Effect of ketogenic diet on hippocampus synaptic reorganization and GluR5 expression in kainic acid induced rat model of epilepsy / 中华儿科杂志

<p><b>OBJECTIVE</b>Ketogenic 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.</p><p><b>METHODS</b>Epilepsy 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.</p><p><b>RESULTS</b>KD-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.</p><p><b>CONCLUSION</b>Mossy 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.</p>

Expression of multidrug resistance gene and topiramate affect expression of multidrug resistance gene in the hippocampus of spontaneous epileptic rats / 中华儿科杂志

<p><b>OBJECTIVE</b>Refractory 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.</p><p><b>METHODS</b>Seizures 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.</p><p><b>RESULTS</b>Expression 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.</p><p><b>CONCLUSION</b>Frequent 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.</p>