The dynamic distribution of fluoro-gold and its interrelation with neural nitric oxide synthase following intracerebroventricular injection into rat brain

We mapped the dynamic distribution of fluoro-gold (FG) within rat brain following intracerebroventricular (icv) injection into the lateral ventricle and observed its interrelation with neural nitric oxide synthase (nNOS) using FG fluorescent microphotography combined with nNOS immunohistochemistry. We also detected the amount of icv administered FG entering the peripheral circulation using a fluorescence microplate assay. The degree of periventricular penetration of FG was significantly increased over time. At 2 min after icv injection, FG primarily labeled the choroid plexus in the lateral and third ventricles, with limited penetration into the ependyma and the subependyma of the same ventricles. Some FG/nNOS-double labeled cerebrospinal fluid-contacting neurons were observed in these ventricles as well. At 15 and 30 min, FG penetrated mainly into forebrain ventricular organs and parenchymal structures. Many FG/nNOS double labeled neurons were found at each of these sites. In addition, at 30 min intense FG labeling was found in the hypophysis, while limited periventricular penetration of FG was detected in the hindbrain circumventricular areas. In the peripheral circulation, a low concentration of FG was detected 2 min after icv injection. The concentration increased slowly, peaked at 20 min, then gradually decreased until the end of the experiment at 30 min. These findings indicate that dynamic penetration of icv administrated agents into the periventricular tissues and peripheral circulation should be considered when designing icv experiments.     

The dynamic distribution of fluoro-gold and its interrelation with neural nitric oxide synthase following intracerebroventricular injection into rat brain

We mapped the dynamic distribution of fluoro-gold (FG) within rat brain following intracerebroventricular (icv) injection into the lateral ventricle and observed its interrelation with neural nitric oxide synthase (nNOS) using FG fluorescent microphotography combined with nNOS immunohistochemistry. We also detected the amount of icv administered FG entering the peripheral circulation using a fluorescence microplate assay. The degree of periventricular penetration of FG was significantly increased over time. At 2 min after icv injection, FG primarily labeled the choroid plexus in the lateral and third ventricles, with limited penetration into the ependyma and the subependyma of the same ventricles. Some FG/nNOS-double labeled cerebrospinal fluid-contacting neurons were observed in these ventricles as well. At 15 and 30 min, FG penetrated mainly into forebrain ventricular organs and parenchymal structures. Many FG/nNOS double labeled neurons were found at each of these sites. In addition, at 30 min intense FG labeling was found in the hypophysis, while limited periventricular penetration of FG was detected in the hindbrain circumventricular areas. In the peripheral circulation, a low concentration of FG was detected 2 min after icv injection. The concentration increased slowly, peaked at 20 min, then gradually decreased until the end of the experiment at 30 min. These findings indicate that dynamic penetration of icv administrated agents into the periventricular tissues and peripheral circulation should be considered when designing icv experiments.     

A METHOD FOR THE STUDY OF CHOLESTEROL BIOSYNTHESIS IN THE CENTRAL NERVOUS SYSTEM

Abstract—

• 1 After intraperitoneal injection, there is negligible incorporation of [2-¹⁴C]-mevalonic lactone into the CNS of the adult rat.
• 2 Mevalonic lactone injected into the CSF is quickly transferred to blood.
• 3 Mevalonic lactone injected in the cistema magna or the lateral ventricle of the brain does not diffuse readily into the whole CSF. Spinal cord cholesterol is most heavily labelled after intracisternal injection, as is brain cholesterol after intraventricular administration.
• 4 After intraventricular perfusion, the diffusion of mevalonic lactone into the ventricle opposite the side of the injection is increased when the rate of perfusion is doubled from 5 to 10 μ1/hr. After injection, optimal homogeneity is obtained if a large volume (70μl) is administered.
• 5 An increase in the volume of injection from 70 μl to 130μl does not alter the distribution of activity between the left and right ventricles, nor does it increase the diffusion of mevalonic lactone from ventricle to spinal cord CSF.
• 6 The mean yield of mevalonic lactone incorporation into brain cholesterol is much higher after injection than after perfusion of precursor into the lateral cerebral ventricle.

