大鼠产前手机辐射对子代小脑白质的影响

目的:探讨大鼠产前850～1 900 MHz手机辐射对成年子代小脑白质的影响。方法:孕鼠随机分为短时产前手机辐射组、长时产前手机辐射组和对照组,短时和长时辐射组于孕期第1～17日分别进行每天6 h和24 h手机辐射,各组雄性子代大鼠(n＝8)于3月龄取小脑组织,进行苏木精-伊红(HE)染色观察小脑皮质细胞形态,免疫组化和Western blot检测髓鞘碱性蛋白(MBP)、神经微丝-L(NF-L)和胶质纤维酸性蛋白(GFAP)表达。结果:与对照组比较,短时程和长时程产前手机辐射组子代大鼠小脑浦肯野细胞出现形态学改变;与对照组比较,长时程辐射组MBP、NF-L表达明显减少(P均＜0.05),而GFAP表达明显增多(P＜0.05);与短时程辐射组比较,长时程组子代大鼠小脑MBP、NF-L表达明显减少(P均＜0.05),而GFAP表达明显增多(P＜0.05)。结论:产前手机辐射会导致雄性子代大鼠小脑髓鞘和轴突的损害,以及星形胶质细胞的活化,且这种改变与产前手机辐射的时程相关。     

产前束缚应激对子代大鼠海马神经干细胞增殖及巢蛋白表达的影响

为了观察产前束缚应激对子代大鼠空间学习记忆能力、海马神经干细胞增殖及巢蛋白表达的影响,将体重240~260 g的Sprague-Dawley雌性母鼠12只随机分成2组,对照组于孕期不做任何处理,束缚应激组于孕14~20 d时给予束缚应激,3次/天,45 min/次。取1月龄子代大鼠进行实验研究。Morris水迷宫定位航行实验结果显示,应激组子代与对照组相比,到达平台的潜伏期延长(P0.05),而在空间探索实验中,应激组子代在原平台象限停留时间与对照组相比无显著差异。免疫组织化学结果显示,应激组雌性子代海马巢蛋白(nestin)和BrdU阳性细胞表达均较对照组显著增加(P0.05),而雄性子代海马nestin和BrdU阳性细胞表达与对照组相比无显著性差异(P0.05)。以上结果提示,产前束缚应激可引起雌性子代大鼠海马神经干细胞数量增加以及增殖能力增强,可能与机体对产前应激所致脑损伤的代偿性反应相关。     

产前束缚应激子代大鼠海马神经颗粒素表达降低

神经颗粒素（neurogranin,NG）是脑特异性突触后蛋白,参与在学习记忆功能中起核心作用的信号转导通路及突触可塑性。本研究旨在探讨产前束缚应激对子代大鼠海马NG表达的影响。连续7d对孕晚期大鼠进行束缚应激,建立产前束缚应激模型,分为对照雌、雄组,应激雌、雄组。采用免疫组化方法观察NG在产前束缚应激子代大鼠海马不同亚区的分布特点;采用蛋白免疫印迹方法检测产前束缚应激子代大鼠海马NG蛋白的表达。结果显示：各组子代大鼠海马各区均有NG蛋白表达,CA1和CA3区表达高于齿状回（dentate gyrus,DG）;应激组雌、雄子代大鼠海马NG的表达明显低于对照组（P〈0．01）,应激组雌性子代比雄性子代减少更显著,对照组雌、雄子代之间无差异。免疫组化与蛋白免疫印迹方法所得结果一致。上述结果表明,NG在产前束缚应激子代大鼠海马表达降低,并且雌性比雄性降低明显,NG对产前束缚应激子代大鼠有差异性调制,NG表达减少可能与产前束缚应激子代大鼠学习记忆能力下降有关。     

产前应激对成年子代大鼠缺血性卒中后细胞凋亡的影响

目的:研究产前应激对雄性子代大鼠大脑中动脉缺血/再灌注后神经功能的影响。方法:SD孕鼠随机进行产前应激处理(孕期每日3次限制活动)和无产前应激处理,并对其雄性子代大鼠采用线栓法制备大脑中动脉局灶性脑缺血(MCAO)模型,共分为假手术组、产前应激+假手术组、MCAO模型组、产前应激+MCAO组(n=10)。于再灌注24 h后进行神经功能评分,并检测脑梗死面积、神经细胞凋亡情况和凋亡相关蛋白表达。结果:产前应激+MCAO组子代大鼠神经功能评分、脑梗死面积百分比、TUNEL阳性细胞、半胱氨酸天冬氨酸蛋白酶3(Caspase3)和活化的Caspase 3蛋白表达均较MCAO组显著增加(P0.05),而B淋巴细胞瘤-2(Bcl-2)蛋白表达较MCAO组减少(P0.05)。结论:产前应激可能通过促进子代大鼠脑缺血/再灌注后神经细胞凋亡,加重神经功能缺损。     

