Expression of ciliary neurotrophic factor in visual cortex of form deprivation amblyopia cat and its effect / 中华实验眼科杂志

ABSTRACT

Background Researches demonstrated that ciliary neurotrophic factor (CNTF) can enhance survival and promote differentiation of neutron.Meanwhile,CNTF also is thought to play an important role in the development of visual pathway.But,less studies are reported in the relationship of CNTF and form deprivation amblyopia.Objective This study was to investigate the expressions of CNTF in visual cortex area 17 in form deprivation amblyopia model.Methods Twelve 4-week-old cats were randomized into normal group and form deprivation amblyopia group.Monocular form deprivation amblyopic models were established in 6 cats by eyelids suture method.Pattern visual evoked potential(P-VEP) was recorded to evaluate the amblyopic models 16 weeks later following the eyelids suturing.Then,bilateral visual cortex tissue was incised at a vertical in sagittal axis fashion to prepare the section.Nissl staining was used to detect the morphologies of neurons.Expression of CNTF in Ⅰ-Ⅵ layers of visual cortex area 17 was located and quantified by immunochemistry.The positive cell number and gray scale for CNTF were calculated and compared between two groups.The use of the animals complied with Regulations for the Administration of Affairs Coucerning Experimental Animals by State Science and Technology Commission.Results Compared with the normal group,P-VEP amplitude was significantly reduced (6.11 ±1.56 μV vs.11.42±t.92 μV) and latency was significantly prolonged(75.77±9.83 ms vs.58.56±7.17 ms) in the form deprivation amblyopia group (t=5.272,3.464,P＜0.05).Nissl staining showed that the number of neurons in the form deprivation amblyopia group was less than that in the normal group.In the form deprivation amblyopia group,neurons became shrinkage and turned round,cytoplasmic processes get shortened,and the nucleus became small.The number of Nissl bodies was decreased.lmmunochemistry showed the positive neutrons for CNTF in Ⅰ-Ⅵ layers of visual cortex area 17 in hoth normal cats and model cats with the more positive cells in Ⅱ-Ⅳ layers.Compared with the normal group,the positive cell number for CNTF was significantly reduced in Ⅱ-Ⅳ layers of visual cortex area 17 in the form deprivation amblyopia group (Ⅱ layer95.93±8.24 vs.116.25±6.52;I layer102.65±7.45 vs.125.23±8.21;Ⅳ layerl10.65±6.85 vs.139.54±4.26) (t=4.737,4.989,8.773,P＜0.05).In addition,the gray scale of CNTF positive cells was significantly lower in Ⅱ-Ⅳ layers of visual cortex area 17 in the form deprivation amblyopia group than that the normal group (Ⅱ layer106.98 ± 8.86 vs.138.65 ± 6.38 ; Ⅲ layer109.56 ± 8.69 vs.149.59 ±8.55;Ⅳ layerl16.65 ±9.52 vs.155.76±9.87) (t=7.105,8.043,6.986,P＜0.05).Both CNTF positive cell number and gray scale in Ⅰ,Ⅴ,Ⅵ layers of visual cortex area 17 had no significant differences between two groups (P＞0.05).Conclusions Form deprivation in critical period of a new born animal may lead to distributing abnormality of CNTF in visual cortex,which maybe play a role in the development of form deprived amblyopia.