Perforant pathway lamination in the dentate gyrus is unaffected by prenatal ethanol exposure

The entorhinal (perforant path) projection to the dentate gyrus was labeled with an anterograde horseradish peroxidase method to test whether prenatal exposure to ethanol affected the normal development of afferent lamination. Mean ethanol consumption of the ethanol-consuming dams was 12.7 g/kg +/- 0.3 g per day during days 1-21 of gestation. Adult offspring of normal and pair-fed controls as well as ethanol-exposed rats were analyzed. Computer-assisted image analysis of the entorhinal terminal field organization revealed no permanent changes in the development of the afferent lamination pattern in the dentate gyrus molecular layer in spite of the heavy in utero ethanol exposure.     

妊娠大鼠低铅暴露对子代海马GFAP表达影响

目的观察母体孕期低水平铅暴露对子代大鼠海马组织胶质原纤维酸性蛋白（GFAP）和mRNA表达的影响，探讨铅影响学习记忆的分子机制。方法孕鼠随机分为4组，自怀孕1d起分别给予蒸馏水、125，250，500mg／L醋酸铅饮水，直到仔鼠出生。分别在仔鼠出生后1，21，60d，采用免疫组化和原位杂交方法观察海马CA1区GFAP蛋白和mRNA表达的变化。结果各染铅组仔鼠1，21d时海马CA1区GFAP蛋白和mRNA阳性细胞数显著高于对照组（P〈0．05），而60d时未见明显差异。结论妊娠期母体低水平铅暴露可以使仔鼠海马CA1区GFAP蛋白和mRNA表达增加，这可能是铅影响学习记忆的分子机制之一。     

妊娠早期暴露低浓度毒死蜱对子代鼠海马脑区及体觉皮层的影响

目的 探讨小鼠妊娠早期暴露低浓度有机磷农药毒死蜱对子代鼠脑结构发育的影响.方法 在母鼠妊娠7.5～11.5 d时,以每天皮下注射5 mg/kg毒死蜱,连续5 d,将子代鼠在出生第35天处死,取脑作定位切片,HE及尼氏染色,显微镜下测量海马CA1、CA3区、DG区厚度,计数大脑皮层S1区神经元和胶质细胞数量及比例.结果 出生35 d的子代鼠海马CA 1区平均厚度下降22.37%,CA3区平均厚度下降25.66%,而DG区平均厚度增加24.14%,与对照组比较,差异均有统计学意义(P<0.01).S1区神经元,胶质细胞比值由81.77%下降至74.61%.结论 小鼠妊娠早期低浓度有机磷农药毒死蜱持续暴露可导致子代鼠脑结构细微损伤.     

胚胎期暴露于甲基汞大鼠的迷宫测试

为研究胚胎期甲基汞暴露对大鼠迷宫学习与记忆能力的影响 ,用不同剂量甲基汞 [0、0 .0 1、0 .0 5和 2 .0 0 mg/ (kg· d) ]于大鼠孕 6～ 9天连续灌胃染毒 ,仔鼠出生 7周时进行 Y型迷宫测试。学习记忆成绩以平均错误次数、到达安全区平均时间和主动回避率表示。整个实验采用双盲法。结果与对照组相比 ,各暴露组大鼠的平均错误次数和到达安全区平均时间显著增高 ,主动回避率显著降低 (P<0 .0 5或 P<0 .0 1) ;各组大鼠学习记忆能力无性别差异。提示甲基汞可通过胎盘屏障和乳汁进入仔鼠体内 ,影响仔鼠神经系统的发育 ,使其学习记忆能力受到明显损害     

