluR subunit immunoreactivity were mirror images of those seen for sbdp. In general, increased sbdp immunoreactivity in dendritic fields was associated with decreased (GluR₁ immunoreactivity. However, increased sbdp immunoreactivity in neuronal perikarya was also associated with increased GluR immunoreactivity. These results indicate that calpain activation following seizure onset exhibits a specific spatio-temporal pattern, with activation in restricted interneurons preceding widespread activation in pyramidal neurons. Calpain activation also precedes neuronal pathology and could thus represent an initial trigger for neuronal pathology. Finally, the results suggest that calpain activation produces rapid alterations in GluR subunit properties which could be involved in the hyperexcitability observed following seizure activity.     

Induction of ornithine decarboxylase by subseizure stimulation in the hippocampus in vivo

Electrical stimulation of the Schaffer-collateral axonal system under conditions which do not elicit detectable seizure activity causes an increase in the activity of ornithine decarboxylase (ODC), the rate limiting enzyme of polyamine synthesis, in the hippocampus, olfactory cortex, neocortex and olfactory bulb. The degree of ODC activation is dependent upon the stimulus parameters. The results support the hypothesis that neuronal activity regulates hippocampal polyamine concentrations.     

Effect of treatment with difluoromethylornithine on polyamine and spectrin breakdown levels in neonatal rat brain.

Impairment of polyamine synthesis by treatment with difluoromehtylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, has been shown to alter normal brain development. In the present study we determined the effect of DFMO treatment during a discrete developmental period on polyamine levels and on the in situ activity of calpain, as reflected by the level of degradation of spectrin, in various brain regions of rat pups. DFMO treatment from postnatal days 5 to 10 produced a marked decrease in putrescine levels in every brain structure and a significant decrease in spectrin breakdown levels in hippocampus and cortex but not in cerebellum. The results indicate that the ODC/polyamine pathway partly regulates the in situ activity of calpain and that polyamines may play a role in both growth and degeneration phenomena.     

The protective effect of a ketogenic diet on kainic acid-induced hippocampal cell death in the male ICR mice

This study was designed to evaluate the antiapoptotic effects of a ketogenic diet (KD) through histological (cresyl violet staining, TUNEL staining and immunohistochemistry) and behavioral studies using kainic acid (KA, 25mg/kg i.p.)-induced seizures in male ICR mice. KA-induced seizure in rodents is widely used as an experimental model for human temporal lobe epilepsy because of their behavioral and pathological similarities. A KA-induced seizure causes neuronal damage in hippocampal pyramidal neurons and involves a caspase-3-mediated apoptotic pathway. In this study, the seizure onset time of the KD-fed group was delayed compared to that of the group fed a normal diet (ND) after a systemic KA injection. Histological studies revealed that KA caused pyknosis in most of the hippocampal areas in the ND-fed group, however, well-preserved pyramidal neurons were detected in the hippocampus of mice that had been on KD for 1 month, which began on postnatal day 21. The number of TUNEL-positive cells and caspase-3-positive cells in the hippocampus of the KD-fed group was lower than that of the ND-fed group. These findings indicate that KD has an antiepileptic effect via a neuroprotective action that involves the inhibition of caspase-3-mediated apoptosis of hippocampal neurons.     

Kainic acid-induced seizures stimulate increased expression of nerve growth factor mRNA in rat hippocampus.

The influence of kainic acid (KA)-induced limbic seizure activity on the expression of mRNA for nerve growth factor (NGF) in adult rat brain was studied using in situ hybridization and S1 nuclease protection techniques with RNA probes complementary to murine and rat NGF mRNA. Within hippocampus, intracerebroventricular injection of 0.5 microgram KA caused a dramatic bilateral increase in hybridization of the 35S-labeled cRNA within stratum granulosum. This increase was first evident 1 h post-KA, appeared maximal at approximately 20-fold control levels at 2-3 h post-injection, and declined to control levels by 48 h post-injection. During the period of maximal hybridization, all but the deepest cells within stratum granulosum appeared to be autoradiographically labeled. Hybridization of the NGF cRNA probe was also increased within superficial layers of piriform and entorhinal cortex and, to much lesser extent, within scattered neurons of layers II and III of neocortex in KA-treated rats. In olfactory cortical areas, hybridization was maximally elevated 15.5-24.5 h after KA injection. In contrast to these effects, KA treatment did not consistently influence the density of hybridization, or number of neurons labeled, within the dentate gyrus hilus or the hippocampus proper (CA1-CA3). In agreement with the in situ hybridization results, S1 nuclease protection assay detected KA-induced increases in hybridization within pooled dentate gyrus/CA1 samples, but not hippocampal CA3 samples. These data support the conclusion that seizure activity stimulates a transient increase in NGF expression by select populations of forebrain neurons and indicates that experimental seizure paradigms might be further exploited for analyses of the mechanisms of NGF regulation and processing in the adult brain.     

