摘要
目的通过产前应用不同疗程地塞米松治疗,了解不同给药疗程产前激素治疗是否会影响后代脑发育及可能的机制。方法SPF级SD孕大鼠34只,随机分为4组,产前1剂组8只,于孕17d肌注地塞米松0.8mg/(kg.d);产前3剂组8只,于孕17、18、19d各肌注地塞米松0.8mg/(kg.d);产前4剂组10只,于孕17、18、19、20d各肌注地塞米松0.8mg/(kg.d);对照组8只肌注等量生理盐水。对各组孕鼠所生仔鼠,分别于生后第1、7、14天每组每个时间点随机取仔鼠16只测量全脑重量、称重后再将脑组织进行凋亡细胞的原位标记检测(每个时间点各8只)脑神经元细胞凋亡及改良的酶联免疫杂交分光光度法检测(每个时间点各8只)脑bcl-2蛋白表达,并与对照组比较。结果产前糖皮质激素治疗(antenatalcorticosteroidstreatment,ACT)1日龄仔鼠1剂组、3剂组、4剂组脑重分别为(0.301±0.030)g、(0.302±0.026)g、(0.296±0.025)g,均低于对照组(0.363±0.041g),P均<0.01;7日龄仔鼠3剂组、4剂组脑重分别为(0.798±0.092)g、(0.785±0.050)g,均低于对照组(0.862±0.049)g,P<0.05或P<0.01;14日龄仔鼠,仅产前4剂组脑重(1.190±0.080)g低于对照组(1.295±0.019)g,P<0.01。1日龄仔鼠产前3剂,4剂组神经元细胞凋亡率分别为(9.82±1.51)%、(10.28±1.50)%,较对照组(6.78±1.35)%增加(P均<0.01);7日龄仔鼠产前4剂组神经元细胞凋亡率(22.85±3.18)%较对照组(18.61±3.34)%显著增加(P<0.01)。1日龄仔鼠产前3剂,4剂组bcl-2蛋白含量分别为(9.50±0.46)U/ml、(9.06±0.46)U/ml,均低于对照组(12.60±1.04)U/ml,P均<0.01;7日龄仔鼠产前4剂组bcl-2蛋白含量(6.87±0.27)U/ml低于对照组(8.40±0.52)U/ml,P<0.01。产前1剂组与对照组相比无明显差异(P>0.05)。结论ACT会影响仔鼠脑发育,可引起脑重量的下降,重复ACT下调脑bcl-2蛋白的表达,通过调节bcl-2基因表达引起脑神经元凋亡增加,使仔鼠脑发育障碍。
Objective To investigate the effect and the possible mechanism of the apoptosis of neurons and the expression of bcl-2 gene in the neonatal rat brain after different courses of Dexamethasone （DXM）. Methods Thirty-four Sprague-Dawley（SD） pregnant rats were randomized into four groups and received different courses of antenatal DXM at the dose of 0.8mg/（kg·d） intramuscularly： （1） Group 1 （n=8） received DXM on the 17th day of gestation only; （2） Group 2 （n=8） received DXM consecutively on the 17th, 18th and 19th day of gestation; （3） Group 3 （n= 10） received DXM consecutively for 4 days（on 17th, 18th, 19th and 20th day of gestation） ; （4） The control group （n= 8） received equivalent volumes of isotonic saline intramuscularly consecutively for 4 days （gestational day 17, 18, 19, 20）. On the postnatal day 1 （P1）, day 7 （P7） and day 14 （P14）, sixteen newborns in each group were randomly selected and sacrificed. The weights of the body and the whole brain were measured. Tunel was used to evaluate the apoptosis of neurons, and the content of bcl-2 protein was examined by improved Western Blot. Results （1） The brains weight of the newbornmice on P1 were （0. 301±0. 030）g, （0. 302±0. 026）g, and （0. 296±0. 025）g in Group 1, 2 and 3, respectively and all significantly lower than that of the control [（0. 363±0. 041）g, P〈0. 01]. The whole brain weight on P7 in the Group 2 and 3 were also lower than that of the control [（0. 798±0.092）g, （0. 785±0. 050）g vs （0. 862±0. 049） g, P〈0.05 and 〈0. 01]. While on P14, only the brain weight in Group 3 was found to be lower than that of the control [（1. 190±0. 080）g vs （1. 295±0. 019）g, P〈0. 01]. （2） The apoptosis ratio of neurons in Group 3 and 4 was higher than that of controls [（9.82±1.51）%, （10.28±1.50）% vs （6.78±1. 35）%, P〈0. 01] on P, and the ratio of the Group 3 was lower than the control on P7[（22.85±3.18）% vs （18.61±3.34）%, P〈0.01]. （3） The expression of bcl-2 protein in newborn mice＇ brain in Group 2 and 3 were lower than that of the control [（9.50±0. 46）U/ml, （9.06±0.46）U/ml vs （12.60±1.04）U/ml, P〈0. 01] on P1 and that of the Group 3 was lower than that of control on P7 [（6.87±0.27）U/ml vs （8.40±0.52）U/ml, P〈0. 01]. No statistical significance was detected between Group 1 and the control group （P 〉 0.05）. Conclusions Repeated doses of antenatal DXM therapy could significantly increase the apoptosis of neurons by down-regulate the bcl-2 expression and handicap the development of newborn mice＇ brain.
出处
《中华围产医学杂志》
CAS
2006年第3期189-192,共4页
Chinese Journal of Perinatal Medicine
基金
温州市科学技术局资助课题(Y2003A114)
