低温冷冻对不同月龄大鼠生殖功能的影响

目的 研究低温冷冻应激对下丘脑-垂体-性腺轴影响及不同衰老程度的影响.方法 青年(2月龄)及老年(15月龄)雌性Wistar大鼠各20只.随机分为青年(2月龄)对照组(10只)和老年(15月龄)对照组(10只)和青年(2月龄)应激组(10只)和老年(15月龄)应激组(10只),共4组.对照组设定(16±1)℃.应激组设定(3±1)℃.各组接受应激刺激28d.各组均于应激结束后即刻以称重法了解生殖器官的发育变化.然后取血2ml.以放射免疫法测定血清雌二醇含量.结果 与对照组相比.应激组大鼠卵巢重量和子宫重量和血清雌二醇水平均显著下降(P<0.05);老年组大鼠较青年组大鼠变化显著(P<0.01).结论 低温冷冻应激对不同月龄大鼠的应激损伤程度存在差异,应激对老年大鼠的外显行为和生殖内分泌功能的损伤程度均较青年大鼠严重,提示衰老是影响机体应激反应性的重要因素之一.     

慢性温和应激对大鼠血管内皮功能的影响

目的：探讨慢性温和应激对大鼠血管内皮功能的影响及其作用机制。方法采用孤养与慢性轻度不可预见性应激模型相结合建立慢性温和应激动物模型,随机分为实验组和对照组,采用 ELISA法检测两组大鼠血清皮质醇、细胞间黏附因子1（ICAM-1）、白介素6（IL-6）、血浆内皮素1（ET-1）的含量,透射电镜观察大鼠血管内皮超微结构的改变。结果实验组大鼠第2周和第3周体质量显著低于对照组（P ＜0．05）;血清皮质醇的含量显著增加（P ＜0．05）;血清 ICAM-1、IL-6、血浆 ET-1均较对照组明显升高（P ＜0．05）;血管内皮超微结构改变明显。结论慢性温和应激可导致大鼠血管内皮功能损伤。     

18 kDa 转位蛋白在异氟醚麻醉致大鼠认知损伤中的神经保护作用

目的：观察18 kDa转位蛋白（ TSPO ）在异氟醚麻醉所致的大鼠认知功能损伤中的神经保护作用。方法选取4月龄SD雄性青年大鼠10只,随机分为青年对照组（ AC组）和青年麻醉组（ AA组）;20月龄SD雄性老年大鼠10只,随机分为老年对照组（ OC组）和老年麻醉组（ OA组）。麻醉组吸入2％异氟醚6h,对照组吸入空气6h。麻醉后1d,2d,3d,4d进行水迷宫测试,检测海马组织TSPO蛋白表达。测定麻醉前（ T1）、麻醉诱导6h（T2）、麻醉后24h（T3）、麻醉后48h（T4）血清TNF-α,IL-1β含量。结果与对照组比较,吸入异氟醚后大鼠逃避潜伏期延长（P＜0．05）,老年大鼠延长明显（P＜0．01）;麻醉后大鼠海马区TSPO蛋白表达增加（P＜0．05）,老年大鼠增加显著（P＜0．01）;与T1相比,T2时大鼠血清TNF-α,IL-1β水平均升高（P＜0．05）,T3,T4时逐渐降至正常水平。结论异氟醚可能通过诱发神经炎症导致大鼠认知功能下降,而其认知功能的恢复可能与海马区TSPO蛋白表达增加有关。     

