脑缺血后脑室内注射胰岛素减轻大鼠学习记忆力损害的实验研究

目的探讨经脑室直接注射胰岛素对全脑缺血后大鼠学习记忆力的影响.方法以4-VO法建立大鼠全脑缺血再灌注模型.全脑缺血20min后行再灌注,于再灌注即刻经脑室注入1U胰岛素,缺血再灌注后8周利用三等分Y型迷宫箱测试大鼠的学习记忆功能,并对大鼠海马CA1区神经元的病理改变进行观察.结果经Y型迷宫测试,对照组、治疗组及缺血组大鼠达9/10正确反应所需电击数分别为5.6±1.2,8.6±1.3,19.6±2.6;对照组、治疗组及缺血组大鼠海马CA1区神经元计数分别为176.5±10.6,112.4±11.7,10.5±0.4.结论全脑缺血后脑室内注射胰岛素可明显减少大鼠海马CA1区神经元的死亡,进而减轻大鼠学习记忆力损害.     

缺血预处理后Fas蛋白表达与迟发性神经元凋亡的关系初步探讨

目的动态观察缺血预处理后大鼠大脑皮层和海马CA1区神经元凋亡与Fas蛋白表达变化情况,初步探讨缺血预处理后Fas蛋白表达与迟发性神经元凋亡的关系。方法四血管阻断法复制全脑缺血模型,动物随机分为非缺血对照组、预处理对照组、缺血预处理组和缺血组。采用尼氏和TUNEL染色法观察皮层及海马CA1区神经元存活数和凋亡细胞数,免疫组化方法检测Fas蛋白在缺血预处理后表达变化情况。结果缺血组缺血6h在皮质及海马CA1区Fas阳性表达细胞计数升高,12h达高峰;缺血预处理组缺血12h阳性细胞计数升高,24h达高峰。缺血组缺血6h出现凋亡细胞,48h凋亡细胞数达到高峰;缺血预处理组凋亡细胞数较缺血组明显减少。缺血组缺血7d神经元数明显减少,12周时神经元大量减少;缺血预处理组缺血7d时神经元数无明显变化,但12周时神经元同样大量减少。结论全脑缺血可能通过诱导Fas蛋白的表达增多,启动细胞凋亡,导致缺血后神经元凋亡的发生;缺血预处理虽可延缓缺血后神经元的凋亡,但无法提供真正的长时期的神经元保护作用,其有限的保护作用可能是通过延缓Fas蛋白的表达而减缓了神经元凋亡的进程。     

葛根素对大鼠全脑缺血再灌注后学习记忆障碍保护作用及其机制的研究

目的 探讨葛根素对大鼠全脑缺血再灌注后学习记忆能力的影响及其机制。方法 采用四血管阻断法建立SD大鼠全脑缺血再灌注损伤模型，暗回避反应法测定学习记忆能力，并应用免疫组织化学法、原位末端标记法，检测大鼠全脑缺血再灌注海马CA，区的bcl-2阳性细胞数、凋亡细胞数的动态变化。结果 (1)与再灌注组相比，葛根素组大鼠潜伏期明显延长；(2)脑缺血再灌注后，海马CA1区bcl-2蛋白的表达随再灌注时间不同而变化，缺血20min后再灌注24h达高峰，葛根素组bcl2蛋白的表达于相应的时间点明显增多；(3)脑缺血再灌注后海马CA1区神经元凋亡损伤在再灌注72h损伤最重，葛根素组可减少相应时点神经细胞凋亡数。结论 葛根素对全脑缺血再灌注后大鼠学习记忆能力具有明显的改善作用，其作用机制可能与通过上调bcl-2基因表达从而抑制或延迟脑缺血再灌注后细胞凋亡有关。     

