Objective To explore the temporal and spatial distribution of CCAAT/enhancer-binding protein homologous protein (CHOP) and calnexin (CNX) in the dentate gyrus of mesial temporal lobe epilepsy (mTLE) mouse model. Methods We used kainic acid (KA) to induce acute phase (12 h and 24 h) mTLE mouse models and performed Western blotting and immunofluorescence to detect the different expressions and distribution pattern of CHOP and CNX in CA3 of the hippocampus. Results Compared with the controls,the expressions of CHOP(F=1.136,P=0.4069) and CNX (F=2.378,P=0.2087) did not increase in CA3 of hippocampus 12 h following KA injection in the acute phase of mTLE mouse models,whereas the expressions in CA1 and CA3 of hippocampus 24 h after injection were significantly higher (F=8.510,P=0.0362;F=6.968,P=0.0497,respectively). As shown by immunofluorescence analysis,CHOP was expressed mainly in CA3 of hippocampus 12 h after KA injection,and increased in CA1 and CA3 24 h after KA administration. Compared with the controls,the expressions of CHOP(F=24.480,P=0.0057) and CNX (F=7.149,P=0.0478) were significantly higher 24 h after KA injection.Conclusions The expression of CHOP increases along with the progression of seizures,indicating the increased level of endoplasmic reticulum stress. An increasing number of CNX,which serves as molecular chaperone,may be needed to facilitate the unfolded protein to complete the folding process.
Animals ; Calnexin ; metabolism ; Dentate Gyrus ; metabolism ; Disease Models, Animal ; Epilepsy, Temporal Lobe ; chemically induced ; metabolism ; Kainic Acid ; Mice ; Seizures ; chemically induced ; metabolism ; Transcription Factor CHOP ; metabolism

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.
Adenylyl Cyclases ; biosynthesis ; genetics ; Animals ; Glutamic Acid ; Hippocampus ; metabolism ; Interleukin-1 ; pharmacology ; Male ; Neocortex ; metabolism ; Rats ; Seizures ; chemically induced ; enzymology

AIMTo further explore the roles of endogenous nitric oxide (NO) or NO derivatives in complex partial seizures and generalized convulsions.

METHODSThe effect of pretreatment with L-nitroarginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), or L arginine (L-Arg), a precursor of NO on kainic acid (KA)-induced seizure in rats and the changes in the concentration of NO2 -/NO- in the hippocampus were determined.

RESULTSThe rats appeared with wet dog shakes (WDS) at 15 min and then occurred generalized convulsions during 1 h to 3 h after administration of KA (10 mg/kg i.p.). However, the pretreatment of L-NNA (50 mg/kg) so dramatically promoted and enhanced KA-induced behavioral seizures that the latency of generalized convulsion was shorten dramatically, and the mortality was greatly high. In contrast, the pretreatment with L-Arg (40 mg/kg) markedly delayed or weakened KA-induced behavioral changes, such as increasing latency of WDS and generalized convulsion, shortening time o f seizure and none of animal died during observed time. The concentration of NO2- /NO3- in the hippocampus increased immediately at 30 min and remained to 7 d after the administration of KA. Compared with control group (pretreatment with NS), the concentration of NO2- / NO3- in the hippocampus apparently increased at 3 h and 3 d after the administration of KA in the rats with L-Arg pretreatment.

CONCLUSIONThe endogenous NO (NO or NO derivatives) mediators may play an important role against excitotoxin induced seizures in rats.

Animals ; Arginine ; pharmacology ; Kainic Acid ; adverse effects ; Male ; Nitric Oxide ; metabolism ; Nitroarginine ; pharmacology ; Rats ; Rats, Wistar ; Seizures ; chemically induced ; metabolism

OBJECTIVETo observe the histopathological changes in rat hippocampus at different maturational stages after repeated kindled seizures, and to explore their underlying epileptogenesis processes.

