心理应激的免疫抑制作用及其与神经内分泌反应的相关性

以给予经定时喂水训练大鼠空瓶刺激为情绪性心理应激源,研究了此情绪应激对大鼠特异性原发体液免疫反应的影响及其可能的作用机制。结果表明每次10分钟,共14次的情绪应激显著降低大鼠抗特异性抗原OVA的抗体水平及脾脏指数,而显著增高血肾上腺素、去甲肾上腺素和皮质酮水平。研究还发现去甲肾上腺素与抗特异性抗原OVA的抗体水平呈显著负相关。该研究证实了情绪性心理应激对大鼠体液免疫功能的抑制作用,并提示交感神经系统可能参与了此免疫调节作用。     

电击信号应激对大鼠体液免疫及内分泌功能的影响

研究了足电击及以电击装置为信号刺激所诱发的情绪应激对大鼠原发性体液免疫反应及内分泌的影响。 结果表明每天１０分钟,共６天的足电击对大鼠抗特异性抗原ＯＶＡ的原发性体液免疫反应无明显作用,而此电击作 用结合每天１０分钟,共８天的情绪应激则可显著降低大鼠体液免疫反应及脾脏指数。同时该应激可显著提高大鼠 血儿茶酚胶和皮质酮水平。该研究证明了情绪应激对大鼠体液免疫功能的调节作用,并对交感神经系统和下丘脑－ 垂体－肾上腺（ＨＰＡ）轴在其中所起的作用进行了初步探讨。     

不同时程应激对大鼠行为、免疫和交感神经系统反应的影响

研究旨在研究不同时程情绪应激诱导的大鼠行为、免疫和神经内分泌反应的动态变化及其相互关系。实验采用一种在程序性饮水的固定时间点不确定性给予大鼠空瓶刺激诱发其情绪反应的应激模式,测定不同时程（14,21和28天）应激对大鼠行为、交感神经系统反应、体液免疫功能及体重增长的影响。结果表明,情绪应激导致大鼠攻击行为显著增加,且在整个应激过程中情绪应激组大鼠的攻击行为都被稳定地诱导;不同时程的情绪应激均导致大鼠特异性抗OVA抗体水平明显降低,且降低的程度类似;在情绪应激的第14天和28天应激组大鼠血中去甲肾上腺素水平明显高于对照组,但后者升高的水平明显低于前者。此外,14天应激明显抑制大鼠的体重增长,但随着应激时程的延长,体重增长逐渐恢复。这些结果表明,随着应激时程的延长,大鼠行为、免疫和神经内分泌反应的适应性改变存在时程差异,有助于进一步了解应激诱发的各种反应间的复杂关系     

对体液免疫反应的条件反射性调节

以饮糖精水作为条件刺激(conditioned stimulus,CS),腹腔注射免疫抑制剂环磷酰胺作为非条件刺激(unconditioned stimulus,UCS)训练Wistar大鼠,3天后腹腔注射卵清蛋白(ovalbunfin,OVA)抗原,观察再次单独条件刺激对原发性体液免疫反应的作用。结果发现．一次CU-UCS结合训练导致CS组大鼠对再现糖精水产生厌恶反应,外周血中抗OVA-IgG抗体水平显著低于UCS组。两次CS-UCS结合训练并多次给予条件刺激后,CS组大鼠抗OVA-IgG的条件性免疫抑制效应与一次CS-UCS结合训练及再次给予一次条件刺激的反应类同。这些结果证明条件刺激增强了环磷酰胺对动物原发性体液免疫反应的抑制作用．这种条件性体液免疫抑制作用是相对稳定和有限度的,不易受条件反射建立参数的影响。     

以兔抗鼠淋巴细胞血清为非条件刺激的条件性免疫抑制

采用一种生物类免疫抑制剂-兔抗鼠淋巴血清（rabbit anti-rat lymphocyte serum,ALS）为非条件刺激（UCS）,糖精水为条件刺激（CS）,以双瓶给水法置于鼠笼前端饮用偏好侧。在一次性CS-UCS结合训练后,单独再次给予CS,使卵清蛋白（OVA）免疫过的大鼠表现出脾淋巴细胞对有丝分裂原PWM的增殖反应降低,血抗OVA抗体的总量及脾内抗OVA抗体生成细胞的减少,但动物未表现出条件性味觉厌恶的行为反应。这些结果表明条件性免疫抑制与味觉厌恶行为条件反射没有必然联系,并非是厌恶行为反应或情绪应激的伴随产物。UCS也并非必需具有感觉的毒副作用,条件性免疫抑制是脑高级神经活动调节免疫功能的结果。     