孕期低水平铅暴露对子代大鼠海马神经生长相关蛋白表达的影响

目的 观察孕鼠低水平铅暴露后子代大鼠海马组织神经生长相关蛋白(GAP-43)及其mRNA表达的变化,探讨铅对学习记忆影响的分子机制.方法 孕鼠随机分为对照组及低(125 mg/L)、中(250 mg/L)、高(500 mg/L)3个不同剂量染铅组,每组8只.各组母鼠自受孕1 d起分别给予蒸馏水、125、250、500 mg/L醋酸铅饮水,直到仔鼠出生.分别在仔鼠出生后1、21,60 d取大脑海马组织,氢化物-原子吸收光谱法测定仔鼠海马铅含量,免疫组化和原位杂交方法检测海马CA1区GAP-43蛋白及其mRNA表达的变化.结果 出生后1、21 d时低、中、高剂量染铅组海马铅含量分别为(1.64±0.32)、(2.33±0.42)、(3.28±0.58)μg/L和(0.94±0.18)、(1.27±0.26)、(1.79±0.42) μg/L,与对照组相比,铅含量明显升高,差异均有统计学意义(P＜0.05).出生后1 d各剂量染铅组和出生后21 d中、高剂量染铅组CA1区GAP-43蛋白和mRNA表达的积分吸光度均明显低于对照组,差异有统计学意义(P＜0.05或P＜0.01),而在60 d时未见明显改变.结论 孕鼠低水平铅暴露后,可以降低子代海马GAP-43蛋白及其mRNA的表达,这可能是铅影响学习记忆的分子机制之一.     

产前束缚应激对大鼠子代的影响

目的:观察产前束缚应激对子代大鼠海马组织脑源性神经生长因子(BDNF)的表达及学习行为的影响。方法:将孕鼠随机分为应激组和对照组,应激组孕鼠在妊娠的第13～19天给予束缚应激。观察两组孕鼠所产雄性仔鼠1月龄时的学习记忆和行为活动,并用免疫组织化学方法检测仔鼠海马组织切片中BDNF的表达。结果:应激组雄性仔鼠海马BDNF的表达低于相应对照组(t=3.377,P=0.004),学习记忆成绩低于对照组(t=3.838,P=0.002),水平运动得分高于对照组(t=2.372,P=0.028),垂直运动得分高于对照组(t=2.625,P=0.016)。结论:产前应激可能减少仔鼠海马组织中BDNF的表达,并影响仔鼠的学习记忆和行为活动。     

Effects of prenatal alcohol exposure on the developmental pattern of temperature preference in a thermocline

Prenatal alcohol exposure is associated with a variety of impairments in neonatal state regulatory systems. Since prenatal alcohol exposure causes thermoregulatory deficits in response to both heat and cold stress in rats, body temperature set-point might be altered in alcohol-exposed offspring. The effect of prenatal alcohol exposure on behavior in a thermocline was investigated in 10-, 15-, and 125-day-old male and female rats from three prenatal treatment conditions: alcohol liquid diet, pair-fed liquid diet control, or standard control. Subjects were placed in the thermocline in the cold, hot, or middle start positions and observed for 60 min. Subjects exposed to alcohol prenatally had a wider “preference zone” than control subjects at 10 and 15 days of age, but did not as adults. This widening of the temperature set-point in young subjects prenatally exposed to alcohol may represent a developmental lag in the development of body temperature set-point or a central compensatory process allowing the animal to adapt to alternating experiences of heat and cold stress.     

Effects of chronic prenatal ethanol exposure on NMDA receptor number and affinity for [3H]MK-801 in the cerebral cortex of the young postnatal and adult guinea-pig

The objective of this study was to test the hypothesis that chronic prenatal ethanol exposure (CPEE) produces changes in the number and/or affinity of N-methyl-D-aspartate (NMDA) receptors in the cerebral cortex that are developmental-age-dependent. Timed, pregnant Dunkin-Hartley-strain guinea-pigs received oral intubation of one of the following regimens, given daily as two equally divided doses 2 h apart, from gestational day (GD) 2 to GD 67 (term, ~GD 68): (i) 4 g ethanol kg(-1) maternal bodyweight; (ii) isocaloric sucrose with pair feeding; or (iii) water. Maternal blood ethanol concentration was measured on GD 57 or 58 at 1 h after the daily dose, and was 51.1 +/- 8.5 mM (235 +/- 39 mg dL(-1); n = 8). At postnatal day (PD) 11 (pre-weaning) and PD 61 (adulthood), body, brain and cerebral cortical weights of the offspring were measured. The number of NMDA receptors and their affinity for [(3)H]MK-801 were measured in a crude cerebral cortical membrane preparation using saturation isotherm analysis to determine the B(max) and K(D). Chronic prenatal ethanol exposure decreased offspring brain and cerebral cortical weights at PD 11 and PD 61. At PD 11, there was no CPEE-induced change of [(3)H]MK-801 binding characteristics in the cerebral cortex. At PD 61, both B(max) and K(D) for [(3)H]MK-801 binding to cerebral cortical NMDA receptors were decreased by CPEE compared with the isocaloric sucrose/pair-fed and water treatment groups. Loss of cerebral cortical NMDA receptors and increased affinity of the remaining receptors for [(3)H]MK-801 in the adult guinea-pig, compared with no change in the number or affinity of these receptors in the young postnatal offspring, demonstrated that the effects of CPEE on these ionotropic glutamate receptors are developmental-age-dependent.     