产前应激对子代大鼠脑缺血/再灌注后星形胶质细胞的影响

目的：探讨产前应激对雄性子代大鼠大脑中动脉缺血/再灌注后星形胶质细胞的影响。方法：SD孕鼠随机分为有产前应激处理（妊娠第15到21天每日3次限制活动）和无产前应激处理,并对其雄性子代大鼠采用线栓法制备大脑中动脉闭塞（MCAO）模型,共分为产前应激+假手术组、MCAO模型组、产前应激+MCAO组（n=10）,于再灌注后第5天检测脑梗死体积,免疫荧光双标染色检测缺血灶边缘区星形胶质细胞形态及促红细胞生成素肝细胞受体A4（EphA4）和胶质纤维酸性蛋白（GFAP）的共表达情况,并采用Western blot检测EphA4、GFAP和神经蛋白聚糖（Neurocan）蛋白表达。结果：产前应激+MCAO组子代大鼠脑梗死体积百分比、EphA4、GFAP和Neurocan蛋白表达均较MCAO组显著增加（P均<0.05）,且GFAP阳性细胞形态学改变及EphA4/GFAP共表达也较MCAO组明显。结论：产前应激可能改变子代大鼠脑缺血/再灌注后星形胶质细胞上EphA4受体的表达,促进星形胶质细胞活化,产生神经蛋白聚糖。     

褪黑素对慢性脑低灌注大鼠海马齿状回区神经再生的影响

目的:研究褪黑素在慢性脑低灌注(Chronic Cerebral Hypoperfusion,CCH)大鼠模型中对神经再生的作用及机制。方法:使用双侧颈总动脉结扎法(bilateral common carotid artery occlusion,BCCAO)制备大鼠CCH模型,80只雄性的SD大鼠随机分为4组,每组20只:生理盐水治疗假手术组(Sham组)、生理盐水治疗模型组(BCCAO组)、褪黑素(5 mg/kg)治疗模型组(MT1组)、褪黑素(10 mg/kg)治疗模型组(MT2组)。连续腹腔注射褪黑素或生理盐水共4周。利用挖掘实验评估大鼠行为学;使用HE染色观察神经细胞变性及坏死;采取尼氏染色法观察大鼠海马齿状回区神经元损伤情况;利用免疫荧光法测定神经元特异核蛋白(NeuN)、胶质纤维酸性蛋白(Ki67)、双皮质素(DCX)的表达;利用Western Blot法测定大鼠海马区脑源性神经营养因子(BDNF)、酪氨酸激酶B受体(TrkB)含量的表达。结果:和Sham组相比,BCCAO组大鼠挖掘能力明显下降(P0.01),HE和尼氏染色出现神经细胞大量坏死、数量减少,NeuN阳性细胞数增加(P0.01)、Ki67/DCX阳性细胞数无明显增加(P0.05),BDNF、TrkB蛋白含量明显低于假手术组(P0.01)。与BCCAO组相比,MT1组和MT2组大鼠挖掘能力均明显改善(P0.01),HE和尼氏染色显示神经元存活数量增加,MT1组NeuN阳性细胞数增加(P0.05)、Ki67/DCX阳性细胞数增加(P0.05),MT2组NeuN、Ki67/DCX阳性细胞数明显增加(P0.01),MT1组及MT2组BDNF、TrkB蛋白含量明显增加(P0.01)。结论:褪黑素促进了CCH大鼠海马齿状回区神经再生和行为学的改变,其机制可能与激活BDNF-TrkB信号转导通路有关。     

