推拿对慢性应激大鼠抑郁行为的影响及其机制

目的: 探讨推拿对慢性应激大鼠抑郁行为的影响及其作用机制。方法: 制备慢性轻度不可预见性的应激大鼠模型^[1-2],造模21 d后,进行推拿治疗14 d。分组:空白对照组、模型组、推拿组、氟西汀组,每组10只。每日推拿膀胱经重要穴位10 min(间隔2 min,共2次)。通过体质量检测、旷场、糖水消耗实验和水迷宫实验评价抑郁模型大鼠行为学改变情况;蛋白质免疫印迹法(Western blot)法检测大鼠海马及前额叶皮质组织中ERK/P-ERK、BDNF蛋白表达情况。结果: 模型组与空白组比较,大鼠的体质量、旷场、糖水消耗实验和水迷宫数据均显著下降(P＜0.01),P-ERK、BDNF蛋白含量均显著降低(P＜0.01);推拿组和氟西汀组与模型组比较,大鼠的体质量、旷场实验、糖水消耗实验和水迷宫实验数据均显著上升(P＜0.01),推拿组和氟西汀组大鼠海马及前额叶皮质组织中P-ERK、BDNF蛋白含量均显著升高(P＜0.05,P＜0.01),氟西汀组升高更为显著(P＜0.01)。结论: 推拿可上调大鼠海马及前额叶皮质组织中ERK蛋白的磷酸化水平,激活ERK信号通路,促进效应蛋白BDNF的表达,改善慢性应激大鼠的抑郁行为。     

香柠檬精油对子代自闭症大鼠焦虑行为与认知能力的影响研究

为研究香柠檬精油对自闭症大鼠焦虑行为与认知能力的作用,本实验采用SD大鼠制备自闭症动物模型,GC-MS分析香柠檬精油的挥发性化学成分,对造模成功的大鼠嗅吸精油治疗,通过行为学实验和脑内神经递质变化来研究精油功效。研究发现中浓度香柠檬精油显著增加模型鼠在旷场实验中的运动总路程与中央区域探索时间,以及高架十字迷宫中探索开臂的次数百分比,在三箱社交实验和第二次Morris水迷宫中,嗅吸香柠檬精油的子代模型鼠社交与学习记忆能力有改善趋势,但未呈现出显著性差异。嗅吸中浓度香柠檬精油显著降低海马区与前额叶皮层中多巴胺、5-羟色胺含量,提高海马区多巴胺相对代谢率和前额叶皮层中5-羟色胺相对代谢率。嗅吸香柠檬精油可以减少模型鼠的焦虑行为,其作用可能与调节大鼠海马区与前额叶皮层中的5-羟色胺以及多巴胺的代谢有关。     

焦虑性抑郁模型大鼠脑区单胺递质含量与神经因子表达的变化

目的研究焦虑性抑郁模型大鼠海马、杏仁核、前额叶皮质内单胺递质的含量变化及脑内神经营养因子的表达趋势,探讨其可能的发病机制。方法 60只SD大鼠随机分为正常对照组、溶媒对照组、焦虑模型组、抑郁模型组、焦虑性抑郁模型组,每组12只。采用慢性束缚应激联合皮质酮注射的方法建立焦虑性抑郁大鼠模型,造模时间为21 d,造模结束后采用高架十字迷宫测试,旷场实验,强迫游泳实验评价大鼠的焦虑和抑郁样行为,HPLC-ECD法检测大鼠海马、杏仁核、前额叶皮质的单胺递质5-HT、NE、DA含量,蛋白印迹法检测大鼠各脑区神经营养因子BDNF、NT-3的含量。结果焦虑性抑郁模型组大鼠在进入开臂的时间、次数、旷场中自主活动次数均与焦虑组相当,与对照组及抑郁组比较差异有显著性(P0.01或P0.05),在强迫游泳中的不动时间显著增加,与对照组及焦虑组对比差异有显著性(P0.01);同时,与对照组比较,焦虑性抑郁模型组大鼠海马5-HT、杏仁核及前额叶皮质区的5-HT和NE含量均显著下降(P0.01或P0.05);此外,与对照组比较,焦虑性抑郁模型组大鼠各脑区BDNF、NT-3含量显著下降(P0.01或P0.05),同时与焦虑组比较,BDNF含量显著下降(P0.05)。结论焦虑性抑郁模型组大鼠具有显著的焦虑及抑郁样行为,其发病机制可能与脑内海马、杏仁核、前额叶皮质区域的单胺递质含量降低及神经营养因子BDNF、NT-3表达下调有关。     

