Strain differences in seizure-induced cell death following pilocarpine-induced status epilepticus

Mouse strains differ from one another in their susceptibility to seizure-induced excitotoxic cell death. Previously, we have demonstrated that mature inbred strains of mice show remarkable genetic differences in susceptibility to the neuropathological consequences of seizures in the kainate model of status epilepticus. At present, while the cellular mechanisms underlying strain-dependent differences in susceptibility remain unclear, some of this variation is assumed to have a genetic basis. However, it remains unclear whether strain differences in susceptibility to seizure-induced cell death observed following kainate administration are observed following systemic administration of other chemoconvulsants. In rodents, the cholinomimetic convulsant pilocarpine is widely used to induce status epilepticus (SE), followed by hippocampal damage and spontaneous recurrent seizures, resembling temporal lobe epilepsy. This model has initially been described in rats, but is increasingly used in mice. We characterized neuronal pathologies after pilocarpine-induced status epilepticus (SE) in eight inbred strains of mice focusing on the hippocampus. A ramping-up dose protocol for pilocarpine was used and behavior was monitored for 4-5 h. While we did not observe any significant differences in seizure latency or duration to pilocarpine among the inbred strains, we did observe a significant difference in susceptibility to the neuropathological consequences of pilocarpine-induced SE. Of the eight genetically diverse mouse strains screened for pilocarpine-induced status, BALB/cJ and BALB/cByJ were the only two strains that were resistant to the neuropathological consequences of seizure-induced cell death. Additional studies of these murine strains may be useful for investigating genetic influences on pilocarpine-induced status epilepticus.     

褪黑素对癫痫大鼠海马GABA、GABAARα5表达的影响

目的 探讨褪黑素(Mel)抗癫痫作用的机制.方法 采用匹罗卡品(PILO)诱导大鼠癫痫持续状态(SE)模型,用免疫组化技术检测大鼠SE后4个时相点即6 h、48 h、72 h和7 d海马γ-氨基丁酸(GABA)和GABAA受体α5(GABAARα5)亚单位表达的动态变化,以及Mel对其变化的影响.结果 PILO组大鼠SE后6h,海马内GABA能神经元和GABAARα5亚单位表达均开始减少,尤其以SE后72 h～7 d改变最为明显,与对照组比较差异有极显著意义(P＜0.01);而Mel组大鼠在SE后72 h～7 d,海马各区的GABA能神经元和GABAARα5亚单位表达均显著高于PILO组大鼠(P＜0.05).结论 Mel可能通过上调GABA和GABAARα5亚单位的表达来发挥抗癫痫作用.     

Cerebral blood flow changes during pilocarpine-induced status epilepticus activity in the rat hippocampus

Introduction

There is a known relationship between convulsive status epilepticus (SE) and hippocampal injury. Although the precise causes of this hippocampal vulnerability remains uncertain, potential mechanisms include excitotoxicity and ischaemia. It has been hypothesised that during the early phase of seizures, cerebral blood flow (CBF) increases in the cortex to meet energy demand, but it is unclear whether these compensatory mechanisms occur in the hippocampus. In this study we investigated CBF changes using perfusion MRI during SE in the pilocarpine rat.

Methods

First, we determined whether SE could be induced under anaesthesia. Two anaesthetic protocols were investigated: isoflurane (n = 6) and fentanyl/medetomidine (n = 7). Intrahippocampal EEG electrodes were used to determine seizure activity and reflex behaviours were used to assess anaesthesia. Pilocarpine was administered to induce status epilepticus. For CBF measurements, MRI arterial spin labelling was performed continuously for up to 3 h. Either pilocarpine (375 mg/kg) (n = 7) for induction of SE or saline (n = 6) was administered. Diazepam (10 mg/kg) was administered i.p. 90 min after the onset of SE.

Results and discussion

We demonstrated time-dependent significant (p < 0.05) differences between the CBF responses in the parietal cortex and the hippocampus during SE. This regional response indicates a preferential distribution of flow to certain regions of the brain and may contribute to the selective vulnerability observed in the hippocampus in humans.     

