喂养型代谢综合征小鼠及大鼠模型的建立方法探讨

目的探讨与人类代谢综合征(metabolic syndrome,MS)临床特征相似的啮齿类动物模型的建立方法,考察造模条件,建立经济、简便、稳定可靠的代谢综合征药物筛选模型。方法高热量饲料喂养KM、C57BL/6、BALB/c小鼠6～8wk,喂养Wistar大鼠23wk,动态监测空腹血清总胆固醇(total cholesterol,TC)、低密度脂蛋白胆固醇(low density lipoprotein-cholesterol,LDL-C)、血糖(fasting blood glucose,FBG)、胰岛素(fasting insulin,FINS)含量,计算稳态模型胰岛素抵抗评价指数(homeostasis model assessment of insulin resistance,HOMA-IR)。实验结束时做口服葡萄糖耐量试验(oral glucose tolerance test,OGTT),称取动物内脏脂肪重量(visceral fat mass,VFM)并计算内脏脂肪系数(visceral fat coefficient,VFC)。结果高热量饲料喂养KM、C57BL/6、BALB/c小鼠及Wistar大鼠均表现出TC、LDL-C、FBG增高和葡萄糖耐量减低的糖脂代谢紊乱。高热量饲料使KM鼠形成腹型肥胖和胰岛素抵抗。C57BL/6小鼠未能形成肥胖,BALB/c小鼠形成整体型肥胖。Wistar大鼠形成腹型肥胖,喂养2～6wk形成脂代谢紊乱、10wk后表现出糖代谢紊乱及胰岛素抵抗,且大鼠摄食重量下降,下丘脑神经肽Y含量增加。结论喂养型KM小鼠具有腹型肥胖、糖脂代谢紊乱和胰岛素抵抗的特征,与人类临床特征相似,符合MS定义要求,适于作为MS治疗和干预药物的快速筛选模型。     

小鼠条件性恐惧模型的建立和品系敏感性研究

目的在敏感品系上建立稳定可靠的小鼠条件性恐惧模型。方法采用给予30 s声音刺激(85 dB,5000 Hz),后2 s伴随给予不可逃避的足底电击(0.6 mA,持续2 s),声音-电击共配对5次,每次间隔2 min的方法建立小鼠条件性恐惧模型,在ICR、DBA/2(简称DBA)和C57BL/6J(简称C57)3种品系小鼠上评价场景恐惧和声音线索恐惧获得和表达的行为特点,以确定敏感品系鼠;分别于条件性恐惧训练第2,7,14,21和28天对C57小鼠场景恐惧和声音线索恐惧进行检测,以评价该品系小鼠条件性恐惧的自然消退特点;采用30 s声音+30 s间隔+10次消退训练的模式进行声音线索恐惧消退训练,并于24 h后进行消退保持测试,以评价该品系小鼠消退训练和保持的特点。结果声音-电击配对5次可成功诱导C57小鼠形成场景恐惧和声音线索恐惧,DBA小鼠可诱导形成声音线索恐惧但无法形成场景恐惧,ICR小鼠场景恐惧和声音线索恐惧均未诱导成功,确定C57小鼠为敏感品系鼠。C57小鼠呈现时间依赖的恐惧反应自然消退,其中场景恐惧在训练后第7天僵住百分率消退至(25±12)%,声音线索恐惧训练后第28天僵住百分率维持在(48±22)%;C57小鼠经10轮30 s声音消退训练,僵住时间百分率由(55±30)%消退至(32±27)%,但24 h后消退保持测试时僵住时间百分率又回升至(47±35)%。结论以敏感品系C57小鼠为研究对象,建立了恐惧获得、表达、自然消退、消退训练和消退保持各阶段恐惧行为检测的实验方法,成功建立小鼠条件性恐惧模型。     

筛选训练对Morris水迷宫测试成绩的影响

目的对东莨菪碱致痴呆模型进行Morris水迷宫实验,观察比较筛选训练对小鼠Morris水迷宫学习记忆的影响,为完善与优化东莨菪碱致记忆获得性障碍痴呆模型提供方法学参考。方法新购进昆明种小鼠,随机分为筛选训练正常组、筛选训练模型组、不筛选训练正常组、不筛选训练模型组。筛选训练各组正式实验前先进行水迷宫筛选训练,将筛选训练不合格的小鼠剔除出实验,确保每只小鼠均能在规定时间内找到平台;不训练各组购进后直接与筛选训练组同时进行Morris水迷宫实验,观察其对学习记忆测试的影响。结果动物筛选训练对Morris水迷宫实验具有显著性影响,可以显著性的缩短小鼠的潜伏期,提高小鼠的学习记忆能力。结论实验前进行水迷宫筛选训练,可大大提高Morris水迷宫实验对东莨菪碱致小鼠痴呆模型进行药物评价实验的结果准确性。     

