OBJECTIVE: To observe the expressions of sphingosine kinase 1 (SphK1) and sphingosine-1-phosphate receptor 2 (S1PR2) in hippocampus of epileptic rats and to investigate the pathogenesis of SphK1 and S1PR2 in epilepsy. METHODS: One hundred and eight male Sprague-Dawley (SD) rats were randomly divided into control group (n=48) and pilocarpine (PILO) group (n=60). A robust convulsive status epilepticus (SE) was induced in PILO group rats by the application of pilocarpine. Control group rats were injected with respective of physiological saline. Pilocarpine group was randomly divided into 6 subgroups (n=8): acute group (E6 h, E1 d, E3 d), latent group (E7 d) and chronic group (E30 d, E56 d). Each subgroup has 8 control rats and 8 epileptic rats. Hippocampal tissue and brain slices were obtained from control rats and rats subjected to the Li-PILO model of epilepsy at 6 h, 1 d, 3 d,7 d,30 d and 56 d after status epilepticus (SE). Western blot technique was used to determine the expressions of SphK1 and S1PR2 in hippocampus at different point of time after pilocarpine treatment. Immunofluorescence was applied to detect the activation and proliferation of hippocampal astrocytes and the localization of SphK1 and S1PR2 in rat hippocampal astrocytes. RESULTS: Compared with control group, the levels of SphK1 in acute phase (E3 d), latent phase (E7 d) and chronic phase (E30 d, E56 d) were significantly increased while the expressions of S1PR2 were decreased in acute phase (E3 d), latent phase (E7 d) and chronic phase (E30 d, E56 d)(P＜0.05 or P＜0.01). Immunofluorescence results showed astrocyte activation and proliferation in hippocampus of epileptic (E7 d) rats (P＜0.05). Confocal microscopy confirmed the preferential expressions of SphK1 and S1PR2 in epileptic rat(E7 d)hippocampal astrocytes. CONCLUSION The results indicate that SphK1 and S1PR2 may play an important role in the pathogenesis of epilepsy by regulating the activation and proliferation of hippocampal astrocytes and altering neuronal excitability.
Animals ; Astrocytes ; enzymology ; Epilepsy ; enzymology ; physiopathology ; Hippocampus ; cytology ; enzymology ; Male ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; Pilocarpine ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Lysosphingolipid ; metabolism

The changed process of bioenergy and the effects of electrode interfering on penicillin-induced epileptic brains in epileptic seizures rats were investigated. Fifty Sprague-Dawley (SD) rats were randomly divided into 4 groups, i. e. normal saline control group (group A), penicillin model group (group B), metal electrode interfere group (group C) and insulated electrode interfere group (group D). The epileptogenic potential and the expressions of the beta subunit of-ATP synthase( ATP5B) in hippocampal neurons were measured. The epileptogenic foucus potential and expressions of ATP5B in hippocampus neurons showed that the trend increased at first and decreased implantation of later, and the implantation of metal electrodes decreased the epileptogenic foucus potential at corresponding time point, but had no effect on the expressions of ATP5B. The change of epileptogenic focus potential was reduced by implantation of metal electrode, possibly due to the alteration of corrosponding bioenergy metabolism which had participated in the process of epileptic seizure.
Animals ; Electrodes ; Energy Metabolism ; Epilepsy ; chemically induced ; enzymology ; physiopathology ; Hippocampus ; enzymology ; Male ; Mitochondrial Proton-Translocating ATPases ; genetics ; metabolism ; Penicillins ; Rats ; Rats, Sprague-Dawley