孕期高果糖摄入对胚胎发育和胎盘血管因子的研究

目的：探讨孕期高果糖摄入对胚胎发育的影响及胎盘血管因子对其影响的机制。方法：成年雌性SD大鼠与正常饮食雄性大鼠进行交配,孕鼠随机分为5组,分别是对照组、正常剂量果糖组、高剂量果糖组、高剂量蔗糖组和超高剂量果糖组,在孕期分别给予1mL去离子水、1.6g/kg、4.8g/kg、4.5g/kg和8.0g/kg的果糖水和蔗糖水灌胃,连续干预3w,于第3w末处死孕鼠,麻醉、取血并剖取胎鼠,检查胎鼠的一般状况、着床、死胎、吸收胎、外观畸形等,制作子代内脏和骨骼标本,观察内脏和骨骼的情况;称量胎重和胎盘重,观察各组间胎盘血管内皮生长因子（VEGF）、血管内皮生长因子受体-1（sFlt-1）和一氧化氮（NO）的变化。结果：对孕鼠连续进行3w的果糖干预后,超高剂量果糖组子代出生体重显著低于对照组（P＜0.05）;高剂量果糖组、高剂量蔗糖组和超高剂量果糖组子代与对照组和正常剂量果糖组相比,死胎数和吸收胎数显著增加（P＜0.05）;但各组子代并没有发生骨骼畸形和内脏出血。超高剂量果糖组胎盘重量显著低于对照组（P＜0.05）;高剂量果糖组、高剂量蔗糖组和超高剂量果糖组胎盘中VEGF和NO水平显著低于对照组和正常剂量果糖组（P＜0.05）;胎盘中sFlt-1水平明显高于对照组和正常剂量果糖组（P＜0.05）。结论：孕期高果糖摄入可增加子代发生死胎和吸收胎等不良结局的风险,胎盘中VEGF、NO的水平降低和sFlt-1水平增高可能是导致子代发生不良结局的原因,具体机制值得深入研究。     

产前应激子代大鼠海马核转录因子-κB表达的性别差异

本研究采用免疫组织化学和Western blot检测NF-κB p65/p50在产前应激子代海马的表达,并探讨其表达是否存在性别差异。研究结果显示,在雌性子代,中、晚期应激组海马齿状回p65表达显著低于对照组（P〈0．01）,而海马各区p50表达均显著高于对照组（P〈0．01）,中、晚期应激组间p65和p50表达均有显著差异（P〈0．01）。在雄性子代,中、晚期应激组海马齿状回p65表达显著高于对照组（P〈0．01）,晚期应激组海马各区p50表达均显著低于对照组（P〈0．05,P〈0．01）,中、晚期应激组间p65和p50表达均有显著差异（P〈0．01）。雌、雄子代比较,对照组雌、雄p65表达差异极显著妒〈0．01）,p50仅在海马CA1区表达差异极显著（P〈0．01）;中期应激组雌、雄子代大鼠海马p65／p50表达无显著差异;晚期应激组雌、雄海马p65／p50表达均有极显著差异（P〈0．01）。Western blot与免疫组织化学结果基本一致。结果表明,产前不同时期的应激显著影响子代海马NF-κB p65和p50表达,且有性别差异,这可能是产前应激对子代雌、雄大鼠学习记忆能力影响差异的机制之一。     

核磁共振磁场照射对子代大鼠海马突触形态的影响

研究观察了孕期磁共振磁场照射对子代大鼠海马突触超微结构的影响。SD孕鼠妊娠第12-18d给予0．35T核磁共振(magnetic resonance imaging,MRI)磁场照射。测量1、2和5月龄雌性仔鼠海马CAl区和齿状回的突触结构参数,用立体计量学方法进行定量测定。结果显示,磁场照射可引起2月龄子代大鼠海马CAl区突触间隙增宽．齿状回突触活性区长度变短、突触界面曲率和活性区面密度减小;5月龄子代大鼠CAl区突触间隙增宽,突触后致密物变薄,突触界面曲率减小,齿状回突触间隙增宽。结果提示,妊娠期接受MRI磁场照射可引起海马突触超微结构的改变。对这些结构变化与行为损害之间的关系进行了讨论。     

地塞米松致子代大鼠海马轴突发育损伤

为了探讨地塞米松对子代大鼠海马轴突的影响,建立了孕期地塞米松暴露（prenatal dexamethasone exposure, PDE）模型。Wistar大鼠于孕中晚期皮下注射地塞米松（0.2 mg·kg^-1·d^-1）,部分子代于孕20天（GD20）、出生后12周（PW12）处死取海马样本,检测海马糖皮质激素受体（glucocorticoid receptor, GR）活化指标以及轴突损伤指标。PDE子代胎鼠海马GR活化,GR、糖皮质激素调节激酶1（glucocorticoid-regulated kinase 1, SGK1）和FK506结合蛋白（FK506 binding protein 5, FKBP5）表达显著增加。轴突损伤指标包括生长相关蛋白43（growth associated protein-43,GAP43）、信号素3A（semaphorin 3A, SEMA3A）和集聚蛋白（agrin）表达明显升高。而PDE成年子代大鼠海马GR无明显活化,轴突损伤指标GAP43、SEMA3A和AGRIN表达明显升高。研究结果证实PDE通过活化胎海马GR引起轴突发育损伤,且轴突损伤可延续至出生后。     

Time-Course of Changes in Phosphorylated CREB in Neuroblasts and BDNF in the Mouse Dentate Gyrus at Early Postnatal Stages