     

Morphological changes in the central canal of the cat after kaolin injection into the cisterna magna

40 adult cats were made hydrocephalic by intracisternal injection of 200 mg Kaolin. 34 survived between 24 hours to 4 months. In 19 cases a ventriculostomy was carried out, whereby in 13 animals a contrast filling of the central canal occurred. The contrast medium injected into the ventricles entered the external CSF-space in the lumbo-sacral junction of the filum terminale. Light- and electron-microscopic studies showed adaptive structural changes of the central canal epithelium in the early stages. In later stages massive destructions of ependyma and spinal cord parenchyma were found.     

Infusions of acetaldehyde into the arcuate nucleus of the hypothalamus induce motor activity in rats

AimsThe hypothalamic arcuate nucleus (ARH) is one of the brain regions with the highest levels of catalase expression. Acetaldehyde, metabolized from ethanol in the CNS through the actions of catalase, has a role in the behavioral effects observed after ethanol administration. In previous studies acetaldehyde injected in the lateral ventricles or in the substantia nigra reticulata (SNR) mimicked the behavioral stimulant effects of centrally administered ethanol.Main methodsIn the present study we assessed the effects of acetaldehyde administered either into the ARH into a dorsal control or into the third ventricle on locomotion and rearing observed in 30 min sessions in an open field.Key findingsAcetaldehyde injected into the ARH induced horizontal locomotion and rearing for 20 min. In contrast, administration of acetaldehyde into a control site dorsal to the ARH did not have any effect on locomotion. Although acetaldehyde administration into the third ventricle also induced locomotion, the time course for the effect in this area was different from the time course following ARH injections. Acetaldehyde in the ARH produced a long lasting induction of locomotion, while with intraventricular injections the effects disappeared after 5 min.SignificanceThe present results are consistent with previous studies demonstrating that acetaldehyde is an active metabolite of ethanol, which can have locomotor stimulant properties when administered in the ventricular system of the brain or into specific brain nuclei. Some brain nuclei rich in catalase (i.e.; SNR and ARH) could be mediating some of the locomotor stimulant effects of ethanol through its conversion to acetaldehyde.     

Glutathione and gamma-glutamyl transpeptidase in the adult female rat brain after intraventricular injection of LHRH and somatostatin

Glutathione content and glutamyl transpeptidase activity in different regions of adult female rat brain were determined at 10 and 30 min following intraventricular injection of LHRH and somatostatin. Hypothalamic glutathione levels were significantly elevated at 10 and 30 min after a single injection of a 0.1 micrograms dose of LHRH. On the contrary, glutathione levels significantly decreased in the hypothalamus, cerebral cortex and cerebellum at 10 and 30 min after 0.5 or 1 microgram dose. However, significant decrease in brain stem glutathione was evident at 30 min after 0.5 microgram and 10 min after the 1 microgram dose. Somatostatin at doses of 0.5 microgram and 1 microgram significantly decreased glutathione levels in all four brain regions both at 10 and 30 min following injection into the 3rd ventricle. Gamma-glutamyl transpeptidase activity in the hypothalamus and cerebral cortex was significantly elevated after intraventricular injection of LHRH. However, a significant increase in gamma-glutamyl transpeptidase activity in cerebellum and brain stem was seen only with 0.5 and 1 micrograms doses of LHRH. Somatostatin also significantly increased gamma-glutamyl transpeptidase activity in hypothalamus, cerebral cortex, brain stem and cerebellum. The decrease in glutathione levels with corresponding increase in gamma-glutamyl transpeptidase activity after intraventricular administration of LHRH and somatostatin suggests a possible interaction between glutathione and hypothalamic peptides.     