The role of MMP-9 in integrin-mediated hippocampal cell death after pilocarpine-induced status epilepticus

Recent studies demonstrate that matrix metalloproteinase-9 (MMP-9) is closely involved in the pathogenesis of epilepsy. This study investigated the role of MMP-9 in hippocampal cell death after pilocarpine-induced status epilepticus (SE). We showed that MMP-9 expression and activity significantly increased and β1-integrin levels decreased on day 3 after SE. β1-integrin degradation was also observed in hippocampal ex vivo extracts incubated with recombinant active MMP-9. Treatment with a selective MMP-9 inhibitor attenuated MMP-9 up-regulation, β1-integrin degradation, the reduction of ILK activity and Akt phosphorylation, and subsequent hippocampal damage after SE. However, co-treatment with anti-β1-integrin antibody almost completely blocked the protective effects of the MMP-9 inhibitor on both integrin-mediated survival signaling and hippocampal cell death. Our study demonstrates that MMP-9 induces apoptotic hippocampal cell death by interrupting integrin-mediated survival signaling after SE and suggests that MMP-9 may be a promising target for a neuroprotective approach to preventing seizure-induced hippocampal damage.     

红藻氨酸致癫痫持续状态大鼠海马neuropilin-2 mRNA及其蛋白表达的研究

目的研究轴索导向分子NPN-2mRNA及其蛋白对癫痫持续状态(SE)后大鼠海马内神经纤维外向性生长和突触重建中的调控作用。方法采用侧脑室内注射红藻氨酸(KA)制作TLE大鼠模型,用Nissl染色、原位杂交和免疫组织化学的方法,分别检测致SE后1d、1w、2w、3w、4w大鼠海马齿状回(DG)、CA1区、CA3区、门区神经元丢失程度以及NPN-2mRNA及其蛋白的表达。结果 KA致SE后1d开始出现神经元丢失,至4w神经元丢失明显增多。KA致SE后1d,NPN-2mRNA及其蛋白在DG和CA1区表达明显下降,持续至3w(P0.01),4w恢复至正常(P0.05);NPN-2mRNA及其蛋白在门区、CA3区表达实验组与对照组无明显差别(P0.05)。结论 KA致SE后,海马DG及CA1区神经元下调NPN-2mRNA及其蛋白的表达,促进DG及CA1区神经纤维外向性生长和突触的重建。     

癫痫持续状态后大鼠海马区钾离子通道Kv1.3的表达研究

目的研究氯化锂-匹罗卡品致癫痫持续状态(status epilepticus,SE)后大鼠海马区钾离子通道Kv1.3的表达及分布变化,探讨钾离子通道Kv1.3与癫痫发作的相关性。方法 48只健康雄性sprague-dawley大鼠随机平分为实验组和对照组,每组继续随机分为6 h、1 d、2 d和3 d 4个观察时间点亚组(n=6)。通过大鼠脑电监测记录大鼠脑电变化情况,通过尼氏染色观察脑组织病理改变,采用免疫组织化学染色和Western-blot方法检测各时间点大鼠海马区Kv1.3的表达及分布变化。结果 (1)脑电监测:正常大鼠脑电图表现为波幅较均匀一致的α波,痫性发作后开始出现慢波、棘波,波幅、节律不规则,SE过程中表现为长程的棘波活动。(2)尼氏染色:SE后6 h未发现明显形态学及神经元数量改变;SE后1 d,海马区神经元结构松散,神经元数量减少;SE后2 d、3 d,海马区神经元进一步减少,且出现神经元肿胀、变形、尼氏小体减少甚至消失。(3)免疫组织化学染色和Western-blot检测:SE后2 d,Kv1.3在海马CA_3和CA_1区表达较对照组明显减少(P0.05)。SE后6 h、1 d、3 d,Kv1.3在海马CA_3和CA_1区表达较对照组无明显变化(P0.05)。SE后6 h、1 d、2 d、3 d,Kv1.3在海马DG区表达较对照组无明显差异(P0.05)。结论 Kv1.3的表达下调可能与癫痫发作相关。     

马桑内酯致大鼠癫痫持续状态后海马神经细胞凋亡的观察

观察马桑内酯（ｃｏｒｉａｒｉａｌａｃｔｏｎｅ，ＣＬ）诱导鼠癫痫持续状态（ＳＥ）时海马细胞中ＤＮＡ损伤及凋亡现象。方法用流式细胞术检测海马细胞中ＤＮＡ状态，用免疫组织化学方法显示海马谷氨酸阳性细胞，并以流式细胞术免疫荧光法测定海马细胞中ＢＣＬ－２样蛋白含量。结果ＳＥ后海马细胞中有ＤＮＡ损伤断裂；海马ＣＡ３区谷氨酸阳性细胞数量减少，着色变淡；海马细胞中ＢＣＬ－２样蛋白增加。结论ＳＥ可诱导海马细胞ＤＮＡ损伤进而凋亡；ＳＥ时谷氨酸过量释放可造成突触后靶细胞损伤。ＢＣＬ－２样蛋白增加可能是ＢＣＬ－２家族蛋白共同变化的结果，是细胞自身的保护机制，以抗损伤和凋亡。     

