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。     

大鼠产前母体冷应激对子代自发、探索及焦虑行为的影响*

目的: 研究产前冷应激对妊娠大鼠子代行为及情绪的影响。方法: 将6只SPF级Wister妊娠母鼠,随机分为常温对照组和冷应激组,每组3只。常温对照组妊娠母鼠在(22±2)℃的环境中饲养,冷应激组妊娠母鼠在产前7 d置于人工智能气候室(4±0.1)℃中饲养,待产下幼鼠以后,分为常温对照组公鼠(MR,22只),常温对照组母鼠(FR,15只),冷应激组公鼠(MC,15只),冷应激组母鼠(FC,15只)四组,在子代第四周龄时进行旷场实验、高架十字迷宫实验。结果: 在旷场实验中,常温对照组公鼠、母鼠与冷应激组公鼠、母鼠的自发活动、探索行为之间无明显差异(P＞0.05)。在高架十字迷宫实验中,冷应激组公鼠、母鼠的开臂滞留时间、开臂进入次数及路程等总体上显著高于常温对照组公鼠、母鼠(P＜0.05)。结论: 产前母体冷应激对子代自发活动、探索行为及活跃程度无显著影响,但子代出现明显的焦虑行为减少的异常行为。     

慢性低氧对雄性大鼠血浆皮质酮及睾酮水平的影响

目的:研究低氧对雄性大鼠性腺及相关激素水平的影响。方法:分别检测3km、5km及杭州海拔水平雄性大鼠睾丸和附睾指数、血浆皮质酮和睾酮水平。结果:3km组体重、睾酮含量均显著下降,睾丸指数、血浆皮质酮显著上升;5km组体重、附睾指数和睾酮含量均显著下降,皮质酮含量显著上升。结论:慢性低氧能显著影响雄性成年大鼠性腺及血浆睾酮水平,该结果显示哺乳动物在慢性低氧条件下生殖内分泌功能呈现抑制状态。     

孕期应激下调成年雄性子代大鼠海马HDAC2表达

目的明确母代大鼠孕期应激对雄性子代海马中组蛋白去乙酰化酶2(histone deacetylase 2, HDAC2)表达变化的影响。方法将16只SD孕鼠随机分为应激组和对照组,每组8只,应激组在孕16-21天进行限制性应激,对照组不做任何处理。ELISA检测成年子代外周血血浆糖皮质激素,用旷场、高架十字迷宫、新物体识别及巴恩斯迷宫四种行为学评估成年子代认知功能,免疫组织化学、Western blot、RT-PCR 检测成年雄性子代海马HDAC2表达变化。结果母代孕期应激成年子代糖皮质激素升高,旷场与高架十字迷宫中表现出焦虑样行为,新物体识别与Barnes迷宫表现出学习记忆与空间记忆能力下降,海马HDAC2 mRNA和蛋白水平均下调。结论孕期应激对子代成年的认知功能损害可能与子代海马HDAC2的表达下调有关。     

ω-3多不饱和脂肪酸和三羟异黄酮孕期营养干预对母鼠及新生子代的影响

目的:了解孕期母鼠摄入ω-3多不饱和脂肪酸和三羟异黄酮对胎儿的影响。方法:采用刚怀孕的SD大鼠,进行孕期营养干预,观察营养物质对母鼠、新生子代大鼠的影响。结果:孕期营养干预对母鼠的孕期长短、产仔数量、性别比、雌激素水平影响没有统计学显著性差异,营养干预后的子代SD大鼠无出生缺陷的发生。结论:ω-3多不饱和脂肪酸和三羟异黄酮孕期营养干预对母鼠和子代无不良影响。     

