早期单眼剥夺对大鼠视网膜中BDNF及受体TrkB表达的影响

目的:探讨早期单眼剥夺对大鼠视网膜中脑源性神经生长因子(BDNF)及受体TrkB表达的影响。方法:40只新生SD大鼠随机分为6组:28日龄正常组、35日龄正常组、42日龄正常组、28日龄模型组、35日龄模型组及42日龄模型组,模型组大鼠于出生后21d缝合右侧眼睑建立单眼剥夺弱视模型,采用免疫印迹及免疫组织化学法检测视网膜中BDNF及受体TrkB的表达。结果:正常大鼠在出生后视觉发育关键期内,随年龄增长视网膜中BDNF及受体TrkB蛋白表达无明显变化。早期单眼剥夺后,模型组大鼠视网膜中BDNF及受体TrkB蛋白表达在28日龄立即呈现显著上升趋势,然而随着剥夺时间延长35日龄时表达剧烈下调,并持续至42日龄。BDNF表达在视网膜神经节细胞层、内核层及外核层,而TrkB受体仅表达在视网膜神经节细胞层。早期单眼剥夺可使28日龄大鼠视网膜神经节细胞层中BDNF及受体TrkB阳性细胞数目显著增多,但随着视觉剥夺时间延长,35日龄至42日龄时两者的阳性细胞数目呈现逐渐减少的趋势。结论:BDNF及受体TrkB的表达呈现一定的视觉经验依赖性,其参与了单眼剥夺弱视的发病。

Influence of early monocular deprivation on the expression of brain derived neurotrophic factor and TrkB receptor in rats' retina

AIM:To explore the influence and significance of early monocular deprivation on the expression of brain derived neurotrophic factor(BDNF)and TrkB receptor in rats' retina.

METHODS: Totally 40 neonatal rats were randomly allocated into 6 groups: normal group of postpartum 28 days(NorP28), normal group of postpartum 35 days(NorP35), normal group of postpartum 42 days(NorP42), monocular deprivation group of postpartum 28 days(MDP28), monocular deprivation group of postpartum 35 days(MDP35)and monocular deprivation group of postpartum 42 days(MDP42). For the MD model, we sutured together the right eyelids of rats at postpartum 21 days. A subset of rats at each time points were killed, then the retinas were removed and frozen for detecting the expression pattern of BDNF and its receptor TrkB by means of Western blot and immunohistochemistry.

RESULTS: During the visual development critical period, the expression of BDNF and TrkB receptor had no significant change with the growth of age. After the early monocular deprivation, BDNF and TrkB receptor were significantly increased its expression at postpartum 28 days, then decreased at postpartum 35 days and maintained a steady level between postpartum 35 days to postpartum 42 days. BDNF expressed in ganglion cell layer, inner nuclear layer and outer nuclear layer of retina, while TrkB receptor expressed only in ganglion cell layer. In response to MD, the expression of BDNF and TrkB receptor positive cells was dramatically up-regulated in ganglion cell layer at postpartum 28 days, and then decreased gradually at postpartum 35 days to postpartum 42 days.

CONCLUSION: The expression of BDNF and its TrkB receptor presents a visual-experience dependency, and they participate in the onset of monocular deprivation amblyopia.