复方珍珠膏药效学及安全性实验研究

目的:研究复方珍珠膏药效学及安全性。方法:以KM小鼠为模型进行抗炎、止痒、镇痛、经皮急性毒性实验;以豚鼠为模型进行急性皮肤刺激、多次给药皮肤刺激、皮肤致敏及经皮急性毒性实验;以雌性SD大鼠为模型进行肉芽肿实验及破损皮肤瘢痕实验。结果:皮肤刺激实验、皮肤过敏实验药物观察期间未见豚鼠皮肤有红斑和焦痂形成;破损皮肤瘢痕实验药物观察期间未见大鼠皮肤出现红斑和水肿,且其皮肤在2周内恢复;豚鼠和KM小鼠1d内以最大给药量(5000 mg·kg^(-1))经皮给予2次复方珍珠膏后,未见明显毒性反应。结论:复方珍珠膏具有抗炎、止痒、镇痛、抗增生的作用,外用无刺激性、过敏性及毒性,且不会造成皮肤瘢痕,预期临床应用安全性良好。     

慢性不可预知性应激刺激后大鼠行为学改变

目的建立长期慢性不可预知性应激刺激大鼠动物模型,观察大鼠应激后全身状态及行为学的改变。方法雄性Wistar大鼠32只,12周龄,分为实验组和对照组,再随机分为3周及6周时间组,各为8只大鼠。实验组进行随机应激刺激,建立慢性不可预知性应激动物模型,对照组不加任何刺激,正常饲养。各组大鼠每周测量体质量,观察动物变化,于实验各时间点进行旷场行为学测试,记录水平活动及垂直活动得分,进行比较。结果实验组大鼠体质量增加明显慢于对照组,行为学测试各实验组与对照组均有显著性差异(P<0.05)。结论大鼠的行为学活动在长期慢性不可预知性应激刺激后明显改变,体质量增长速率减缓,表明大鼠在长期应激刺激下正常生长、生活会造成很大的障碍。     

重复性经颅磁刺激对大鼠学习和记忆的影响

目的研究重复性经颅磁刺激(repetitive transcran ial m agnetic stimu lation,rTMS)对大鼠学习和记忆的影响。方法W istar♂大鼠接受300次刺激(10 Hz,1.0 Tesla,200μs),用Morris水迷宫实验,考察训练前或后给予大鼠rTMS处理对空间参考记忆和工作记忆的影响。结果训练后施加rTMS可增强空间参考记忆的获取,而训练前施加rTMS则无显著影响;训练前、后施加rTMS对短期和长期参考记忆无显著影响,对工作记忆也无显著影响。结论rTMS对空间参考记忆有增进作用。     

二十二碳六烯酸-磷脂对AD大鼠学习记忆的影响

目的 研究二十二碳六烯酸-磷脂(docosahexaenoic acid-phosphatidylcholine, DHA-PC)对海马CA1区注射Aβ25-35所致的阿尔茨海默病（Alzheimer’s disease,AD）大鼠模型学习记忆能力改善作用,为DHA-PC的药用开发奠定理论基础。方法 SPF级雄性Wistar大鼠40只,250~300 g,随机分为正常对照组、AD组、多奈哌齐组、DHA-PC组。大鼠双侧海马CA1区注射Aβ25-35制作AD大鼠模型,水迷宫检测学习记忆能力改变,检测Tau(Ser 396)蛋白的含量,检测超氧化物歧化酶活性。结果 水迷宫结果显示：与AD组相比,定向航行实验DHA-PC组大鼠的潜伏期明显降低（P<0.05）;空间探索实验DHA-PC组大鼠在安全平台所在象限的活动时间明显增加（P<0.05）。与AD组相比,DHA-PC组和DHCI组大鼠皮层和海马的Tau（Ser396）蛋白含量明显降低（P<0.05,P<0.01）,DHA-PC组和DHCI组皮层SOD活性增强（P<0.01）。结论 DHA-PC可通过降低皮层和海马396位点磷酸化Tau蛋白的表达和增强SOD活性,改善AD大鼠学习记忆能力,具有较好的药用开发前景。     