METHODSThree groups of Wistar rats (postnatal days: P10, P20, P60) were given pentylenetetrazol (PTZ) intraperitoneal injection for 5 days to induce repeated kindled seizures, and the age-matched rats in control group were injected with normal saline. The behavioral changes, the morphology and the neurons counting in hippocampus, as well as the expression of NF-kappaB were observed.

RESULTS(1) In the three groups, the latency of seizure and the latency of IV/V grade were significantly lower in the rats of group P10 and P20 [(1.2 +/- 0.6) min and (14.4 +/- 2.3) min vs. (4.7 +/- 1.6) min and (24.5 +/- 4.5) min] than group P60 [(8.6 +/- 2.0) min and (41.9 +/- 4.5) min], whereas the duration of convulsion in group P10 and P20 [(46.2 +/- 4.8) min and (29.8 +/- 5.9) min] was longer than those of group P60 [(17.1 +/- 5.0) min]. (2) The neuron counting of CA(1), CA(3) and hilar in the P10 and P20 groups showed no differences as compared to their controls, whereas adult rats (P60) had a significant neuron loss in CA(1) and CA(3) pyramidal cells, compared with the control group [(6.3 +/- 1.5)/250 microm(2), (3.6 +/- 1.4)/250 microm(2) vs. (8.2 +/- 1.9)/250 microm(2), (5.6 +/- 1.7)/250 microm(2)]. However, the dentate granule cells in immature rats (P10) with daily seizures had a significant increase as compared with the controls [(23.3 +/- 3.1)/250 microm(2) vs. (16.3 +/- 1.6)/250 microm(2)]. (3) Prominent sprouting was seen in the CA(3) stratum pyramidal layer in all experimental rats with 5 daily seizures, regardless of the age. But the degree of sprouting had significant differences among the experimental groups (P < 0.05). (4) NF-kappaB was expressed significantly in CA(3), CA(1) and dentate granule cells 24 hours after PTZ-kindling when compared with the control groups, with the spectral density decreased with age.

CONCLUSION(1) There were great differences in the vulnerability to the repeated seizure-induced brain damage at different maturational stages in rats. The immature brain appeared to be less vulnerable to the repeated seizures. (2) There was less hippocampus neuron loss and milder mossy fiber sprouting after repeated seizures in the developing rats than mature ones, which may be a pathological evidence underlying the prospect that the immature brain was more resistant to the seizure-induced neuronal injury. (3) The high expression of NF-kappaB may exert a certain biological effects in the seizure-induced neuronal injury.

Age Factors ; Animals ; Hippocampus ; drug effects ; pathology ; NF-kappa B ; metabolism ; Pentylenetetrazole ; adverse effects ; Rats ; Rats, Wistar ; Seizures ; chemically induced

OBJECTIVETo investigate the modulatory effects of morphine on the susceptibility to pentylenetetrazole-induced seizures, and the involvement of endogenous histamine in this process.

METHODSBoth the wild-type (WT) mice and histidine decarboxylase (a key enzyme for histamine biosynthesis) deficient (HDC-KO) mice were subcutaneously injected with different doses of morphine, and 1 hour later the pentylenetetrazole solution (1.5 %) was infused into the tail vein at a constant rate of 0.3 ml/min. The minimal dose of pentylenetetrazole (mg/kg) needed to induce myoclonic jerks and clonus convulsion was recorded as the thresholds of seizures.

RESULTIn WT mice, morphine dose-dependently decreased the thresholds of both myoclonic jerks and clonus convulsion. In HDC-KO mice, morphine at 10 mg/kg only significantly decreased the threshold of myoclonic jerks from (38.6 +/-2.9)mg/kg to (32.5 +/-0.7)mg/kg, but had no significant effect on the threshold of clonus convulsion [from (51.8 +/-2.1)mg/kg to (47.6 +/-1.2)mg/kg]. In addition, the value of decreased myoclonic jerks (15.8 +/-1.4)% and clonus convulsion (8.3 +/-0.9)% thresholds were much lower in HDC-KO mice than in WT mice [(26.1 +/-2.5)% and (20.8 +/-2.4)%, respectively].

