OBJECTIVETo explore the effect of up-regulation of KA1 subunit of the kainate receptor on endoplasmic reticulum stress (ERS)-induced excitotoxic neurodegeneration in mouse hippocampus.

METHODSSeventy adult male KM mice were subjected to microinjections into the hippocampus of kainic acid (KA) or 500, 1000, or 2000 µg/ml tunicamycin (TM). At 1, 2, 3, 4, 5, 8, and 12 h after the injections, the mice were assessed for Bederson scores and sacrificed for FJB staining and immunofluorescence observation of the brain slices.

RESULTSAt 3, 4, 5, and 8 h after KA injection and at 4 and 5 h after of 2000 µg/ml TM injection, the mice showed severe central nervous system dysfunction, and FJB staining revealed increased cell death in the hippocampus, where up-regulated expressions of KA1 receptor and ERS marker P-eIF2α were found by immunofluorescence staining (P<0.05).

CONCLUSIONMicroinjection of KA or TM into the hippocampus causes neuronal death and ERS with up-regulated expression of KA1. In this process of neuronal apoptosis, the membrane receptor KA1 receives the apoptosis signal and transfers it to the inside of the cells to cause cell endoplasmic reticulum dysfunction and ERS response, which ultimately leads to neuronal death.

Animals ; Apoptosis ; Endoplasmic Reticulum Stress ; Hippocampus ; pathology ; Kainic Acid ; pharmacology ; Male ; Mice ; Neurons ; pathology ; Receptors, Kainic Acid ; metabolism ; Tunicamycin ; pharmacology ; Up-Regulation

The KA1 kainate receptor (KAR) subunit in the substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) has been implicated in the processing of nociceptive information from the orofacial region. This study compared the expression of the KA1 KAR subunit in the SG of the Vc in juvenile, prepubescent and adult mice. RT-PCR, Western blot and immunohistochemistry analyses were used to examine the expression level in SG area. The expression levels of the KA1 KAR subunit mRNA and protein were higher in juvenile mice than in prepubescent or adult mice. Quantitative data revealed that the KA1 KAR subunit mRNA and protein were expressed at levels approximately two and three times higher, respectively, in juvenile mice than in adult mice. A similar expression pattern of the KA1 KAR subunit was observed in an immunohistochemical study that showed higher expression in the juvenile (59%) than those of adult (35%) mice. These results show that the KA1 KAR subunits are expressed in the SG of the Vc in mice and that the expression level of the KA1 KAR subunit decreases gradually with postnatal development. These findings suggest that age-dependent KA1 KAR subunit expression can be a potential mechanism of age-dependent pain perception.
Age Factors ; Animals ; Gene Expression Profiling ; *Gene Expression Regulation, Developmental ; Mice ; Receptors, Kainic Acid/*metabolism ; Substantia Gelatinosa/*metabolism

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

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

OBJECTIVETo observe the dynamics of hippocampal release of glutamate (Glu) and gamma-aminobutyric acid (GABA) in epilepsy (TLE) after administration with high frequency stimulation (HFS).

METHODSThe SD were divided into four groups (n =10): (1) Control group (KB) the rats were injected intraperitoneally with saline 0.9%. (2) Kainic acid (KA) group: the rats were injected with KA. (3) Pseudo-deep brain stimulation (DBS) group: the KA-induced rats were implanted with rheophores alone. (4) DBS group: KA induced-rats with DBS in hippocampal epileptic foci. We then collected hippocampal extracellular fluid by microdialysis and the levels of Glu and GABA were measured by high-performance liquid chromatography (HPLC) and fluorescence detection.

RESULTSThere was no difference in the baseline of Glu and GABA in the four groups. In contrast, a significant increase in the content of Glu and GABA was shown in the three periods of KA-kindled seizures. Electrical stimulation of hippocampus resulted in a decrease of hippocampal Glu contents, while there was no change in GABA contents. Additionally, HFS of hippocampus normalized the Glu/GABA ratio in the chronic period of seizures.

CONCLUSIONThe high frequency stimulation of epileptic foci may protect against seizures by modulating the extracellular release of hippocampal Glu.

Animals ; Electric Stimulation ; methods ; Epilepsy ; chemically induced ; therapy ; Glutamic Acid ; secretion ; Hippocampus ; metabolism ; Kainic Acid ; Kindling, Neurologic ; drug effects ; Male ; Rats ; Rats, Sprague-Dawley ; gamma-Aminobutyric Acid ; secretion

OBJECTIVETo study the changes of excitatory and inhibitory amino acid content in hippocampus of epileptic rats treated with volatile oil of A. tatarinowii, and explore the possible antiepiletic mechanism.

METHODThe volatile oil was extracted through Supercritical-CO2 Fluid Extraction (SFE-CO2), and epileptic models were built up by kainic acid (KA) lateral ventricle injection. The content of amino acid in hippocampus of epileptic rats treated with volatile oil was calculated.

RESULTThe content of GABA increased and Glu decreased prominently (P < 0.05) after volatile oil 35 mg x kg(-1) intraperitoneal injection.

