Internal environment of the developing brain

描述（由申请人提供）：大脑在局部（内部）环境中发育，与胚胎的其他部分不同，但也与成人不同。构成大脑内部环境的液体（脑细胞外液和脑脊液）的成分由统称为“血脑屏障”的机制控制。Pl小组最近的工作表明，在发育中的大脑中，通过脑脊液从血液进入大脑的途径可能比直接穿过血管的途径更重要，而在未成熟的大脑中，直接穿过血管的途径很少。长期目标是了解控制发育中的大脑内部环境组成的机制的本质，并确定其对大脑发育特定特征的贡献特性。另一个目的是了解病理生理障碍对屏障机制对大脑发育的影响。这些建议集中在发育中的大脑内部环境控制的两个方面，一个是大脑屏障机制的正常特性，另一个是炎症反应引起的屏障特性的病理生理变化：(i)在发育的早期阶段血液、脑脊液和大脑之间的渗透性机制和途径的定义。（ii）模拟感染性炎症反应（通过注射脂多糖引起）对不同发育阶段和成人脑屏障通透性的急性和长期影响的研究。研究对象为南美负鼠（Monodelphis domestica）；他们出生在大脑发育的早期阶段（相当于13天的胎鼠）。研究的渗透机制和途径是蛋白质和小分子量极性分子。生物素（244da）、生物素标记探针（如生物素葡聚糖，3000Da）和蛋白质（白蛋白和胎儿蛋白，胎蛋白）将在不同出生年龄(P)至P65（断奶后的年轻人）腹腔注射，并通过光镜和电镜检查其在脑脊液和大脑中的分布。它们向脑脊液的转移将被量化，并与经典但不可可视化的渗透性探针（放射性标记的蔗糖和菊糖）的结果进行比较。类似的实验，将研究急性或慢性炎症反应（不同时期注射LPS诱导）对不同年龄层屏障通透性的影响。

DESCRIPTION (provided by applicant): The brain develops in a local (internal) environment that is distinct from the rest of the embryo, but is also different from the adult. The composition of the fluids (brain extracellular fluid, ECF and cerebrospinal fluid, CSF) that form the internal environment of brain is controlled by mechanisms referred to collectively as "the blood-brain barrier". Recent work of the Pl's group suggests the route of entry from blood to brain via the CSF in the developing brain may be more important than a direct route across blood vessels, which in immature brain are few. The long term aim is to understand the nature of mechanisms that control the composition of the internal environment of developing brain and to determine properties of its contribution to specific features of brain development. An additional aim is to understand effects on brain development resulting from pathophysiological disturbances to barrier mechanisms. The proposals concentrate on two aspects of control of the developing brain's internal environment, one a normal property of brain barrier mechanisms and the other, pathophysiological changes in barriers properties due to an inflammatory response:(i) Definition of permeability mechanisms and pathways between blood, CSF and brain at very early stages of development. (ii) Studies of acute & long-term effects of simulated infectious inflammatory responses (evoked by injection of lipopolysaccharide, LPS) on brain barrier permeability at different stages of development and in adults. The studies will be in S. American opossums (Monodelphis domestica); they are born at a very early stage of brain development (equivalent to 13 day fetal rats). The permeability mechanisms and pathways to be studied are to proteins and small molecular weight (mw) polar molecules. Biotin (244 Da), biotin labelled probes (eg biotin dextran mw 3000Da) and proteins (albumin & fetal protein, fetuin) will be injected intraperitoneally at different postnatal (P) ages up P65 (postweaning young adult) and their distribution in CSF and brain examined by light and electronmicrosopy. Their transfer into CSF will be quantitated and compared with results with classical but non-visualizable permeability probes (radiolabelled sucrose & inulin). Similar experiments, will study the effects of an acute or chronic inflammatory response (induced by injection of LPS for different periods) on barrier permeability at different ages.