Mesial temporal lobe epilepsy (MTLE) is associated with severe neuronal death and reactive gliosis in hippocampus. However, the molecular mechanisms underlying these pathological changes remain unanswered. ERK has been reported chronically activated in reactive glia of human epileptic hippocampus. In the present study, we investigated which of the downstream signaling molecules of ERK would be involved in MTLE. Western blot analysis demonstrated that CREB and p90RSK were strongly activated in MTLE patients. Increase in the active forms of CREB and p90RSK resulted not only from the increase in their phosphorylation levels but also from the increase in the protein levels. Activation of CREB and p90RSK was noted in the whole subfields of hippocampus with Ammon's horn sclerosis (AHS) representing a distinctive cellular distribution. However, the common major change was present in proliferating reactive astrocytes. In contrast, their activation was not significant in adjacent temporal lobes despite the presence of a number of astrocytes expressing high levels of GFAP. Our results demonstrate that chronic activation CREB and p90RSK in the epileptic hippocampus may be closely associated with the histopathological changes of AHS.
Blotting, Western ; DNA-Binding Protein, Cyclic AMP-Responsive/*metabolism ; Enzyme Activation ; Epilepsy/enzymology/*metabolism ; Epilepsy, Temporal Lobe/enzymology/metabolism ; Hippocampus/enzymology/*metabolism ; Human ; Immunohistochemistry ; Mitogen-Activated Protein Kinases/metabolism ; Ribosomal Protein S6 Kinases, 90kD/*metabolism ; Signal Transduction ; Support, Non-U.S. Gov't ; Temporal Lobe/enzymology/metabolism

OBJECTIVETo determine the spatio-temporal expression of p70S6k activation in hippocampus in mesial temporal lobe epilepsy.

METHODSTemporal lobe epilepsy model was established by stereotaxically unilateral and intrahippocampal injection of kainite acid (KA) in adult male C57BL/6 mice. Latent and chronic epileptogenesis were represented by mice 5 days after KA injection (n = 5) and mice 5 weeks after KA injection (n = 8), respectively. Control mice (n = 5) were injected with saline. Immunohistochemical assays were performed on brain sections of the mice.

RESULTSHippocampus both ipsilateral and contralateral to the KA injection displayed significantly up-regulated pS6 immunoreactivity in dispersed granule cells in 5-day and 5-week model mice.

CONCLUSIONThe activation of p70S6k is mainly located in the dentate gyrus in KA-induced mouse model of temporal lobe epilepsy, indicating that the activation may be related with the disperse degree and hypertrophy of granule cells.

Animals ; Epilepsy, Temporal Lobe ; enzymology ; Hippocampus ; enzymology ; Immunohistochemistry ; Male ; Mice ; Mice, Inbred C57BL ; Phosphorylation ; Ribosomal Protein S6 Kinases, 70-kDa ; analysis ; metabolism

This study investigated calcium/calmodulin kinase II (CaMKII) activity related to long-standing neuronal injury of the hippocampus in kainate (KA)-induced experimental temporal lobe epilepsy. Epileptic seizure was induced by injection of KA (1 g/L) dissolved in phosphate buffer (0.1 M, pH 7.4) into the left amygdala. Clinical seizures, histopathologic changes and CaMKII activity of the hippocampus were evaluated. Characteristic early limbic and late seizures were developed. Hippocampal CaMKII activity increased significantly 4 and 8 weeks after intra-amygdaloid injection of KA, when late seizures developed. The histopathologic changes of the hippocampus included swelling of neuronal cytoplasm with nuclear pyknosis and loss of neurons in CA3 during this period. The increased activity of CaMKII may correlate with appearance of distant damage in the hippocampus. The above results indicate that intra-amygdaloid injection of KA produces excitatory signals for ipsilateral CA3 neurons in the hippocampus and that subsequently increased levels of CaMKII in postsynaptic neurons induce neuronal injury via phosphorylation of N-methyl-D-aspartate type glutamate receptor.
Animal ; Ca(2+)-Calmodulin Dependent Protein Kinase/*metabolism ; Epilepsy, Temporal Lobe/chemically induced/*enzymology/pathology ; Hippocampus/*enzymology/pathology ; Kainic Acid/*toxicity ; Long-Term Potentiation/drug effects ; Male ; Rats ; Rats, Wistar