丰富环境提升孕期应激子鼠学习能力和海马Arc的相关性研究

目的 从子鼠海马中细胞骨架蛋白Arc的变化,来探讨丰富环境方式对孕期慢性应激所产子鼠学习能力影响的干预机制。方法 建立孕期慢性应激大鼠模型,并采用丰富环境干预子鼠,利用水迷宫和Y-迷宫测定子鼠学习记忆能力、RT-PCR和Western Blotting测定海马中 Arc 表达情况。结果 模型组母鼠皮质酮增高,提示模型组母鼠处于应激状态。丰富环境后,子鼠血浆皮质酮降低(P<0.05);水迷宫中逃避潜伏期和跨平台次数、Y-迷宫中所需的训练次数和正确反应率情况均转好(P均<0.05);经丰富环境后,模型子鼠组海马组织 Arc mRNA和蛋白表达增高(P均<0.05)。结论 丰富环境可以作为孕期受到应激因素影响学习能力提高的手段,与血浆皮质酮降低及海马突触相关蛋白 Arc升高有关。     

The development of β1-adrenoreceptors in brown adipose tissue following prenatal alcohol exposure

Prenatal alcohol exposure delays the development of thermoregulation in newborn rats. Newborns generate heat by the sympathetic nervous system's activation of nonshivering thermogenesis in brown adipose tissue (BAT). In this study, the effects of prenatal alcohol exposure on the development of the β-adrenergic receptor system of BAT was investigated by assessing the number and pharmacological properties of β-adrenergic receptors in BAT in 1-, 5-, 10-, and 20-day-old offspring. Pregnant dams were given either a liquid diet with 35% of the calories derived from alcohol, a liquid diet without alcohol to control for any effects of the liquid diet administration, or ad lib food and water. Offspring from the alcohol prenatal treatment group had a greater number of β₁ adrenergic receptors compared to offspring from both from the pair-fed and lab chow control groups, which did not differ from each other. The greater number of receptor sites in 5-day-old subjects suggests that the number of binding sites in alcohol-exposed BAT cells continues to rise due to the absence of sufficient neurotransmitter, and perhaps reflects a delay in the arrival of sympathetic nervous system neurons. During the second and third postnatal weeks, when NE concentrations are rising and reaching asymptotic levels, the number of β₁ adrenergic receptors in BAT of control subjects is decreasing. This expected compensatory “downregulation” response in receptor concentration was not seen in BAT from subjects exposed to alcohol prenatally. These findings may have important implications for understanding the effects of prenatal alcohol exposure on developing plasticity in the peripheral nervous system.     

Postnatal Choline Supplementation Rescues Deficits in Synaptic Plasticity Following Prenatal Ethanol Exposure

Prenatal ethanol exposure (PNEE) is a leading cause of neurodevelopmental impairments, yet treatments for individuals with PNEE are limited. Importantly, postnatal supplementation with the essential nutrient choline can attenuate some adverse effects of PNEE on cognitive development; however, the mechanisms of action for choline supplementation remain unclear. This study used an animal model to determine if choline supplementation could restore hippocampal synaptic plasticity that is normally impaired by prenatal alcohol. Throughout gestation, pregnant Sprague Dawley rats were fed an ethanol liquid diet (35.5% ethanol-derived calories). Offspring were injected with choline chloride (100 mg/kg/day) from postnatal days (PD) 10–30, and then used for in vitro electrophysiology experiments as juveniles (PD 31–35). High-frequency conditioning stimuli were used to induce long-term potentiation (LTP) in the medial perforant path input to the dentate gyrus of the hippocampus. PNEE altered synaptic transmission in female offspring by increasing excitability, an effect that was mitigated with choline supplementation. In contrast, PNEE juvenile males had decreased LTP compared to controls, and this was rescued by choline supplementation. These data demonstrate sex-specific changes in plasticity following PNEE, and provide evidence that choline-related improvements in cognitive functioning may be due to its positive impact on hippocampal synaptic physiology.     