全氟辛烷磺酸盐对胚胎期大鼠雄性生殖系统的影响

目的:研究全氟辛烷磺酸盐(PFOS)对胚胎期大鼠雄性生殖系统发育的影响.方法:PFOS分别以5、10、20 mg· kg-1·d-1灌胃染毒孕12-19天的SD母鼠,染毒结束后,测量雄性胎鼠体重、身长、睾丸重量、AGD;酶联免疫吸附法检测雄性胎鼠睾丸内睾酮水平;实时荧光定量PCR法测睾丸组织类固醇激素合成急性调节蛋白(StAR)、胰岛素样因子3(INSL3)mRNA的相对表达量.结果:与对照组相比,高剂量染毒组雄性胎鼠体重、体长、AGD长度显著降低(P＜0.01),睾丸重量减轻(P＜0.05);高剂量染毒组雄性胎鼠睾丸中内睾酮水平下降(P＜0.05);高剂量染毒组雄性胎鼠睾丸组织中StAR mRNA的表达量降低(P＜0.05),而中剂量染毒组StAR mRNA和INSL3 mRNA表达量则明显升高(P＜0.01).结论:孕期染毒PFOS对雄性胚胎生殖系统的发育有毒性作用,其机制可能与PFOS影响睾酮合成和INSL3 mRNA的表达有关.     

模拟海拔3600m低氧环境对人的认知灵活性的影响

目的：探讨模拟高原低氧环境对人认知灵活性的影响。方法：低氧舱模拟海拔3600m低氧环境,采用任务转换范式观察低氧模拟各阶段的认知灵活性,同时监测焦虑状态及基本生理指标的变化。23名无高原生活经验、平均年龄25．1岁的男性受试者参加了实验。结果：与低氧暴露1个月后的基础对照相比,低氧阶段的反应时转换损失显著增加;低氧阶段焦虑水平显著高于适应阶段;在适应阶段,焦虑水平与反应时转换损失显著负相关;而在降舱阶段,焦虑水平与反应时转换损失显著正相关。结论：中度低氧暴露影响人的认知灵活性和焦虑状态;低氧暴露前,焦虑可促进个体的认知灵活性;低氧暴露后,焦虑会阻碍个体的认知灵活性。     

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。     

低氧对小鼠学习记忆力及脑中tau蛋白磷酸化的影响

目的：研究不同低氧暴露对小鼠学习记忆及脑中tau蛋白磷酸化的影响。方法：雄性昆明小鼠40只,随机分为4组（n=10）：对照组（control）、8h低氧暴露组（8h）、7d低氧暴露组（7d）和28d低氧暴露组（28d）。将低氧暴露模型组置于模拟高原海拔5500m的低压氧舱,每天低氧暴露8h,避暗和旷场实验检测其活动能力及学习记忆能力：免疫印迹技术检测小鼠海马和皮层中tau蛋白磷酸化水平。结果：随着低氧时间的增加,小鼠短期学习记忆力及活动能力下降程度增大,28d低氧暴露后其下降程度最大;海马中tau蛋白多个位点的磷酸化水平呈现升高趋势,28d时tau蛋白磷酸化程度最高（P〈0．05）;皮层中的磷酸化水平在低氧暴露7d时达到最高,低氧暴露28d时略有降低,但与control组相比仍有明显差异（P〈0．05）。结论：慢性间歇性低氧可导致小鼠学习记忆能力下降,其机制可能与tau蛋白过度磷酸化相关。     

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。     

根田鼠母体捕食应激对其雄性子代性行为去雄性化的效应

母体应激效应是母体在妊娠期经历的环境变化对子代发育、繁殖及存活等特征的影响(MousseauandFox ,1 998;Bernado ,1 996 )。该效应不仅能使子代生活史特征产生迟滞性效应(Beckermanetal.,2 0 0 2 ) ,而且在密度制约过程中,导致对种群的迟滞性密度制约(Delayeddensitydependenc     