间歇性低氧预处理对创伤后应激障碍模型小鼠恐惧和焦虑行为的改善作用

间歇性低氧(intermittent hypoxia, IH)对高血压、心肌梗死、脑缺血以及抑郁症有一定预防和治疗作用,但IH对创伤后应激障碍(post-traumatic stress disorder, PTSD)的作用尚不清楚。本研究采用不可逃避足底电击联合场景再现制备PTSD小鼠模型,通过旷场测试、高架十字迷宫测试及条件性恐惧测试反映其恐惧和焦虑水平;通过Y迷宫测试反映其空间记忆能力;通过免疫组化染色检测海马、杏仁核和内侧前额叶皮层Fos阳性神经元的数量;采用Western blot方法检测海马、杏仁核和内侧前额叶皮层低氧诱导因子1α(hypoxia inducible factor-1α, HIF-1α)、血管内皮生长因子(vascular endothelial growth factor,VEGF)和脑源性神经营养因子(brain derived neurotrophic factor, BDNF)蛋白表达水平。结果显示,IH与模型(电击)对高架十字迷宫测试中进入开放臂次数所占百分比、条件性恐惧测试中僵住时间和排便数量存在交互作用,IH能增加PTSD模型小鼠在高架十字迷宫中开放臂运动次数,减少条件性恐惧测试中僵住时间和排便数量。同时,IH预处理能减少PTSD模型小鼠海马、杏仁核和内侧前额叶皮层Fos阳性神经元的数量,增加这些脑组织中HIF-1α、VEGF和BDNF蛋白的表达水平。以上结果表明,IH预处理对PTSD模型小鼠恐惧和焦虑行为有改善作用,提示IH有可能成为预防PTSD的有效手段。     

白藜芦醇甙对慢性酒精中毒大鼠前额叶皮质cdk5表达的影响

目的:研究白藜芦醇甙对慢性酒精中毒大鼠学习记忆及前额叶皮质区细胞周期依赖性蛋白激酶5(cdk5)表达的影响。方法:建立大鼠慢性酒精中毒模型,Y-型迷宫测试空间学习与记忆成绩,实时定量PCR分析前额叶皮质组织cdk5 mRNA的表达;免疫组织化学方法检测大鼠前额叶皮质区cdk5表达。结果:学习记忆测试显示模型组大鼠学习记忆成绩比正常组明显下降,白藜芦醇甙各剂量组与模型组相比,学习记忆成绩明显上升;免疫组化结果表明模型组大鼠前额叶皮质区cdk5阳性表达较正常组明显增多,各剂量组与模型组相比,cdk5阳性表达明显减少;实时定量PCR结果表明模型组大鼠前额叶皮质区cdk5 mRNA表达较正常组明显上升,各剂量组与模型组相比,cdk5 mRNA表达明显下降。结论:白藜芦醇甙可能通过对cdk5表达的调节而发挥抗酒精中毒作用。     

