Study Of Disorders Of Cortical Development Rat Models Using X-Ray Irradiation-Induced And The Mechanism Related Of Epileptogenic

PARTⅠESTABLISHED AND EVALUATED THE DISORDERS OF CORTICAL DEVELOPMENT RAT MODELS USING X-RAY IRRADIATION-INDUCEDObjective:The disorders of cortical development (DCDs) rat models were established using X-ray irradiation-induced. The characteristics of the DCDs rat models were evaluated. The seizure susceptibility of the DCDs rat models were investigated through Rapid amygdala kindling and so on.Methods : Six SD pregnant rats were randomly divided into experimental group and control group. The experimental group: The pregnant rats were induced using X-ray irradiation with linear accelerator, on the 16th day of pregnancy. The control group: No treatment. The general behavior and the brain shape of offspring were observed on P60d,and the brain pathological changes were observed through HE and Nissl staining;The ability of learning and spatial memory were researched through water maze test;Two groups after discharge threshold and rapid amygdala kindling were compared using rapid electrical amygdala kindling. Results:Compared with the control group, activity of experimental group rats was increased, but there were not spontaneous epilepsy, the brain volumes of experimental group rats were smaller. Cortical neurons arranged disorder, hippocampal structure were disorder and neuron were abnormal aggregation in HE and Nissl staining. In the water maze test, The latency of experimental group rats were significantly longer than the control group(p<0.05). Ability of space exploration of experimental group rats were significantly lower than the control group(p<0.05). The number of stimulations to achieve the fully kindled state were significantly reduced (65.57±10.22 vs 38.57±7.44; p<0.01) and the after discharge threshold were significantly lower(151.43±51.45μA vs.74.29±22.25μA; p<0.05) in experimental group. Those results show that the DCDs rat models have the characteristic of diffuse DCDs rat models in behavior, cognitive impairment, seizure susceptibility and pathology, moreover this models are simple and Stability.Conclusion:The typical DCDs rat models can be established by radiating pregnant rats with X-ray irradiation. Rapid amygdala kindling is an effective method to test seizure susceptibility. PARTⅡABNORMAL EXPRESSION OF SOMATOSTATIN RECEPTOR 1 AND TRANSFORMING GROWTH FACTORΒ2 IN THE HIPPOCAMPUS OF THE DISORDERS OF CORTICAL DEVELOPMENT RAT MODELSObjective:To study the Expression of somatostatin receptor 1 and Transforming growth factorβ2 (TGFβ-2) and to investigate the epileptogenic mechanism and the mechanism of morphological changes in the hippocampus of the disorders of cortical development(DCDs)rat models..Methods: To establish the DCDs rat models. The expression Changes of SSTR-1 and TGFβ-2 in the hippocampus of the DCDs rat models were analyzed by using immunohistochemistry, western blot and quantitative PCR.Results: (1) The protein expression of SSTR-1 and TGFβ-2 in the hippocampus of the DCDs rat models were both significantly lower when compared with the control group(0.59±0.15 vs 1.02±0.14;p<0.05),(0.60±0.17 vs 0.92±0.19;p<0.05)(.2)The RNA expression of SSTR-1 and TGFβ-2 in the hippocampus of the DCDs rat models were significantly lower when compared with the control group(0.50±0.23 vs 1.17±0.19;p<0.05),(0.48±0.07 vs 1.12±0.16;p<0.05).Conclusions: These results suggest that the SSTR-1 and TGFβ-2 could play an important role in disorder migration of hippocampal neurons and epileptogenic mechanism in the DCDs rat models.PARTⅢSTUDY OF LEARNING & MEMORY BEHAVIOUR AND LTP IN HIPPOCAMPAL SLICES OF DCDS RAT MODELSObjective:To investigate the changes of spatial learning, memory and hippocampal LTP in vitro of the DCDs rat models.Methods: To establish the DCDs rat models. The spatial learning and memory behavior of the DCDs rat models were assessed by Morris water maze. Long-term potentiation (LTP) in CA1 region of hippocampal slices of the DCDs rat models were analyzed through patch clamp technique.Results: In the Morris water maze, latency to find a hidden platform were significantly longer, the times of crossing the situation of platform and the times percent of swimming in the former platform quadrant significantly decreased in the experimental group. Compared with the control group, the probability of the induction of LTP and Average population spike amplitudes of LTP in the CA1 region of the DCDs rat models were significantly decreased ( 40% vs 100% ; p<0.05 );( 108±5.6% vs 132±15.4%;p<0.05).Conclusions: The ability of spatial learning and memory of the DCDs rat models were decreased. The hippocampal synaptic plasticity of the DCDs rat models was decreased.PARTⅣCHANGES OF NMDA RECEPTORS-MEDIATED EEPSCS IN HIPPOCAMPAL CA1 REGION OF THE DCDS RAT MODELSObjective: To observe the changes of N-methyl-D-aspartate receptor (NMDAR) andα-amino-3-hydroxy-5-methyl-4-isox-Azoleprop- ionic acid receptor (AMPAR) mediated eEPSCs in hippocampal CA1 region of the DCDs rat models. To investigate the epileptogenic mechanism in the DCDs rat models.Methods: the amplitude and decay time constant of NMDAR and AMPAR mediated eEPSCs in hippocampal CA1 region pyramidal neurons of the DCDs rat models were observed using visual patch clamp whole-cell recording technique when the offspring rats were P10d–P20d. Results: Compared with the control group, The amplitude of NMDAR mediated eEPSCs in DCDs rat models was Significantly increased(119.54±10.97 pA vs 83.69±10.23 pA;p<0.05). The decay time constant of NMDAR mediated eEPSCs in DCDs rat models was Significantly delayed(154.59±3.92 vs 117.18±4.04;p<0.05). The amplitude and decay time constant of AMPAR mediated eEPSCs were not different between the DCDs group and the control group. (139.99±23.41 pA vs 135.50±26.44 pA;p>0.05)(47.23±2.28 vs 48.68±2.20;p>0.05)Conclusions: The NMDAR mediated hyper excitable synaptic responses could play an important role in epileptogenic mechanism of the DCDs rat models.