Secondary Generalization in Kainic Acid-Induced Focal Seizures in Unanesthetized Cats

Abstract: Seizure propagation was studied with different seizure models induced by a kainic acid (KA) microinjection in nonanesthetized cats. These seizures were characterized with a focal onset of seizures followed by secondarily generalized seizures. The mesencephalic reticular formation (MRF) played an important role when an epileptogenic focus was located in a unilateral amygdala, hippocampus, thalamus or visual cortex. When the focus was located in a unilateral lateral geniculate body, a fast, synchronous and bidirectional propagation was observed in the sensorimotor cortex (SMC) and MRF. Brain stem seizure (generalized tonic seizure) was elicited by the KA injection into MRF. The EEG of generalized seizure was characterized by the propagations of seizure activities of MRF immediately to the bilateral SMC and thalamus. The results suggested that MRF participated actively in the generalization of the KA-induced seizures .     

Dentate granule cells are essential for kainic acid-induced wet dog shakes but not for seizures

The purpose of this study was to determine the role that dentate granule cells play in wet dog shakes (WDS), behavioral seizures, and hippocampal cell loss caused by systemic administration of kainic acid (KA). Rats were given bilateral injections of colchicine (COL) into the hippocampal formation to selectively lesion dentate granule cells. Two weeks later, they were injected subcutaneously with KA and were observed for WDS and seizures. Seizures were terminated with pentobarbital 2.5 hr after KA injection, and the rats were killed 48 hr later. The integrity of hippocampal cell populations and projections to the hippocampal formation from entorhinal cortex was assessed with radioimmunoassay and immunostaining for methionine-enkephalin (ME) and dynorphin (DYN) A, as well as with Timm and Nissl staining. Results indicate that COL injections eliminated KA-induced WDS, did not affect the latency to onset of seizures, and potentiated KA-induced cell loss in the CA3 region of hippocampus. COL lesions eliminated ME and DYN immunostaining of granule cells, but not ME immunostaining of entorhinal afferents to the dentate gyrus or Ammon's horn. These findings indicate that granule cells are an essential neuronal link in the expression of KA-induced WDS, but that seizures propagate along other pathways in the limbic system.     

Effect of the calcineurin inhibitor FK506 on K+–Cl? cotransporter 2 expression in the mouse hippocampus after kainic acid-induced status epilepticus

Calcineurin (CaN)-mediated excitotoxicity impairs γ-aminobutyric acid (GABA) transmission and induces neuronal apoptosis. Ca(2+)-dependent K(+)-Cl(-) cotransporter 2 (KCC2) participates in GABAergic inhibitory transmission. However, the mechanism by which CaN mediates GABA receptor-mediated KCC2 in seizures is not fully understood. In the present study, we investigated the altered expression of KCC2 and the effects of the CaN inhibitor FK506 on KCC2 expression in the mouse hippocampus following kainic acid (KA) treatment. FK506 was injected twice 24 h and 30 min before KA treatment and then mice were treated with KA and killed 2 days later. FK506 had anticonvulsant effect on KA-induced seizure activities. CaN cleavage was evident in the hippocampus 24 h after KA treatment. FK506 pretreatment blocked the truncation of CaN in the KA-treated hippocampus. Cresyl violet and TUNEL staining showed that FK506 prevented KA-induced hippocampal cell death. In particular, Western blot analysis showed that KCC2 expression was time dependent, with a peak at 6 h and a return to decreased levels at 48 h, whereas FK506 pretreatment inhibited the KA-induced decrease in KCC2 expression in the hippocampus. Immunofluorescence showed that FK506 pretreatment protected the loss of inhibitory GABAergic KCC2-expressing neurons following KA treatment. Taken together, these results provide evidence that altered KCC2 expression may be associated with Ca(2+)-mediated seizure activity and indicate that neuron-specific KCC2 may be involved in neuroprotection after seizures.     

Inhibition of delayed induction of p38 mitogen-activated protein kinase attenuates kainic acid-induced neuronal loss in the hippocampus

The activation of p38 mitogen-activated protein kinase (MAPK) has been implicated in the pathological changes accompanying inflammatory and apoptotic processes of various cell types including neurons. In a kainic acid (KA)-induced mouse seizure model, p38 MAPK is induced in reactive astrocytes in the CA3 region of the hippocampus where severe neuronal loss occurs. Here we report the delayed and protracted activation of p38 MAPK in the CA3 region of the hippocampus of mice treated with KA. In this model, the inhibition of p38 MAPK isoforms by SB203580, a specific inhibitor, attenuated neuronal loss in the CA3 and CA1 regions of the hippocampus, which was accompanied by the suppression of the p38 MAPK activation as well as astrogliosis. Thus, the delayed and sustained induction of p38 MAPK plays a crucial role in the neuronal damage of KA-induced brain seizures.     