石杉碱甲透皮控释贴片对小鼠学习记忆的改善作用

目的:观察石杉碱甲透皮控释贴片(Hup -ATDDS)对正常小鼠及记忆障碍模型小鼠学习记忆功能的影响。方法:跳台试验测定Hup -ATDDS对正常小鼠学习成绩的影响;建立东莨菪碱记忆获得障碍模型及亚硝酸钠记忆巩固障碍模型,采用一次性训练的空间辨别反应实验-电迷宫实验和一次性学习的回避性条件反射试验-跳台试验测定小鼠记忆功能,观察Hup-ATDDS对其影响。结果:Hup -ATDDS 5 3.4 μg/只对正常小鼠跳台试验有促进学习成绩作用,对1mg/kg东莨菪碱引起的记忆获得障碍及12 0mg/kg亚硝酸钠产生记忆巩固障碍有明显的反转作用。结论:石杉碱甲透皮控释贴片具有较好的促进正常小鼠及记忆障碍小鼠的学习记忆功能作用     

吴茱萸水煎液对大、小鼠肝药酶亚型影响的比较研究

目的比较吴茱萸水煎液对大鼠、小鼠肝药酶亚型的影响。方法取KM小鼠随机分为吴茱萸高剂量组(56 mg生药·g-1)、低剂量组(28 mg生药·g-1)和正常组,另取Wistar大鼠随机分为吴茱萸高剂量组(40 mg生药·g-1)、低剂量组(20 mg生药·g-1)和正常组,连续灌胃给予吴茱萸水煎液或等容量蒸馏水21 d后,采用药物探针法测定动物肝药酶亚型CYP1A、CYP2C、CYP2D、CYP2E1、CYP3A的活性。结果①小鼠实验结果显示,与正常组比较,吴茱萸高、低剂量组均诱导肝药酶亚型CYP1A、CYP2E1和CYP3A的活性(P<0.01),低剂量组诱导CYP2C活性(P<0.05);吴茱萸高、低剂量组对CYP2D活性无明显影响。②大鼠实验结果显示,与正常组比较,吴茱萸高、低剂量组均诱导肝药酶亚型CYP1A活性(P<0.01)。高剂量组诱导CYP2C和CYP2E1活性(P<0.05或0.01);吴茱萸高、低剂量组对CYP3A活性无明显影响;吴茱萸高、低剂量组均抑制CYP2D活性(P<0.01)。③实验结果对比显示,吴茱萸水煎液对大、小鼠肝药酶亚型的影响相同点是诱导了CYP1A、CYP2C及CYP2E1活性,尤其对CYP1A活性诱导更为明显。不同点是吴茱萸诱导了小鼠CYP3A活性,而对大鼠CYP3A活性无明显影响;吴茱萸对小鼠CYP2D活性无明显影响,而对大鼠CYP2D活性有明显抑制作用。结论吴茱萸水煎液对大、小鼠部分肝药酶亚型活性的影响有一定的差异性。     

不同剂量的DEHP对子代大鼠学习记忆的影响

目的 探讨不同剂量的DEHP对子代大鼠学习记忆的影响.方法 成熟Wistar大鼠,在妊娠期7～16 d,每天经口灌胃给予DEHP高(1000 mg/kg)、中(750 mg/kg)、低(250 mg/kg)三剂量组,对照组经口灌胃给予照物玉米油.采用跳台实验和避暗实验方法,观察DEHP对子代大鼠学习记忆障碍的影响.结果 神经行为学实验方法结果显示,跳台实验中高、中、低剂量组与对照组比较,错误次数明显增多,平均潜伏期明显缩短(P＜0.05);高剂量组与中、低剂量组比较,子代大鼠错误次数明显增多,潜伏期明显缩短(P＜0.05).避暗实验中高、中、低剂量组子代大鼠进入暗箱的潜伏期缩短明显低于对照组(P＜0.05)及子代大鼠5 min内受电击次数明显高于对照组(P＜0.05);高剂量组子代大鼠进入暗箱的潜伏期缩短与中、低剂量组比较有统计学意义(P＜0.05);高剂量组子代大鼠进入暗室的错误次数增多与低剂量组比较有显著性(P＜0.05).结论 DEHP对子代大鼠中枢神经系统损害有一定的影响,于代大鼠学习记忆能力明显减退.     