Morphology of ventricular wall surfaces following neurotoxin induced degeneration of supraependymal afferents

Following intraventricular injection of 5,7-dihydroxytryptamine in rats and survival periods up to 25 weeks, the supraependymal serotonergic axon plexus in the lateral and fourth ventricle, except for the plexus upon the hippocampal fimbria in some cases, showed no evidence of regenerative capacities. This contrasts with many reports on regeneration of intraparenchymal serotonergic fibre systems in the mammalian brain following mechanical or neurotoxin-induced experimental degeneration. The supraependymal plexus appears to be critically involved in maintainance of normal ependymal integrity in that following its experimentally induced death many ependymal cells exhibit various pathological alterations in all regions examined. Degeneration of this plexus is also associated with heavy phagocytotic reactions. Morphology, distribution and possible origins of supraependymal macrophages are briefly discussed.     

Distribution of 1-14C palmitic acid in brain tissue after intraventricular injection in the conscious cat]

The distribution of (1-14C) palmitic acid in the brain tissue following the injection into the cerebral ventricles of conscious cats was investigated. The radioactive material was found in the brain tissue surrounding the cerebral ventricles and in the cerebral cortex, but in varying amounts : the smallest amounts were found in the cerebral cortex, while the highest in the thalamus and in the hippocampus. Radioactive material was also found in the peripheral venous blood. The amount of the radioactive material in the grey matter lining the cerebral ventricles as well as in the cerebral cortex was time-dependant. The labelled material in the structures surrounding the cerebral ventricles and in the cerebral cortex increased within first four hours after its intraventricular administration. Thereafter, throughout subsequent 48 hours either it slowly disappeared in the caudate nucleus and in the thalamus, or it was retained in the hypothalamus and in the floor of the IV ventricle.     

Ultrastructure of blood capillaries in vascular plexuses of the lateral ventricles of the human brain

Ultrastructure of the wall of the microcirculatory bed links in the lateral ventricles of the human brain has been studied, as well as their interrelations with neural elements and ependyma. Together with typical morphological structural signs, certain peculiarities are revealed, characterizing organic specificity. Elements, performing function of the blood-brain barrier are determined: epithelium (ependyma), basal membranes, interstitium. A well developed afferent and efferent nervous apparatus of the vascular plexus, evidently, actively participates in regulation of the microcirculatory blood bed and in formation of liquor.     

3D Modeling of the Lateral Ventricles and Histological Characterization of Periventricular Tissue in Humans and Mouse

The ventricular system carries and circulates cerebral spinal fluid (CSF) and facilitates clearance of solutes and toxins from the brain. The functional units of the ventricles are ciliated epithelial cells termed ependymal cells, which line the ventricles and through ciliary action are capable of generating laminar flow of CSF at the ventricle surface. This monolayer of ependymal cells also provides barrier and filtration functions that promote exchange between brain interstitial fluids (ISF) and circulating CSF. Biochemical changes in the brain are thereby reflected in the composition of the CSF and destruction of the ependyma can disrupt the delicate balance of CSF and ISF exchange. In humans there is a strong correlation between lateral ventricle expansion and aging. Age-associated ventriculomegaly can occur even in the absence of dementia or obstruction of CSF flow. The exact cause and progression of ventriculomegaly is often unknown; however, enlarged ventricles can show regional and, often, extensive loss of ependymal cell coverage with ventricle surface astrogliosis and associated periventricular edema replacing the functional ependymal cell monolayer. Using MRI scans together with postmortem human brain tissue, we describe how to prepare, image and compile 3D renderings of lateral ventricle volumes, calculate lateral ventricle volumes, and characterize periventricular tissue through immunohistochemical analysis of en face lateral ventricle wall tissue preparations. Corresponding analyses of mouse brain tissue are also presented supporting the use of mouse models as a means to evaluate changes to the lateral ventricles and periventricular tissue found in human aging and disease. Together, these protocols allow investigations into the cause and effect of ventriculomegaly and highlight techniques to study ventricular system health and its important barrier and filtration functions within the brain.     

