Internal environment of the developing brain

描述(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，但也不同于成人。构成大脑内部环境的液体(脑细胞外液、ECF和脑脊液，CSF)的组成受统称为血脑屏障的机制控制。Pl的研究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路线可能比穿过血管的直接路线更重要，而在未成熟的大脑中，血管进入大脑的路线很少。长期目标是了解控制大脑发育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的性质。另一个目的是了解障碍机制的病理生理障碍对大脑发育的影响。这些建议集中在控制发育中的大脑内部环境的两个方面，一个是脑屏障机制的正常性质，另一个是炎症反应引起的屏障性质的病理生理变化：(I)在发育的非常早期阶段定义血液、脑脊液和脑之间的渗透机制和途径。(Ii)模拟感染性炎症反应(由注射脂多糖引起)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。这些研究将在南美负鼠(Monodelphis Home Tica)身上进行；它们出生在大脑发育的非常早期阶段(相当于13日龄的胎鼠)。需要研究的渗透机制和途径是对蛋白质和小分子质量(MW)极性分子的渗透。将生物素(244Da)、生物素标记的探针(如生物素葡聚糖MW 3000Da)和蛋白质(白蛋白、胎儿蛋白、胎球蛋白)在出生后不同年龄(P>65岁)(断奶后的青年)进行腹腔注射，并用光镜和电子显微镜观察其在脑脊液和脑中的分布。它们向脑脊液的转移将被定量，并与经典但不可见的渗透性探头(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(由注射不同时期的内毒素引起)对不同年龄段屏障通透性的影响。

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.