CONCLUSIONMorphine can decrease the thresholds of pentylenetetrazole in induction of seizure, and the endogenous histamine may be involved in this process.

Animals ; Disease Susceptibility ; chemically induced ; metabolism ; physiopathology ; Dose-Response Relationship, Drug ; Histamine ; metabolism ; physiology ; Histidine Decarboxylase ; genetics ; metabolism ; Male ; Mice ; Mice, Knockout ; Morphine ; pharmacology ; Myoclonus ; chemically induced ; metabolism ; physiopathology ; Narcotics ; pharmacology ; Pentylenetetrazole ; Random Allocation ; Seizures ; chemically induced ; genetics ; physiopathology ; Sensory Thresholds ; drug effects

Kainic acid, an analogue of glutamate, causes limbic seizures and induces cell death in the rat brain. We examined the activation of MAPK family kinases; ERKs, JNKs and p38 kinase in rat hippocampus after KA treatment. Activation of all three kinases were observed at 30 min after the treatment, but, in contrary to ERK phosphorylation, which lasted up to 3 h, the phosphorylation of JNK and p38 returned to the basal level by 2 h. The phosphorylation of' upstream kinases for the MAPK family was distinct. The phosphorylation of MEK1 clearly increased at 30 min but diminished rapidly thereafter. The phosphorylation of MKK6 was also increased but reached peak at 2 h after KA treatment. However, the phosphorylation of other upstream kinases, SEK1 and MKK3, gradually decreased to 3 h after KA treatment. These results indicate that the KA activates all of the three MAPK family kinases with different time patterns and suggest the possibility that MKK3 and MKK6, and SEK1 may not be the upstream kinases for p38 and JNK in rat hippocampus.
Animal ; Enzyme Activation ; Hippocampus/*drug effects/enzymology ; Kainic Acid/*pharmacology ; Limbic System/drug effects ; Male ; Mitogen-Activated Protein Kinases/*metabolism ; Rats ; Seizures/*chemically induced

OBJECTIVETo investigate the expression of N-methyl-D-asparate (NMDA) receptor subunit proteins after administration of different doses of pentylenetetrazol (PTZ).

METHODSAfter ip injection of a subconvulsant (35 mg/kg) and convulsant (50 mg/kg) dose of PTZ, the rats were decapitated at different time points. The levels of cortical NR1 NR2A and NR2B subunit proteins were detected by immunoblotting.

RESULT35 mg/kg PTZ and 50 mg/kg PTZ elicited different behavioral changes (P<0.001). The NR2A subunit in the cortex significantly increased 1 h after PTZ injection (P<0.05). For the 50 mg/kg group, both the NR2A and NR2B subunits proteins increased at 1 h in the cortex and then decreased; the protein levels returned to normal after 48 h. However, NR1 subunit had no changes.

CONCLUSIONThe NR2 subunit is involved in PTZ-induced seizure.

Animals ; Cerebral Cortex ; chemistry ; Dose-Response Relationship, Drug ; Male ; Pentylenetetrazole ; administration & dosage ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; analysis ; Seizures ; chemically induced ; metabolism

OBJECTIVEIn the past the mortality and sequelae rate of the patients with severe fluoroacetamide (FAM) poisoning treated only with traditional remedies was high. During the recent ten years the authors treated children with severe FAM poisoning with charcoal hemoperfusion (HP) and achieved better results. However evidence was not sufficient to show that reduced mortality and sequelae rates were obtained from HP without traditional treatment because of lack of prospective randomized, controlled clinical studies. Thus, a dog model for FAM poisoning was designed in order to study the therapeutic effect, high-efficiency time of HP, the time of tissue-poisoning to release after HP, and to investigate the toxicokinetics of the poison in the course of treatment and after HP.

