BDNF和NT-3对胚胎大鼠脊髓神经元生长发育的影响

为研究脑源性神经营养因子 (BDNF)和神经营养因子 3(NT 3)对体外培养的胚胎大鼠脊髓神经元存活和生长发育的影响 ,在倒置相差显微镜下观察原代培养的神经细胞存活和生长发育情况 ,计数并进行显微测量。实验数据均以均数±标准差表示 ,进行方差分析和SNK检验。结果 :BDNF和NT 3均能促进培养的胚胎大鼠脊髓神经元的存活 ,BDNF的作用更显著。两者还促进脊髓神经元的生长发育 ,BDNF主要促进胞体的发育 ,NT 3主要促进突起的生长。提示 :BDNF和NT 3对培养的胚胎大鼠脊髓神经元的存活和生长发育有促进作用 ,其作用具有选择性     

BDNF和NT-3对体外培养胎鼠脊髓神经元生长发育的影响

目的:观察脑源性神经生长因子(BDNF)和神经营养因子-3(NT-3)单独及联合应用对体外培养胚胎大鼠脊髓神经元存活和生长发育的影响。方法:胚胎大鼠脊髓神经细胞原代培养,倒置相差显微镜下进行细胞记数和显微测量,观察神经元存活和生长分化的状况。结果:BDNF和NT-3均能促进培养胚胎大鼠脊髓神经元的存活,BDNF的作用效果更好。BDNF主要促进胞体发育;NT-3主要促进突出分化和伸长,二者有互补作用。结论:BDNF和NT-3能促进体外培养大鼠发育期脊髓神经元存活、分化和生长,其作用具有选择性。     

人基因组DNA片段对胚胎小鼠脊髓培养神经元的影响

目的：研究人基因组ＤＮＡ对培养的小鼠脊髓神经元活性及突起生长的影响．方法：用酚－氯仿抽提法从人胚脑中提取人基因组ＤＮＡ片段,用此ＤＮＡ片段加至体外培养的胚胎小鼠脊髓神经元培养液中,培养３ｄ后作ＭＴＴ实验,ＮＳＥ染色,图像分析神经元突起的长度．结果：实验组的神经元突起长度明显长于对照组而活性与对照组无明显差异．结论：提示人基因组ＤＮＡ或其某些片段可促进神经元突起的生长而对神经元活性无影响     

PKC在NGF促进胚胎大鼠脊髓神经元生长发育中的作用

目的：研究蛋白激酶C(PKC)在神经生长因子（NGF）促进胚胎大鼠脊髓神经元生长发育中的作用。方法：体外培养胚胎大鼠颈段脊髓神经元，施加NGF，观测神经元生长发育情况并检测胞膜及胞浆PKC活性。结果：培养2，4d时，实验组与对照组相比细胞膜PKC活性增强；膜质比增高，4，7d时神经元存活数量增多，神经突起生长明显增强。结论：在NGF促进体外培养的胚胎大鼠脊髓神经元生长发育过程中，PKC有可能发挥了正向调节作用。     

脊髓腹角神经元共存NGF,BDNF,NT_3,NT_4和GDNF

用NGF ,BDNF ,NT3,NT4 和GDNF抗血清 ,以免疫组织化学方法观察NGF ,BDNF ,NT3,NT4 及GDNF在成年猫L5脊髓腹角神经元是否共存 结果 :L5脊髓腹角神经元均含有上述被检测的 5种神经营养因子的免疫反应物 ,表明腹角神经元共存NGF ,BDNF ,NT3,NT4 及GDNF ,提示这 5种神经营养因子可能与脊髓腹角神经元的生理过程有关     

巨噬细胞条件培养基对脊髓腹侧神经元突起生长的影响

目的：为临床采用积极手段治疗神经损伤提供资料。方法：用细胞培养、ＡＣｈＥ组化染色等方法观察巨噬细胞条件培养基对胚鼠脊髓腹侧神经元突起生长的影响。结果：巨噬细胞条件培养基有促进脊髓腹侧神经元突起生长的作用。当神经细胞培养达６ｄ时，实验组神经突起生长长度平均为１４５．９０±３１．４８μｍ，对照组仅为６０．４４±１６．６６μｍ（Ｐ＜０．００１）。结论：临床上治疗周围神经损伤，特别是陈旧性损伤时，如在损伤处人为的造成一种巨噬细胞浸润的微环境或使用巨噬细胞源性的营养因子，可促进运动神经再生。     

成年猫备用背根节内神经营养素-3对节内神经元的神经营养作用

目的 探讨成年猫部分去传入后备用背根节内神经营养素-3对节内神经元的神经营养作用。方法 切断L1、L3、L5和L7背根．术后第7d摘取L2、L4和L6背根节做分离细胞培养。对正常背根节、备用背根节和备用背根节加抗体封闭3个实验组中神经元存活、突起生长等情况进行观察比较。结果 备用背根节组存活细胞和细胞微团数目以及神经突起长度均明显高于正常组和抗体封闭组。结论 备用背根节内神经营养素-3对节内神经元有维持存活、促进突起生长的作用。     