槲皮素对大鼠癫痫持续状态后海马XIAP mRNA与蛋白表达的影响

目的研究大鼠癫痫持续状态(SE)后海马组织XIAP的表达变化及槲皮素对其表达的影响。方法建立氯化锂-匹罗卡品致痫大鼠SE模型,应用免疫组化和RT-PCR方法检测XIAP与caspase-3蛋白以及XIAP mRNA的表达。结果海马CA3区XIAP蛋白在SE后2 h(0.5503±0.0172)起逐渐增加,8 h(0.6221±0.0238)达高峰,与对照组比较(0.1507±0.0165),差异有统计学意义(P<0.01)。海马CA3区caspase-3活性蛋白在对照组未见明显表达,在SE后4~72 h明显增多。与对照组比较,SE组海马XIAP mRNA表达水平在2~8 h增加(P<0.01)。与SE组比较,槲皮素组海马XIAP mRNA表达水平及CA3区XIAP蛋白表达在8 h、24 h高于SE组(P<0.01),CA3区caspase-3活性蛋白表达在8 h、24 h、72 h低于SE组(P<0.01)。结论XIAP可能参与了SE后神经元凋亡的调控过程,槲皮素可以提高SE后海马神经元XIAP的表达。     

Mu-calpain mediates hippocampal neuron death in rats after lithium-pilocarpine-induced status epilepticus

Status epilepticus (SE) is a severe clinical manifestation of epilepsy which causes brain damage. The pathological process and underlying mechanisms involved in the programmed cell death (PCD) are still not fully clear. In the current study, rats were induced SE by lithium–pilocarpine administration. Our data showed hippocampal neurons death appeared at 6 h after SE and sustained for 7 days. By blotting the activation of μ-calpain and its specific cleavage of nonerythroid -spectrin (SpII) (145 kDa) was evident at 1 and 3 days after SE, which coincided with Bid activation, apoptosis inducing factor (AIF) translocation and cytochrome c release from mitochondria, whereas, activated caspase-3 and caspase-3-specific fragments of SpII (120 kDa) predominantly appeared at 5 and 7 days after SE. Moreover, MDL-28170, a calpain inhibitor, partially rescued the neuron death and attenuated the expression of activated μ-calpain, cleavage of Bid (15 kDa), AIF translocation and cytochrome c release. Taken together, our study indicated that μ-calpain mediated hippocampal neuron PCD is prior to caspase-3 activation. It functioned via translocation of Bid, AIF and cytochrome c release.     

Nitric oxide synthase immunoreactivity in the rat hippocampus after status epilepticus induced by perforant pathway stimulation

Nitric oxide has recently been implicated in mediation of neuronal excitotoxicity and damage. This study aimed at elucidating the changes in the expression of neuronal isoform of nitric oxide synthase (nNOS) in the hippocampus after status epilepticus induced by perforant pathway stimulation. nNOS-immunoreactivity (nNOS-ir) and neuronal damage, assessed by silver staining, were evaluated separately in different hippocampal subfields 2 weeks after induction of status epilepticus. Perforant pathway stimulation resulted in an increase in the number of nNOS-immunoreactive neurons in the stratum radiatum of the CA1 and CA3 subfields of the hippocampus proper, and the hilus of the dentate gyrus. The morphology and distribution of the nNOS-ir neurons resembled that of interneurons. No correlation of the number of nNOS-ir neurons to the neuronal damage score was observed. Our results suggest that status epilepticus provokes a de novo expression of nNOS protein, and the nNOS expressing neurons may be selectively resistant to epileptic brain injury.     

