Expressions Of Caspase-3in Visual Cortex And Lateral Geniculate Nucleus Of Form Deprivation Amblyopia Rats

ObjectiveThis paper aims to study the expression of Cysteine protease protein32KD,Caspase-3acting on visual cortex and lateral geniculate body of form deprivationamblyopia rats, discuss the relationship between Caspase-3and the pathogenesis ofamblyopia, expecting to have a positive impact on the treatment of amblyopia.Methods1.40newly born healthy SD (Sprague Dawley) rats. After14days of feeding,randomly selected20of them and sewed up their eyelids. This was the group ofMonocular Deprivation, MD. The rest were Normal Postnatal, NP. No specialtreatment. All of the animals were sacrified14days,21days,45days and120dayslater. Group MD was divided into MD14、MD21、MD45、MD120; while Group NPwas divided into NP14、NP21、NP45、NP120.2. Oweighing and anesthetizing NP21, MD21and conduct P-VEP inspection,wrote down the latency and amplitude of P100.3. Applying staining and immunohistochemical method and image analysissystem to do position observation on immunoreactive neurons in visual cortex andlateral geniculate body of MD and NP, and to study the changes of the average graydetermination according to the quantitative value.The results1. P-VEP test: the peak latency of P-VEP P100in MD21extended significantlythan that of NP21(P<0.01), its amplitude decreased remarkably(P<0.01), indicatingthat Visual electrophysiology in amblyopia had changed, and that Form deprivationamblyopia model could be formed through Monocular lid sewing up.2.(1) HE staining: visual cortex neurons in the brain of NP45is normal, the cell outline being clear, and the morphology and staining neurons being clear; while theoutline of neurons in the brain of MD45was irregular, its membrane structure beingnot clear, its neuronal degenerated. For some neurons karyopyknosis were observed,and also a strong basophilia. Their cytoplasm was deeply stained, revealing a unclearstructure.(2) Expression of Caspase-3immunoreactive neurons in the visual cortex:Caspase-3presented pale brown after dyeing, and the negative cells showed blue.There was no significant differences between average gray value of Caspase-3in NP14and MD14after14days after birth(P=0.074). The expression of immune reactionproduct in visual cortex of MD rats gathered when at21days,45days,120days afterbirth. While the expression of immune reaction product in visual cortex of NP did notchanged. The average gray value of Caspase-3in MD increased remarkably comparedto NP in P21, P45, P120(P＜0.05). MD21did not differ much from MD45(P>0.05).MD14differed much from MD120(P＜0.05).The condition of MD21and MD45isobviously different between that of MD14and MD120.(3) The expression of Caspase-3immunoreactive neurons in the lateralgeniculate body: particulates in LGN distributed densely in MD rats, and its densitychanged in different period. Caspase-3expression products distributed sparsely. InP14, the difference between MD and NP is not clear(P=0.168). The average grayvalue of Caspase-3in MD increased remarkably compared to NP in P21, P45, P120(P＜0.05). The condition of MD21and MD45is obviously different between that ofMD14and MD120(P＜0.05).(4) The expression level of Caspase-3in visual cortex and the lateral geniculatechanges with deprivation time. It increased at the critical period of visualdevelopment when form deprivation started, developed to high expression at the earlyand middle period, and declined at the end of critical period of visual development,still overtopping the figure at the very beginning.Conclusion1. At the early time of critical period of visual development of rats, form deprivation amblyopia model can be founded successfully applying eyelids sewing up,despite that deprivation time was short(7days).2. Monocular deprivation in rats can lead to morphological changes of nerve cellin visual cortex and induce cell para-apoptosis.3. The expression level of Caspase-3in visual cortex and the lateral geniculate inthe deprivation: it started to increased14days later, and increased markedly21dayslater, with a pick45days later and a trend to decline120days later, still overtoppingthe figure at the very beginning.4. Monocular deprivation caused the increase of Caspase-3, and further causedapoptosis and injury of neuron. This may be one of the cause of amblyopia.