Cyclic AMP (cAMP) response element-binding protein (CREB) is involved in memory, learning, and synaptic transmission. In this study, we observed changes of phosphorylated CREB (pCREB) immunoreactivity and its protein levels as well as brain-derived neurotrophic factor (BDNF) levels in the hippocampal dentate gyrus at postnatal (P) 1, 7, 14, and 21 in mice. In addition, we also investigated pCREB expression in doublecortin (DCX, a marker for neuronal progenitors) immunoreactive neuroblasts at P21. pCREB immunoreaction at P1 was detected in most of cells in the dentate gyrus, thereafter pCREB immunoreactivity was decreased in all the layers of the dentate gyrus with time, however, strong pCREB immunoreactivity was shown in cells confined to the subgranular zone of the dentate gyrus at P21. In this group, many pCREB immunoreactive cells were co-localized with DCX immunoreactive neuroblasts. In addition, pCREB protein levels were decreased with age, showing that their levels were very low at P21, while BDNF protein levels were increased with age. These results suggest that pCREB may play important roles in functional maturity of granule cells in mice.     

Long term effects of prenatal cocaine exposure on bone in rats

Prenatal exposure to cocaine has been shown to produce a variety of effects on skeletal development and mineralization in humans, mice, and rats. The effects of cocaine on bone cell function and mineral metabolism pre- and postnatally are poorly understood. The present study examined the long term effects of prenatal cocaine exposure on femoral growth and mineralization in male rats. Pregnant rats were given 80 or 100 mg cocaine hydrochloride/kg during days 7-20 of gestation. At birth, body weights of pups born to these females were significantly decreased compared to normal and pair-fed controls. At the termination of the study (32 weeks), body weights of offspring from C100-treated females were still lower than normal. Long term effects of prenatal exposure to cocaine on femoral growth were most pronounced in offspring of C80-treated females. Femur dry weight, ash weight, organic matrix weight and density were significantly reduced in these animals compared to normal or pair-fed controls. The apparent osteopenic effects of prenatal exposure to cocaine suggests some long term postnatal impact on bone cell or mineral metabolism. Previous studies of cocaine use during pregnancy in humans and animals have focused primarily on physical and behavioral defects in offspring. The present findings indicate that prenatal exposure to cocaine may also have long term consequences to the skeleton.     

Age-related Differentiation in Newly Generated DCX Immunoreactive Neurons in the Subgranular Zone of the Gerbil Dentate Gyrus

In the present study, we investigated age-related changes of newborn neurons in the gerbil dentate gyrus using doublecortin (DCX), a marker of neuronal progenitors which differentiate into neurons in the brain. In the postnatal month 1 (PM 1) group, DCX immunoreactivity was detected in the subgranular zone of the dentate gyrus, but DCX immunoreactive neurons did not have fully developed processes. Thereafter, DCX immunoreactivity and its protein levels in the dentate gyrus were found to decrease with age. Between PM 3 and PM 18, DCX immunoreactive neuronal progenitors showed well-developed processes which projected to the granular layer of the dentate gyrus, but at PM 24, a few DCX immunoreactive neuronal progenitors were detected in the subgranular zone of the dentate gyrus. DCX protein level in the dentate gyrus at PM 1 was high, thereafter levels of DCX were decreased with time. The authors suggest that a decrease of DCX immunoreactivity and its protein level with age may be associated with aging processes in the hippocampal dentate gyrus.     

Relations among birth condition, maternal condition, and postnatal growth in captive common marmoset monkeys (Callithrix jacchus)

The present study characterizes the relations among maternal condition, litter size, birth condition, and growth in body weight for a population of common marmosets. The subjects of the study were marmosets born into a single colony between 1994 and 2001. Three sets of analyses were conducted to answer the following questions: 1) Is there a relationship between litter size, maternal condition, and birth condition? In the study population, maternal body weight, maternal age, litter size, and birth condition were related in a complex fashion. Birth weight and prenatal long‐bone growth, as reflected in knee–heel length, were both related to maternal age, with older mothers supporting higher prenatal growth. Age and maternal condition appeared to interact as determinants of long‐bone growth, as the combination of older and larger mothers resulted in significantly longer knee–heel lengths in their offspring. 2) Is there a relationship between birth condition or maternal condition and subsequent growth or final adult size? The early growth rate in this population was similar to early growth rates reported for three different marmoset colonies, suggesting that early growth may be relatively inflexible in this species. However, within this population, the variation that did occur in early growth rate was related to birth weight and maternal weight. Later growth and adult weight were related to birth weight and litter size: small twin infants displayed slower later growth rates and were smaller as adults than twins that began life at a higher birth weight, while the birth weight of triplets was not related to adult size. In these marmosets, small infants that were the result of increased litter size differed from small infants whose small birth size resulted from other factors. This reinforces the proposal that the causes of low birth weight will be relevant to the development of the marmoset as a model of prenatal environmental effects. Am. J. Primatol. 62:83–94, 2004. © 2004 Wiley‐Liss, Inc.     

