成年大鼠脑内5-HT能神经纤维向胎鼠脑皮层移植物内投射的研究

目的:探讨大鼠胎脑皮层组织同种移植后的存活情况,以及宿主脑组织与移植物之间是否能建立神经纤维联系.方法:移植受体(宿主)为正常雄性成年Wistar大鼠,移植供体取自胎龄15～17d的Wistar孕鼠.在移植手术后不同时间取脑切片,用ABC法进行免疫组织化学染色,显示5-HT能神经纤维及其在宿主脑内和移植物中的分布情况.结果:同种胎鼠脑皮层组织移植后存活率为30%,ABC法显示有5-HT能神经纤维从宿主脑组织长入移植物中.结论:同种胎脑皮层组织移植后移植物与宿主脑组织可以建立神经纤维联系.     

成年大鼠脑内5-HT能神经纤维向胎鼠脑皮层移植物内投射的研究

目的：探讨大鼠胎脑皮层组织同种移植后的存活情况，以及宿主脑组织与移植物之间是否能建立神经纤维联系。方法：移植受体(宿主)为正常雄性成年Wistar大鼠。移植供体取自胎龄15～17d的Wistar孕鼠。在移植手术后不同时间取脑切片。用ABC法进行免疫组织化学染色。显示5-HT能神经纤维及其在宿主脑内和移植物中的分布情况。结果：同种胎鼠脑皮层组织移植后存活率为30%，ABC法显示有5-PIT能神经纤维从宿主脑组织长入移植物中。结论：同种胎脑皮层组织移植后移植物与宿主脑组织可以建立神经纤维联系。     

脑组织移植

脑组织移植是一个有着广阔临床应用前景的领域。本文从移植物的选择、制备、植入方式 ,移植物 -宿主间的神经联系 ,移植物对宿主脑功能的影响以及移植后的免疫排斥反应等几方面对脑组织移植做一较为详细的综述     

胎脑组织移植对额叶皮层损伤大鼠辨别学习、记忆之影响

本研究观察了胎脑组织移植对双侧额叶皮层损伤的大鼠学习、记忆功能的影响。学习、记忆再现测验在Y型迷宫中进行。结果表明,胎脑组织移植能促进双侧额叶皮层受损动物明—暗分辨学习及记忆再现功能的恢复,且移植时间长短与其功能恢复呈正相关。组织学检查表明,移植的胎脑组织不仅存活,且分化良好,移植3、6个月后,与宿主脑界面有部分融合,提示移植脑组织与宿主脑可能有纤维联系形成。     

大鼠小脑组织移植的实验研究

应用不同胎龄的大鼠小脑组织(E15和E18)做移植物,以组织块和细胞悬液两种方法植入受体鼠小脑人工毁损灶内,2月后处死动物。在HE制备的切片上观察移植物成活情况,以组织块移植的胎脑组织未见成活。以细胞悬液植入成活的受体鼠小脑,显微镜检成活的移植物可根据细胞结构特点易与受体脑组织区别,可见到良好分化及成熟的神经细胞。     

胚胎组织脑内移植研究回顾和瞻望

近年来,脑内移植实验研究证实,未成熟的神经元移植到成熟宿主的脑内不仅可以存活,而且可以保持其原来的神经功能特性,因此,神经病学家和临床医生越来越重视,从人类流产的胎儿中获取脑组织作为移植物,用来治疗人类的某些疑难疾病的探索和研究。由于未成熟的胎儿神经元在宿主脑内具有很强的生命力和明显的可塑性,脑内移植后加用适当的免疫抑制剂环胞菌素A或皮质激素等,有助脑移植物存活,发挥其神经功能和神经内分泌功能的作用。因此,有关脑内组织移植的报道逐渐增多,并引起了医学界的兴趣和关注。     

胎脑黑质脑内移植对PD鼠纹状体内D_2RmRNA表达的影响

为了研究胎脑黑质脑内移植后对ＰＤ鼠纹状体神经元Ｄ２Ｒ基因表达的影响，采用核酸斑点杂交技术对纹状体内Ｄ２ＲｍＲＮＡ进行了连续定量观察，发现胎脑黑质移植物能够使ＰＤ鼠纹状体内过度表达的Ｄ２ＲｍＲＮＡ水平恢复正常。本研究结果提示：Ｄ２ＲｍＲＮＡ过度表达及ＰＤ鼠旋转行为被矫正的程度可能反映出胎脑黑质移植物对宿主形成神经再支配的程度。     