METHODFourteen dogs were given intraperitoneal FAM at a dose of 0.3 mg/kg body weight. HP was performed on 9 poisoned dogs for 30 - 120 minutes post intoxication. Each procedure lasted for 4 hours. Blood samples of the 9 poisoned dogs were collected before HP and 30, 60, 90, 120, 180, 240 minutes during HP and 2, 6, 24 hours after HP. Blood plasma was separated from blood samples and stored at -20 degrees C. The concentration of the poison was measured by gas chromatography (GC). The clinical symptoms of all the dogs were observed for one day.

RESULTSThe FAM concentration (ng/ml) of blood samples in poisoned dogs before HP, and 60, 120, 180, 240 minutes during HP were 230.11 +/- 52.48, 184.56 +/- 62.57, 141.00 +/- 44.83, 126.78 +/- 61.04, 113.11 +/- 54.65 respectively. The differences were significant (chi(2) = 31.978, P < 0.0005). The dispersion count between pre-HP and HP for 1 was 45.55, between 1 h and 2 h was 43.56, between 2 h and 3 h was 14.22 and between 3 h and 4 h was 13.67. The values of FAM had declined by 38.7%, 45.0% and 50.8% respectively at 2 h, 3 h, 4 h of HP compared with pre-HP. The rate of cleaning efficacy of FAM of every hour during HP were 19.79%, 23.6%, 10.09% and 10.78% respectively during HP 1, 2, 3, 4 h. The cleaning efficacy of HP was high within 2 hours during HP. The concentration of FAM slightly rose again 6 h after HP. The level of FAM had declined at 24 hour after HP when compared with pre-HP level. The reduction rate of FAM level for every hour during HP was higher than that after HP (12.71% vs 0.27% - 2.22%). The t(1/2) of FAM with and without HP were (4.50 +/- 1.20) h and (49.60 +/- 10.56) h. All the 5 poisoned dogs not treated with HP died. However 6 poisoned dogs treated with HP kept alive after HP. Three dogs had frequent seizures again 4h after HP. After HP the charcoal container was washed by 0.9% saline and FAM could not be detected in the douche.

CONCLUSIONSCharcoal HP was an effective treatment for severe FAM poisoning. T(1/2) of the poison was shortened, and the poison clearing rate was accelerated by HP. The high-efficiency time of HP was 2 - 2.5 h. Activated charcoal can adsorb the poison vigorously, and return of blood to the body after HP by using 0.9% saline was feasible and safe.

Animals ; Charcoal ; therapeutic use ; Dogs ; Fluoroacetates ; poisoning ; Hemoperfusion ; methods ; Metabolic Clearance Rate ; Poisoning ; metabolism ; therapy ; Poisons ; toxicity ; Seizures ; chemically induced ; Treatment Outcome

OBJECTIVERefractory temporal lobe epilepsy (TCE) shows a unique type of hippocampal damage, referred to as hippocampal sclerosis. The mechanisms underlying drug-refractoriness in TCE are poorly understood, which may be connected with pharmacoresistance to antiepileptic drugs (AEDs). Some studies show that expression of the multidrug resistance gene (mdr1a and mdr1b) and p-glycoprotein encoded by mdr1a and mdr1b are high in the brain, especially in the hippocampus, and the expression may lead to reduction of AEDs concentration in the brain. But most of these studies focused on acute epileptic activity shortly after status epilepticus (SE), spontaneous seizures are seldom studied. The authors used a rat model of kainic acid induced spontaneous seizures to investigate expression of mdr1a and mdr1b mRNA, and explore whether topiramate (TPM) affects expression of mdr1a and mdr1b in the hippocampus.

