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Effects of Stress on the Behavior and Learning of the Rat Offsprings

Author: MaoFengXia
Tutor: YaoMeiLing
School: Zhengzhou University
Course: Pediatrics
Keywords: Prenatal stress Open field test Y-shaped maze CREB BDNF
CLC: R714.2
Type: Master's thesis
Year: 2009
Downloads: 34
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Abstract

With the social pressure of competition is increasing, people are facing a variety of stressful events are also growing, increasing attention has been paid on stress caused by a variety of physical and mental illnesses. Pregnancy is a special time within this period, they also inevitably will experience a variety of stressful events during pregnancy stress can impact on the offspring of women experienced scholars increasingly a subject of concern. The experimental rat model of stress during pregnancy to detect stress group and control group sub hippocampal tissue the inner ring adenosine monophosphate response element binding protein (CAMP-responsive element binding protein CREB) and brain-derived neurotrophic factor (brain derived neurotrophic factor BDNF) expression, and to detect the offspring behavior and learning and memory, to investigate the stress affect offspring rats during pregnancy. Materials and methods an object using the Experimental Animal Center of Zhengzhou University School of Medicine thoroughbred mature Wistar rats. 32 female rats, eight male rats. 2 Methods 2.1 modeling: 22:00 pm so that male and female rats in the same cage, the next morning at 8:00 on the female vaginal smear, visible under a microscope sperm female mice treated as conception, the conception of the female mice were randomly divided into a control group and stress group, the control group of normal feeding to childbirth, pregnancy restraint stress stress group. Pregnancy of pregnant mice on day 19, were taken to the control group and stress group of pregnant mice tail blood 1ml, using the enzyme-linked immunosorbent assay in blood of pregnant rats in each group glucocorticoid levels. Groups of pregnant mice produced offspring the normal feeding each group were randomly selected to one-month-old male and female offspring 30 experiments. 2.2 open field test: the use of the open field test device behavior activity detection, the number of offspring across horizontal grid as horizontal movement score hindlimb standing as the number of vertical movement score, recorded the score and vertical movement of each group of sub-mouse horizontal movement score, and then compare the group differences. 2.3 Y-type electric maze experiment: the use of Y-type electric maze learning and memory testing, each offspring were tested for three days, taking the results of the third day as the offspring of learning and memory, and then compare the group differences. 2.4 Specimen collection: after the end of the Y-type electric maze experiment, the offspring of each group were sacrificed after anesthesia, embedded in paraffin, sliced ??hippocampus, were done hematoxylin - eosin staining and immunohistochemical staining. 2.5 CREB and BDNF expression level of determination: hippocampal tissue immunohistochemical staining slices, using computer image analysis system, select a positive area measured gray value and calculate the average gray value (OD), using the average gray value to compare the differences in the levels of CREB and BDNF expression in offspring hippocampus. Statistical analysis using SPSS15.0 statistical package for statistical analysis of each group of data are (?) ± s, compared among groups by independent samples t-test and single-factor analysis of variance, α = 0.05 as the level of inspection . Results 1 pregnant rats glucocorticoid levels compare experimental results show that the stress group of pregnant rats tail blood glucocorticoid levels (41.95 ± 10.47) was significantly greater than the control group (20.58 ± 9.39), the difference was statistically significant (t = 16.836, P = 0.027). Prenatal stress can increase glucocorticoid levels of pregnant mice. The sub 2 mouse open field test results stress group sub-mouse with the control group offspring comparison in the level of activity score: the level of stress group sub-rat activity score than the control group (F = 4.316, P = 0.003), the control group of male and female between male and female stress group, there is no gender difference (P> 0.05); between the stress group offspring with the control group offspring comparison of vertical activity score: stress group offspring vertical activity score than the control group ( F = 7.471, P = 0.002), there is no gender difference (P> 0.05) between the control group between male and female and male and female stress group. 3 sub-mouse Y-type electric the maze results of comparison of the stress group sub mice and the control group offspring in learning and memory: stress group sub mice learning and memory scores than the control group (F = 6.562, P = 0.002), the control group there is no gender difference (P> 0.05) between the male and female and between male and female stress group. 4 the offspring hippocampus HE staining results female, male control group offspring hippocampus dentate gyrus granule cells arranged more densely ordered, female and male offspring, stress group dentate gyrus granule cells arranged in loose messy, hippocampal volume and shape, there was no significant difference. The immunohistochemistry results 5.1 CREB immunoreactive cells was brown, mainly located in the nucleus in the CA1 region of the hippocampus, CA2 area, CA3 and the dentate gyrus were expressed mainly distributed in the hippocampal dentate gyrus granule cells layer. CREB expression in the hippocampus of female stress group (87.77 ± 6.34) lower than that of the female control group (92.51 ± 6.53), P <0.05; expression in the hippocampus of male stress group (86.73 ± 7.25) was significantly lower than that of the male control group (93.33 ± 6.43), P <0.05; between CREB in the control group, male and female, the expression between the stress group of male and female gender differences (P> 0.05). 5.2 BDNF immunoreactive cells was brown, mainly located in the cytoplasm and cell membrane expression in the CA1 region of the hippocampus, CA2 area, CA3 and the dentate gyrus region, the particles in the hippocampal CA1 and dentate back deep layer of cells staining. BDNF expression in the hippocampus of female stress group (86.96 ± 7.32) is lower than the female control group (94.85 ± 6.96), P <0.05; expression in the hippocampus of male stress group (87.32 ± 7.00) was significantly lower than male control group (95.32 ± 7.01), P <0.05; BDNF between male and female of the control group, the expression between the stress group of male and female gender differences (P> 0.05). Conclusion 1. Pregnant rats prenatal stress may lead to the decline of the offspring hippocampus CREB and BDNF expression. Prenatal stress in pregnant mice may lead to offspring hyperactivity, excitement and other acts of emotional problems. Pregnant rats prenatal stress may result in offspring learning memory decline. Pregnant rats prenatally stressed offspring may no gender differences.

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