哺乳动物脑组织移植技术的一些原则和研究进展(综述)

自1890年 Thompson 首先报告用成年猫和狗的大脑皮质进行移植以来已有近一个世纪的历史,但只是在近十几年人们才开始认识到哺乳动物中枢神经系统(CNS)具有很强的能力同移植的神经组织形成纤维联系;而且这些神经移植组织可改变宿主的功能和行为。哺乳动物脑组织移植是以 CNS 组织作为移植物,将其植入宿主脑的不同部位,如脑实质内、预制的脑组织腔隙内、脑表面或脑室系统中。本文拟就脑组织移植技术的一些基本原则及其研究进展进行讨论。     

胎脑黑质脑内移植对PD鼠纹状体内D2RmRNA表达的影响

为了研究胎脑黑质脑内移植后对ＰＤ鼠纹状体神经元Ｄ２Ｒ基因表达的影响，采用核酸斑点杂交技术对太体内Ｄ２ＲｍＲＮＡ进行了连续定量观察，发现胎脑黑质移植物能够使ＰＤ鼠纹状体内过度表达的Ｄ２ＲｍＲＮＡ水平恢复正常。本研究结果提示，Ｄ２ＲｍＲＮＡ过度表达及ＰＤ鼠旋转行为被矫正的程度可能反映出胎脑黑持移植物对宿主形成神经再支配的程度。     

带蒂大网膜移植治疗脑缺血的实验研究

实验目的是了解大网膜移植到缺血脑皮层后,侧支循环建立的时间,方式,从而估价网膜颅内移植的效果。实验采用家兔30只。首先探讨制备兔脑缺血的各种实验模型,发现电凝闭塞大脑中动脉分支操作方便,缺血效果可靠,确认为制备脑缺血的标准实验方法。 实验分甲,乙两组进行。甲组观察带蒂大网膜移植于缺血脑皮层后侧支循环建立的时间;乙组了解网膜和脑皮层之间的联接方式。结果证实,网膜移植到缺血兔脑皮层后3天,发生了肯定的血管吻合,网膜和脑皮层之间有一层增厚的纤维层相隔,网膜和脑组织不仅通过该纤维层发生联系,而且网膜组织本身和网膜内的血管可以穿过该纤维层和脑组织发生直接的连接。     

酒精中毒大鼠脑血管病变及相应脑组织损伤的病理观察

目的　观察酒精中毒后大鼠脑血管病变、脑组织损伤情况及探讨相关机制。方法　 Wistar雄性大鼠酒精灌胃 4周造成慢性酒精中毒模型。通过光学显微镜观察酒精中毒后大鼠脑血管的病理变化及相应脑组织的损伤。结果　酒精中毒组大鼠额叶脑内小血管内弹力膜厚薄不一 ,出现皱褶 ,内皮细胞部分脱落 ,中膜平滑肌细胞及外膜胶原纤维增生 ;大脑皮质、海马、小脑皮质等部位均有神经细胞数目缺失及不同程度的细胞变性及损伤 ,但以小脑皮质的改变尤为明显。结论　酒精中毒后可以引起脑血管自身结构的改变并影响脑血流 ,造成缺血缺氧性改变 ,可能是酒精中毒后脑损伤的机制之一。     

大鼠脑出血后脑水肿形成特点的研究

目的 :研究脑出血后脑水肿形成的特点。方法 :建立大鼠尾状核出血模型 ,用干湿重法分别测定不同部位的脑组织在出血后1 ,2 ,3 ,5 ,7d的脑组织水分含量的变化 ,并与正常脑组织对比。结果 :脑出血后 2 4h内在血肿同侧基底节区及血肿同侧对应的皮质区形成明显的水肿 ,水肿的高峰在第 3天 ,持续 1周仍不消退 ,而血肿对侧对应的基底节区及皮质区脑组织水分含量则无明显变化。结论 :大鼠脑出血后脑水肿在 2 4h内形成 ,第 3天达到高峰 ,提示对临床脑出血病人脑水肿的防治要尽可能早     

