| Objective To explore the effect of repeated periorbital alternating current stimulation(r PACS) to the visual cortex plasticity of c57bl/6 in critical period through observing the functional and morphologic changes in primary area by pattern visual evoked potentials(PVEP)and synaptic quantitative means..Methods 30 C57bl/6 of P26 days were used in this study.Divided into three groups;normal group didn’t do any processing,monocular deprivation group(DM group) suture the right eye three days and cut off the suture, electro stimulation group suture the right eye three days and cut off the suture then stimulate with r PACS three days,other raise condition is the same.after all this processing,three group all test PVEP.Record the PVEP amplitudes and latencies of right eye and left eye.calculated C/I ratio(contralateral VEP amplitude to inspilateral VEP ampllitude).,Two mouce were selected from each group.each mouce was given breath anaethesia and perfused transcardially. First with warm 0.9% saline rinse the blood until saline effluent clarification from the right atrium, then 4% paraformaldehyde perfusion 10 min, to the limbs stretched, stiffness, then cut out each left and right hemisphere cortex, immediately put in 3% paraformaldehyde + 2.5% glutaraldehyde mixture inspection. After the specimen has 2.5% glutaraldehyde fixative, 1% osmium tetroxide fixative; rise graded ethanol dehydration; propylene oxide transition, Epon812 embedding,Slice thickness of 50 nm ±; uranyl acetate- lead citrate double staining. Observed under HITACHI-7500 transmission electron microscope and photographed.the following parameters of synaptic in primary vision area in the three groups were quantified with image software: Synaptic interface curvature, width of the synaptic cleft, postsynaptic density(PSD) thickness, the length of synaptic active zone. Results1.pattern visual evoked potential(PVEP) changes in mouce after repetitive stimulation periorbital alternating the amplitudes in the right eyes of three groups have statistics differences( F=28.713,p=0.000) all three group is fifferent with the other two groups.meanwhile,on the left eyes,there is no differents in three groups(F=3.716,p=0.038).the latencies in the right eyes of three groups have statistics differences(F=3.370,p=0.049),with groups DM group is fifferent with the normal group.latencies in the left eyes of three groups have differences(F=6.053,p=0.007),with groups DM group is fifferent with the normal group.In normal group,,the P100 ampllitudes of the right eye were raiser and the P100 latencies were shorter than the left eyes( t=5.472, p=0.000;t=-3.550,p=0.002).Compared with normal group,the P100 amplitudes were decreased and the P100 latencies was longer in DM group( t=-7.976, p=0.000;t=2.391,p=0.028),the change of left eye is on the contrary(t=2.500,p=0.022;t=-4.176,p=0.001).Meanwhile,in electro stimulation group, the right eye’s P100 amplitudes were raised and P100 latencies were shorten( t=4.774, p=0.000;t=-2.437,p=0.025),and there was no change in the left eye(t=0.169,p=0.868,t=0.870,p=0.396),when compared with DM group.The C/I ratio of the three groups were 1.96±0.82,0.54±0.18,1.11±0.41, DM group is decreased than normal group(t=-5.309,p=0.000),meanwhile difference is appear between electro stimulation group and DM group,which the former is raised than the latter,(t=4.020,p=0.001). 2 changes of synaptic and neurons ultrastructures in primary visial area after repetitive stimulation periorbital alternating In the normal group neuronal nuclei round, perinuclear space was normal, long and straight in the rough endoplasmic reticulum, ribosomes package, consisting of Nissl, Golgi vesicular three to eight cavities, mitochondrial membrane clear, crest recessed and matrix neat; amblyopia group nucleus nuclear membrane shrinkage, swelling perinuclear space, Nissl body structure disappeared, Golgi swelling cavitation, mitochondrial membrane is unclear, disordered matrix, showing a large number of necrotic cells phagocytic lysosomes substances; nuclear membrane nucleus in electrical stimulation group tends to be full, round shape yet, perinuclear space backto normal, visible Golgi and Nissl bodies, scattered in a large number of cytoplasmic ribosomes, mitochondria become normal, swallowed up debris of damaged cells lysosomal persists. Compared with amblyopia group, after electrical stimulation, thickness of postsynaptic density is raised(t = 3.291, p = 0.002), synaptic interface curvature is reduced(t =-2.969, p = 0.005). Crying Synaptic reduce, laughing synapses increase(χ2 = 11.379, p = 0.001). Cortical Area 17 in the control group with a straight-type synapse mainly while amblyopia group to crying synaptic mainly, electrical stimulation group with a straight-type synapse based.Conclusion 1. After r PACS the right eyes’ reaction is stronger than the right eye in DM group, C / I ratio increases, the ocular dominance shift; 2. After r PACS neurons synaptic activity is enhanced, compared with the DM group. |
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