依达拉奉对毒死蜱所致大鼠脑损伤的保护作用及其机制*

目的: 探讨依达拉奉在毒死蜱诱导的神经元凋亡中的保护作用及其线粒体机制。方法: 在随机双盲的原则下,将大鼠分为对照组、毒死蜱组、依达拉奉组(n=6);以毒死蜱(18 mg/ 0.7 ml/ kg, sc.)造模,在注射毒死蜱1 h后用依达拉奉(10 mg/1.6 ml/kg, ip.)治疗。连续注射毒死蜱及依达拉奉28 d后,通过旷场和水迷宫试验测试大鼠学习记忆能力。在心脏灌流后取大鼠脑组织,通过HE染色检测大脑海马区的神经元损伤情况以及透射电子显微镜观察线粒体和细胞核损伤情况。测定Na⁺-K⁺-ATP酶、ATP含量判断线粒体损伤情况。用免疫组织化学和免疫印迹法测定线粒体分裂蛋白DRP1及DRP1的Ser 637位点磷酸化的表达。结果: 与对照组相比,毒死蜱组大鼠在旷场实验的3 min内的总运动距离和平均速度明显减小(P＜0.01),在水迷宫试验中的1 min内的逃避潜伏期明显延长、平台穿越次数明显减少(P＜0.01),脑组织的ATP酶活性明显降低(P＜0.01)且ATP含量下降(P＜ 0.05)、线粒体DRP1的Ser637位点磷酸化水平显著下降(P＜0.01);依达拉奉治疗后,大鼠在旷场试验中的运动总距离增大、平均速度增加(P＜0.05),在水迷宫试验中的潜伏期减短、穿越平台次数增加(P＜0.01),脑部病理切片显示神经细胞排列整齐、细胞核和线粒体损伤明显改善,脑组织的ATP酶活性升高(P＜0.01)、ATP水平上升(P＜ 0.05)、线粒体DRP1的Ser637位点磷酸化水平升高(P＜0.01)。结论: 依达拉奉通过促进DRP1的Ser637位点磷酸化的表达减轻毒死蜱所致大鼠脑损伤。     

D-半乳糖致衰老模型大鼠的学习记忆和行为学观察及中药干预作用

目的观察D-半乳糖致衰老模型大鼠学习记忆能力和行为学情况,并探讨中药的干预作用。方法大鼠每日一次颈背部皮下注射5%D-半乳糖100 mg/kg。诱导大鼠衰老模型,连续7周,观察衰老模型大鼠的自主活动次数、空间记忆能力、主动回避遭受电击能力、探究活动等行为学表现和学习记忆能力,并用抗衰老片与首乌延寿片进行干预,观察中药的干预作用。结果皮下注射D-半乳糖造模后,衰老模型大鼠自主活动次数显著减少（P〈0.05,P〈0.01）,水迷宫试验探索路径长度和搜台潜伏期显著延长（P〈0.05,P〈0.01）,旷场试验移动路程长度和直立次数显著减少（P〈0.01）,穿梭回避试验平均潜伏期、进入错误区时间显著增加（P〈0.05,P〈0.01）。给予抗衰老片与首乌延寿片干预后,衰老大鼠的自主活动次数显著增加（P〈0.01）,水迷宫试验探索路径长度和搜台潜伏期显著缩短（P〈0.01）,旷场试验移动路程长度和直立次数显著增加（P〈0.01）,穿梭回避试验平均潜伏期、进入错误区时间显著减少（P〈0.05,P〈0.01）。结论D-半乳糖致衰老模型大鼠的自主活动次数减少,对新环境探索能力下降,学习记忆力下降;抗衰老片与首乌延寿片等中药可有效增强衰老模型大鼠的行为活动,提高衰老模型大鼠的学习记忆能力。     

磁场对小鼠两种迷宫学习记忆的影响

据发现,磁场对生物体有一定作用,但是磁场对于人类或实验动物的学习记忆是否有影响,目前的报道结果很不一致。本实验采用实验小白鼠,给予不同强度（65高斯／50Hz,35高斯/25Hz）的低频磁场照射（每天1小时,持续25天）。磁场照射后,采用旷场行为测试、Y-迷宫和Morris水迷宫,检测小鼠的活动性、空间辨别、空间学习记忆和非空间学习记忆能力。结果表明：65高斯／50Hz磁场显著增高小鼠的活动性,并损伤小鼠Y-迷宫的空间辨别能力,但对Morris水迷宫的空间、非空间学习记忆无明显影响。35高斯／25Hz磁场处理动物行为在三个指标上均接近对照组。提示：长期的磁场照射可能会给动物,甚至人类造成一些影响。     

