维生素A缺乏对初生大鼠脑发育的影响

目的 :　探讨维生素 A缺乏 (VAD)对初生大鼠脑发育的影响及其分子生物学机制。方法 :　建立不同程度 VAD母鼠模型。仔鼠出生后测定其血清维生素 A(VA)水平、脑组织 VA含量、体重、脑重、脑组织蛋白质含量、脑细胞增殖周期和脑内视黄酸受体 α、β(RARα、RARβ)、视黄醇X受体 β(RXRβ)和多巴胺受体 - 2 (D2 R) m RNA表达。结果 :　 (1 )初生鼠血清 VA水平和脑组织VA含量三组间有显著性差异 (P<0 .0 1 ) ,重度维生素 A缺乏 (SVAD)组明显低于对照组和边缘型维生素 A缺乏 (MVAD)组 ,MVAD组也明显低于对照组。 (2 ) SVAD组初生鼠体重和脑重明显低于对照组和 MVAD组 (P<0 .0 1 ) ,MVAD组与对照组相比无显著性差异。 (3 )全脑蛋白质含量、每克脑组织蛋白质含量和脑细胞增殖指数 (PI) SVAD组均明显低于对照组 (P<0 .0 1 ) ,MVAD组仅全脑蛋白质含量明显低于对照组 (P<0 .0 1 ) ,其它指标与对照组相比也有降低但无统计学意义。(4)脑细胞 RARα、RARβ、RXRβ 和 D2 R m RNA表达 SVAD组仅 RARα和 D2 R有微弱表达 ,MVAD组与对照组相比除 RARβ外均有不同程度降低。结论 :　VAD会导致初生大鼠脑发育受损 ,其作用可能是通过降低脑细胞内视黄酸受体表达而产生的

EFFECTS OF VITAMIN A DEFICIENCY ON EMBRYONIC BRAIN DEVELOPMENT IN RATS

Objective: To study the effects of vitamin A deficiency (VAD) on brain development in rats and its molecular mechanisms. Methods: 9 female Wistar rats were randomly divided into severe VAD(SVAD) ,marginal VAD(MVAD) and control groups. The rats were fed with vitamin A (VA) 0, 400 and 6 500 IU/kg diets respectively for 3 weeks before pregnancy. Body and brain weight, serum VA level, brain VA and protein content, brain cell proliferative cycle and the expression of RAR α, RAR β, RXR β and D 2R mRNA were measured at birth. Results: (1) The VA levels of serum and brain tissue in SVAD and MVAD rats were decreased significantly compared with the control.The VA levels of serum and brain tissue in SVAD were also signficantly lower than that in MVAD. (2) The body weight, brain weight, brain protein content and cell proliferative index (PI) in SVAD rats were decreased compared with the control. The body weight, brain weight, whole brain protein content in SVAD rats were also significantly lower than that in MVAD. There was no significant difference between MVAD and the control. (3) The expression of RAR α and D 2R mRNA in SVAD rats was lower than that in control and MVAD, and the expression of RAR β and RXR β in SVAD was not detectable; while the expression of RAR α, RXR β and D 2R mRNA in MVAD was decreased significantly compared with the control. Conclusion: VAD can affect brain development in rats and the brain development defects may be related with the decreased expression of RAR α, RAR β, RXR β and D 2R in brain cells.