Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
J Mol Neurosci. 2010 May;41(1):156-64. doi: 10.1007/s12031-009-9312-6. Epub 2009 Nov 21.
Maternal morphine consumption has been shown to result in physical and neurobehavioral defects in fetus and offspring, but the underlying molecular mechanisms of these defects remain unclear. Regarding the critical role of apoptosis in normal development of central nervous system, the present study was designed to investigate the effect of intrauterine morphine exposure on programmed cell death of neuroblasts during the early development of neural system. Pregnant Wistar rats received morphine sulfate through drinking water at the concentration of 0.01 mg/ml (20 ml water per day for each rat) from the first day of gestation to the time of sampling. Control groups received tap water. Control and morphine-treated pregnant rats, each in five separated groups, were killed on gestational days 9.5 to 13.5, and the embryos were taken out, fixed, and embedded in paraffin. Immunohistochemical assay was used to reveal the protein expression of Bax, Bcl2, and the activation of caspase 3. The results showed a significant increase in Bax immunoreactivity in all of the mentioned embryonic days (E9.5 to E13.5) and a significant decrease in Bcl-2 immunoreactivity at days E10.5 and E12.5 in morphine-treated groups compared with control. Data analysis revealed that Bax/Bcl2 ratio was increased in all of the morphine-exposed groups. Consistent with these results, immunostaining of cleaved caspase 3 showed a significant increase at days E11.5 to E13.5. These findings suggest that morphine exposure during the first embryonic days may enhance the susceptibility of neuroblasts to apoptosis by upregulating the ratio of Bax to Bcl-2 protein expression and increasing downstream caspase-3 activity. The increased probability of neuroblast apoptosis may be the cause of morphine-induced defects in the central nervous system development and its structural and neurobehavioral consequences.
母体吗啡摄入已被证明会导致胎儿和后代的身体和神经行为缺陷，但这些缺陷的潜在分子机制仍不清楚。鉴于细胞凋亡在中枢神经系统正常发育中的关键作用，本研究旨在探讨宫内吗啡暴露对神经系统早期神经母细胞程序性细胞死亡的影响。妊娠 Wistar 大鼠从妊娠第一天开始通过饮用水摄入硫酸吗啡，浓度为 0.01mg/ml（每只大鼠每天 20ml 水），直至取样。对照组给予自来水。对照组和吗啡处理的妊娠大鼠，每组分为 5 个亚组，在妊娠第 9.5 至 13.5 天处死，取出胚胎，固定，包埋在石蜡中。免疫组织化学检测法用于揭示 Bax、Bcl2 蛋白的表达和 caspase 3 的激活。结果显示，在所有提到的胚胎日（E9.5 至 E13.5）中，Bax 免疫反应性显著增加，而在吗啡处理组中，Bcl-2 免疫反应性在 E10.5 和 E12.5 日显著降低。数据分析显示，在所有吗啡暴露组中，Bax/Bcl2 比值增加。与这些结果一致，cleaved caspase 3 的免疫染色显示，在 E11.5 至 E13.5 日显著增加。这些发现表明，在胚胎的头几天暴露于吗啡可能通过上调 Bax 与 Bcl-2 蛋白表达的比值并增加下游 caspase-3 活性，增加神经母细胞对凋亡的易感性。神经母细胞凋亡概率的增加可能是吗啡引起中枢神经系统发育缺陷及其结构和神经行为后果的原因。