Ependyma and supraependymal structures in some areas of the fourth ventricle in the rat

The ependyma was investigated in five areas of the rat ventricle system by means of both light and electron microscopy. The columnar, cuboidal and flattened types of the ependymal cells were mainly seen. All of them were seen in the fourth ventricle, while in the aqueductus cerebri and in the central canal the flattened type of the cell was lacking. An unusual variation as to the form of the ependymal cells was found on the roof of the fourth ventricle. Three groups of intraventricular structures were found in all investigated parts of the ventricle system: supraependymal globular structures containing irregularly arranged cristae, supraependymal protrusions appearing as homogeneous contents, and nerve profiles including nerve endings and nerve axons. The morphological characteristics of the ependyma and intraventricular profiles in the fourth ventricle allow to suppose a certain role of these structures in the exchange of various materials between the CSF, ependyma and neuropile.     

Intracisternal injection of TRH precursor, TRH-glycine, stimulates gastric acid secretion in rats

Intracisternal injection of thyrotropin-releasing hormone (TRH)-Gly (pGlu-His-Pro-Gly) produced a dose-dependent (1-100 micrograms) stimulation of gastric acid secretion in urethane-anesthetized rats implanted acutely with a gastric fistula. The peak response occurred 20-30 min after intracisternal injection and lasted for more than 2 h. Intravenous injection of TRH-Gly (100 micrograms) did not modify gastric acid secretion. Following intracisternal injection of TRH-Gly, a peak elevation of both TRH-Gly and TRH levels is observed in the cerebrospinal fluid (CSF) within 15 min. Thereafter, TRH values are returned to basal levels at 75 min after the injection, whereas TRH-Gly concentrations remain significantly elevated throughout the 2-h period of measurement. Compartmental analysis revealed that CSF conversion of TRH-Gly to TRH was only 0.0072%/min. Medullary coronal sections containing the dorsal vagal complex and the raphé nucleus revealed increased content of TRH-Gly, but not TRH, 40 min after administration of TRH-Gly at an intracisternal dose effective in stimulating gastric acid secretion (100 micrograms). In addition, TRH but not TRH-Gly (10(-7)-10(-5) M) displaced [3H]MeTRH binding from rat medullary blocks containing the dorsal vagal complex. These data suggest that the intracisternal TRH-Gly-induced stimulation of gastric acid secretion is not related to its conversion to TRH in the CSF, or direct activation of TRH receptors in the medulla. The acid secretory response of TRH-Gly may be due to the formation of TRH at the active brain sites, or alternatively to activation of its own specific receptors.     

Ultrastructural study of the uptake of peroxidase by the rat median eminence

An active role of the ependymal cells (tanycytes) of the median eminence in the transport of hypothalamic hormones has been recently suggested. In order to investigate the fate of material present in the cerebrospinal fluid, a protein tracer, horse-radish peroxidase (HRP) was injected into the left lateral ventricle of rats. Two minutes after the injection, HRP had largely diffused between tanycytes and hypendymal cells. As soon as 5 min after the injection, HRP had completely penetrated all the layers of the median eminence. A few labelled vesicles and lysosomes were occasionally seen in ependymal and glial cells. At longer time intervals (20 min, 1 and 4 hrs), a reaction was observed in the lumen of fenestrated capillaries of the pituitary portal plexus. In many nerve endings of the external zone, vesicles and lysosomes were seen to contain HRP. An interesting observation was the localization of HRP between nerve endings and cells in both the pars nervosa and the pars intermedia of the pituitary gland. No reaction was recorded in the anterior pituitary and the kidney. Seventeen hours after the injection, the extracellular space was free of reaction but a few positive intracellular structure were still found. These results clearly indicate that some material from the third ventricle can rapidly diffuse between cells and axons of the median eminence to reach the fenestrated capillaries of the pituitary portal plexus and the posterior pituitary without involving an active transport by tanycytes.     

Ultrastructure of ependyma in brain third ventricle of the rats exposed to repeated tail-suspension. Scanning electron microscopical study

By means of scanning electron microscopy the ultrastructure of ependyma was studied in the brain third ventricle of the rats repeatedly exposed to 14-day tail-suspension (TS). Animals were subjected to TS for 30 days, then readapted to horizontal position during 30 days and again, repeatedly subjected to TS for 14 days simultaneously with the rats which were in TS for the first time during 14 days. Repeated TS of rats, inspite of repeated redistribution of body liquid mediums in cranial direction, results in considerably less expressed destructive changes in ultrastructure of ependymocyte cilia, then after primary 14- and 30-day TS, showing much greater cerebrospinal fluid (CSF) outflow from brain ventricles into sagittal venous sinus at postponed for a long time, repeated simulation of weightlessness effects in comparison with CSF outflow at primery one.     