亚低温对大鼠短暂全脑缺血后神经元凋亡的影响

目的 探讨亚低温对大鼠脑缺血后神经元凋亡的影响，揭示亚低温的部分神经保护机制。方法 采用“双侧颈总动脉阻断＋全身低血压”方法来建立大鼠短暂性全脑缺血模型。用神经元尼氏体亚甲兰特殊染色法观察大鼠脑缺血后海马CA1区神经元损害情况；原位细胞凋亡检测法（TUNEL染色）及电镜观察脑缺血后CA1区神经元凋亡情况。结果 与假手术组、低温缺血组相比，常温缺血组海马CA1区神经元缺失明显（P＜0．01）。常温及低温缺血组海马CA1区均存在神经元凋亡，但低温缺血组海马CA1区凋亡神经元数明显少于缺血组（P＜0．01）。结论 经“双侧颈总动脉阻断＋全身低血压”方法建立的大鼠短暂全脑缺血模型证实了亚低温的脑保护作用。全脑缺血后的迟发性神经元死亡很可能经由凋亡途径，而亚低温可通过抑制缺血性神经元凋亡而发挥一定的神经保护作用。     

亚低温对缺血性神经元凋亡、细胞色素C释放的影响

通过大鼠短暂全脑缺血模型来探讨亚低温对大鼠脑缺血后细胞色素C(CytochromeC ,CytC)释放及缺血性神经元凋亡的影响 ,揭示亚低温的部分神经保护机制。用原位细胞凋亡检测法 (TUNEL染色 )检测及电镜观察脑缺血后大鼠脑海马CA1区神经元凋亡发生情况 ;免疫组织化学法测定脑缺血后大鼠脑海马区神经元中细胞色素C释放情况。结果显示 :①低温缺血组海马CA1区凋亡神经元数明显少于常温缺血组 (P <0 .0 1) ;②低温缺血3h组海马CA1区神经元CytC阳性表达低于常温缺血 3h组 (P <0 .0 1)。据此认为 ,全脑缺血后的迟发性神经元死亡很可能经由凋亡途径 ,而CytC激活、释放是缺血性神经元凋亡的一个关键事件。亚低温可抑制CytC的释放 ,推测经此途径减少缺血性神经元凋亡而发挥一定的神经保护作用。     

局灶性脑缺血再灌注大鼠海马CA1区神经元凋亡研究

目的 观察大鼠局灶性脑缺血再灌注(ischemia reperfusion,I/R)损伤后海马CA1区神经元凋亡、TUNEL阳性细胞变化,以及凋亡相关蛋白Bcl-2与Bax蛋白的表达情况.方法 将健康雄性SD (Sprague-Dawley)大鼠随机分为假手术组和I/R组,每组再分为缺血再灌注后3、6、12、24、48、72 h亚组.应用免疫组化方法检测再灌注后不同时间点大鼠海马CA1区神经元凋亡基因Bcl-2和Bax蛋白的表达及Bcl-2/Bax比值变化,采用原位细胞凋亡检测(TUNEL)技术检测凋亡阳性细胞数.结果 各组非缺血侧相应区域神经元胞质中Bcl-2均有微弱表达.I/R组缺血侧海马CA1区于再灌注3 h开始出现Bcl-2和Bax蛋白微弱表达,随再灌注时间延长神经元内Bcl-2表达逐渐增强,再灌注24 h后Bcl-2表达达高峰,假手术组与I/R组比较差异有统计学意义(P<0.05).结论 I/R损伤后海马CA1区神经元不仅存在变性坏死,还存在明显的细胞凋亡且细胞凋亡在大鼠I/R损伤中发挥重要作用;I/R可诱导海马CA1区细胞凋亡基因Bcl-2和Bax蛋白表达,且其表达呈一定规律.     