慢性应激对大鼠行为和免疫细胞热休克蛋白70表达的影响

目的：研究慢性不确定应激对大鼠急性整体热水浴后外周血和脾脏免疫细胞热休克蛋白70（Heat shock protein 70, HSP70）表达的影响。方法：随机将大鼠分成慢性应激组和控制组（每组14只）。通过4周的慢性不确定性应激诱发实验组大鼠明显的抑郁行为,此期间控制组大鼠正常饲养。随后给予大鼠42度整体热水浴刺激,维持直肠温度41度25min。热刺激后6h,采用流式细胞仪测定大鼠外周血和脾脏免疫细胞HSP70 水平。结果：与控制组大鼠相比,慢性应激大鼠在急性热刺激后HSP70合成明显减少。控制组大鼠的所有被检测的免疫细胞热应激后HSP70合成均明显增加。相反,慢性应激大鼠仅在外周血的单核细胞和粒细胞检测到HSP70合成增加,同时升高的水平明显低于控制组大鼠。结论：慢性应激降低大鼠免疫细胞HSP70的热诱导反应,提示HSP70保护性作用减弱可能参与了慢性应激损害免疫细胞功能的生物学过程     

情绪应激对不同脑区c-fos表达的影响

利用电击信号和空瓶刺激两种情绪应激体液免疫调节作用动物模型,以c-fos原癌基因为探针,观察情绪应激后2个小时,大鼠全脑的c—fos原癌基因表达情况,探讨情绪应激对不同脑区c—fos表达的影响。结果表明,电击信号和空瓶刺激两种情绪应激源均能引起某些脑区或核团的c—fos蛋白表达明显增加,包括额皮质、扣带皮质、杏仁内侧核、前连合核、下丘脑背内侧核弥散部、弓状核、孤束核。结果提示,这些脑区或核团是情绪应激主要激活的中枢部位。     

不同应激范式对大鼠行为和脑神经颗粒素含量的影响

为探讨慢性情绪应激、生理应激对大鼠旷场行为和脑神经颗粒素（Neurogranin,NG）含量的不同作用,以及NG含量变化与应激性行为效应之间的相互关系。分别以不确定性空瓶刺激和饮水剥夺,建立情绪应激和生理应激动物模型。将40只雄性SD大鼠随机分为情绪应激组（ES）、生理应激组（PS）、定时饮水组（C1）和正常对照组（C2）（n=10）。以旷场行为任务来评定大鼠应激后的行为变化,Western blotting方法测定海马和前脑皮层中的NG含量。结果表明：应激后四组大鼠海马的NG含量差异无显著性;ES组前脑皮层的NG含量低于C2组,差异具有显著性,p<0.01;PS组的前脑皮层NG含量也下降,但与C2组相比差异无显著性; 应激后ES组、PS组修饰行为多于C2组,差异具有显著性,分别为p<0.01,p<0.05;前脑皮层NG含量与修饰行为之间的相关达显著水平。提示慢性情绪和生理应激均能导致前脑皮层NG含量下降,修饰行为增加,情绪应激作用更显著。修饰行为可能是反映情绪状态的较敏感行为指标,前脑皮层NG水平可能是预测情绪应激所致焦虑或抑郁行为的较敏感生物学指标。     

脂多糖免疫激活对强迫游泳应激导致的抑郁样行为的影响

应激导致抑郁样行为的同时导致免疫激活敏感化, 但是免疫激活对应激导致的抑郁样行为的影响目前并不清楚。研究目的：利用脂多糖(Lipopolysaccharide, LPS)作为外周免疫激活启动剂, 强迫游泳应激(forced swim stress)作为应激模式, 考察免疫激活背景是否影响应激导致的抑郁样行为。方法：42只SD雄性大鼠随机分为四组：LS组(LPS + swim, n=12), LC组(LPS +空白, n=10), AS组(生理盐水+swim, n=10), AC组(生理盐水+空白, n=10)。在实验期第一天根据分组分别注射脂多糖(LPS, 50 μg/kg, 腹腔注射)或生理盐水一次, LS组和AS组大鼠于注射后2小时进行第一次游泳应激, 此后持续应激2周。分别在应激一次后, 应激2周, 应激结束后1周和应激结束后2周测定大鼠的糖精水偏爱、旷场行为和高架十字迷宫行为。结果显示：应激一次后, 应激2周, 应激后1周LS组大鼠与AC组相比较, 糖精水偏爱分数, 旷场中的水平活动显著下降; 应激2周, AS组大鼠相对于AC组大鼠的糖精水偏爱分数以及旷场中的水平活动都显著下降, 结论：慢性强迫性游泳应激导致抑郁样行为, 应激前LPS免疫激活能够促使应激导致的抑郁样行为更容易出现, 症状加剧, 并持续较长的时间。     