Effects of benactyzine and adiphenine on instrumental avoidance conditioning in a shuttle-box

Summary The effects of Benactyzine (Suavitil^?) and Adiphenine (Trasentine^?) on avoidance conditioning were investigated in naive male Wistar albino rats. An automatically operated shuttle-box with light as conditioning stimulus and shock as unconditioned stimulus was utilized. Six daily conditioning sessions of 50 trials each were given to all animals. Benactyzine over a wide dosage range (0.5 to 20 mg/kg daily s. c.) facilitated avoidance conditioning. The effect on the final level of performance was more marked than the effect on the first phases of acquisition of the conditioned response. Adiphenine (5 mg/kg s. c.) was inactive in the same experimental conditions. These results are discussed in the light of the data concerning the effects of cholinergic and anticholinergic drugs on the central nervous system. I wish to thankLuigi Amorico for his expert technical assistance.     

Permanent bilateral common carotid arterial ligation impairs visual but not auditory conditioned avoidance behavior in rats.

The effect of permanent bilateral common carotid arteries ligation (BCCAL) on visual function was investigated using conditioned avoidance task in Wistar rats. Behavioral experiments began 1 month after ligation. When light was used as a conditioned stimulus, the number of avoidance failures of BCCAL rats was higher than that of sham-operated control animals. However, the performance of the same avoidance task using a buzzer instead of light stimulus was not impaired by BCCAL. BCCAL impaired performance in the Morris water maze learning task and the rhythm of diurnal and nocturnal spontaneous motor activities. These results indicate that BCCAL treatment induces dysfunction of the visual system in rats, and consequently results in apparent deficits in conditioned avoidance behavior. BCCAL-induced deficits in performance in the water maze and rhythm of the motor activities are at least partially attributable to optical dysfunction.     

Lesions of cholinergic forebrain nuclei: Changes in avoidance behavior and scopolamine actions

The acquisition of active (shuttle-box) and passive avoidance conditioned responses and the effects of scopolamine on acetylcholine (ACh) output in freely moving rats and on conditioned responses were investigated 20 days after placing a unilateral lesion in the magnocellular forebrain nuclei (MFN). In the lesioned rats spontaneous ACh output from the cerebral cortex ipsilateral to the lesion was slightly decreased, while on the other hand the increase in ACh output elicited by scopolamine was strongly reduced. Sham operated rats always performed more active avoidance responses than MFN lesioned rats in the daily training shuttle-box sessions, and the facilitating effect of scopolamine (1 mg/kg IP) on the shuttle-box performance was suppressed. However the lesion did not disrupt the shuttle-box performance whenever training had taken place before the lesion. In the lesioned rats retested 30 min after the training trial, an impairment of the passive avoidance response was found. The effect of the lesion was potentiated by scopolamine. The results show therefore that MFN lesions impair the cortical cholinergic mechanisms, whose activity seems to play an important role in cognitive functions.     

Effects of MPEP on avoidance learning in rats

In recent years metabotropic glutamate receptors (mGluRs) have received considerable attention as a potential target for psychotropic drugs, but their influence on learning and memory is still unclear. The aim of the present study was to examine whether intraperitoneal (i.p.) administration of selective mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyrydine (MPEP), injected prior to, immediately after or 30 min after training, affects acquisition and/or retrieval of the inhibitory step-down and active shuttle-box avoidance in rats. Our results indicate that 5 or 10 mg/kg i.p. MPEP in all tested groups impaired memory consolidation of step-down training without affecting acquisition and had no effect on learning and retention in shuttle-box trained rats. The data are in agreement with the statement that mGluR5s may contribute very little and task-dependently to the actual acquisition of new information, but memory formation, appears to require mGluR5s through modulation of consolidation and/or recall.     