Fetal Neocortical Tissue Blocks Implanted in Brain Infarcts of Adult Rats Interconnect with the Host Brain

The purpose of the present study was to study if the connectivity of fetal neocortical tissue blocks placed in ischemic brain infarcts of adult rats would be enhanced in rats housed in an enriched environment. We also investigated whether the enriched housing conditions could enhance the postischemic and postgrafting functional outcome, in terms of motor behavior. This part of the study has been published recently. The middle cerebral artery was ligated on the right side in 37 inbred, adult male spontaneously hypertensive rats. The rats were placed at random either in an enriched environment (groups A and B) or in standard laboratory cages (group C). Three weeks after the artery occlusion, blocks of fetal sensorimotor cortex (Embryonic Day 17) were transplanted into the infarct cavity of rats from groups B and C. After 9 weeks all transplanted rats received an injection, into the graft, of a mixture containing the two tracers Fluoro-Gold and biotinylated Dextran amine. The transplants revealed a structured morphology with whorls and bands of cells reminiscent of normal neocortex. Tracing of efferent transplant to host fibers with biotinylated Dextran amine showed pronounced intrinsic transplant projections, as well as fibers, although significantly fewer, to the host ipsilateral sensorimotor cortex, striatum, and thalamus. Host to transplant projections were revealed by Fluoro-Gold-labeled cells found in the ipsilateral host sensorimotor cortex, the basal nucleus of Meynert, the thalamic ventrobasal, ventrolateral and posterior nuclei, and in the dorsal raphe nuclei. We conclude that fetal frontal neocortical block grafts placed in brain infarcts of adult rats develop a morphology reminiscent of normal neocortex and that both afferent and efferent neural connections, although sparse, are established with the host brain, whether the rats are reared under enriched housing conditions or not.     

锰增强磁共振在大脑功能活动评价中的初步探索

目的：探讨用锰增强磁共振功能成像（ME-MRI）检测大脑功能活动的可能性，为示踪移植神经干细胞（NSCs）在创伤性脑损伤大鼠脑内的功能作铺垫。方法：A组正常SD大鼠静脉缓慢输注四水合氯化锰（MnCl2·4H2O），用甘露醇开放其一侧血脑屏障，然后电刺激其对侧肢体，即刻行T1加权MRI扫描；同时比较C组未开放血脑屏障、D组未行肢体电刺激和应用钙通道阻断剂的ME-MRI图像。结果：仅静脉输注MnCl2·4H2O、开放血脑屏障和行电刺激的T1加权MRI上体感皮质区表现出高信号。结论：ME-MRI可在体评估大脑功能活动，并为移植NSCs在创伤性脑损伤大鼠脑内的功能评价提供依据。     

Brain differences in newborn rats predisposed to helpless and depressive behavior

Inborn brain differences in metabolic capacity were mapped in congenitally helpless rats, a genetically selected strain predisposed to show helpless and depressive behavior. There are a number of brain regions showing abnormal metabolism in adult congenitally helpless rats. Some of these alterations may be innate while others may be due to environmental factors, such as maternal care and postnatal stress. To identify which brain structures show innate differences, brains of newborn rats from congenitally helpless and non-helpless strains were compared using cytochrome oxidase histochemistry, an endogenous marker of regional metabolic capacity. A smaller subset of regions affected in adults showed significantly less metabolic activity in the newborn brains, including paraventricular hypothalamus, habenula, hippocampus, subiculum, lateral septal nucleus, anterior cingulate cortex, infralimbic cortex, and medial orbitofrontal cortex. A covariance analysis further revealed a striking reduction of functional connectivity in the congenitally helpless brain, including a complete decoupling of limbic forebrain regions from midbrain/diencephalic regions. This pattern of brain metabolism suggests that helplessness vulnerability is linked to altered functioning of limbic networks that are key to controlling the hypothalamic-pituitary-adrenal axis. This implies that vulnerable animals have innate deficits in brain systems that would normally allow them to cope with stress, predisposing them in this manner to more readily develop helpless and depressive behaviors.     