亚低温对大鼠全脑缺血再灌注损伤后海马CA1区c-Jun蛋白表达的影响

目的研究亚低温对大鼠全脑缺血再灌注损伤后海马CA1区神经元的保护作用,并探讨其可能的机制。方法采用四血管阻断法建立大鼠全脑缺血模型。SD大鼠,随机分为假手术组(SH组)、常温组(IR组)和亚低温组(HIR组)。各组在全脑缺血15min后分别再灌注6h、12h、1d、3d,采用苏木素-伊红(HE)染色观察各时间点海马CA1区细胞形态学变化和TUNEL法检测海马CA1区神经元凋亡,免疫印迹检测c-Jun蛋白表达。结果(1)HE染色结果 IR组和HIR组于全脑缺血再灌注后6h,HE染色未见明显改变,IR组缺血再灌注1d时CA1区出现严重改变,3d时损伤最严重,出现细胞数目减少,细胞胞体缩小、胞核固缩深染,损伤严重,排列紊乱,核膜不清,核仁消失。而HIR组海马存活的锥体细胞数较之IR组12h、1d、3d时间点均明显增加(P<0.05)。(2)TUNEL标记IR组于缺血再灌注后6h在海马CA1区阳性细胞开始增多,缺血再灌注1 d时阳性细胞数最多。而HIR组各时间点阳性细胞数均较IR组明显减少(P<0.01)。(3)免疫印迹结果全脑缺血再灌注后6h c-Jun蛋白在IR组海马CA1区表达开始增加,12h达高峰,持续到3d;HIR组在各时间点的表达均弱于IR组(P<0.01)。结论亚低温通过减少海马CA1区c-Jun的表达,抑制海马CA1区神经元的凋亡,可能是亚低温脑保护作用的机制之一。     

亚低温对缺血性神经元凋亡、细胞色素C释放的影响

通过大鼠短暂全脑缺血模型来探讨亚低温对大鼠脑缺血后细胞色素c(Cytoehrome c,CytC)释放及缺血性神经元凋亡的影响,揭示亚低温的部分神经保护机制.用原位细胞凋亡检测法(TUNEL染色)检测及电镜观察脑缺血后大鼠脑海马CAi区神经元凋亡发生情况;免疫组织化学法测定脑缺血后大鼠脑海马区神经元中细胞色素C释放情况.结果显示:①低温缺血组海马CAi区凋亡神经元数明显少于常温缺血组(P<0.01);②低温缺血3 h组海马CA1区神经元CytC阳性表达低于常温缺血3 h组(P<0.01).据此认为,全脑缺血后的迟发性神经元死亡很可能经由凋亡途径,而CytC激活、释放是缺血性神经元凋亡的一个关键事件.亚低温可抑制CytC的释放.推测经此途径减少缺血性神经元凋亡而发挥一定的神经保护作用.     

酸敏感离子通道2a对缺血预处理诱导大鼠海马缺血耐受的作用

目的探讨脑缺血时的组织病理学变化及酸敏感离子通道2a（ASIC2a）在缺血预处理诱导的脑缺血模型耐受中的作用。方法取成年雄性SD大鼠160只,随机分为假手术组、预缺血组、缺血组、缺血预处理组共4组。行焦油紫染色观察各组大鼠海马CAI区存活神经元密度,TUNEL染色观察大鼠海马CA1区神经元凋亡情况,RT—PCR和Western blotting检测ASIC2a在大鼠海马CAl区mRNA和蛋白表达情况。结果缺血预处理能够显著减少大鼠海马CA1区锥体神经元的死亡和凋亡,PC＋Isch组和Isch组相比具有显著性差异（P〈0．01）。全脑缺血能够上调ASIC2a在大鼠海马CA1区mRNA和蛋白表达,在24h达到高峰,而缺血预处理进一步上调ASIC2a表达,呈进行性上升,在24h和72h时相点,PC＋Isch组和Isch组相比具有显著性差异（P〈0．01）。结论在脑缺血耐受中,缺血预处理对第二次致死性缺血表现出保护作用。在这个过程中,大鼠海马CA1区ASIC2a基因和蛋白表达上调发挥了重要的保护作用。     

小檗碱对小鼠全脑缺血后神经元凋亡相关基因的影响

目的 探讨小檗碱对小鼠全脑缺血后神经元凋亡相关基因的影响,以了解小檗碱保护脑缺血的机制,为其开发利用提供理论依据。方法 利用改良的Pulsinelli-Brierley4血管闭塞法制成小鼠全脑缺血再灌注动物模型。小檗碱用量为1mg/kg,于术前30min,术后每日1次,腹腔注射。免疫组织化学技术检测凋亡相关基因Bcl-2,Bax蛋白的表达。结果 正常组海马区未见Bcl-2或Bax蛋白表达;缺血组再灌注6h海马CA3区可见Bcl-2阳性细胞,24h达到高峰,48h开始下降;小檗碱治疗组再灌注24h、48h及168hBcl-2阳性细胞明显减少（P＜0．01）。缺血组再灌注6h海马CA1区可见Bax阳性细胞;48h达高峰;168h明显下降;小檗碱组再灌注24h,48h及168hBax阳性细胞数明显减少（P＜0．01）。结论 小檗碱可以增加小鼠全脑缺血后海马CA3区bcl-2基因的表达,降低CA1区Bax基因的表达,从而减少凋亡的发生,可能为其保护脑缺血的机制之一。     