低氧脑水肿大鼠脑组织VEGF和AQPs基因及蛋白表达的变化

目的：探讨低氧脑水肿时血管内皮细胞生长因子（VEGF）、水通道蛋白（AQP1和AQP4）基因和蛋白表达变化,为阐明急性低氧对脑组织的损伤及低氧脑水肿的发病机制提供实验依据。方法：Wistar大鼠随机分为4个组：常氧对照组（Control）、低氧暴露4 000 m组（4 000 m）、低氧暴露6 000 m组（6 000 m）和低氧暴露8 000 m组（8 000 m）,低氧组于低压舱中模拟相应海拔高度持续暴露8 h建立低氧脑水肿模型。用干-湿重法测定脑组织水含量,常规光镜观察脑组织形态学的改变;用RT-PCR法和免疫组化法检测低氧脑水肿时大鼠脑组织VEGF、AQP1和AQP4mRNA和蛋白表达的变化。结果：①干-湿重法测定表明,低氧（≥6 000 m）暴露后,大鼠脑组织水含量明显增加（P〈0.01）。②常规光镜检测结果表明,低氧暴露4 000 m时大鼠脑神经细胞、血管内皮细胞和星形胶质细胞足突轻度肿胀,组织中出现漏出液;低氧暴露6 000 m时脑血管内皮细胞和星形胶质细胞足突肿胀加重,血管与组织间隙扩大,组织中漏出液增多;低氧暴露8 000m时脑血管内皮细胞和星形胶质细胞足突重度肿胀,血管与组织间隙进一步扩大,组织中漏出液明显增多。③低氧脑水肿时,VEGF、AQP1、AQP4mRNA表达水平增高,AQP1在内皮细胞异常表达,内皮细胞VEGF和AQP1、星形胶质细胞足突AQP4蛋白质表达水平增高。结论：低氧脑水肿时,VEGF、AQP1和AQP4表达和分布的变化可能是引起血脑屏障损伤、导致低氧脑水肿的发病机制之一。     

Developmental programming of cardiovascular dysfunction by prenatal hypoxia and oxidative stress

Fetal hypoxia is a common complication of pregnancy. It has been shown to programme cardiac and endothelial dysfunction in the offspring in adult life. However, the mechanisms via which this occurs remain elusive, precluding the identification of potential therapy. Using an integrative approach at the isolated organ, cellular and molecular levels, we tested the hypothesis that oxidative stress in the fetal heart and vasculature underlies the molecular basis via which prenatal hypoxia programmes cardiovascular dysfunction in later life. In a longitudinal study, the effects of maternal treatment of hypoxic (13% O(2)) pregnancy with an antioxidant on the cardiovascular system of the offspring at the end of gestation and at adulthood were studied. On day 6 of pregnancy, rats (n = 20 per group) were exposed to normoxia or hypoxia ± vitamin C. At gestational day 20, tissues were collected from 1 male fetus per litter per group (n = 10). The remaining 10 litters per group were allowed to deliver. At 4 months, tissues from 1 male adult offspring per litter per group were either perfusion fixed, frozen, or dissected for isolated organ preparations. In the fetus, hypoxic pregnancy promoted aortic thickening with enhanced nitrotyrosine staining and an increase in cardiac HSP70 expression. By adulthood, offspring of hypoxic pregnancy had markedly impaired NO-dependent relaxation in femoral resistance arteries, and increased myocardial contractility with sympathetic dominance. Maternal vitamin C prevented these effects in fetal and adult offspring of hypoxic pregnancy. The data offer insight to mechanism and thereby possible targets for intervention against developmental origins of cardiac and peripheral vascular dysfunction in offspring of risky pregnancy.     

Could neonatal testosterone replacement prevent alterations induced by prenatal stress in male rats?

The present study was designed to examine whether testosterone replacement is able to prevent some effects of maternal restraint stress — during the period of brain sexual differentiation — on endocrine system and sexual behavior in male rat descendants. Pregnant rats were exposed to restraint stress for 1 h/day from gestational days 18 to 22. At birth, some male pups from these stressed rats received testosterone propionate. The neonatal testosterone replacement was able to prevent the reduction in anogenital distance at 22 days of age observed in pups from stressed pregnant rats as well as prevents the decrease in testosterone levels during the adulthood of these animals. Testosterone replacement in these males also presented an improvement in sexual performance. In this way, testosterone replacement probably through increasing neonatal level of this hormone was able to prevent the later alterations caused by the prenatal stress during the period of brain sexual differentiation.     