Valproate suppresses status epilepticus induced by 4-aminopyridine in CA1 hippocampus region

PURPOSE: We investigated the effects of valproate (VPA) on an in vivo model of status epilepticus (SE) induced by intrahippocampal application of 4-aminopyridine (4-AP). METHODS: To induce continuous epileptiform activity without a clinical component, 4-AP (100 mM) was slowly injected in the hippocampus of adult rats. Extracellular field potential from the CA1 region of the rat hippocampus was recorded to assess abnormal epileptiform activity. Once the SE seizures were induced by 4-AP, the test drug was injected. In some experiments to test the ability of a drug to prevent the induction of SE, the drug was administered before 4-AP injection. RESULTS: Intrahippocampal injection of 4-AP induced continuous epileptic activity without a clinical component that lasted >60 min. The intravenous injection of 400-600 mg/kg VPA rapidly (approximately 100 s) abolished the SE, and this effect persisted for >/=4 h in our experimental model. The intravenous injection of 100-300 mg/kg VPA did not abolish previously induced SE, but prevented the appearance of SE when applied before the induction of SE. The intravenous injection of 80 mg/kg phenytoin or carbamazepine did not abolish or prevent SE. CONCLUSIONS: We conclude that 4-AP-induced SE was suppressed by VPA at 400-600 mg/kg, whereas minor doses (100-300 mg/kg) only prevent the 4-AP-induced SE. Present results suggest the revisiting of VPA as a useful drug for the treatment of SE.     

癫痫持续状态诱导发育幼鼠海马神经的发生

目的 观察发育期幼鼠癫痫持续状态(SE)后海马内神经干细胞(NSCs)的增殖、迁移与分化特点.方法 日龄7d、14 d、21 d、28 d(P7、P14、P21、P28)健康SD大鼠共320只,完全随机法分为SE组和正常对照组,戊四氮造模后各个日龄组大鼠再随机分为1、7、14、21、28 d5个时间点,每个时间点8只,通过免疫组织化学法观察发作后不同时间点的齿状回区细胞增殖、迁移情况.再选P14日龄大鼠64只随机分为SE组和正常对照组,通过荧光免疫双标记5-溴脱氧尿嘧啶核苷(Brdu)和神经元特异性核蛋白(NeuN)、Brdu和胶质纤维酸性蛋白(GFAP)观察NSCs分化情况.结果 (1)P7、P14、P21、P28幼鼠SE后1d齿状回出现nestin阳性细胞,7 d nestin阳性细胞逐渐增多,14 d达到峰值,21 d逐渐减少,28 d下降至最低.其中P7幼鼠SE后7 d nestin阳性细胞数为177.00±3.22(t=16.033)、14 d幼鼠nestin阳性细胞数为195.00±3.41(t =28.840)明显高于各自正常对照组(147.50±2.08,136.50±2.65,均P＜0.05),总体表现出先上升后下降的趋势.同时SE发作日龄越小,nestin表达强度越大,而在生理状态下幼鼠齿状回中nestin表达随着日龄的增加而逐渐减少;(2)SE后1d及7d时大部分nestin阳性细胞分布于颗粒细胞下层,14 d nestin阳性细胞逐渐向颗粒细胞层迁移,迁移时细胞形态发生改变.在P14、P21、P28 3个日龄组有少部分异位迁移入海马的门区,同时在海马CA1、CA3及顶皮质区也见到形态不同的nestin阳性细胞;(3)Brdu阳性细胞大多同时表达NeuN,有4％ ～5％共表达GFAP.结论 SE可诱导发育幼鼠海马齿状回区的神经发生,并且具有年 龄相关性特点.新生细胞大部分从齿状回颗粒细胞下层迁移到颗粒细胞层,少部分异位迁移到海马门区,多数分化为神经元,少部分分化为胶质神经细胞.     

大鼠癫痫持续状态后水通道蛋白-4的表达

目的 探讨癫痫持续状态（SE）后大鼠水通道蛋白-4（AQP4）的表达变化与脑水肿形成之间的关系。方法 54只SD大鼠随机分为对照组（n=6），SE后6h，12h，24h，48h，72h，96h，120h，168h组（n=6）。腹腔注射锂-匹罗卡品建立大鼠SE模型，免疫组织化学染色和逆转录PCR方法检测AQP4蛋白和基因在SE形成后的表达。结果 SE后AQV4蛋白和mRNA24h表达水平明显增加，48h达到高峰，持续72h后下降，168h时仍有表达。SE后AQP4表达变化和脑水肿形成过程在时间上呈明显的正相关（r=0．73，氏0．05）。结论 SE后AOP4表达明显增强，在时间上与脑水肿形成呈正相关，提示AQP4在SE后脑水肿形成过程中起着重要作用。     

Volumetric magnetic resonance imaging of functionally relevant structural alterations in chronic epilepsy after pilocarpine-induced status epilepticus in rats