Organization of the commissural projection to the dentate gyrus is unaltered by heavy ethanol exposure during gestation

The anterograde horseradish peroxidase method was used to determine if prenatal exposure to ethanol affected the development of the characteristic afferent lamination pattern of the commissural projection to the dentate gyrus. Mean ethanol consumption for the ethanol-consuming dams was 12.7 g/kg +/- 0.3 g per day. Adult offspring of rats that consumed a liquid diet containing 35% ethanol-derived calories during days 1-21 of gestation, and both pair-fed and normal controls were examined. Brain weights and volumes of the ethanol and pair-fed control rats did not differ significantly from normal controls. However, body weights of ethanol-exposed rats were significantly reduced compared to normal controls. Computer-assisted image analysis of the HRP-labeling revealed that in spite of the heavy ethanol exposure there was no evidence of alterations in the spatial distribution of the commissural terminal field.     

Prenatal ethanol exposure during the last third of gestation in rat reduces hippocampal NMDA agonist binding site density in 45-day-old offspring.

The effect of ethanol exposure during different periods of prenatal or postnatal development on hippocampal N-methyl-D-aspartate (NMDA) receptor binding was studied in rat. Fetal rat pups were exposed to ethanol for different periods of time during gestation via maternal consumption of a 3.35% ethanol liquid diet. In a separate experiment, neonatal pups were fed 2.51 g ethanol/kg body weight/day from Postnatal Day (PD) 4 to PD 10 via intragastric feeding tube. These two ethanol administration paradigms produced average peak maternal and pup blood ethanol concentrations of 39 mg/dl and 57 mg/dl, respectively. At 45 days of age, offspring from each treatment group were sacrificed for measurements of hippocampal NMDA-sensitive [3H]-glutamate binding site density using in vitro radiohistochemical techniques. As observed previously, prenatal ethanol exposure throughout gestation resulted in NMDA-sensitive [3H]-glutamate binding site reductions in the apical dendritic field regions of dentate gyrus, hippocampal CA1 and subiculum of dorsal hippocampal formation compared to the ad lib or pair-fed control groups. NMDA-sensitive [3H]-glutamate binding was not different than control in rats exposed to ethanol during the first half of gestation only. Prenatal ethanol exposure during the last half or the last third of gestation resulted in NMDA-sensitive [3H]-glutamate binding site reductions comparable to the binding site reductions observed in rats exposed to ethanol throughout gestation. Hippocampal NMDA-sensitive [3H]-glutamate binding site density in postnatal ethanol-exposed rats was not different than the suckling or gastrostomy control groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of prenatal trimethyltin exposure on development and learning in the rat

Developmental effects of single prenatal trimethyltin exposure were examined in THA rats. Pregnant rats were injected on gestational day 12 with single dose of trimethyltin chloride (TMT) ip at either 0, 5, or 7 mg/kg. Significant differences between treated and control offspring rats could not be observed in terms of body weight, pinna detachment, incisor eruption, eye opening, surface righting, cliff avoidance, pivoting, negative geotaxis and auditory startle. Spontaneous motor activity and open field behavior in the rats were also not affected by TMT. In Sidman avoidance test, however, the avoidance rate of the treated offspring rats was lower when compared to that of the controls. These results suggest that prenatal TMT administration disrupts learning acquisition.     