Synergistic effects of prenatal hypoxia and postnatal high-fat diet in the development of cardiovascular pathology in young rats

We have previously shown that adult offspring exposed to a prenatal hypoxic insult leading to intrauterine growth restriction (IUGR) are more susceptible to cardiovascular pathologies. Our objectives were to evaluate the interaction between hypoxia-induced IUGR and postnatal diet in the early development of cardiovascular pathologies. Furthermore, we sought to determine whether the postnatal administration of resveratrol could prevent the development of cardiovascular disorders associated with hypoxia-induced IUGR. On day 15 of pregnancy, Sprague-Dawley rats were randomly assigned to hypoxia (11.5% oxygen), to induce IUGR, or normal oxygen (control) groups. For study A, male offspring (3 wk of age) were randomly assigned a low-fat (LF, <10% fat) or a high-fat (HF, 45% fat) diet. For study B, offspring were randomized to either HF or HF+resveratrol diets. After 9 wk, cardiac and vascular functions were evaluated. Prenatal hypoxia and HF diet were associated with an increased myocardial susceptibility to ischemia. Blood pressure, in vivo cardiac function, and ex vivo vascular function were not different among experimental groups; however, hypoxia-induced IUGR offspring had lower resting heart rates. Our results suggest that prenatal insults can enhance the susceptibility to a second hit such as myocardial ischemia, and that this phenomenon is exacerbated, in the early stages of life by nutritional stressors such as a HF diet. Supplementing HF diets with resveratrol improved cardiac tolerance to ischemia in offspring born IUGR but not in controls. Thus we conclude that the additive effect of prenatal (hypoxia-induced IUGR) and postnatal (HF diet) factors can lead to the earlier development of cardiovascular pathology in rats, and postnatal resveratrol supplementation prevented the deleterious cardiovascular effects of HF diet in offspring exposed to prenatal hypoxia.     

Postparturitional testosterone surge in male offspring of rats stressed and/or fed ethanol during late pregnancy

Male offspring of rats exposed to restraint stress and/or alcohol during late pregnancy show aberrant patterns of sexual behavior masculinization and defeminization that vary as a function of treatment. The impact of these treatments on the postparturitional testosterone (T) surge that contributes to sexual behavior differentiation was investigated. Plasma T was measured using radioimmunoassay in individual males sampled on day 21 of gestation within 10 min of cesarean delivery or 1, 2, or 4 h thereafter. Neonatal T in the group exposed only to stress did not differ from that in the control group. T was lower than control levels at birth in both alcohol groups. The magnitude of the T surge that occurred during the first hour of birth in the control group was diminished by 50% in both alcohol groups, whose T pattern was very similar. There was no common alteration in postparturitional T associated with the increased lordotic behavior potential that males in all three treatment groups typically share, nor were there idiosyncratic endocrine abnormalities linked to the very different male copulatory pattern each exhibits. Exposure to an abnormal T milieu during fetal as well as neonatal ontogeny may underlie the etiology of the different sexual behavior patterns exhibited by males exposed to stress and/or alcohol. Possible unique effects each treatment exerts on perinatal plasma T and it's aromatization to estradiol in hypothalamic targets are discussed.     

Influence of maternal stress on offspring sexual behaviour

During the last trimester of gestation, pregnant rats were exposed to crowded living conditions, or to immobilization combined with intense illumination. In adulthood, male offspring of mothers exposed to either condition of stress showed increased readiness to display feminine sexual behaviour (lordosis) while no deficits were observed in their masculine sexual behaviour. It was concluded that prenatal stress adversely affects sexual differentiation by causing a feminization but not a demasculinization of male offspring.     