眶额叶微量注射谷氨酸和γ-氨基丁酸对胃运动的影响及其机制探讨

目的:研究眶额叶(OFC)的谷氨酸(Glu)和γ-氨基丁酸(GABA)含量变化对胃运动的影响及其调节神经机制。方法:实验采用了大鼠眶额叶微量注射给药,结合核团损毁的方法,以记录胃内压,统计胃收缩幅度作为胃运动变化的指标。结果:①OFC注射Glu可显著降低胃收缩幅度,损毁杏仁核后可反转该效应,胃收缩幅度显著增强;损毁蓝斑核后,Glu的作用无显著性变化。②OFC注射GABA可显著增强胃的收缩幅度,损毁蓝斑核后消除该效应;损毁杏仁核后,胃收缩幅度进一步增强。结论:外源性增加OFC区Glu含量导致的抑胃效应可能是通过增强了杏仁核的经常性抑胃作用而引起的;而增加OFC区GABA的含量引起的胃运动增强与蓝斑核密切相关。     

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。     

Novelty-seeking behavior and stress-induced locomotion in rats of juvenile period differentially related to morphine place conditioning in their adulthood

The relationship between motor responses in a novel environment and susceptibility to place conditioning effect of psychostimulants has been reported in adult rats. However, it is in question whether this correlation could be generalized to motor activity in rats of juvenile period and place conditioning effect in their adulthood for narcotic morphine. In the present study, we tested locomotor activity in an arena open-field and the subsequent novelty-seeking behavior after adaptation process in juvenile rats (P42) and morphine (2 mg/kg) place conditioning effect 56 days later in the same rats' adulthood (P98). Our results showed that rats with high response to novelty (HRN) spent more prolonged duration in the drug-paired compartment in the place conditioning test compared with their low response counterparts (LRN), with the latter group no salient change on this measure. Moreover, rats with high response to the open-field test (HRS) expressed equally elevated duration in drug-paired side relative to their low response counterparts (LRS). The present research demonstrated that novelty-seeking behavior and locomotor activity in the open-field in rats of juvenile period differentially related to morphine place conditioning in their adulthood, with slow acquisition of morphine place conditioning effect in LRN animals.     

Coexistence of Anhedonia and anxiety-independent increased novelty-seeking behavior in the chronic mild stress model of depression

Previous research demonstrated excessive decreases in reward sensitivity and increases in harm avoidance in depressed individuals. These results straightly lead to a hypothesis that depressed patients should avoid novelty or express reduced novelty-seeking behavior. Nevertheless, literature in this regard is inconsistent. Furthermore, whether the potentially altered novelty-associated behavior is dependent on changed anxiety/fear or related to altered goal-directed approaching tendency is unclear. Here, we tested novel object-approaching behavior in a free-exploration paradigm in chronic mild stress (CMS)-induced anhedonic and stress-resistant rats respectively. Other CMS-induced, emotional behaviors were also examined in a battery of behavioral tests including novel cage, exploration, locomotor activity and elevated plus maze (EPM). We found that compared with controls, stress-resistant rats who consistently showed lower anxiety level in EPM (time in open arms) and, open-field (OF) test (time in central area) showed no sign of enhanced novel object approaching behavior. To the contrary, the anhedonic ones who did not express any sign of reduced anxiety showed paradoxically intensified novelty-approaching behavior. We concluded that reduced anxiety would not necessarily lead to enhanced novelty-seeking behavior; anhedonia coexists with anxiety-independent, increased novelty-seeking behavior. The salient paradox of coexistence of anhedonia and increased novelty-seeking behavior was critically discussed.     