孕期低水平铅暴露对子代大鼠海马肾母细胞瘤过度表达基因的影响

目的 观察孕鼠低水平铅暴露对子代大鼠海马组织肾母细胞瘤过度表达基因(NOV)蛋白及mRNA表达的影响,探讨铅影响学习记忆的分子机制.方法 孕鼠随机分为对照组及低剂量(125 mg/L)、中剂量(250 mg/L)、高剂量(500 mg/L)3个染铅组,每组8只.母鼠自受孕1d起分别给予蒸馏水和不同剂量的醋酸铅饮水,直到仔鼠出生.分别在胚胎18 d及仔鼠出生后1、21、60 d时,采用氢化物-原子吸收光谱法测定仔鼠血铅、海马铅含量,免疫组化和原位杂交方法 检测海马NOV蛋白及mRNA的变化.结果 低、中、高剂量染铅组胚胎18d及仔鼠出生后1、21 d时,血铅[(312.46±43.55)、(419.35±62.25)、(541.45±47.90)μg/L、海马铅[(2.10±0.18)、(2.58±0.12)、(3.41±0.23)μg/L]明显高于对照组[分别为(214.31±40.77)、(0.76±0.13)μg/L伽,差异有统计学意义(P<0.05),至60 d龄时,染铅组仔鼠血铅、海马铅含量与对照组无明显差异.免疫组化结果 显示,中、高剂量染铅组在仔鼠出生后1、21 d时,NOV蛋白表达量明显低于对照组,差异有统计学意义(P<0.05,P<0.01),60 d龄时无明显差异.原位杂交结果 显示,各染铅组在胚胎18 d及仔鼠出生后1、21 d时,NOV mRNA表达量明显低于对照组,差异有统计学意义(P<0.05,P<0.01),60d龄时,仅高剂量组NOV mRNA表达量(0.0355±0.0100)与对照组(0.0900±0.0200)的差异有统计学意义(P<0.01).结论 孕期低水平铅暴露可使子代海马组织中NOV蛋白及其mRNA表达降低,这可能是铅影响学习记忆能力的分子机制之一.     

Effects of chronic prenatal ethanol exposure on hippocampal glutamate release in the postnatal guinea pig.

This study was designed to test the hypothesis that chronic prenatal ethanol exposure decreases basal and stimulated L-glutamate release in the hippocampus of young, postnatal guinea pigs. Timed, pregnant guinea pigs were randomly assigned to one of the following three chronic treatment groups: 4 g ethanol/kg maternal body weight/day, isocaloric-sucrose and pair-feeding to the ethanol group, and water. Each oral treatment was given daily throughout gestation. Spontaneous locomotor activity was increased on postnatal day (PD) 10, and brain and hippocampal weights were decreased on PD 12 in the offspring of the ethanol group compared with the isocaloric-sucrose/pair-fed and water groups. On PD 12, the 45 mM K(+)- and 10 microM veratridine-stimulated release of glutamate in transverse hippocampal slices was decreased in the ethanol group compared with the two control groups. This alteration in glutamate release produced by chronic prenatal ethanol exposure may decrease the efficiency of excitatory synaptic transmission in the hippocampus during postnatal life.     

妊娠期母体低水平铅暴露对大鼠子代学习记忆能力的影响

目的探讨大鼠妊娠期间低水平铅暴露对其子代学习记忆能力的影响.方法孕鼠随机分为4组,3个处理组自怀孕第1天起分别给予醋酸铅含量为125、250和500 mg/L的饮水,对照组给予不含铅的双重蒸馏水,采用流动注射氢化物发生-原子吸收光谱法测定仔鼠血铅、脑海马组织铅含量,以避暗穿梭箱试验、Morris水迷宫试验测定仔鼠的学习记忆能力.结果各处理组的1、21 d龄仔鼠血铅、海马组织铅水平明显高于对照组仔鼠,差异有统计学意义（P＜0.05）,至60 d龄,差异无统计学意义（P＞0.05）;Morris水迷宫试验显示,各处理组21、60 d龄仔鼠连续4 d训练期间,第2、3、4天潜伏期均高于同期对照组仔鼠,差异有统计学意义（P＜0.05）;避暗穿梭箱试验显示,各处理组21、60 d龄仔鼠连续5 d训练期间,主动回避次数低于同期对照组仔鼠,差异有统计学意义（P＜0.05）;主动回避潜伏期、被动回避潜伏期高于同期对照组仔鼠,差异有统计学意义（P＜0.05）.结论母体妊娠期低水平铅暴露可以影响仔鼠的空间学习记忆能力,且影响至少可持续至仔鼠成熟期.     