PURPOSE: After pilocarpine-induced epilepsy in rats, volumetric magnetic resonance imaging (MRI) reveals significant morphologic changes in functionally relevant structures of the brain. To relate structural changes to functional alteration, we studied the correlation of regional brain atrophy (e.g., of the hippocampus) with lesion-induced learning deficits in the Morris water maze. METHODS: MRI experiments were performed on an MR scanner at 4.7 Tesla. For volumetric analysis, various cerebral structures were segmented in horizontal and coronal T(2)-weighted MR images. Before the MRI investigations, animals were trained for 10 days in a Morris water maze. RESULTS: Volumetric MRI revealed a significant loss in hippocampal size in both the dorsal and ventral parts, correlated with an increase in ventricular size. Furthermore, significant losses were found in the relative size of thalamus, putamen, cortex, and the combined areas of perirhinal, entorhinal, and piriform cortices adjacent to the hippocampus. A significant correlation of learning performance in the Morris water maze with the relative hippocampal area and not with other areas tested was observed in pilocarpine-treated animals. CONCLUSIONS: The data provide a quantitative analysis of functionally relevant structural alterations in rats with chronic epilepsy. Water maze performance of pilocarpine-treated animals correlates with the degree of hippocampal but not with the degree of cortical damage, demonstrating the potential of this method for the investigation of cognitive impairments in relation to cerebral changes. In addition, the data point to an important role of even the residual hippocampus in memory formation.     

大鼠癫(癎)持续状态后海马内X-连锁凋亡抑制蛋白及其负性调控因子的表达

目的 研究大鼠癫(癎)持续状态(SE)后海马组织中X-连锁凋亡抑制蛋白(XIAP)及其负性调控因子Smac、HtrA2、XAF1的表达变化.方法 建立氯化锂-匹罗卡品致(癎)大鼠SE模型,应用免疫组织化学染色和Western blot方法检测大鼠SE后各时点海马CA3区XIAP、Smac、HtrA2、XAF1及半胱氨酸蛋白酶(caspase)-3蛋白的表达.结果 SE后大鼠海马CA3区XIAP蛋白呈弥散性分布于整个神经元内,SE后2 h(0.5503±0.0172)起逐渐增高(t=115.87),8 h(0.6221±0.0238)达高峰(t=136.69).与对照组(0.1507±0.0165)比较,差异有统计学意义(P<0.01).Same、HtrA2及XAF1蛋白在对照组弱表达,在SE后呈弥散性分布于整个神经元内.2～72 h增高.海马CA3区caspase-3活性蛋白在对照组呈阴性,在SE后4～72 h明显增高.Western blot发现,SE组各时间点XIAP蛋白表达量与对照组比较差异无统计学意义(P>0.05),Smac、HtrA2及caspese-3蛋白在对照组很少表达,在SE后2～72 h增高(P<0.01).结论 XIAP及其负性调控因子Smac、HtrA2、XAF1涉及了SE后神经元凋亡的调节,参与了SE后神经元损伤.     

Furosemide terminates limbic status epilepticus in freely moving rats

PURPOSE: To evaluate the anticonvulsant properties of furosemide and to determine sedative side effects compared with pentobarbital and diuretic side effects compared with saline-treated controls in an experimental model of limbic status epilepticus. METHODS: Self-sustaining status epilepticus was induced in rats by continuous electrical stimulation of the perforant path. Five minutes after the end of the stimulation, animals were given 100 mg/kg furosemide, 30 mg/kg pentobarbital, or an equal amount of saline, intraperitoneally. After administration of the substance, animals were monitored clinically and electrographically for 3 h regarding status epilepticus, level of sedation, and diuresis. RESULTS: In seven of 10 animals, furosemide terminated status epilepticus after 68 +/- 26 min, whereas pentobarbital was successful in all animals after 5 +/- 0.8 min. In contrast to pentobarbital, sedation did not occur with furosemide. Weight loss after furosemide was 10.2 +/- 1.7% compared with 6.5 +/- 1.1% in animals given saline (p < 0.001). CONCLUSIONS: The results suggest that furosemide may serve as an alternative or additional agent for refractory complex partial status epilepticus in patients in whom common anesthetics are not justifiable.     