慢性温和应激抑郁模型大鼠S100β蛋白水平的变化

目的：观察慢性不可预知的温和应激抑郁模型（Chronic unpredictable mild stress,CUMS）大鼠行为学的改变以及血浆、脑匀浆中S100β蛋白水平的变化,探讨S100β蛋白在抑郁发生、发展中的作用.方法：30只Wister雄性大鼠随机分为正常对照组和抑郁模型组,利用慢性不可预知的温和应激建立大鼠抑郁模型,正常对照组不予任何刺激,观察并比较2组大鼠行为学表现及液体消耗情况,采用放射免疫法测定血浆皮质醇水平（换算成皮质酮水平）,采用酶联免疫吸附试验夹心法测定S100β蛋白水平,并对2组进行比较.结果：造模4周后,与对照组相比,模型组大鼠水平、垂直运动得分及清洁动作次数、糖水消耗量、1%蔗糖偏爱百分比均明显降低（P＜0.05～0.01）,而纯水消耗量明显增加（P＜0.01）;血浆皮质酮水平在应激2周达高峰,明显高于对照组（P＜0.01）,应激第3周有下降的趋势,与对照组相比差异无统计学意义（P＞0.05）.应激结束后,模型组大鼠血浆S100β蛋白水平明显高于对照组（P＜0.05）,但脑匀浆水平低于对照组（P＜0.01）.结论：CUMS大鼠行为学表现与抑郁症临床表现中的精神运动性阻滞症状极为相似,其S100β蛋白水平的变化可能与CUMS持续性精神行为障碍的发生、发展有关.     

归脾汤对抑郁模型大鼠行为学和雌二醇水平的影响

目的：观察归脾汤对抑郁模型大鼠行为学及血清雌二醇含量的影响，探讨归脾汤抗抑郁的作用机理。方法：雌性Wistar大鼠40只随机分为正常对照组、抑郁症模型组（模型组）、抑郁模型加盐水组（盐水组）、抑郁模型加归脾汤组（中药组），选用慢性不可预见性应激模型。Open—Field法检测造模前后大鼠行为学得分，酶联免疫方法检测血清雌二醇。结果：与正常对照组比较，模型组与盐水组行为学指标及雌二醇含量显著下降，中药组行为学得分及雌二醇含量无明显变化，显示归脾汤具有明显的抗抑郁作用。     

普萘洛尔和哌唑嗪对应激大鼠的保护作用

目的观察肾上腺素能受体拮抗剂普萘洛尔和哌唑嗪对慢性轻度不可预知应激模型(CUMS)大鼠行为学及急应激暴露后血清皮质酮水平(CORT)、中枢海马诱导型一氧化氮合酶(iNOS)表达的影响,探讨其应激保护作用。方法健康成年Wistar雄性大鼠32只,随机分为4组：空白对照组、CUMS组、普萘洛尔组和哌唑嗪组。CUMS造模前后,用旷场实验测各组大鼠的行为学变化。造模结束后,应激动物接受1.0?mA,5?s,持续60次的急性电击刺激,2?h?后断头处死。放射免疫分析法测大鼠血清皮质醇含量换算成皮质酮含量;Western blot测中枢海马中iNOS表达量。结果与对照组比较,普萘洛尔组大鼠水平运动得分、竖立次数和修饰次数减少（P＜0.05）,中枢海马iNOS表达量明显增加（P＜0.01）;哌唑嗪组大鼠与对照组比较无明显差异,血清CORT水平明显高于普萘洛尔组（P＜0.05）。结论哌唑嗪可明显改善CUMS模型大鼠的行为学改变,有利于应激个体再次遭遇急性应激时CORT的调动,减轻应激导致中枢海马损伤的程度。普萘洛尔可缓解应激时的焦虑水平,但不能扭转应激对中枢海马的损伤。     