Changes in masculine sexual behavior, corticosterone and testosterone in response to acute and chronic stress in male rats

Chronic exposure to stressors increases HPA axis activity and concomitantly reduces HPG axis activity. This antagonistic relationship between both these axes has been proposed to underlie the inhibition of reproductive function due to stress. Sexual behavior in males may be the most vulnerable aspect of male reproduction to acute and chronic stress and it has been suggested that alterations in sexual behavior during stress are due to the antagonistic relationship between testosterone and corticosteroids. However, only in a few studies has a correlation between the levels of testosterone and corticosterone, and sexual behavior been made. In this study, we evaluated the effects of different stressors, applied both acute and chronically, on masculine sexual behavior and whether or not these effects on sexual behavior are accompanied by changes in plasma levels of corticosterone and testosterone. Additionally, we evaluated the effect of testosterone treatment on the effects of stress on sexual behavior. Sexually experienced male rats were exposed to one of the following stressors: immobilization (IMB), electric foot shocks (EFS) or immersion in cold water (ICW). Sexual behavior and plasma levels of testosterone and corticosterone were assessed on days 1, 5, 10, 15, and 20 of stress. In a second experiment, males were castrated, treated with 3 different doses of testosterone propionate (TP) and exposed to ICW for 20 consecutive days. Sexual behavior was assessed on days 1, 5, 10, 15, and 20 and steroids were evaluated on day 20. Parameters of masculine sexual behavior were modified depending on the characteristics of each stressor. Mount, intromission and ejaculation latencies increased significantly, the number of mounts increased, and ejaculations decreased significantly in males exposed to EFS and to ICW but not in males exposed to IMB. Associated with these effects, testosterone decreased in the EFS and ICW groups on days 1, 15, and 20. However, corticosterone increased only in males exposed to ICW. In castrated males, TP treatment failed to block the effects of stress by ICW on sexual behavior and corticosterone. These results indicate that the effects of stress on sexual behavior depend on the characteristics of each stressor, and these effects, as well as the decrease in testosterone are not necessarily associated with the increase in corticosterone. The fact that testosterone treatment did not prevent the effects of stress on sexual behavior suggests that other mediators could be involved in the alterations of sexual behavior caused by stress.     

Training in the Morris Water Maze of Female and Male Rats Exposed to Hypoxia at Various Periods of Prenatal Development

Capability for learning was studied in the offspring of rats exposed to hyporbaric hypoxia on the days 11–13, 14–16 or 18–20 of pregnancy. Training in the Morris water maze has been shown to lead to consequences of effect of prenatal hypoxia evident in males, but not in females. The most pronounced changes are found at training in the male rats whose mothers were exposed to hypoxia on the days 14–16 of pregnancy. The revealed differences in the character of learning depend on experimental conditions. Under “severe” stress conditions (at the water temperature of 16–17°C), prenatal hypoxia leads to an improvement of learning parameters as compared with control, while under more favorable conditions (at the water temperature of 23–24°C), to their deterioration.     

Maternal care interacts with prenatal stress in altering sexual dimorphism in male rats

The present study analyzes the interaction between prenatal stress and mother's behavior on brain, hormonal, and behavioral development of male offspring in rats. It extends to males our previous findings, in females, that maternal care can alter behavioral dimorphism that becomes evident in the neonates when they mature. Experiment 1 compares the maternal behavior of foster mothers toward cross-fostered pups versus mothers rearing their own litters. Experiment 2 ascertains the induced “maternal” behavior of the male pups, derived from Experiment 1 when they reached maturity. The most striking effect was that the males non-exposed to the stress as fetuses and raised by stressed foster mothers showed the highest levels of “maternal” behavior of all the groups (i.e., induction of maternal behavior and retrieving behavior), not differing from the control, unstressed, female groups. Furthermore, those males showed significantly fewer olfactory bulb mitral cells than the control males that were non-stressed as fetuses and raised by their own non-stressed mothers. They also presented the lowest levels of plasma testosterone of all the male groups.