尼莫地平对慢性高眼压兔外侧膝状体神经元损伤的影响

Effect of nimodipine on lateral geniculate nucleus injury in rabbit with chronic ocular hypertension

目的观察尼莫地平对慢性高眼压兔外侧膝状体神经元形态及Bcl-2、Bax表达的影响。方法将18只健康新西兰白兔随机分为正常组、损伤组和治疗组,每组6只。正常组兔不予处置,损伤组、治疗组兔给予复方卡波姆建立慢性高眼压模型,模型建立后次日起,治疗组兔每日给予尼莫地平片13.2 mg·kg-1(溶于1 m L注射用水中)灌胃1次,正常组、损伤组兔每天给予等量生理盐水灌胃1次,连续灌胃4周。4周后兔耳缘静脉注射250 g·L-1乌拉坦全身麻醉,采用颈动脉灌注法完成血-生理盐水-甲醛溶液置换,内固定成功后开颅取出完整大脑组织,多聚甲醛固定48 h以上,取出中脑组织石蜡包埋,切片行Nissl染色观察外侧膝状体神经元形态,免疫组织化学染色检测Bcl-2、Bax凋亡因子阳性细胞表达率。结果 Nissl染色结果显示,正常组兔外侧膝状体的细胞核呈淡蓝色,尼氏小体呈深蓝色,细胞大小均匀,排列紧密;损伤组兔外侧膝状体多数神经元水肿,体积变大,排列疏松,可见较多尼氏小体溶解甚至消失;治疗组兔外侧膝状体部分神经元水肿,排列较损伤组紧密,可见少量尼氏小体溶解。免疫组织化学染色结果显示,正常组兔外侧膝状体仅有极少量的Bcl-2、Bax阳性表达神经元,损伤组、治疗组兔外侧膝状体可见较多Bcl-2、Bax阳性表达神经元。损伤组、治疗组兔外侧膝状体Bcl-2、Bax阳性细胞率均显著高于正常组(P<0.05);治疗组兔外侧膝状体Bcl-2阳性细胞率显著高于损伤组(P<0.05),Bax阳性细胞率显著低于损伤组(P<0.05)。损伤组与正常组兔外侧膝状体Bcl-2阳性细胞率/Bax阳性细胞率比值比较差异无统计学意义(P>0.05);治疗组兔外侧膝状体Bcl-2阳性细胞率/Bax阳性细胞率比值显著高于正常组及损伤组(P<0.01)。结论慢性高眼压可以引起外侧膝状体神经元的损伤。尼莫地平能够在一定程度上促进慢性高眼压兔外侧膝状体抑凋亡因子Bcl-2的表达,抑制促凋亡因子Bax的表达,从而减轻慢性高眼压所致的外侧膝状体损伤。

Objective To observe the effect of nimodipine on the morphology and the expression of Bcl-2 and Bax in lateral geniculate neurons of rabbits with chronic ocular hypertension.Methods Eighteen healthy New Zealand rabbits were randomly divided into normal group,injury group and treatment group,6 rabbits in each group.The rabbits in the normal group were not treated.The rabbits in the injury group and the treatment group were given compound carbomer to establish the chronic ocular hypertension model.The rabbits in the treatment group were treated with nimodipine tablets 13.2 mg·kg-1(dissolved in 1 mL aseptic injection water)by intragastric administration from the next day after the establishment of the model,once a day for four weeks.The rabbits in the normal group and the injury group were treated with equal physiological saline by intragastric administration,once a day for four weeks.The rabbits were anaesthetized with 250 g·L-1 urethane by ear vein injection.The blood-physiological saline-formaldehyde solution replacement was completed by carotid artery perfusion.The intact brain tissues were collected by craniotomy,and fixed with paraformaldehyde for more than 48 hours after successful internal fixation.The brain tissues were performed with paraffin embedding and slicing.The morphology of neurons in the lateral geniculate body was observed by Nissl staining.The positive expression rates of Bcl-2 and Bax were detected by immunohistochemistry.Results The Nissl staining of the lateral geniculate body showed that the nucleus of the lateral geniculate body was pale blue,and the Nissl′s body was dark blue,the size of the cells was uniform,and the arrangement was close in the normal group.In the injury group,most of the neurons in the lateral geniculate body were edema,the cells became larger and spreaded loosely,and more Nissl′s bodies were dissolved or even disappeared.In the treatment group,some of the neurons in the lateral geniculate body were edematous and spreaded closely,and fewer Nissl′s bodies were found.The rates of Bcl-2 and Bax positive expression neurons in the lateral geniculate body in the injury group and the treatment group were significantly higher than those in the normal group(P<0.05).The rate of Bcl-2 positive expression neurons in the lateral geniculate body in the treatment group was significantly higher than that in the injury group(P<0.05),and the rate of Bax positive expression neurons was significantly lower than that in the injury group(P<0.05).There was no significant difference in the ratio of Bcl-2 positive expression neurons to Bax positive expression neurons between the injured group and the normal group(P>0.05).The ratio of Bcl-2 positive expression neurons to Bax positive expression neurons in the treatment group was significantly higher than that in the injured group and the normal group(P<0.01).Conclusion Chronic intraocular hypertension can cause neuronal damage in the lateral geniculate body.Nimodipine can reduce the injury of lateral geniculate body caused by chronic intraocular pressure,and its mechanism may be related to the promotion of Bcl-2 expression and the inhibition of Bax expression.