Delayed induction of alpha B-crystallin in activated glia cells of hippocampus in kainic acid-treated mouse brain

Small heat shock proteins have been implicated in playing a role in various cellular processes, including stress-induced cell death. In kainic acid (KA)-treated rat brain, the immunoreactivity of heat-shock protein 27 (HSP27) was markedly increased in glia cells of the limbic system. In the present study, we demonstrated that alpha B-crystallin, a member of the small heat-shock protein family, was strongly induced in reactive astrocytes in hippocampus after KA-induced seizure. The induction was localized mainly in the CA3 region of hippocampus, where massive neuronal loss occurred. We also demonstrated that the delayed induction of alpha B-crystallin and HSP27 immunoreactivities in the hippocampus of epileptic animals was repressed to the levels seen in control animals with preadministration of the selective nNOS inhibitor 7-nitroindazole (7-NI). This repression was reversed by coinjection of L-arginine, a substrate of NOS. Together, these data suggest a role for alpha B-crystallin and HSP27 in reactive gliosis and/or in delayed neuronal death proceeded after KA-induced seizure.     

外周型苯二氮卓受体对海人酸点燃大鼠癫痫敏感性的影响

目的:探讨外周型苯二氮卓受体对海人酸点燃大鼠癫痫敏感性的影响。方法:大鼠随机分为海人酸组和对照组,海人酸组动物注射惊厥剂量海人酸(8mg.kg-1)建立化学点燃模型。注射7d后再注射阈下剂量海人酸(4mg.kg-1),将癫痫敏感性形成的动物作为癫痫敏感性形成组,未形成的动物作为癫痫敏感性未形成组。对照组分别经皮下注射阈下剂量的海人酸及生理盐水作为单独阈下剂量组和空白对照组。观察120min内动物癫痫发作情况,然后动物断头取脑,采用梯度离心技术制备大脑皮质线粒体,利用放射性配基结合实验测定外周型苯二氮卓受体特异结合量。结果:癫痫敏感性形成组大脑皮质线粒体外周型苯二氮卓受体水平显著高于其他3组(P<0.001)。癫痫敏感性形成组大脑皮质线粒体外周型苯二氮卓受体特异结合量与注射阈下剂量海人酸后动物湿狗样抖动次数、癫痫发作潜伏期、癫痫发作最大强度均具有显著相关性(P<0.001)。结论:大脑皮质线粒体外周型苯二氮卓受体水平与海人酸点燃大鼠癫痫敏感性有关。     

The calpain inhibitor MDL-28170 and the AMPA/KA receptor antagonist CNQX inhibit neurofilament degradation and enhance neuronal survival in kainic acid-treated hippocampal slice cultures

The cytoskeleton controls the architecture and survival of the central nervous system neurons by maintaining the stability of axons, dendrites and cellular architecture, and any disturbance in this genuine structure could compromise cell survival. The developmentally regulated intracellular intermediate filament protein neurofilament (NF), composed of the light (NF-L), medium (NF-M) and high (NF-H) molecular weight isoforms, is expressed abundantly in nerve cells but its significance in nerve cell survival in stress situations in the brain is unknown. We have used Western blotting, immunocytochemistry, and Fluoro-Jade B and thionine stainings to clarify the effect of kainic acid (KA) treatment on NF protein stability, and its importance for neuronal survival in hippocampal slice cultures. The contribution of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/KA glutamate receptor subtypes, calpain proteases and L-type Ca2+-channels to these processes were also assessed. Our results indicated that KA-induced degradation of NF was a fast process, similarly affecting all three NF proteins. It was effectively inhibited by the AMPA/KA receptor antagonist CNQX and the calpain inhibitor MDL-28170, whereas the Ca2+-channel blocker nifedipine and the NMDA receptor antagonist MK-801 had no significant effect. Moreover, KA-induced neuronal damage was effectively decreased in cultures treated with CNQX and MDL-28170. Our results suggest that the stability of NF proteins is an important factor contributing to neuronal survival after excitotoxic injury, and that both AMPA/KA receptor antagonists and calpain inhibitors might serve as neuroprotectants against this type of insult in the immature hippocampus.     