人胚胎脊髓神经干细胞生长及分化过程中BDNF的作用研究

目的研究脑源性神经营养因子对人胚胎脊髓神经干细胞生长和分化的影响。方法孕20周水囊引产胎儿标本经家属同意捐赠,分离培养脊髓神经干细胞,分为正常对照组、BDNF蛋白组、BDNF抗体封闭组,计数神经球数目并以MTT法检测细胞活力,免疫组织化学检测NeuN和GFAP的表达情况并进行计数。结果与对照组相比,BDNF蛋白组神经球数目或MTT值均无明显变化,BDNF抗体封闭组的神经球数目和MTT值有明显减少(P<0.05);BDNF蛋白组NeuN阳性细胞数明显多于对照组(P<0.05),GFAP阳性细胞数与对照组相比有明显减少(P<0.05),BDNF抗体封闭组NeuN或GFAP阳性细胞数均少于对照组(P<0.05)。结论外源性BDNF可促进人胚胎脊髓神经干细胞向神经元样细胞分化;内源性BDNF在人胚胎脊髓神经干细胞的增殖分化过程中发挥重要作用。     

针刺对神经营养素3在脊髓可塑性中表达的影响

目的：探讨针刺对神经营养素3（NT3）在脊髓可塑性中表达的影响。方法：用NT3抗血清和NT3 cRNA探针，以免疫组化和原位杂交技术观察针刺前后备用背根节及脊髓Ⅱ板层中NT3表达的变化。结果：针刺侧备用背根节（DRG）NT3及其mRNA阳性大神经元（＞57um)和小神经元（P＜42um)百分数均较非针刺侧者明显增多（P＜0．05），此外，脊髓针刺侧Ⅱ板层NT3阳性神经元及胶质细胞百分数针刺侧亦较非针刺侧明显增多（P＜0．05），但两侧均未见NT3 mRNA的杂交信号。结论：针刺促进脊髓可塑性可能与DRG大，小神经元表达NT3和脊髓Ⅱ板层NT3阳性神经元和胶质细胞百分数的增多有关。     

神经营养因子对体外培养多巴胺能神经元营养作用比较研究

目的：比较5种神经营养因子对体外培养多巴胺能（DA）神经元营养作用差别。方法：在培养孕14－16d大鼠胚胎黑质神经元中加入5种神经营养因子（NTF）。采用免疫组化染色及计算机图像的分析系统对培养细胞进行观察。结果：脑源性神经营养因子（BDNF）、血小板源性生长因子（PDGF）及碱性成纤维细胞生长因子（bFGF)能促进中脑DA神经元发育,提高神经元及长突起神经元存活率。BDNF在整个培养期都有较强营养作用,PDGF在早期、bFGF在中期有轻度作用,神经生长因子（NGF）和白细胞介素－6（IL－6）则无作用。结论：体外DA神经元培养过程中,BDNF有较强的神经营养作用,PDGF和bFGF次之,NGF和IL－6无作用。     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.     

Effects of unpredictable chronic stress on behavior and brain-derived neurotrophic factor expression in CA3 subfield and dentate gyrus of the hippocampus in different aged rats

Background Brain-derived neurotrophic factor (BDNF) is a stress-responsive intercellular messenger modifying hypothalamic-pituitary-adrenal (HPA) axis activity. The interaction between stress and age in BDNF expression is currently not fully understood. This study was conducted to observe unpredictable stress effect on behavior and BDNF expression in CA3 subfield (CA3) and dentate gyrus of hippocampus in different aged rats. Methods Forty-eight Wistar rats of two different ages (2 months and 15 months) were randomly assigned to six groups: two control groups and four stress groups. The rats in the stress group received three weeks of unpredictable mild stress. The depression state and the stress level of the animals were determined by sucrose preference test and observation of exploratory behavior in an open field (OF) test. The expressions of BDNF in CA3 and dentate gyrus of the hippocampus were measured using immunohistochemistry. Results Age and stress had different effects on the behavior of different aged animals (age: F=6.173, P <0.05, stress: F=6.056, P <0.05). Stress was the main factor affecting sucrose preference (F=123.608, P <0.05). Decreased sucrose preference and suppressed behavior emerged directly following stress, lasting to at least the eighth day after stress in young animals (P <0.05). The older stress rats showed a lower sucrose preference than young stress rats (P <0.05). Older control rats behaved differently from the younger control animals in the OF test, spending more time in the central square (P <0.05), exhibiting fewer vertical movements (P <0.05) and less grooming (P <0.05). Following exposure to stress, older-aged rats showed no obvious changes in vertical movement and grooming. This indicates that aged rats were in an unexcited state before the stress period, and responded less to stressful stimuli than younger rats. There was significantly lower BDNF expression in the CA3 and dentate gyrus regions of the hippocampus following stress in both age groups (P <0.05), a reduction that was still present at the eighth day after stress (P <0.05). Stress and age were the main factors affecting the expression of BDNF (F=9.408, P <0.05; F=106.303, P <0.05). The aged stress group showed lower BDNF expression compared to the young stressed group at every testing time point. Conclusion Stress has age-dependent effects on behavioral responses and hippocampal BDNF expression in rats.