慢性应激对大鼠葡萄糖耐量及胰岛素抵抗的影响

目的：探讨慢性应激对大鼠葡萄糖耐量及胰岛素抵抗的影响。方法：将40只SD大鼠按体重随机分成应激组和对照组各20只。应激组通过8周的慢性复合应激刺激作为慢性应激动物模型，对照组在此期间正常饲养。在试验4、8周监测大鼠体重、旷场实验、24h尿皮质醇，在实验8周采尾血检测葡萄糖耐量（酶氧化法）、空腹胰岛素（化学发光法）．并计算胰岛素抵抗和B细胞功能。结果：慢性应激大鼠4、8周后体重下降显著（P〈0．05），有明显的行为学改变。应激组大鼠OGTT曲线高峰前移，下降缓慢，在0、30min时两组血糖差异显著（P〈0．05）。应激组大鼠空腹胰岛素、30min胰岛素、胰岛素抵抗、B细胞功能以及24h尿皮质醇与对照组之间差异显著（P〈0．01）。结论：慢性应激引起大鼠糖耐量异常，胰岛素抵抗增加。     

DFO通过HIF-1α/VEGF信号通路促进脊髓损伤修复

目的 探讨去铁胺（DFO）对缺氧诱导因子-1α（HIF-1α）/血管内皮生长因子（VEGF）表达的调控作用,以及因此对脊髓损伤修复的促进作用。〖HTH〗方法 对40只SD大鼠进行脊髓损伤造模,并随机分为4组：假手术组10只,对照组10只,DFO 30 mg/Kg腹腔注射组（DFO 30组）10只以及100 mg/Kg腹腔注射组（DFO 100组）10只。术后观察大鼠行为学功能,脊髓病理学改变以及HIF-1α/VEGF表达情况。结果 术后1周开始,DFO两组大鼠行为学功能较对照组明显改善（均P＜0.05）;而术后2周开始,DFO 100组大鼠行为学功能较对照组进一步明显改善,且DFO 100组改善程度优于DFO 30组（均P＜0.05）。术后4周,对照组大鼠脊髓组织明显减少,内仅有少量HIF-1α/VEGF表达,而DFO 30组髓鞘残余面积相对于对照组明显恢复,DFO 100组髓鞘残余面积明显高于DFO 30组（均P＜0.05）;DFO 30组HIF-1α/VEGF表达量明显高于对照组,DFO 100组HIF-1α/VEGF表达量较DFO 30组更明显（均P＜0.05）。结论 DFO通过调控HIF-1α/VEGF表达有效促进脊髓损伤修复,大剂量DFO应用可能具有更好的脊髓损伤修复效果。     

不同年龄实验大鼠肾脏缺血再灌注的比较研究

①目的探讨不同年龄实验大鼠肾缺血再灌注后氧化和抗氧化状态及其机制。②方法SD大鼠24只，随机按鼠龄分为青年大鼠对照组（YCG）、青年大鼠实验组（VMC）、老年大鼠对照组（ACC）、老年大鼠实验组（AMG），每组均为6只。实验组制作肾缺血再灌注模型。分别用硫代巴比妥酸法测定血清MDA含量，亚硝酸盐法检测血清SOD活性。③结果老年大鼠对照组及老年大鼠实验组血清SOD活性显著低于青年大鼠对照组及青年大鼠实验组（P〈0．01）；老年大鼠实验组血清MDA含量显著高于其对照组（P〈0．01）。④结论老年大鼠肾脏缺血再灌注损伤与活性氧引起的氧化损伤以及抗氧化作用的减弱有关；老年大鼠肾脏氧化和抗氧化能力的随增龄变化，其损伤改变更为明显.     

