Pérez-Fígares J M, Jimenez A J, Rodríguez E M
Departamento de Biología Celular y Genética, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain.
Microsc Res Tech. 2001 Mar 1;52(5):591-607. doi: 10.1002/1097-0029(20010301)52:5<591::AID-JEMT1043>3.0.CO;2-7.
Under normal physiological conditions the cerebrospinal fluid (CSF) is secreted continuously, although this secretion undergoes circadian variations. Mechanisms operating at the vascular side of the choroidal cells involve a sympathetic and a cholinergic innervation, with the former inhibiting and the latter stimulating CSF secretion. There are also regulatory mechanisms operating at the ventricular side of the choroidal cells, where receptors for monoamines such as dopamine, serotonin, and melatonin, and for neuropeptides such as vasopressin, atrial natriuretic hormone, and angiotensin II, have been identified. These compounds, that are normally present in the CSF, participate in the regulation of CSF secretion. Although the mechanisms responsible for the CSF circulation are not fully understood, several factors are known to play a role. There is evidence that the subcommissural organ (SCO)--Reissner's fiber (RF) complex is one of the factors involved in the CSF circulation. In mammals, the predominant route of escape of CSF into blood is through the arachnoid villi. In lower vertebrates, the dilatation of the distal end of the central canal, known as terminal ventricle or ampulla caudalis, represents the main site of CSF escape into blood. Both the function and the ultrastructural arrangement of the ampulla caudalis suggest that it may be the ancestor structure of the mammalian arachnoid villi. RF-glycoproteins reaching the ampulla caudalis might play a role in the formation and maintenance of the route communicating the CSF and blood compartments. The SCO-RF complex may participate, under physiological conditions, in the circulation and reabsorption of CSF. Under pathological conditions, the SCO appears to be involved in the pathogeneses of congenital hydrocephalus. Changes in the SCO have been described in all species developing congenital hydrocephalus. In these reports, the important question whether the changes occurring in the SCO precede hydrocephalus, or are a consequence of the hydrocephalic state, has not been clarified. Recently, evidence has been obtained indicating that a primary defect of the SCO-RF complex may lead to hydrocephalus. Thus, a primary and selective immunoneutralization of the SCO-RF complex during the fetal and early postnatal life leads to absence of RF, aqueductal stenosis, increased CSF concentration of monoamines, and a moderate but sustained hydrocephalus.
在正常生理条件下，脑脊液（CSF）持续分泌，尽管这种分泌存在昼夜变化。脉络丛细胞血管侧的作用机制涉及交感神经和胆碱能神经支配，前者抑制脑脊液分泌，后者刺激脑脊液分泌。在脉络丛细胞的脑室侧也存在调节机制，已鉴定出多巴胺、5-羟色胺和褪黑素等单胺以及血管加压素、心房钠尿肽和血管紧张素II等神经肽的受体。这些通常存在于脑脊液中的化合物参与脑脊液分泌的调节。尽管脑脊液循环的机制尚未完全了解，但已知有几个因素起作用。有证据表明，联合下器官（SCO）-赖斯纳纤维（RF）复合体是参与脑脊液循环的因素之一。在哺乳动物中，脑脊液进入血液的主要途径是通过蛛网膜绒毛。在低等脊椎动物中，中央管远端的扩张，即终脑室或尾壶腹，是脑脊液进入血液的主要部位。尾壶腹的功能和超微结构排列均表明，它可能是哺乳动物蛛网膜绒毛的祖先结构。到达尾壶腹的RF糖蛋白可能在脑脊液和血液腔室连通途径的形成和维持中起作用。SCO-RF复合体在生理条件下可能参与脑脊液的循环和重吸收。在病理条件下，SCO似乎参与先天性脑积水的发病机制。在所有发生先天性脑积水的物种中均已描述了SCO的变化。在这些报告中，SCO发生的变化是先于脑积水还是脑积水状态的结果这一重要问题尚未阐明。最近，已获得证据表明，SCO-RF复合体的原发性缺陷可能导致脑积水。因此，在胎儿期和出生后早期对SCO-RF复合体进行原发性和选择性免疫中和会导致RF缺失、导水管狭窄、脑脊液中单胺浓度升高以及中度但持续的脑积水。