苯并芘对大鼠记忆及谷氨酸盐受体基因表达影响

目的观察慢性苯并芘染毒大鼠对记忆及海马组织中谷氨酸盐受体基因(AMPA1)表达影响。方法将36只雄性SD大鼠分为高、中、低剂量组及溶剂对照组,每组9只;染毒结束后,用Morris水迷宫测试大鼠空间学习记忆能力,基因芯片技术进行AMPA1基因表达谱分析,再用逆转录-实时荧光定量PCR技术测量大鼠海马组织中AMPA1基因表达状况。结果第5 d定位航行试验中,与对照组(6.50±2.57)s比较,中、高剂量组寻找平台平均潜伏期(17.90±7.71)、(16.20±4.74)s,明显延长(P<0.05);基因芯片扫描提示AMPA1 mRNA在暴露组中表达量是对照组的2.052倍,荧光定量PCR检测显示AMPA1mRNA上调4.257倍。结论苯并芘影响大鼠的空间学习记忆能力,且明显诱导海马组织内的AMPA1基因高表达。     

Regional differences in cell loss associated with binge-like alcohol exposure during the first two trimesters equivalent in the rat.

Women who abuse alcohol during pregnancy may deliver offspring who could be diagnosed with fetal alcohol syndrome (FAS) or a less severe deficit involving cognitive and behavioral disorders. The severity of the deficits may involve the interaction of several known risk factors, such as alcohol consumption pattern or duration, the timing of alcohol consumption relative to critical windows of vulnerability, or the inherent differential vulnerability among the various brain regions to alcohol-induced brain injury. In this study, we explore the vulnerability of the different brain regions by making cell counts from multiple brain regions. Specifically, we used stereological cell-counting techniques to estimate the total cell numbers in the cerebellum (Purkinje and granule cells), olfactory bulb (mitral and granule cells), hippocampus (CA1 and CA3 cells), and dentate gyrus (granule cells). Groups of timed-pregnant Sprague-Dawley rats were assigned to one of five treatments: alcohol by intragastric intubation (2.25, 4.5, or 6.5 g/kg/day), nutritional control [pairfed and intubated=Pairfed) and intubated], and normal control (Chow). Treatments began on embryonic day 1 (E1) and continued through E20. On E33 (usually postnatal day 10), all offspring were perfused intracardially with saline followed by fixatives. Representative forebrains, cerebella, and olfactory bulb from each group were processed for cell counting. The optical dissector was used to obtain cell densities, while Cavalieri's principle was used to calculate the reference volume. The product of density and volume gave unbiased estimates of the total neuronal number within each brain region. Overall peak BACs (regardless of sampling day) for the three alcohol groups averaged 136, 290, and 422 mg/dl for the 2.25-, 4.5-, and 6.5-g/kg groups, respectively. The total number of cerebellar Purkinje cells was reduced in the 6.5-g/kg group relative to controls, while the total number of olfactory bulb mitral cells and hippocampal CA1 and CA3 pyramidal cells from all alcohol-treated groups was not different from controls. Total numbers of granule neurons were reduced in the cerebellum and olfactory bulb of offspring exposed to 4.5 or 6.5 g/kg/day, but granule cell numbers in the dentate gyrus were not affected by the prenatal alcohol treatment. Taken together with previous findings, these data demonstrate that prenatal alcohol exposure results in regional vulnerability of various brain structures and underscores the variability of deleterious effects of alcohol on brain development.     

产前束缚应激对大鼠子代行为活动的影响

目的观察产前束缚应激对子代大鼠海马组织中环单磷酸腺苷反应元件结合蛋白（CREB）的表达及行为活动的影响。方法将孕鼠随机分为应激组和对照组,应激组孕鼠在妊娠的第13 d-19 d给予束缚应激。利用旷场试验（Open-field test）观察两组孕鼠所产雌性仔鼠1月龄时的行为活动,并用免疫组织化学方法检测仔鼠海马组织切片中CREB的表达。结果应激组仔鼠海马组织CREB的表达低于对照组（P〈0.05）;水平运动得分和垂直运动得分高于对照组（P〈0.05）结论产前束缚应激可能减少仔鼠海马组织中CREB的表达,并增加仔鼠的行为活动。