MRS Metabolic Markers of Seizures and Seizure-Induced Neuronal Damage

Summary: Purpose: Proton magnetic resonance spectroscopy (MRS) was used to identify specific in situ metabolic markers for seizures and seizure-induced neuronal damage. Kainic acid (KA)-induced seizures lead to histopathologic changes in rat brain. The protective effect of cycloheximide treatment against neuronal damage caused by KA-induced seizures was studied, using in situ proton MRS imaging technique.
Methods: Rats were pretreated with placebo or cycloheximide 1 h before KA injection. Rat brains (n = 25) were scanned at the level of the hippocampus before, during, and 24 h after seizures. Spectra were recorded and the relative ratios of N-acetylaspartate (NAA), choline (cho), and lactate (Lac) to creatine (Cr) were calculated and compared between groups.
Results: A significant increase in Lac ratios was observed in KA-treated rats during and 24 h after seizure onset and this increase was prevented by cycloheximide pretreatment. NAA ratios were significantly higher during the ictal phase following KA treatment and this effect was not affected by cycloheximide pretreatment. Nissl staining confirmed previously reported prevention of KA-induced neuronal loss in CA1 and CA areas of the hippocampus by cycloheximide pretreatment.
Conclusions: Our results suggest that in situ Lac increase is a marker of seizure-induced neuronal damage, whereas N-acetylaspartate (NAA) changes during and after status epilepticus may be a reflection of neuronal activity and damage, respectively.     

Mitochondrial dysfunction and ultrastructural damage in the hippocampus during kainic acid-induced status epilepticus in the rat

PURPOSE: Prolonged and continuous epileptic seizure (status epilepticus) results in cellular changes that lead to neuronal damage. We investigated whether these cellular changes entail mitochondrial dysfunction and ultrastructural damage in the hippocampus, by using a kainic acid (KA)-induced experimental status epilepticus model. METHODS: In Sprague-Dawley rats maintained under chloral hydrate anesthesia, KA (0.5 nmol) was microinjected unilaterally into the CA3 subfield of the hippocampus to induce seizure-like hippocampal EEG activity. The activity of key mitochondrial respiratory chain enzymes in the dentate gyrus (DG), or CA1 or CA3 subfield of the hippocampus was measured 30 or 180 min after application of KA. Ultrastructure of mitochondria in those three hippocampal subfields during KA-induced status epilepticus also was examined with electron microscopy. RESULTS: Microinjection of KA into the CA3 subfield of the hippocampus elicited progressive build-up of seizure-like hippocampal EEG activity. Enzyme assay revealed significant depression of the activity of nicotinamide adenine dinucleotide cytochrome c reductase (marker for Complexes I+III) in the DG, or CA1 or CA3 subfields 180 min after KA-elicited temporal lobe status epilepticus. Conversely, the activities of succinate cytochrome c reductase (marker for Complexes II+III) and cytochrome c oxidase (marker for Complex IV) remained unaltered. Discernible mitochondrial ultrastructural damage, varying from swelling to disruption of membrane integrity, also was observed in the hippocampus 180 min after hippocampal application of KA. CONCLUSIONS: Our results demonstrated that dysfunction of Complex I respiratory chain enzyme and mitochondrial ultrastructural damage in the hippocampus are associated with prolonged seizure during experimental temporal lobe status epilepticus.     

Melatonin attenuates the changes in polyamine levels induced by systemic kainate administration in rat brains

Systemically administered kainate has been demonstrated to induce neuronal damage and changes of the levels of biochemical substances related to neurotoxicity. Polyamines are thought to be important in the generation of edema and neuronal cell loss associated with various type of excitotoxicity. Melatonin exerts potent free radical scavenging, antioxidant, and neuroprotective properties. This study was designed to estimate the effect of exogenous melatonin administration on the changes of polyamine levels in rat brains after systemic administration of kainate. Kainate [10 mg/kg, intraperitoneally (i.p.)] was injected into the rats to produce excitotoxicity. Melatonin (15 mg/kg, i.p.) was administered 1 h before, immediately after, and 1 h after kainate treatment. We examined the polyamine [putrescine (PU), spermidine (SD) and spermine (SM)] levels in the cerebral cortex and hippocampus and neuronal density in the hippocampal CA1 and CA3 subsectors in brain sections. PU levels were increased 8 and 24 h after kainate treatment and the administration of melatonin attenuated these changes. Only minor changes were noted in the levels of the polyamine SD and SM after the kainate treatment. In histology, neuronal injuries in the hippocampal CA1 and CA3 subsectors were examined 3 days after kainate treatment and melatonin reduced the kainate-induced neuronal injuries. Our results show that melatonin inhibits the polyamine responses in the cerebral cortex and hippocampus following kainate-induced excitotoxicity and PU may be responsible for the protective effect of melatonin against kainate-induced excitotoxicity.     