慢性强迫游泳应激对大鼠情绪和脑细胞外信号调节激酶的影响

为探讨慢性强迫游泳应激对动物情绪和脑组织细胞外信号调节激酶（extracellular signal-regulated kinase, ERK1/2）的影响,动物情绪和脑组织ERK1/2之间的关系,将动物随机分为游泳应激组、装置对照组和控制组。分别对三组大鼠给予相应的干预14天, 然后进行行为观察,免疫印记法测定海马和前脑皮质ERK1/2水平。结果表明强迫游泳应激组和装置对照组都出现明显的情绪障碍。两组大鼠ERK1/2在前脑皮质的表达水平均显著升高,海马无显著变化。前脑皮质ERK2与糖精水摄入量呈显著负相关。提示慢性强迫游泳应激能够诱导大鼠的情绪障碍,提高ERK1/2在前脑皮质的表达水平,ERK1/2与情绪关系密切,可能是脑组织应激性情绪调节的重要生理机制。强迫游泳应激能够导致动物明显的抑郁反应,是比较理想的抑郁动物模型     

Stress applied during primary immunization affects the secondary humoral immune response in the rat: involvement of opioid peptides

The effect of unpredictable, inescapable and uncontrollable electric tail shocks (ES) on the humoral immune response to bovine serum albumin (BSA) was investigated in the rat. Contributions of the procedures that accompany shock delivery, such as witnessing the ES procedure (stress witnessing, SW) and exposure to the apparatus for shock delivery (apparatus control, AC) to the changes in specific immunity induced by ES were also tested. All procedures were applied during primary and/or secondary immunization. It was demonstrated that exposure to ES during primary immunization with BSA significantly suppressed specific anti-BSA antibody production after secondary and tertiary immunization with the same antigen. Exposure to the SW procedure during primary immunization with BSA enhanced the specific antibody level after secondary immunization, while exposure to the apparatus alone did not influence the development of either the primary or secondary humoral immune response to BSA. Both ES-induced suppression and SW-induced potentiation of the humoral immune response were partially inhibited by prior treatment with the opioid receptor antagonist naloxone. Additionally, treatments with the opioid peptides methionine- and leucine-enkephalin decreased anti-BSA antibody level, mimicking to some extent the effects of ES. It is suggested that ES and endogenous opioid peptides had long-term effects on humoral immunity through mechanisms involving immunologic memory.     

Stressor exposure produces long-term reductions in antigen-specific T and B cell responses

Exposure to an acute laboratory stressor at the time of keyhole limpet hemocyanin (KLH) immunization results in a long-term suppression in circulating anti-KLH antibody. The mechanism for the stress-induced reduction in anti-KLH immunoglobulin (Ig) remains unknown. Given that the generation of anti-KLH antibody requires T cell help, we hypothesize that stress reduces the proliferation of anti-KLH T cells, thus leading to a reduction in anti-KLH antibody. The present studies examined the effect of tail shock stress (100, 1.6 mA, 5-s, 60 s ITI) on the KLH specific T cell response. Fischer F344 rats were immunized either intraperitoneally (i.p.) or subcutaneously (s.c.) at the base of the tail with 200 microg KLH, and exposed to inescapable tail shock (IS) or remained in their home cages (HCC). T cell proliferation after KLH restimulation, but not ConA, was markedly suppressed in IS animals in both the spleen after i.p. immunization and the draining lymph nodes after s.c. immunization. Other secondary lymphoid cells did not differ in their proliferative capacity. Anti-KLH IgG, IgG1 and IgG2a, but not anti-KLH IgM serum levels were significantly suppressed. These data support the conclusion that stress suppresses the generation of antigen specific T cells. In addition, the methods employed in the current study allow the isolation of the site of the acquired T cell immune response, making it possible to further elucidate the cellular mechanisms that contribute to stress-induced modulation of the antigen-specific acquired immune response.     

Cytokine production by spleen cells after social defeat in mice: activation of T cells and reduced inhibition by glucocorticoids

Social disruption (SDR) is an effective model of social stress associated with an enhanced inflammatory reactivity of the immune system. The aim of the present study was to further describe SDR effects on cytokine production by spleen cells, testing selectively monocyte and T cell functions as a result of this stressor. For this purpose, splenocytes from control mice (C) and mice socially stressed for 7 days (SDR) were cultured in the presence of lipopolysaccharide (LPS) or concanavalin A (Con A). Splenocyte proliferation, cytokine production and sensitivity of spleen cells to corticosterone were assessed in vitro. The humoral response to keyhole limpet hemocyanin (KLH) immunization was assessed. SDR induced splenomegaly and enhanced splenocyte basal proliferation. The pro-inflammatory influence of SDR was confirmed by an increased release of interleukin-6 (IL-6) by LPS-stimulated cultures and by a reduced sensitivity of spleen cells to the anti-inflammatory effect of corticosterone. The mechanism increasing cytokine production in response to LPS was cytokine specific, since among inflammatory cytokines, IL-6 but not interferon-gamma (IFN-gamma) was enhanced by stress. In stressed mice, the increase in IL-6 and IFN-gamma and the decrease in IL-10 release in Con A-stimulated cultures indicate that SDR did not modify the Th1/Th2 cytokine balance but globally activated T cells. Plasma anti-KLH antibody levels were similar in both groups. Wounded and non-wounded mice presented similar responses to stress. This study shows that social disruption stress enhances the reactivity of cells from both the acquired and innate immune systems.