Effects Of 2R, 4R-APDC On The Plasticity Of Structure And Function After Status Epilepticus Induced By Pilocarpine In The Adult Rat Brain

PARTâ… DYNAMIC CHANGES OF PLASTICITY OF HIPPOCAMPUS AFTER PILOCARPINE INDUCED STATUS EPILEPTICUS INRATSObjective To investigate the alteration of behavior, electrophysiology and pathology of pilocarpine model of temporal lobe epilepsy, and so to decipher dynamic changes of plasticity of hippocampus after pilocarpine induced status epilepticus (SE).Methods Male SD rats received pilocarpine to induce SE. After 3h when the rats developed SE, they were treated by diazepam to stop SE. Afterwards all rats were monitored by video recordings to assure development of spontaneous recurrent seizures (SRS), record EEG, study the pathological changes with HE, Nissl and Timm staining at 3h, 7d and 45d after SE induced by pilocarpine and Triple-labeling immunohistochemistry was performed using BrdU with NeuN and BrdU with GFAP antibodies to estimate the percentage of BrdU-labeled cells which were neurons or astrocytes.Results After injection of pilocarpine, 87% of the rats were induced to develop SE. EEG showed accumulated spike waves in acute phase, normal during the latency phase and showed epileptic waves during the chronic phase. The pathologic investingation using HE, Nissl and Timm staining showed the hippocampal neuronal damage and mossy fiber sprouting (MFS). Colocalization of BrdU-immunolabeled cells with NeuN and GFAP showed that pilocarpine-induced SE caused a dramatic increase in cell proliferation in the dentate SGZ and the vast majority of these mitotically active cells differentiated into neurons in the granule cell layer. However, some BrdU-labeled cells were colabeled with GFAP, indicating that a population of newly dividing cells also included astrocytes. Some of the newly born cells which arise after seizures appear to migrate incorrectly, because they can be found deep in the hilar region and inner molecular layer.Conclusions Epilepsy induced by pilocarpine develops in 3 phase according to alteration of behavior and EEG: acute phase (status epilepticus), latency phase and chronic phase (spontaneous recurrent seizures). Epileptic seizures induced by pilocarpine can cause neuronal damage, MFS, astroglisis and neurogenesis in the hippocampus of rats. All these alterations of pathology of pilocarpine model oftemporal lobe epilepsy might contribute to the phenomenon of hippocampal kindling.PARTâ…¡EFFECTS OF 2R, 4R-4-AMINOPYRROLIDINE- 2,4-DICARBOXYLATE ON DENTATE GYRUS CELLPROLIFERATION AFTER SEIZURES INDUCED BYPILOCARPINE IN THE ADULT RAT BRAINObjective Using systemic bromodeoxyuridine (BrdU) to label dividing cells, to examine the effects of Groupâ…¡metabotropic glutamate receptor(mGluR) agonist, 2R, 4R-4-aminopyrrolidine- 2,4-dicarboxylate (2R, 4R-APDC), on cell proliferation in the dentate gyrus after pilocarpine-induced status epilepticus(SE).Methods 1 hour after preconditioning with 2R, 4R-APDC or Saline, Male SD rats received pilocarpine to induce SE. The effect of 2R, 4R-APDC on Pilocarpine-induced seizures was assessed on the basis of the SE incidence percentage and the latency to SE. BrdU immunohistochemistry was performed to observe the pattern of distribution and morphological characteristics of newborn cells in the dentate gyrus. Double-label immunofluorescence was performed to examine the neuronal or glial differentiation.Results We found that- 2R, 4R-APDC significantly inhibited behavioral seizures.The number of BrdU-positive cells within the SGZ/GCL and hilus exhibited a significant increase in SE animals and 2R, 4R-APDC pretreatment could significantly reduced the number of BrdU labeled cells in the SGZ/GCL (p<0.05), especially in hilus (p<0.01). In addition, there was no significant difference in the number of BrdU-labeled cells between control rats without PILO treatment and the rats receiving 2R, 4R-APDC and PILO (p>0.05).Conclusions 2R, 4R-APDC has an anticonvulsant effect against seizures induced in adult rats by pilocarpine and blocked seizure-induced increase in the number of BrdU-labeled cells in the dentate gyrus especially in hilus. Double-label immunofluorescence staining showed that APDC treatment did not affect the ability of newborn cells to differentiate into neurons or astrocytes. Our findings indicate that seizures may promote cell proliferation in the adult rat dentate gyrus through glutamatergic mechanisms acting on mGluR and 2R, 4R-APDC not only has an anticonvulsant effect against seizures induced in adult rats by pilocarpine, but also affords very potent neuroprotection via inhibiting aberrant neurogenesis in this modelof seizures. PARTâ…¢EFFECTS OF 2R, 4R-APDC ON LEARNING AND MEMORY OFRATS AFTER EPILEPSYObjective To study the affect of 2R,4R-APDC, a selective groupâ…¡metabotropic glutamate receptor (â…¡mGluR) agonist, on learning and memory and emotional behavior after seizure induced by pilocarpineMethod SD rats were used to reproduce pilocarpine epileptic model, Then the rats were divided randomly into 4 groups: A group (APDC+EP); B group(NS + EP); C group(APDC); D group(NS).2R, 4R-APDC at dose of 10nmol or normal saline was given intracerebroventricularly(icv). 24 hours later began to detect the change of behavior. The elevated plus maze test was used to measure the level of anxiety and morris water maze test was used to to evaluate the learning and memory ability.Result SE rats became anxious and the ability of learning and memory decreased. After the epileptic rats having been given 2R,4R-APDC intracerebroventricularly, the time spent in open arms was shorten and the number of entries to open arms was reduced(P<0.05), the mean escape latency was shorten(P<0.01), the ability of spatial memory and the efficiency of their search strategy were improved(P<0.05).Conclusion The experimental results showed that SE could result in the changes of emotional behavior and damages of spatial learning and memory in rats. 2R, 4R-APDC icv could improve the epileptic rats' ability of learning and memory.