肥胖与雌性幼龄SD大鼠青春期发育提前的相关性研究

【摘要】目的 探讨肥胖与雌性幼龄SD大鼠与青春发育提前之间的相关性。方法 将10只雌性SD大鼠与6只雄性SD大鼠随机分为两组,分别为亲代模型组（雌鼠n=5,雄鼠n=3）、亲代对照组（雌鼠n=5,雄鼠n=3）,造模筛选后保证雄雌谁昂比为2：1。模型组以高脂饲料饲喂8周造模,对照组用普通大鼠饲料饲喂,8周后筛选体质量大于对照组20%的模型组亲代大鼠体进行交配,繁殖的雌性仔鼠设定为模型组仔鼠,亲代对照组大鼠繁殖的雌性仔鼠作为对照组仔鼠。模型组仔鼠造模方法与模型组亲代大鼠相同,均为同配方高脂饲料饲喂,21日龄断乳后饲喂5周,对照组仔鼠则用普通饲料饲喂5周。自21日龄起每日观察仔鼠阴门开启情况,阴门开启后每日均进行阴道涂片检查,观察动情周期,并称量体重;体长及腹围的测量每两周进行一次;两组实验仔鼠均在56日龄时结束实验,腹主动脉取血,检测两组幼鼠56日龄血清胆固醇（CH）、甘油三酯（TG）、血清卵泡刺激素（FSH）、促黄体生成素（LH）、雌二醇（E2）。实验结束后解剖56日龄仔鼠,取材子宫、卵巢,计算卵巢指数、子宫指数,子宫、卵巢做病理切片HE染色,计数卵巢最大横截面黄体个数和成熟卵个泡数。结果 ①56日龄造模结束,模型组幼鼠体重、腹围均高于对照组幼鼠,P＜0.001;②模型组幼鼠血清TG、CH均高于对照组,P＜0.001;③模型组幼鼠血清LH、E2浓度高于对照组幼鼠,P＜0.001,血清FSH浓度低于对照组,P＜0.001;④模型组幼鼠卵巢病理切片中最大横截面黄体计数较对照组多,P＜0.001;成熟卵泡计数少于对照组,P＜0.001;⑤Pearson相关性分析结果为：幼龄SD大鼠体质量与第一次动情间期、阴门开启时间两项指标呈成负相关,与血清LH、卵巢最大横截面切片黄体计数两项指标成正相关;幼龄SD大鼠腹围与第一次动情间期出现时间、阴门开启时间两项指标成负相关,与血清LH、卵巢最大横截面切片黄体计数两项指标成正相关。结论 幼龄SD大鼠青春发育评判指标与肥胖指标具有相关性,呈正相关。即具有肥胖特征的幼龄SD大鼠青春发育较之正常对照组幼鼠提前。     

大黄对雌性幼年大鼠血清GnRH、LH、FSH、P、E2水平的影响

目的：：观察大黄水提物对雌性幼年大鼠血清促性腺激素释放激素(GnRH)、黄体生成素(LH)、卵泡刺激素(FSH)、孕酮(P)、雌二醇(E2)水平的影响。方法：4周龄雌性SD大鼠20只,随机分为正常对照组和大黄水提物2.0g/kg组,每组10只,连续灌胃给药30天。采用ELISA法检测各组大鼠血清GnRH、LH、FSH、P、E2的水平。结果：与正常对照组大鼠比较,大黄水提物2.0g/kg组大鼠GnRH、P、E2激素水平明显降低(P＜0.05),LH、FSH激素水平明显升高(P＜0.05)。结论：大黄水提物可明显影响雌性幼年大鼠下丘脑-垂体-卵巢轴的激素水平。     

慢性应激在慢性胃炎发病中的作用研究

目的 探讨慢性应激在慢性胃炎发病中的作用.方法 75只雄性SD大鼠随机分为应激组(50只)和对照组(25只).应激组大鼠以束缚浸水法制备慢性应激模型,对照组不进行任何应激.观察指标:(1)大鼠应激前后的体重及进食量;(2)实验后大鼠脑脊液中5-羟色胺(5-HT)、5-羟吲哚乙酸(5-HIAA)、去甲肾上腺素(NA)和3-甲氧基-4-羟基苯乙二醇(MHPG)、多巴胺(DA)和高香草酸(HVA)水平;(3)用酚红排泄试验测定实验后大鼠的胃排空速率;(4)实验后大鼠胃黏膜的病理变化.结果 (1)应激前两组大鼠体重、体重增长百分率及进食量间差别无统计学意义(P>0.05);而应激后两组大鼠体重、体重增长百分率及进食量间差别有统计学意义(P<0.001).(2)应激后两组大鼠脑脊液中MHPG、5-HT及5-HIAA水平间差别有统计学意义(P<0.001),而NA、DA、HVA水平间差别无统计学意义(P>0.05).(3)两组大鼠胃组织大体标本显示炎症发生率间差别有统计学意义(P<0.001);光镜检查显示两组大鼠慢性炎症发生率间差别有统计学意义(P<0.001).(4)两组大鼠胃内酚红残留率间差别有统计学意义(P<0.05).结论 慢性应激可以引起胃黏膜的慢性炎症性变化,可能是通过改变脑脊液神经递质水平来影响胃运动.     