CONCLUSIONThe volatile oil of A. tatarinowii can modulate the balance of excitatory and inhibitory amino acid in epileptic rats, thereby exerting its antiepileptic effect.

Acorus ; chemistry ; Animals ; Anticonvulsants ; pharmacology ; Aspartic Acid ; metabolism ; Epilepsy ; chemically induced ; metabolism ; Glutamic Acid ; metabolism ; Hippocampus ; metabolism ; Kainic Acid ; Male ; Oils, Volatile ; isolation & purification ; pharmacology ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley ; gamma-Aminobutyric Acid ; metabolism

OBJECTIVETo explore the temporal and spatial distribution of growth-associated protein 43(GAP-43)and phosphorylated growth-associated protein 43(p-GAP-43)in the dentate gyrus of mesial temporal lobe epilepsy(MTLE)mouse model.

METHODSMTLE mouse model was established by using the kainic acid(KA)induction. Immunohistochemistry and Western blotting were applied to detect the expressions of GAP-43 and p-GAP-43 in different stages of epileptogenesis.

RESULTSBoth in the epileptic and control mice, high GAP-43 expression level was detected in the dentate gyrus, hilus, and inner molecular layer of hippocampus. Decreased p-GAP-43 expression was detected 5 days, 2 weeks, and 5 weeks after KA-induced seizures.

CONCLUSIONThe decreased p-GAP-43 expression in the duration of seizure may play an important role in the synaptic reorganization of the sclerotic hippocampus.

Animals ; Dentate Gyrus ; metabolism ; Disease Models, Animal ; Epilepsy ; Epilepsy, Temporal Lobe ; metabolism ; GAP-43 Protein ; metabolism ; Hippocampus ; metabolism ; Kainic Acid ; Mice ; Seizures

An increased level of reactive oxygen species is a key factor in neuronal apoptosis and epileptic seizures. Irisin reportedly attenuates the apoptosis and injury induced by oxidative stress. Therefore, we evaluated the effects of exogenous irisin in a kainic acid (KA)-induced chronic spontaneous epilepsy rat model. The results indicated that exogenous irisin significantly attenuated the KA-induced neuronal injury, learning and memory defects, and seizures. Irisin treatment also increased the levels of brain-derived neurotrophic factor (BDNF) and uncoupling protein 2 (UCP2), which were initially reduced following KA administration. Furthermore, the specific inhibitor of UCP2 (genipin) was administered to evaluate the possible protective mechanism of irisin. The reduced apoptosis, neurodegeneration, and spontaneous seizures in rats treated with irisin were significantly reversed by genipin administration. Our findings indicated that neuronal injury in KA-induced chronic epilepsy might be related to reduced levels of BDNF and UCP2. Moreover, our results confirmed the inhibition of neuronal injury and epileptic seizures by exogenous irisin. The protective effects of irisin may be mediated through the BDNF-mediated UCP2 level. Our results thus highlight irisin as a valuable therapeutic strategy against neuronal injury and epileptic seizures.
Rats ; Animals ; Kainic Acid/toxicity* ; Brain-Derived Neurotrophic Factor/metabolism* ; Fibronectins/metabolism* ; Hippocampus/metabolism* ; Rats, Sprague-Dawley ; Epilepsy/metabolism* ; Seizures/prevention & control*

AIMTo investigate the effects of scorpion venom heat-resistant protein (SVHRP) on kainic acid induced-damage of cultured primitive rat hippocampal neuropeptide Y-nergic neurons.

METHODSWe observed morphological changes, celluar vigor, NPY-immunoreactivity and NPY mRNA expression by means of Thionine staining, MTT assay, immunocytochemistry and RT-PCR, respectively, on the primitively cultured Sprague-Dawley rat hippocampal neuron treated with KA and SVHRP for 24 h.

RESULTSMTT assay and morphologic analysis showed that SVHRP markedly increased neuron survival-rate, and protected them from kA-induced damage. The expression of NPY-immunoreactivity and NPY mRNA in SVHRP group increased obviously compared with other groups.

CONCLUSIONSVHRP protected the primitively cultured hippocampal neurons from KA-induced neuroexcitotoxicity and promoted the expression of NPY.

Animals ; Cell Death ; Cells, Cultured ; Hippocampus ; cytology ; metabolism ; Kainic Acid ; pharmacology ; Male ; Neurons ; drug effects ; metabolism ; pathology ; Neuropeptide Y ; metabolism ; Rats ; Rats, Sprague-Dawley ; Scorpion Venoms ; pharmacology

3-Hydroxybutyric Acid ; blood ; Animals ; Dietary Carbohydrates ; administration & dosage ; Dietary Fats ; administration & dosage ; Dietary Proteins ; administration & dosage ; Disease Models, Animal ; Epilepsy ; diet therapy ; metabolism ; pathology ; Hippocampus ; metabolism ; Kainic Acid ; Ketone Bodies ; metabolism ; Male ; Mossy Fibers, Hippocampal ; pathology ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptors, Kainic Acid ; analysis ; genetics