OBJECTIVE: To observe the expression of cyclin-dependent kinase 5 (Cdk5) and p35 in rat hippocampus during pentetrazole kindling process and their relation with mossy fiber sprouting (MFS), and to investigate the role of Cdk5/p35 in epileptogenesis. METHODS: Altogether 120 healthy male SD rats were randomly divided into a control group and a pentylenetetrazole (PTZ) treated group. The epileptic models were established by the injection of PTZ intraperitoneally while the control rats were injected with an equal dose of saline. At the 3rd day, 1st week, 2nd week, 4th week, and 6th week after daily injection, Timm staining was performed in area CA3 and dentate gyrus, and the mRNA and protein of Cdk5 and p35 were analyzed in the hilus and stratum granulosum of dentate gyrus and area CA1 and CA3 of hippocampus, by in situ hybridization and immunohistochemistry, respectively. RESULTS: The expression levels of Cdk5 and p35 mRNA were significantly higher in the PTZ treated subgroups of the 3rd day, 1st week, 2nd week, and 4th week than those in the controls. Thereafter, the expression decreased to the level of controls. The expression level of Cdk5 and p35 protein increased from the 3rd day to 2nd week, and then gradually decreased to the level of the controls. Timm scores for PTZ groups were 1 to approximately 4 before kindling and 4~5 after kindling in area CA3. CONCLUSION Change of Cdk5/p35 expression in the hippocampus may play a role in epileptogenesis by influencing the process of mossy fiber sprouting.
Animals ; Cyclin-Dependent Kinase 5 ; genetics ; metabolism ; Epilepsy ; chemically induced ; metabolism ; Kindling, Neurologic ; drug effects ; metabolism ; Male ; Mossy Fibers, Hippocampal ; metabolism ; Pentylenetetrazole ; toxicity ; Phosphotransferases ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To determine the changes of mossy fiber sprouting in hippocampus of pre-kindling and post-kindling rats of chronic epilepsy induced by pentylenetetrazole (PTZ). METHODS: Sixty rats were randomly divided into a control group and a PTZ group (PTZ 30 mg/kg, intraperitoneal injection, once daily). The changes of mossy fiber sprouting in hippocampus of pre-kindling and post-kindling rats were examined by Timm staining. RESULTS: Before the occurrence of convulsion confirmed by behavior and EEG, the mossy fiber sprouting was found in the PTZ group. The grade of the mossy fiber sprouting increased with the gradual establishment of kindling effect. CONCLUSION Mossy fiber sprouting may play an important role in the onset and development of epilepsy.
Animals ; Disease Models, Animal ; Epilepsy ; chemically induced ; pathology ; Hippocampus ; drug effects ; pathology ; Kindling, Neurologic ; drug effects ; Male ; Mossy Fibers, Hippocampal ; growth & development ; Neurons ; metabolism ; Pentylenetetrazole ; pharmacology ; Rats ; Rats, Sprague-Dawley

OBJECTIVEKetogenic diet (KD) is a high fat, low protein, low carbohydrate diet. Its antiepileptic effect is certain but the underlying mechanism is unknown. The aim of the study was to reveal the possible mechanism from the view points of synaptic reorganization and GluR(5) expression in hippocampus.

METHODSEpilepsy was induced in Sprague-Dawley rats by kainic acid at postnatal day 28, all control animals were fed with normal rodent chow, whereas experimental rats were fed with ketogenic feed for 8 weeks. Spontaneous recurrent seizures were recorded. Mossy fiber sprouting and neuron damage in hippocampus were investigated by Timm staining and Nissl staining. Western blot and RT-PCR methods were applied to detect the expression of GluR(5) and GluR(5) mRNA in hippocampus.

RESULTSKD-fed rats (1.40 +/- 1.03) had significantly fewer spontaneous recurrent seizures than control diet-fed rats (7.36 +/- 3.75). The mean A of mossy fiber sprouting in the inner molecular layer of dentate gyrus was markedly higher in KA induced animals than that in saline control animals but it was similar in different diet fed groups. No significant differences were found in the mean A of Timm staining in CA(3) area and Nissl staining of neuron in hilus, CA(3) and CA(1) area. After KA kindling, KD-fed animals [(189.38 +/- 40.03)/mg pro] had significantly higher GluR(5) expression in hippocampus than control diet-fed animals [(128.79 +/- 46.51)/mg pro] although their GluR(5) mRNA was the same.

CONCLUSIONMossy fiber sprouting may be responsible for epileptogenesis in KA induced model and KD can suppress seizures in these animals. KD may upregulate young rat GluR(5) in inhibitory interneurons of CA(1) thus lead to an increased inhibition to prevent the propagation of seizure.

Animals ; Blotting, Western ; CA1 Region, Hippocampal ; metabolism ; pathology ; CA3 Region, Hippocampal ; metabolism ; pathology ; Chromosome Pairing ; drug effects ; Dentate Gyrus ; metabolism ; pathology ; Diet, Ketogenic ; methods ; Disease Models, Animal ; Epilepsy ; chemically induced ; diet therapy ; genetics ; metabolism ; pathology ; Excitatory Amino Acid Agonists ; Hippocampus ; drug effects ; metabolism ; pathology ; Kainic Acid ; Male ; Mossy Fibers, Hippocampal ; metabolism ; pathology ; Pyramidal Cells ; metabolism ; pathology ; RNA, Messenger ; metabolism ; Rats ; Receptors, Kainic Acid ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

Kainic acid (KA) is well-known as an excitatory, neurotoxic substance. In mice, KA administered intracerebroventricularly (i.c.v.) lead to morphological damage of hippocampus expecially concentrated on the CA3 pyramidal neurons. In the present study, the possible role of gamma-aminobutyric acid B (GABA B) receptors in hippocampal cell death induced by KA (0.1 microgram) administered i.c.v. was examined. 5-Aminovaleric acid (5-AV; GABA B receptors antagonist, 20 microgram) reduced KA-induced CA3 pyramidal cell death. KA increased the phosphorylated extracellular signal-regulated kinase (p-ERK) and Ca2+ /calmodulin-dependent protein kinase II (p-CaMK II) immunoreactivities (IRs) 30 min after KA treatment, and c-Fos, c-Jun IR 2 h, and glial fibrillary acidic protein (GFAP), complement receptor type 3 (OX-42) IR 1 day in hippocampal area in KA-injected mice. 5-AV attenuated KA-induced p-CaMK II, GFAP and OX-42 IR in the hippocampal CA3 region. These results suggest that p-CaMK II may play as an important regulator on hippocampal cell death induced by KA administered i.c.v. in mice. Activated astrocytes, which was presented by GFAP IR, and activated microglia, which was presented by the OX-42 IR, may be a good indicator for measuring the cell death in hippocampal regions by KA excitotoxicity. Furthermore, it showed that GABA B receptors appear to be involved in hippocampal CA3 pyramidal cell death induced by KA administered i.c.v. in mice.
Amino Acids, Neutral/pharmacology ; Animals ; Ca(2+)-Calmodulin Dependent Protein Kinase/metabolism ; Cell Death/drug effects ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Glial Fibrillary Acidic Protein/metabolism ; Hippocampus/anatomy & histology/*cytology/*drug effects ; Kainic Acid/*toxicity ; Mice ; Mice, Inbred ICR ; Mossy Fibers, Hippocampal/drug effects/metabolism ; Phosphorylation/drug effects ; Proto-Oncogene Proteins c-fos/metabolism ; Proto-Oncogene Proteins c-jun/metabolism ; Receptors, GABA-B/*metabolism ; Research Support, Non-U.S. Gov't