妊娠期亚临床甲减大鼠对子代学习记忆能力及脑发育相关基因表达的影响  

Effect of maternal subclinical hypothyroidism during pregnancy on brain development in rat offspring

作　　者：刘迪杰[1] 单忠艳[1] 滕卫平[1] 于晓会[1] 高芸[1] 王森[1] 范晨玲[1] 王红[1] 张红梅[1] 

机构地区：[1]中国医科大学附属第一医院内分泌科,内分泌研究所,沈阳110001

出　　处：《中华内分泌代谢杂志》2010年第11期936-941,共6页Chinese Journal of Endocrinology and Metabolism

基　　金：基金项目：辽宁省科技攻关项目（2007225010）;辽宁省教育厅重点实验室基金课题项目（20060905）;教育部高等学校博士学科点专项科研基金（20092104120003）

摘　　要：目的 通过建立妊娠期亚临床甲状腺功能减退（甲减）孕鼠动物模型,观察母鼠亚临床甲减对仔鼠行为学改变的影响,并从脑发育相关基因表达方面探讨母体亚临床甲减导致胎儿脑发育障碍的机制.方法将60只SPF级雌性成年Wistar大鼠随机分成3组（每组n=20）：（1）亚临床甲减组：手术切除甲状腺,于背部皮下植入微渗泵,L-T4装入泵中持续泵入;（2）甲减组：手术完全切除甲状腺,术后注入等量生理盐水,作为阳性对照;（3）正常对照组（假手术组）：行甲状腺切除假手术,术后注入等量生理盐水.取仔鼠出生后第3、7及21天海马组织,以实时定量PCR法检测各时间点脑源性神经营养因子（BDNF）、神经细胞黏附分子（NCAM）mRNA表达;以Western印迹法检测BDNF、Rap1的蛋白含量;第40天仔鼠进行Morris水迷宫学习与记忆测试.结果（1）与正常对照组比较,亚临床甲减组的仔鼠第3天BDNF mRNA和蛋白表达减弱（均P＜0.05）,NCAM mRNA表达差异无统计学意义（P＞0.05）;第21天Rap1蛋白表达明显增强（P＜0.05）;水迷宫结果显示第44天逃避潜伏期明显高于对照组,第49天长时记忆试验中在目标象限游泳时间明显低于对照组（均P＜0.05）.（2）与甲减组比较,亚临床甲减组的仔鼠出生后各时点BDNFmRNA及蛋白表达明显增强（P＜0.05或P＜0.01）.Rap1蛋白表达明显降低（P＜0.05）;水迷宫结果显示第44天逃避潜伏期明显低于甲减组,第49天长时记忆试验中在目标象限游泳时间明显高于甲减组（均P＜0.05）.结论母体亚临床甲减的仔鼠空间学习能力及空间记忆能力均下降,其作用机制可能与甲状腺激素调控基因BDNF表达下调、Rap1表达升高有关.Objective To explore whether maternal subclinical hypothyroidism gives rise to poor performance in the offspring and whether this is associated with the expression of several genes that are under the control of thyroid hormones. Methods Sixty female rats were divided into three groups （ each group n = 20）： （ 1 ）maternal subclinical hypothyroidism （ total thyroidectomy with T4 infusion）, （2） maternal hypothyroidism （ total thyroidectomy without T4 infusion）, and （3） control （sham operated）. All rats were mated 10 days after the start of infusion. The infusion continued until 10 days postpartum. Pups were sacrificed at postnatal day 3, 7, and 21. The hippocampus was collected and tested for brain-derived neurotrophic factor （BDNF） and Rap1 protein expression by Western blotting and for BDNF and neural cell adhesion molecule （ NCAM ） mRNA expression by real-time polymerase chain reaction. On day 41-49, rat pups explored the Morris water maze. Time spent in the quadrant previously containing the plat form was recorded. Results The present study found decreases in BDNF mRNA （on day 3 ） and protein levels （on day 3 and 7 ） in hippocampi of pups from subclinical hypothyroidism dams （P〈0.05）. No change was observed in the levels of NCAM mRNA, whereas at day 21, expression of Rap1 protein was higher than that of control offspring. In addition, pups of subclinical hypothyroidism dams showed a trend toward depression in short-term memory （P〉0.05）, and long-term memory testing revealed a trend toward subclinical hypothyroidism group pups being less able to remember a fixed platform position than controls, spending less time in the proper quadrant （ P〈0. 05 ）. Conclusion The long-term memory deficits of pups born to maternal subclinical hypothyroidism dams are likely related with decrease in BDNF expression as well as increase in Rap1 expression in hippocampi.

关 键 词：亚临床甲状腺功能减退症 妊娠 脑发育 

分 类 号：R686[医药卫生—骨科学]