Stress inhibits psychomotor performance differently in simple and complex open field environments

Stress affects psychomotor profiles and exploratory behavior in response to environmental features. Here we investigated psychomotor and exploratory patterns induced by stress in a simple open-field arena and a complex, multi-featured environment. Groups of rats underwent seven days of restraint stress or no-stress conditions and were individually tested in three versions of the ziggurat task (ZT) that varied according to environmental complexity. The hyperactivity of the hypothalamic–pituitary–adrenal (HPA) axis due to stress procedure was evaluated by the pre- and post-stress levels of circulating corticosterone (CORT). Horizontal activity, exploration, and motivation were measured by the number of fields entered, the time spent in the central fields, path length and speed, and stop duration. In addition, vertical exploratory behavior was measured by the times rats climbed onto ziggurats. Stress-induced psychomotor changes were indicated by reduced path length and path speed and increased duration of stops only within the complex arena of the ZT. Rats in stress groups also showed a significant decline in the vertical movements as measured by the number of climbing onto ziggurats. No stress-induced changes were revealed by the simple open-field arena. The exploratory patterns of stressed animals suggest psychomotor inhibition and reduced novelty-seeking behaviors in an environment-dependent manner. Thus, multi-featured arenas that require complex behavioral strategies are ideally suited to reveal the inhibitory effects of stress on psychomotor capabilities in rodents.     

Basolateral amygdala lesions abolish orbitofrontal-dependent reversal impairments

Damage to orbitofrontal cortex (OFC) has long been associated with deficits in reversal learning. OFC damage also causes inflexible associative encoding in basolateral amygdala (ABL) during reversal learning. Here we provide a critical test of the hypothesis that the reversal deficit in OFC-lesioned rats is caused by this inflexible encoding in ABL. Rats with bilateral neurotoxic lesions of OFC, ABL, or both areas were tested on a series of two-odor go/no-go discrimination problems, followed by two serial reversals of the final problem. As expected, all groups acquired the initial problems at the same rate, and rats with OFC lesions were slower to acquire the reversals than sham controls. This impairment was abolished by accompanying ABL lesions, while ABL lesions alone had no effect on reversal learning. These results are consistent with the hypothesis that OFC facilitates cognitive flexibility by promoting updating of associative encoding in downstream brain areas.     

Differential effects of testosterone metabolites in the neonatal period on open-field behavior and lordosis in the rat

Two experiments were done to compare the effects of neonatal exposure to testosterone and its major metabolites, dihydrotestosterone (DHT) and estradiol (E₂), on the development of sex differences in open-field behavior in the rat. In Experiment 1 female rats administered either testosterone propionate (TP), DHT, or estradiol benzoate (EB) were found as adults to have low activity scores, more typical of adult males, when compared to the high scores of oil-treated females. In Experiment 2 the adult open-field behavior of female rats treated neonatally with testosterone or the metabolites was compared to that of male rats treated from Day 1 to 10 of life with the aromatizing enzyme inhibitor, androst-1,4,6-triene-3,17-dione (ATD). These same animals were later tested for lordotic behavior after gonadectomy and priming with EB and progesterone. All male animals and female animals exposed neonatally to testosterone or to either of the metabolites had suppressed open-field activity scores compared to oil-treated females. However, the lordotic behavior of females exposed to DHT and of males exposed to ATD was not defeminized and was comparable to that of oil-treated females. These observations were discussed in terms of a role for the androgenic actions of testosterone in establishing sex differences in nonreproductive behavior in the rat.     

Prefrontal cortex aspiration in pups and juvenile rats: behavioural changes and recovery of function

Male Wistar rats sustaining prefrontal cortex aspiration or sham operation at 6 days or 30 days of age were submitted to the following behavioural tests: open-field, acquisition and retention of two-way active as well as passive avoidance tasks. In the open-field the locomotor activity proved enhanced in all the aspirated animals and this enhancement lasted for 30 days. In the two-day active avoidance task, an acquisition deficit was observed in both aspirated groups; but when retrained one month later, they were able to acquire the avoidance task like sham-operated rats and no difference appeared between the groups aspirated at 6 or at 30 days of age. Concerning the passive avoidance task, no difference could be detected between aspirated and sham-operated animals of both groups except that the rats aspirated at an early age (6 days) seemed to display a better avoidance ability in the retention test. These behavioural alterations (hyperactivity and impairment of the acquisition of the 2-way active avoidance) resulted from the prefrontal cortex aspiration, at whatever age this aspiration was performed (6 days or 30 days). They disappeared after a postoperative recovery period of about one month, as evidenced by this longitudinal study.     