Brain capillaries and cholinergic neurons persist in organotypic brain slices in the absence of blood flow

Angiogenesis plays an important role during development of the brain and under pathological conditions. The aim of the present study was to observe interaction of brain capillaries and cholinergic neurons in organotypic brain slices. Immunohistochemistry was used to visualize brain capillary-like structures (RECA-1 antigen) and cholinergic neurons (choline acetyltransferase). Under normal culture conditions, a very low number of brain capillaries was found in 2- and 4-week-old cortex brain slices. Treatment of slices with acidic medium (pH 6) or hyperthermia (42 degrees C) markedly enhanced the number of brain capillaries. Incubation with 10 ng/mL vascular endothelial growth factor only enhanced angiogenesis in more developed slices. Cholinergic neurons survived in slices of the basal nucleus of Meynert; however, hyperthermia but not acidosis markedly decreased their number. In coslices of the basal nucleus of Meynert and cortex (pretreated with acidic medium), a high number of RECA-1-positive capillaries and cholinergic neurons persisted and displayed strong nerve fibre growth of cholinergic fibres into the cortex. In conclusion, we have demonstrated that RECA-1-positive capillaries and cholinergic neurons can be studied in slice cultures in the absence of blood perfusion, and that this model could provide a system to study mechanisms involved in vascular dementia.     

Brain Adrenergic receptors and resistance to stress

The relationship between brain beta-adrenergic receptors and adaptation to stress was studied in rats subjected to repeated restraint stress. The stress was found to produce a reduction in the density of these receptors in the hypothalamus, cerebral cortex and brain stem. This change first appeared after 4–7 days and persisted for the duration of the two-week stress. Adaptation, as judged by resistance to the anorexic and gastric lesion-inducing effects of the stress, occurred progressively over the full two-week period. The loss of beta-receptors was found to correlate positively with the degree of adaptation. The relationship was strongest for the hypothalamus but was also apparent in the cortex and brain stem. These findings support the hypothesis that a reduction in the number of brain adrenergic receptors is one of the biochemical factors underlying adaptation to stress.     

Brain beta-endorphin-like immunoreactivity in adult rats given beta-endorphin neonatally

beta-endorphin-like immunoreactivity was measured by radioimmunoassay in the brains of adult rats treated neonatally with beta-endorphin, naloxone, or vehicle. After treatment with beta-endorphin, the decreases observed in beta-endorphin-like immunoreactivity in the hypothalamus, pineal, midbrain, pons-medulla, hippocampus, striatum, frontal cortex, occipital cortex, and posterior cortex were highly significant but the 23% decrease in the thalamus was not significantly different from that of control rats. Neonatal administration of naloxone only resulted in a significant decrease in beta-endorphin-like immunoreactivity in the hypothalamus. In contrast, no differences were discernible in content of either beta-endorphin-like immunoreactivity or ACTH-like immunoreactivity in the pituitary of rats treated with beta-endorphin, naloxone, or vehicle in the neonatal period. These same rats had shown an increased threshold to painful thermal stimulation by the tail-flick test after administration of either beta-endorphin or naloxone at birth. The results suggest that neonatally injected beta-endorphin may alter the levels of beta-endorphin-like immunoreactivity in rat brain as well as the response to pain.     

Brain micromotion around implants in the rodent somatosensory cortex

The magnitude of brain tissue micromotion relative to stationary brain implants and its impact on the viability and function of the surrounding brain tissue due to mechanical stresses is poorly understood. The central goal of this study is to characterize surface micromotion in the somatosensory cortex against stationary cylindrical implants. We used a differential variable reluctance transducer (DVRT) in adult rats (n = 6) to monitor micromotion normal to the somatosensory cortex surface. Experiments were performed both in the presence and in the absence of dura mater and displacement measurements were made at three different locations within craniotomies of two different sizes. In anesthetized rats, pulsatile surface micromotion was observed to be in the order of 10-30 microm due to pressure changes during respiration and 2-4 microm due to vascular pulsatility. Brain displacement values due to respiration were significantly lower in the presence of the dura compared to those without the dura. In addition, large inward displacements of brain tissue between 10-60 microm were observed in n = 3 animals immediately following the administration of anesthesia. Such significant micromotion can impact a wide variety of acute and chronic procedures involving any brain implants, precise neurosurgery or imaging and therefore has to be factored in the design of such procedures.