Changes in microtubule-associated protein-2 (MAP2) expression during development and after status epilepticus in the immature rat hippocampus

In this study, we analyzed the spatiotemporal expression patterns of the high-molecular weight (MAP2a and b) and low-molecular weight (MAP2c and d) cytoskeletal microtubule-associated protein-2 (MAP2) isoforms with Western blotting, and the cellular localization of the high-molecular weight MAP2 isoforms with immunocytochemistry in the hippocampi of 1- to 21-day-old rats. Moreover, the temporal profile (from 30 min to 1 week) of MAP2 isoform reactivity to kainic acid-induced status epilepticus was studied in P9 rats. During development, the expression of the high-molecular weight MAP2 isoforms significantly increased, while the low-molecular weight isoforms decreased, the most prominent changes occurring during the second postnatal week. This developmental increase in the high-molecular weight MAP2 expression was also confirmed with immunocytochemistry, which showed increased immunoreactivity, particularly in the molecular layers of the dentate gyrus, and in CA1 and CA3 stratum radiatum. In 9-day-old rats, status epilepticus resulted in a rapid transient increase (about 210%) in the high-molecular weight MAP2 expression, without any effect on the low-molecular weight MAP2. Moreover, disturbed dendritic structure in the CA1 and CA3 stratum radiatum was manifested as formation of varicosities 3h after the kainic acid treatment. The strictly developmentally regulated MAP2 isoform expression suggests different functional roles for these proteins during the postnatal development in the rat hippocampus. Moreover, high-molecular weight MAP2s may play a role in nerve cell survival during cell stress.     

Modulation of CaM kinase II activity is coincident with induction of status epilepticus in the rat pilocarpine model

PURPOSE: This study was conducted to characterize the early cellular changes in CaM kinase II activity that occur during the induction of status epilepticus (SE). METHODS: The pilocarpine model of SE was characterized both behaviorally and electrographically. At specific time points after the first discrete seizure, specific brain regions were isolated for biochemical study. Phosphate incorporation into a CaM kinase II-specific substrate, autocamtide III, was used to determine kinase activity. RESULTS: After the development of SE, the data show an immediate inhibition of both cortical and hippocampal CaM kinase II activity in homogenate, but a delayed inhibition in synaptic kinase activity. The maintenance of synaptic kinase activity was due to a translocation of CaM kinase II protein to the synapse. However, despite the translocation of functional kinase, CaM kinase II activity was not maintained, membrane potential was not restored, and the newly translocated CaM kinase II did not terminate the SE event. Unlike the homogenate samples, in the crude synaptoplasmic membrane (SPM) subcellular fractions, a positive correlation is found between the duration of SE and the inhibition of CaM kinase II activity in both the cortex and hippocampus. CONCLUSIONS: The data support the hypothesis that alterations of CaM kinase II activity are involved in the early events of SE pathology.     

Age-dependent cyclooxygenase-2 induction and neuronal damage after status epilepticus in the postnatal rat hippocampus

PURPOSE: Epileptic seizures lead to age-dependent neuronal damage in the developing brain, particularly in the hippocampus, but the mechanisms involved have remained poorly elucidated. In this study, we investigated the contribution of apoptosis and inflammatory processes to neuronal damage after status epilepticus (SE) in postnatal rats. METHODS: SE was induced by an intraperitoneal injection of kainic acid (KA) in 21- and 9-day-old (P21 and P9) rats. The expression of Bax, Bcl-2 and caspase-3, markers for apoptosis, and cyclooxygenase-2 (COX-2), an indicator for activation of inflammatory processes, were studied from 6 h up to 1 week after SE by Western blotting and immunocytochemistry. Neuronal damage was verified by Fluoro-Jade B staining. RESULTS: In P21 rats, SE resulted in neuronal damage in the CA1 neurons of the hippocampus. COX-2 expression was extensively, but transiently, increased and its immunoreactivity pronouncedly enhanced in several hippocampal subregions, amygdala, and piriform cortex by 24 h after SE. The expression of Bax and caspase-3 remained unchanged, whereas the antiapoptotic factor Bcl-2 transiently decreased by 24 h. Single caspase-3 positive neurons appeared in the CA1 region of both control and KA-treated rats. In P9 rats, no neuronal death was detected, and COX-2 expression and immunoreactivity remained at the control level. DISCUSSION: Our results suggest that SE provokes age-specific effects on COX-2 expression. This together with the activation of putative inflammatory processes may contribute to neuronal cell death in the hippocampus of postnatal rats, whereas caspase-dependent apoptosis seems not to be involved in the death process.