Morse D C, Plug A, Wesseling W, van den Berg K J, Brouwer A
Department of Toxicology, Agricultural University, Wageningen, The Netherlands.
Toxicol Appl Pharmacol. 1996 Aug;139(2):252-61. doi: 10.1006/taap.1996.0164.
Pregnant Wistar WU rats were exposed to 0, 5, and 25 mg of the commercial polychlorinated biphenyl (PCB) mixture Aroclor 1254 per kilogram of body weight on Days 10 to 16 of gestation. Pregnant rats were sacrificed on Gestation Day 20 to observe effects on fetal body and brain weights. Male and female offspring were sacrificed on Postnatal Days 21 and 90 (PND21 and PND90, respectively) and examined for treatment-related effects on neurochemical parameters. The concentrations of the neuronal and glial cell markers, synaptophysin and glial fibrillary acidic protein (GFAP), were measured in diverse brain regions from the offspring using immunochemical techniques. The level of calcineurin (a calmodulin-regulated protein phosphatase) activity was measured in cerebellar homogenates. In addition, ethoxyresorufin O-deethylase (EROD) activity was determined in hepatic microsomes as a measure of a well-characterized response to PCB exposure in experimental animals. The major alterations of GFAP levels following maternal PCB treatment were significant increases in the lateral olfactory tract (LOT) and the cerebellum (CB) and significant decreases in the brain stem (BS) of the offspring on PND21 and 90. Synaptophysin levels were significantly decreased relative to controls in the LOT, prefrontal cortex, and striatum of the offspring on PND90. In the BS, synaptophysin levels were significantly decreased relative to controls in male and female weanlings on PND21 and males on PND90; however, significant increases were observed in the BS of females on PND90. No effect of maternal PCB treatment was observed on levels of GFAP and synaptophysin in the dorsal hippocampus on PND21 and 90. Due to analytical restrictions statistical comparisons of GFAP levels were limited to examining the effect of maternal PCB treatment per brain region per sex per time point. Calcineurin activity was decreased in the female CB on PND21, but a significant increase in activity was observed in the female CB on PND90. No effect of maternal PCB treatment was observed on the cerebellar calcineurin activity in male offspring on PND21 and 90. EROD activity was highly induced in maternal microsomes from both PCB treatment groups, but only slightly induced in fetal hepatic microsomes. On PND21 weanling hepatic microsomal EROD activity was highly induced following gestational and lactational PCB exposure; however, on PND90 EROD activity was unaffected by maternal PCB treatment in male offspring and significantly decreased in female offspring. The results of the present study indicate that gestational and lactational exposure to the commercial PCB mixture results in long-term alterations in a neuronal and glial cell markers in specific brain regions of rats. These marker proteins may be useful for determining the structure-activity relationships in PCB-induced developmental neurotoxicity.
妊娠第10至16天，将妊娠的Wistar WU大鼠按每千克体重0、5和25毫克的剂量暴露于商业多氯联苯（PCB）混合物Aroclor 1254中。在妊娠第20天处死妊娠大鼠，以观察对胎儿体重和脑重的影响。在出生后第21天和第90天（分别为PND21和PND90）处死雄性和雌性后代，并检查与治疗相关的神经化学参数影响。使用免疫化学技术测量后代不同脑区中神经元和神经胶质细胞标志物、突触素和神经胶质纤维酸性蛋白（GFAP）的浓度。在小脑匀浆中测量钙调神经磷酸酶（一种钙调蛋白调节的蛋白磷酸酶）的活性水平。此外，测定肝微粒体中的乙氧基异吩嗪酮O-脱乙基酶（EROD）活性，作为实验动物对PCB暴露特征性反应的一种衡量指标。母体PCB处理后，GFAP水平的主要变化是，在PND21和90时，后代的外侧嗅束（LOT）和小脑（CB）显著增加，而脑干（BS）显著降低。在PND90时，后代LOT、前额叶皮质和纹状体中的突触素水平相对于对照组显著降低。在PND21时，雄性和雌性断奶仔鼠BS中的突触素水平相对于对照组显著降低，在PND90时，雄性后代的BS中也显著降低；然而，在PND90时，雌性后代的BS中观察到显著增加。在PND21和90时，未观察到母体PCB处理对背侧海马体中GFAP和突触素水平有影响。由于分析限制，GFAP水平的统计比较仅限于检查每个脑区、每个性别、每个时间点母体PCB处理的影响。在PND21时，雌性CB中的钙调神经磷酸酶活性降低，但在PND90时，雌性CB中的活性显著增加。在PND21和90时，未观察到母体PCB处理对雄性后代小脑钙调神经磷酸酶活性有影响。两个PCB处理组母体微粒体中的EROD活性均被高度诱导，但胎儿肝微粒体中仅轻微诱导。在PND21时，经妊娠和哺乳期PCB暴露后，断奶仔鼠肝微粒体EROD活性被高度诱导；然而，在PND90时，雄性后代的EROD活性不受母体PCB处理的影响，而雌性后代则显著降低。本研究结果表明，妊娠和哺乳期暴露于商业PCB混合物会导致大鼠特定脑区神经元和神经胶质细胞标志物的长期改变。这些标志物蛋白可能有助于确定PCB诱导的发育神经毒性中的构效关系。
