形觉剥夺性弱视幼猫视皮质17区生长相关蛋白-43的表达

目的　观察形觉剥夺性弱视动物模型应用左旋多巴（ｌｅｖｏｄｏｐａ，ＬＤ）治疗后视皮质１７区生长相关蛋白-４３（ｇｒｏｗｔｈａｓｓｏ-ｃｉａｔｅｄｐｒｏｔｅｉｎ-４３，ＧＡＰ-４３）的表达，探讨ＬＤ对形觉剥夺性弱视视觉功能恢复作用的可能机制。方法　５０只４周龄幼猫，随机分为正常组、剥夺组、对照组、低剂量ＬＤ组及高剂量ＬＤ组共５组，每组１０只。通过单眼眼睑缝合制备形觉剥夺的弱视模型，观察不同干预条件下各组图形视觉诱发电位（ｐａｔｔｅｒｎｖｉｓｕａｌｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ，ＰＶＥＰ）的Ｐ１００波的峰时及振幅的变化。应用免疫组织化学法测定各组视皮层１７区ＧＡＰ-４３的差异。结果　８周龄时，剥夺组、对照组、低剂量ＬＤ组、高剂量ＬＤ组剥夺眼Ｐ１００波振幅比对侧眼及同周龄正常组幅值降低，潜时延长（均为Ｐ＜０．０５）；１２周龄时，低剂量ＬＤ组剥夺眼Ｐ１００波振幅增高，与对侧眼及同周龄正常组相比差异均无统计学意义（均为Ｐ＞０．０５），而Ｐ１００波潜时则未达到正常（Ｐ＜０．０５）；高剂量ＬＤ组剥夺眼Ｐ１００波振幅增高、潜时缩短，与对侧眼及同周龄正常组相比差异均无统计学意义（均为Ｐ＞０．０５）。８周龄时剥夺组视皮质１７区Ⅱ／Ⅲ、Ⅳ、Ⅴ／Ⅵ层ＧＡＰ-４３免疫阳性细胞密度均低于正常组，差异均有统计学意义（均为Ｐ＜０．０５）；１２周龄时高剂量ＬＤ组各层ＧＡＰ-４３免疫阳性细胞密度与正常组基本相等，差异无统计学意义（Ｐ＞０.０５）；对照组、低剂量ＬＤ组和正常组相比差异均有统计学意义（均为Ｐ＜０．０５）。结论　ＧＡＰ-４３在形觉剥夺性弱视形成过程中起一定的作用，ＬＤ对形觉剥夺性弱视视功能改善的机制是通过ＧＡＰ-４３表达的改变而实现的。

Expression of GAP-43 in 17 area of visual cortex in form-deprived amblyopic cats

Objective To investigate expression of growth associated protein-43 ( GAP-43 ) , a growth associated protein .in 17 area of visual cortex in monocular formdeprived amblyopia model after treated with levodopa ( LD ) . and discuss the possible mechanism of monocular form-deprived amblyopia and therapeutic effect of LD. Methods Fifty cats with 4-week-old were randomly divided into five groups :normal group , monocular form-deprived group , control group , low-dose group , high-dose group , ten cats in each group. The arumal models of monocular form deprived amblyopia were established. Pattern-visual evoked potential ( P-VEP) was recorded to check the visual acuity of the cats. The cell number density of GAP-43 expression in visual cortex area 17 was detected and calculated by immunohistochemistry. Results At 8-week-old, the latency and amplitude of PlOO of PVEP was significantly delayed and declined in monocular deprived eyes of monocular form-deprived group control group , low dose and high dose group , there was statistical difference compared with fellow eyes and normal eyes (P < 0. 05 ). At-12-week-old. the amplitude of low dose group in monocular deprived eyes had no sigruficant difference compared with fellow eyes and normal eyes ( all P > 0. 05 ) ; But the latency did not recover to normal (P < 0. 05 ) . In high dose group , the amplitude and latency recovered to normal. there was no statistical difference compared with fellow eyes and normal eyes ( all P > 0. 05 ) . The density of GAP-43 immunopositive cells of the monocular form-deprived group in visual cortex area 17 was significantly lower than that of the normal group [ ( 180. 05 +4. 96) mm -- vs ( 188. 17 + 7. 82) mm -z ,P < 0. 05 ) . However, there was no sigruficant difference between the highdose group and normal group [ ( 198. 50 + 2. 92 ) mm -z vs ( 200. 98 + 9. 64 ) mm -2 ,p > 0. 05 ) . Compared with the normal group , there was significant difference between the control group and the low-dose group ( P < 0. 05 ) . Conclusion GAP-43 play an important role in formation of amblyopia , the improved visual function of amblyopia may be brought into effect through GAP-43 expression.