METHODSSeizures were induced by intraperitoneal injection of 10 mg/kg kainic acid at postnatal day 28. Control rats were injected with sodium chloride. All rats were divided into 4 groups 1 week after spontaneous seizures developed: status epilepticus complicated with spontaneous seizures (SE, n = 8) group, status epilepticus complicated with spontaneous seizures treated with TPM (SE + TPM, n = 9) group, spontaneous seizures without status epilepticus (N-SE, n = 7) group, spontaneous seizures without status epilepticus treated with TPM (N-SE + TPM, n = 8) group, control (n = 7) group and control treated with TPM (control + TPM, n = 7) group. The treated rats were given therapeutic dose of TPM (25 mg/kg). All the rats were killed on the 42nd day of administration. The mdr1a and mdr1b mRNAs in the hippocampus were measured by RT-PCR.

RESULTSExpression of mdr1a and mdr1b mRNA in the hippocampus increased significantly in the SE + TPM group, SE group and N-SE + TPM group compared with control group (P < 0.001 or < 0.05). The mRNA in SE + TPM group increased significantly compared with the SE group, too (P < 0.01). The mdr1a and mdr1b mRNA expression in the hippocampus in control + TPM and N-SE groups did not change.

CONCLUSIONFrequent seizures, especially status epilepticus resulted in overexpression of mdr1a and mdr1b mRNAs in the hippocampus. The drug-refractoriness mechanism in TCE may be related to overexpression of mdr1a and mdr1b mRNAs. TPM could enhance the expression of mdr1a and mdr1b mRNAs in the hippocampus. Seizure activity and TPM are likely to be the main determinant in enhancing mdr1a and mdr1b mRNA expression in epilepsy.

ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Animals ; Anticonvulsants ; pharmacology ; Fructose ; analogs & derivatives ; pharmacology ; Hippocampus ; metabolism ; Kainic Acid ; RNA, Messenger ; metabolism ; Rats ; Seizures ; chemically induced ; drug therapy ; metabolism ; Status Epilepticus ; drug therapy ; metabolism

OBJECTIVETo study the effects of immunoglobulin on the neuronal expression of IL-1beta and IL-1ra and the neuronal death at hippocampus in rats with convulsion induced by pentylenetetrazol.

METHODSThe epilepsy model was established by injecting intraperitoneally pentylenetetrazol (PTZ) into Wistar rats. Forty-five rats were randomly divided into three groups, normal control group, PTZ plus intravenous immunoglobulin (PTZ-IVIG); PTZ plus normal saline (PTZ-NS). Neuronal death was assessed by light microscopy with the hematoxylin-eosin (HE) staining and with in situ terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). IL-1beta and IL-1ra expressions were examined by histochemistry.

RESULTSThe ratio of IL-1beta/IL-1ra at hippocampal CA(1) region in PTZ-IVIG group (0.5 +/- 0.1) was significantly lower than that in PTZ-NS group (1.9 +/- 0.5, t = 12.9, P < 0.05). Apoptotic cell numbers at the hippocampal CA(1) region were significantly decreased in the PTZ-IVIG group, compared to PTZ-NS group (t = 27.1, P < 0.05). The numbers of positive cells were 16.4 +/- 3.3/1000 microm(2) in the former and 41.7 +/- 3.5/1000 microm(2) in the latter. Necrotic cell numbers at the hippocampal CA(1) region were significantly decreased in the PTZ-IVIG group (19.0 +/- 2.6/1000 microm(2)), compared to PTZ-NS group (42.3 +/- 4.9/1000 microm(2), t = 20.9, P < 0.05).

CONCLUSIONImmunoglobulin could inhibit neuronal death induced by convulsion and its possible mechanism might be the regulation of IL-1 system in neurons.

Animals ; Apoptosis ; Hippocampus ; drug effects ; immunology ; metabolism ; Immunoglobulins, Intravenous ; pharmacology ; Interleukin 1 Receptor Antagonist Protein ; metabolism ; Interleukin-1beta ; metabolism ; Neurons ; drug effects ; Pentylenetetrazole ; adverse effects ; Rats ; Rats, Wistar ; Seizures ; chemically induced ; immunology ; metabolism