Effect of 8-OH-DPAT on electrographic activity during the kainic acid-induced status epilepticus in rats.

The effect of 8-OH-DPAT, a 5-HT1A receptor agonist, on electrographic activity during the kainic acid (KA)-induced status epilepticus (SE) was evaluated in male Wistar rats. Electrographic (EEG) recordings from the ventral hippocampus and the frontal cortex along with behavioral changes were evaluated in animals that received KA administration (10mg/kg, i.p.) 20 min after saline solution (control group) or 8-OH-DPAT (1mg/kg, s.c.) injection. Rats pretreated with 8-OH-DPAT presented augmented latency for wet dog shakes (71%), generalized seizures (54%) and behavioral SE (31%). 8-OH-DPAT delayed occurrence of the first KA-induced paroxystic spikes (70%), increased latency to the EEG SE (39%) and decreased spike frequency (35-43%) recorded from the frontal cortex, and increased the time necessary for the high voltage EEG activity synchronization of the hippocampus and the frontal cortex (125%). However, EEG ictal activity recorded in hippocampus was not modified after 8-OH-DPAT pretreatment. These results indicate that 8-OH-DPAT reduces the EEG activity associated with the KA-induced SE in the frontal cortex, but not the hippocampus, and suggest an inhibitory effect in the propagation of epileptic seizures during the KA-induced SE.     

The cyclooxygenase and lipoxygenase inhibitor BW755C protects rats against kainic acid-induced seizures and neurotoxicity

In this study the effect of the anti-inflammatory drugs indomethacin, ibuprofen, ebselen (PZ 51, 2-phenyl-1,2-benzoiso-selenazol-3(2H)-one), and BW755C (3-amino-1-(m-(trifluoromethyl-phenyl)-2-pyrazoline) on kainic acid (KA)-induced behavioral and neurochemical changes in rats was investigated. Rats injected with KA (10 mg/kg s.c.) developed seizure activity with a 20% mortality within the first 4 h and neuronal degeneration in the limbic system after 3 days. Pretreatment with the cyclooxygenase inhibitor indomethacin (10 mg/kg i.p.) augmented KA-induced epileptic activity and increased the mortality in status epilepticus to 80%. Another cyclooxygenase inhibitor, ibuprofen (20 mg/kg i.p.), and the lipoxygenase inhibitor ebselen (20 mg/kg i.p.) showed no effect on KA-induced symptoms and neurochemical changes. Application of the cyclooxygenase/lipoxygenase inhibitor BW775C (40 mg/kg i.p.) reduced the severity of seizures and protected significantly from irreversible brain lesions induced by KA. The marked reduction of glutamate decarboxylase (GAD; 53.3 ± 12.2% of control) and choline acetyltransferase (ChAT; 60.9 ± 9.1% of control) activities in amygdala/pyriform cortex and GAD activity in hippocampus (69.4 ± 5.6% of control) observed 3 days after KA injection was abolished by BW755C treatment. Histopathological analyses of brain tissue showed that treatment with BW755C prevented the KA-induced nerve cell degeneration, edema, hemorrhages, and tissue necrosis in amygdala/pyriform cortex. However, some cell loss in the hippocampus was present, predominantly in its CA3 sector, and to a mild extent also in insular cortex and entorhinal/pyriform cortex. Our results indicate that BW755C may inhibit seizure-induced brain damage either through the blockade of both prostaglandin and leukotriene synthesis or by its action as an oxygen radical scavenger.     

红藻氨酸致痫后大鼠海马ERK、P38 MAPK和JNK的活性变化

目的研究红藻氨酸(KA)诱导大鼠癫痫发作后海马组织细胞外调节蛋白激酶(ERK)、p38MAPK和c-jun氨基末端激酶(JNK)的活性(磷酸化状态)的变化情况。方法立体定向大鼠侧脑室内注射KA引起大鼠癫痫发作,采用Western-blot方法观察KA致痫后大鼠海马中活性ERK、p38MAPK和JNK的变化。结果KA诱导大鼠癫痫发作后,海马组织ERK、p38MAPK和JNK的磷酸化水平开始增高,分别于30min、1h和30min后达高峰,呈对照组的4.76倍、2.16倍和3.95倍,两组比较差异具有显著性(P<0.01),之后逐渐下降。结论KA致痫大鼠癫痫发作后,海马组织MAPKs的活性产生变化,其信号通路可能参与癫痫发作后海马组织的病理生理反应过程。