The effect of neurochemical damage of dopaminergic terminals in early ontogenesis on the behavior of adult rats

6-Hydroxydopamine (75 mkg), producing selective degeneration of dopaminergic neurons in the brain, was injected intraamniotically to every rat fetus on 13th or 17th day of mother pregnancy. The other experiment was performed, when 6-hydroxydopamine administered i.p. to newborn rats on 4th or 10th day of life. All rats were growing, and several dopamine-dependent behaviors were investigated in adult animals: open field, rotation behavior, anxiety in elevated plus maze, conditioned placed preference, differentiation of novel and known alleys of Y-maze, aggressive behavior in intruder-resident test, selfs-stimulation of lateral hypothalamus. Prenatal administration of 6-hydroxydopamine initiated rotations and stereotypy, decreased anxiety in elevated maze, reduced reinforcing properties of amphetamine in place preference test, disturbed differentiation of novel and known alley in Y-maze, high aggression and decreased self-stimulation in less degree that postnatal injection of neurotoxin. Therefore, the early postnatal period is more sensitive to neurotoxin action than prenatal period of development. This phenomenon is connected with critical periods of development of dopaminergic system in ontogeny.     

Involvement of the oxytocin system in the nucleus accumbens in the regulation of juvenile social novelty-seeking behavior

Exploration of novel environments, stimuli, and conspecifics is highly adaptive during the juvenile period, as individuals transition from immaturity to adulthood. We recently showed that juvenile rats prefer to interact with a novel individual over a familiar cage mate. However, the neural mechanisms underlying this juvenile social novelty-seeking behavior remain largely unknown. One potential candidate is the oxytocin (OXT) system, given its involvement in various motivated social behaviors. Here, we show that administration of the specific oxytocin receptor antagonist desGly-NH₂,d(CH₂)₅-[Tyr(Me)²,Thr⁴]OVT reduces social novelty seeking-behavior in juvenile male rats when injected into the nucleus accumbens (10 ng/0.5 μl/side). The same drug dose was ineffective at altering social novelty-seeking behavior when administered into the lateral septum or basolateral amygdala. These results are the first to suggest the involvement of the OXT system in the nucleus accumbens in the regulation of juvenile social novelty-seeking behavior.     

Contribution of Nucleus Accumbens Core (AcbC) to Behavior Control during a Learned Resting Period: Introduction of a Novel Task and Lesion Experiments

In recent years, the study of resting state neural activity has received much attention. To better understand the roles of different brain regions in the regulation of behavioral activity in an arousing or a resting period, we developed a novel behavioral paradigm (8-arm food-foraging task; 8-arm FFT) using the radial 8-arm maze and examined how AcbC lesions affect behavioral execution and learning. Repetitive training on the 8-arm FFT facilitated motivation of normal rats to run quickly to the arm tips and to the center platform before the last-reward collection. Importantly, just after this point and before confirmation of no reward at the next arm traverse, locomotor activity decreased. This indicates that well-trained rats can predict the absence of the reward at the end of food seeking and then start another behavior, namely planned resting. Lesions of the AcbC after training selectively impaired this reduction of locomotor activity after the last-reward collection without changing activity levels before the last-reward collection. Analysis of arm-selection patterns in the lesioned animals suggests little influence of the lesion in the ability to predict the reward absence. AcbC lesions did not change exploratory locomotor activity in an open-field test in which there were no rewards. This suggests that the AcbC controls the activity level of planned resting behavior shaped by the 8-arm FFT. Rats receiving training after AcbC lesioning showed a reduction in motivation for reward seeking. Thus, the AcbC also plays important roles not only in controlling the activity level after the last-reward collection but also in motivational learning for setting the activity level of reward-seeking behavior.