Stages of avoidance strategy formation in gerbils are correlated with dopaminergic transmission activity

This detailed analysis of behavior is aimed at the differentiation of the components of information processing during associative conditioning. In gerbils, the influences of various acquired non-avoidance strategies as pre-experience were studied during the learning of a standard avoidance task in the same shuttle-box. Identical cue stimuli, frequency-modulated tones as conditioned stimuli and electric footshocks as unconditioned stimuli, were used in various behavioral tasks. In addition to common parameters such as avoidance performance and reaction times, behavioral events such as the attention response and the orienting response were quantified. Thereby, components of shuttle-box learning such as signal detection and signal evaluation were found to be affected by pre-experience-dependent dynamics. Using a microdialysis technique during avoidance learning in the shuttle-box, we found that only strategy formation was correlated with high dopamine levels in medial prefrontal cortex. The increase in dopamine in medial prefrontal cortex may be an indicator of the involvement of working memory principles in signal evaluation stages of conditioning.     

Memory effects of the Ca2+ and 5-HT antagonists dotarizine and flunarizine

In experiments on Wistar and Long Evans rats, using behavioral methods for passive (step-down and step-through) and active (shuttle-box two-way avoidance with punishment reinforcement) the newly synthesized diphenyl-methyl-piperazine derivative with Ca2+ and 5-HT antagonistic action dotarizine (DOT) administered repeatedly at oral doses of 50 and 10 mg/kg in some cases improve memory process. Under the same experimental conditions the chemically related to dotarizine Ca2+ antagonist flunarizine significantly facilitated retention. In old (Long Evans and Wistar) rats DOT in large dose decreases values of learning criterion. Probably this is a manifestation of the inherent to drugs with nootropic action "therapeutic window". Earlier investigations of the same and other authors suggest the participation of serotonergic neurotransmission in the mechanism of the memory effects of the drug DOT.     

Active avoidance behavior in guinea pigs: effects of physostigmine and scopolamine.

Behavioral training of guinea pigs by conventional methods, such as used for rats and mice, appears difficult. Hence, only a few behavioral experiments with guinea pigs have been described in the literature. An active avoidance technique in an automated two-way shuttlebox is described using sound as a conditioned (CS) and a tactile stimulus (a stream of air ruffling their fur) as an unconditioned (UCS) stimulus. Acquisition is fairly rapid and reproducible. Doses of physostigmine that caused moderate blood acetylcholinesterase inhibition induced dose-dependent performance decrements. These decrements were counteracted by a sign-free dose of scopolamine.     

Different effects of 3-chlorophenylpiperazine on locomotor activity and acquisition of conditioned avoidance response in different strains of mice

Summary Mice of C57BL/6 (C57), Balb/c (BALB), and CD-1 (CD) strains were injected with 3-chlorophenylpiperazine (CPP), 1–10 mg/kg ip, and their exploratory and basal locomotor activities and acquisition of conditioned avoidance response in a shuttle-box were tested. In C57 mice CPP did not affect either locomotor activity or shuttle-box performance. In BALB mice CPP inhibited both basal and exploratory activities (the latter only in higher doses) and facilitated the acquisition of conditioned avoidance response. In CD mice CPP did not affect exploration, but inhibited basal locomotor activity and facilitated the shuttle-box performance. It is concluded that there exist large interstrain differences in responsiveness of mice to CPP, and that the drug may facilitate acquisition of conditioned avoidance response through a strain-specific, serotonin-independent mechanism.     

Repeated nicotine exposure enhances reward-related learning in the rat.

Repeated exposure to addictive drugs causes neuroadaptive changes in cortico-limbic-striatal circuits that may underlie alterations in incentive-motivational processes and reward-related learning. Such drug-induced alterations may be relevant to drug addiction because enhanced incentive motivation and increased control over behavior by drug-associated stimuli may contribute to aspects of compulsive drug-seeking and drug-taking behaviors. This study investigated the consequences of repeated nicotine treatment on the acquisition and performance of Pavlovian discriminative approach behavior, a measure of reward-related learning, in male rats. Water-restricted rats were trained to associate a compound conditioned stimulus (tone+light) with the availability of water (the unconditioned stimulus) in 15 consecutive daily sessions. In separate experiments, rats were repeatedly treated with nicotine (0.35 mg/kg, s.c.) either (1) prior to the onset of training, (2) after each daily training session was completed (ie postsession injections), or (3) received nicotine both before the onset of training as well as after each daily training session. In this study, all nicotine treatment schedules increased Pavlovian discriminative approach behavior and, thus, prior repeated exposure to nicotine, repeated postsession nicotine injections, or both, facilitated reward-related learning.