Characteristics of the sympathetic innervation of the nictitating membrane and of the vasculature of the nose and tongue of the cat

Summary Vasomotor responses from the nasal mucosa and tongue, and contractions of the nictitating membrane, were recorded on stimulation of the cervical sympathetic or internal carotid nerves.Preganglionic sympathetic nerve fibres which elicited a membrane response possessed a lower threshold than those which evoked nasal vasoconstriction, while the latter displayed a lower threshold than fibres which evoked tongue vasoconstriction. The sympathetic vasodilator fibres to the tongue, whose activity was revealed after-receptor blockade, had a similar threshold to the vasoconstrictor fibres.Membrane contraction, nasal vasoconstriction and occasionally tongue vasoconstriction could be evoked by stimulating the internal carotid nerve. The postganglionic fibres innervating the nasal mucosa had a similar threshold to those of the nictitating membrane, which may indicate that there are small myelinated fibres innervating the mucosa.The preganglionic compound nerve action potential had four major components, S₁–S₄. S₁, S₂ and usually S₃ fibres were associated with membrane contraction; S₂, S₃ and sometimes S₁ fibres were associated with nasal vasoconstriction; and S₃, usually S₂ and occasionally S₁ fibres were associated with vasoconstriction in the tongue. It is concluded that each of these three groups of nerve fibres, but not S₄ fibres, may include fibres associated functionally with the three effectors.There was a considerable difference between the relative amplitude of the responses of the three effectors elicited by stimulation of the cervical sympathetic nerve at frequencies between 0.2 and 2 Hz. Vasoconstrictor responses were relatively larger than membrane contractions suggesting differences in the mechanisms of neurotransmission at the neuroeffector junctions.     

Mechanisms of the suppression of the nociceptive reflex of the opening of the mouth during stimulation of the structures of the limbic brain

The comparative effectiveness of the inhibitory influence of tetanic stimulation of hypothalamus, amygdala and limbic cortex on EMG-response of m. digastricus evoked by electrical stimulation of tooth pulp nociceptive afferents was studied in cats anesthetized with a mixture of chloralose and nembutal. It was found that inhibition of the EMG-component of the jaw-opening reflex is most pronounced in case of stimulation of medial and lateral region of the hypothalamus, the inhibitory effect of central and medial nuclei of the amygdala is less pronounced and the effect of the limbic cortex is the weakest. It was shown that the mechanism of the antinociceptive effect of tetanic stimulation of the hypothalamus is not related to the concomitant increase of the blood pressure. After stabilization of the blood pressure the suppressive effect of the hypothalamus remains without changes, that points out to a direct, primary, not baro-afferent mechanism of the inhibition of the activity of nociceptive neurons of the trigeminal sensory nuclei. Noradrenaline, injected intravenously, induced a large increase of the blood pressure accompanied by a pronounced inhibition of the pain reflex. Angiotensin causes the same degree of blood pressure elevation without changes in the amplitude of the EMG-response of the pain reflex. Hypothalamic and noradrenergic mechanisms for control of pain sensitivity are discussed.     

Development of the projection from the nucleus of the brachium of the inferior colliculus to the superior colliculus in the ferret

