锌对仔鼠中枢神经系统胶质酸性纤维蛋白表达的影响

EFFECT OF ZINC ON GLIAL FIBRILLARY ACIDIC PROTEIN (GFAP) EXPRESSION IN THE CENTRAL NERVOUS SYSTEM OF MICE

目的 探讨微量元素锌缺乏与胶质酸性纤维蛋白 ( GFAP)表达的关系及锌调节胶质细胞分化的机制。方法 给处于孕期及哺乳期的 ICR母鼠喂饲含不同锌水平饲料 ,采用 West-ern blot技术检测其仔代胚胎、大脑、小脑及肝组织中 GFAP的表达情况 ;同时在穿梭箱内检测成年仔鼠 ( 70日龄 )的学习能力 ;行为实验结束后 ,在仔鼠的海马脑片上进行诱导长时程增强 ( LTP)实验。结果 实验仔鼠小脑在新生期 (出生第 1天 ,P1 )开始表达 GFAP,而大脑在出生后第 5天( P5)才开始有 GFAP印迹出现 :之后至成年小脑及大脑持续表达 GFAP;实验鼠肝组织在发育全过程中均未见有 GFAP印迹。比较各实验组 GFAP表达量为 :P1至 P5期非缺锌组 ( 30 mg/kg及1 0 0 mg/kg) GFAP杂交条带明显强于缺锌组 ( 1 mg/kg及 5mg/kg) ;P1 0至成年期 ,缺锌组 ( 1 mg/kg及 5mg/kg)大脑及小脑 GFAP的杂交条带反而强于非缺锌组 ( 30 mg/kg及 1 0 0 mg/kg) ,其强度与膳食锌呈负依赖关系。行为学检测表明 ,轻度缺锌组 ( 5mg/kg)达到学会标准所需次数明显多于高锌组 ( 1 0 0 mg/kg) ;电生理检测表明 ,轻度缺锌组仔鼠海马脑片上诱导的 LTP明显低于高锌组上所诱导的。结论 补充锌在发育早期可促进神经前体细胞向神经胶质细胞分化及 GFAP表达 ;

Objective: To determine the effects of zinc deficiency on microtubules polymerization and the expression of α tubulin and β tubulin subunits in the central nervous system (CNS) of mice. Methods: Maternal ICR mice were fed experimental diets containing different levels of zinc (1 mg, 5mg, 30 mg and 100 mg zinc per kg diet) during pregnancy and lactation respectively. From weaning period (post day 20) to postnatal day 70 (P70), all experimental offsprings were fed normal diets. The α tubulin and β tubulin subunits expression in heads and bodies at embryonic day 10 (E10), in cerebrum, cerebellum and liver at embryonic day 15 (E15), postnatal day 1 (P1), postnatal day 5 (P5), postnatal day 10 (P10), postnatal day 20 (P20) and P70 were examined by Western blot assays. Results: The results showed that α tubulin and β tubulin subunits were expressed in neural tube (E10), cerebrum and cerebellum from early embryonic stage (E10) to adult (P70). No α tubulin and β tubulin subunits were found in livers. The patterns of α tubulin and β tubulin expressions in cerebrum and cerebellum were similar in that its expression was up regulated at early development stage. After the expressions of α tubulin and β tubulin subunits arrived the expression peaks (α tubulin at P5 and β tubulin at P10), they began to down regulate. There was a close relationship between the concentration of dietary zinc and the level of α tubulin and β tubulin subunits expressions. The order of expression levels was 1 mg/kg group<5 mg/kg group<30 mg/kg group<100 mg/kg group. Conclusion: Zinc deficiency in developing period can inhibit the expression of tubulin subunits, and zinc supplementation can improve its expression. The decline of tubulin subunits expression is one of important mechanisms for microtubules polymerization impairments resulting from zinc deficiency.