截瘫大鼠血液生化及骨密度改变

目的：探讨脊髓损伤继发骨质疏松的理论依据以指导临床治疗。 方法： 雄性Wistar大鼠120只随机分12组（每组10只）,各对照组分别行胸₁₀椎板切除,不损伤硬膜及脊髓后0、1、2、3、7和11周,实验组分别于胸₁₀椎板切除后行Allen's法（60gcm）损伤脊髓(导致截瘫)后0、1、2、3、、7和11周,检测血钙（Ca）、血磷(P)、血清碱性磷酸酶（ALP）及肱骨外科颈部、股骨粗隆部、胫骨平台部松质骨骨密度（BMD）改变情况。 结果：实验组( ALP术后1及3周低于对照组（P<0.05）;7周时明显高于对照组（P<0.01）;实验组血磷（P）术后1、2周高于对照组（P<0.01）,实验组血钙（Ca）术后1～3周时均明显高于对照组（P<0.01）,然后逐渐降至略高于正常。实验组肱骨 BMD术后3、7及11周时均明显低于对照组（P<0.01）,以3周时最低;实验组股骨BMD术后7周时低于对照组（P<0.05）,11周时与对照组比较差异无显著性（P>0.05）;实验组胫骨BMD术后 7及11周时均明显低于对照组(P<0.01)实验组术后7与11周比较差异无显著性（P>0.05）。结论：大鼠脊髓损伤截瘫后血液生化指标改变,损伤平面上下均继发骨质疏松,损伤平面上骨密度恢复较早。     

高剂量维生素E对大鼠氧化应激状态和甲状腺功能的影响

目的：检测大鼠体内氧化产物水平和甲状腺相关激素水平,探讨高剂量维生素E（VE）对机体的氧化应激水平及甲状腺功能的影响,为人群VE应用过量有可能产生的问题提供实验参考。方法：30只Wistar大鼠随机分为对照组、溶剂组、低剂量VE组、中剂量VE组和高剂量VE组,每组6只。VE的溶剂为花生油,低、中和高剂量VE组大鼠给药量分别为400、800和1 600 mg/kg。给药30 d后,处死大鼠,检测各组大鼠血清中丙二醛（MDA）浓度、超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）活性、血清中游离三碘甲腺原氨酸（FT3）和血清游离甲状腺素（FT4）水平。结果：中和高剂量VE组大鼠出现毛色变黄且杂乱无光泽,嗜睡、精神萎靡等状态。高剂量VE组大鼠血清MDA浓度明显高于对照组、溶剂组、低和中剂量VE组（P<0.05）,中和高剂量VE组大鼠血清SOD活性显著低于对照组、溶剂组、低剂量VE组（P<0.05）,中和高剂量VE组大鼠血清GSH-Px活性显著高于对照组、溶剂组、低剂量VE组（P<0.05）;与对照组和溶剂组比较,低、中和高剂量VE组大鼠血清FT3和FT4水平显著降低（P<0.05）;与对照组和溶剂组比较,中和高剂量VE组大鼠甲状腺滤泡上皮增生明显,细胞核变大且不规则。结论：高剂量VE的摄入可导致大鼠体内发生氧化应激状态,对甲状腺的结构和功能产生影响。     

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.