Neurons in the deeper layers of the superior colliculus (SC) have spatially tuned receptive fields that are arranged to form a map of auditory space. The spatial tuning of these neurons emerges gradually in an experience-dependent manner after the onset of hearing, but the relative contributions of peripheral and central factors in this process of maturation are unknown. We have studied the postnatal development of the projection to the ferret SC from the nucleus of the brachium of the inferior colliculus (nBIC), its main source of auditory input, to determine whether the emergence of auditory map topography can be attributed to anatomical rewiring of this projection. The pattern of retrograde labeling produced by injections of fluorescent microspheres in the SC on postnatal day (P) 0 and just after the age of hearing onset (P29), showed that the nBIC-SC projection is topographically organized in the rostrocaudal axis, along which sound azimuth is represented, from birth. Injections of biotinylated dextran amine-fluorescein into the nBIC at different ages (P30, 60, and 90) labeled axons with numerous terminals and en passant boutons throughout the deeper layers of the SC. This labeling covered the entire mediolateral extent of the SC, but, in keeping with the pattern of retrograde labeling following microsphere injections in the SC, was more restricted rostrocaudally. No systematic changes were observed with age. The stability of the nBIC-SC projection over this period suggests that developmental changes in auditory spatial tuning involve other processes, rather than a gross refinement of the projection from the nBIC.     

Origins of the sympathetic innervation of the cervical end of the uterus in the rat

A retrograde neuronal tracer (Fast Blue) was injected in the cervical end of the uterine horn of virgin rats. The majority of the retrogradely labeled post-ganglionic sympathetic neurons were found in the sympathetic chain (74%). The superior mesenteric ganglia, inferior mesenteric ganglia and suprarenal ganglia accounted for 22, 3 and <1%, respectively. The distribution of neurons in the sympathetic chain labeled from the uterus resembles that described for other pelvic organs.     

Sexual pheromones and the evolution of the reward system of the brain: the chemosensory function of the amygdala

The amygdala of all tetrapod vertebrates receives direct projections from the main and accessory olfactory bulbs, and the strong similarities in the organization of these projections suggest that they have undergone a very conservative evolution. However, current ideas about the function of the amygdala do not pay sufficient attention to its chemosensory role, but only view it as the core of the emotional brain. In this study, we propose that both roles of the amygdala are intimately linked since the amygdala is actually involved in mediating emotional responses to chemical signals. The amygdala is the only structure in the brain receiving pheromonal information directly from the accessory olfactory bulbs and we have shown in mice that males emit sexual pheromones that are innately attractive for females. In fact, sexual pheromones can be used as unconditioned stimuli to induce a conditioned attraction to previously neutral odorants as well as a conditioned place preference. Therefore, sexual pheromones should be regarded as natural reinforcers. Behavioural and pharmacological studies (reviewed here) have shown that the females' innate preference for sexual pheromones is not affected by lesions of the dopaminergic cells of the ventral tegmental area, and that the systemic administration of dopamine antagonists do not alter neither the attraction nor the reinforcing effects of these pheromones. Anatomical studies have shown that the vomeronasal amygdala gives rise to important projections to the olfactory tubercle and the islands of Calleja, suggesting that these amygdalo-striatal pathways might be involved in the reinforcing value of sexual pheromones.     

Topographical organization of the motoneuron pools that innervate the muscles of the pinna of the cat

The topographical organization of the 22 motoneuron pools that innervate the pinna muscles of the cat was examined by injecting the B-subunit of cholera toxin conjugated to horseradish peroxidase into individual muscles. All 22 pools are found in the facial nucleus, organized as rostro-caudally oriented columns, and arranged according to the action of the muscles they innervate. Pools innervating muscles that pull the pinna dorsally are located in the dorsal two thirds of the medio-dorsal subdivision, and those innervating muscles that pull the pinna ventrally are located in the ventral one half of the nucleus. Motoneurons innervating muscles that pull the pinna cranially are located laterally, those that pull the pinna caudally are located medio-ventrally, and those that change the shape of the pinna are located along the entire dorso-ventral extent in the center of the medio-dorsal subdivision. This topographical layout is consistent with the somatotopic organization of the entire facial nucleus as demonstrated in a variety of species. © 1995 Wiley-Liss, Inc.     

Histochemical methods for the further characterisation of the tumourettes of the posterior lobe of the pituitary

Summary The granular cell tumourettes of the posterior lobe of the pituitary possess neuraminic acid containing carbohydrate. After removal of neuraminic acid with neuraminidase and exposure to FITC (Fluorescein isothiocyanate) labelled peanut agglutinin (Arachis hypogaea) (PNA), intracellular receptor structures could be demonstrated. The significance of the findings is discussed.