Effects of prenatal X-irradiation on the 14th-18th days of gestation on postnatal growth and development in the rat

Thirty-nine pregnant adult Wistar strain rats were randomly assigned to one of three exposure groups: 0, 0.75, or 1.50 Gy X-radiation total exposure. Animals were exposed from the 14th to the 18th days of gestation at 0, 0.15, or 0.30 Gy per day. At term, 15 rats were killed and morphologic analyses were completed. Twenty-four rats were allowed to deliver their offspring. On the first day of postnatal life, litters were reduced to a maximum of eight pups per litter, with equal numbers of male and female offspring wherever possible. A total of 187 pups were observed for the age of acquisition of five reflexes (air righting, surface righting, visual placing, negative geotaxis, auditory startle) and the appearance of four physiologic markers (pinna detachment, eye opening, vaginal opening, testes descent). There was significant dose-related weight reduction in term fetuses and offspring throughout the 86-day postnatal period. Postnatal growth rate (g gained/day) was unaffected. Adult offspring brain and gonadal weight and organ weight:body weight ratios were reduced. Using the PAC50 methodology, dose-related alterations occurred in the acquisition of several reflexes. All physiologic markers exhibited a dose-related delay in appearance. These results indicate that fractionated exposure to X-radiation during the fetal period in the rat results in dose-dependent alterations in postnatal growth and physiologic development. These studies are important for our understanding of the long-range effects of prenatal exposure to ionizing radiation late in gestation.     

Differences in Doublecortin Immunoreactivity and Protein Levels in the Hippocampal Dentate Gyrus Between Adult and Aged Dogs

Doublecortin (DCX), a microtubule-associated protein, specifically expresses in neuronal precursors. This protein has been used as a marker for neuronal precursors and neurogenesis. In the present study, we observed differences in DCX immunoreactivity and its protein levels in the hippocampal dentate gyrus between adult and aged dogs. In the adult dog, DCX immunoreactive cells with well-stained processes were detected in the subgranular zone of the dentate gyrus. Numbers of DCX immunoreactive cells in the dentate gyrus of the aged dog were significantly decreased compared to those in the adult dog. DCX immunoreactive cells in both adult and aged dog did not show NeuN (a marker for mature neurons) immunoreactivity. NeuN immunoreactivity in the aged dog was poor compared to that in the adult dog. DCX protein level in the aged dentate gyrus was decreased by 80% compared to that in the adult dog. These results suggest that the reduction of DCX in the aged hippocampal dentate gyrus may be involved in some neural deficits related to the hippocampus.     

Processes at the origin of similarities in dispersal behaviour among siblings

Processes which generate natal dispersal are largely unknown. This is particularly the case for the sources of differences among families. Three types of processes can generate the variability among families: genetic, prenatal and postnatal. We first tested the family resemblance of dispersal behaviour in the common lizard (Lacerta vivipara). We then experimentally investigated the role of pre‐ and postnatal factors in the variability of dispersal among families. From 1989 to 1992, we studied dispersal of juveniles from pregnant females captured in the field and maintained in laboratory until parturition. We manipulated the conditions of gestation to test for prenatal effects on juvenile dispersal. We tested postnatal effects by releasing siblings of the same family in contrasted environments. We also examined covariances of natal dispersal with maternal and offspring traits. The results showed that: (1) dispersal behaviour was similar among siblings, (2) determinants of offspring dispersal differed between sexes and years, (3) offspring dispersal was related to litter sex‐ratio and offspring corpulence at birth, (4) postnatal conditions influenced male dispersal, (5) short‐term prenatal conditions (i.e. maternal conditions during gestation) influenced juvenile dispersal, varying per year, (6) long‐term prenatal conditions (i.e. maternal conditions during gestation in the previous year) could also influence juvenile dispersal (marginally significant). Thus, several types of processes determine natal dispersal in the common lizard. Resemblance among siblings can partly be explained by both pre‐ and postnatal effects. The environment seems to be the major factor influencing juvenile dispersal in this species, i.e. dispersal essentially appears condition‐dependent. The genetic basis of dispersal in vertebrates remains to be demonstrated by studies controlling for both prenatal and postnatal conditions.