Intraventricular blood vessels associated with the deep pineal gland of the Mongolian gerbil,Meriones unguiculatus

Summary Intraventricular blood vessels and choroidal-like cells were studied using scanning electron microscopy and correlative light microscopy. The intraventricular blood vessels were covered on their ependymal surface with a layer of cells essentially identical to the ependyma of the choroid plexus in the gerbil. Similar choroidal-like cells were seen either singly or in clusters associated with the cerebrospinal fluid-contacting pinealocytes of the suprapineal recess. Processes of the cerebrospinal fluid-contacting pinealocytes were seen extending to and making contact with the choroidal-like cells. The intraventricular blood vessels appeared to be derived from the choroid plexus, and typically took one of three courses in and around the surface of the deep pineal: (1) the vessels or their equivalent were located in the suprapineal recess with no indication of penetration into the substance of the deep pineal; (2) the vessels coursed from the suprapineal recess around the anterior surface of the habenular commissure to enter the ventral surface of the deep pineal; or (3) the vessels entered the parenchyma of the deep pineal from its dorsal surface and could be seen coursing through the substance of the gland. The close association between the choroidal-like cells and the intraventricular blood vessels with the deep pineal gland add morphological support for the possibility of interaction between the cerebrospinal fluid, or perhaps the choroid plexus, and the deep pineal gland.     

Über die Entwicklung von Ependym und Plexus chorioideus der Ratte

Zusammenfassung Formentwicklung der Seiten- und des 3. Ventrikels, Histogenese und Chemodifferenzierung des Ventrikelependyms und der Plexus chorioidei der Ratte (163 Tiere) vom 14. Embryonaltag bis zum 40. Lebenstag und bei erwachsenen Kontrolltieren werden lichtmikroskopisch untersucht. Die wesentlichsten Formmerkmale der Ventrikel sind bis zur Geburt ausgeprägt. Die Anpassung an die weitere Größenzunahme des Gehirns ist jedoch erst etwa am 30. Lebenstag abgeschlossen. — Die Bildung der Plexus chorioidei beginnt im Seitenventrikel am 15., im 3. Ventrikel am 17. Embryonaltag. Der Glykogengehalt des Plexusepithels nimmt bis zur Geburt zu und wird bis zum 15. Lebenstag vollständig reduziert. Die postnatale Aktivitätszunahme der verschiedenen Dehydrogenasen (NADH, NADPH, SDH, LDH, -HB-DH, Glu-6-DH), Cytochromoxidase und sauren Phosphatase im Plexusepithel ist etwa am 30. Lebenstag beendet. — Die Histogenese des zunächst mehrreihigen Ependyms aus der Matrix beginnt am 18. Embryonaltag. Die Aktivität der verschiedenen Fermente steigt pränatal nur mäßig an. Im Seitenventrikel tritt Wimpernependym auf; hier ist die morphologische Differenzierung an der medialen Wand (Hippocampusformation) am 3. Lebenstag, an der lateralen Wand (gleichzeitig mit der Rückbildung der subependymalen Zellschicht) zwischen dem 11. und 21. Lebenstag, die Chemodifferenzierung bis zum 30. Lebenstag abgeschlossen. Im 3. Ventrikel beginnt am 19. Embryonaltag die Differenzierung in Wimpernependym und Tanycytenependym; letzteres besitzt keine Wimpern, entsendet jedoch lange Zellfortsätze in den Hypothalamus und zur basalen Oberfläche des Zwischenhirns. Es kleidet nur den ventralen Ventrikelbezirk (Radix und Rec. infundibuli, Rec. inframammillaris) aus und kommt auch in einer schmalen mittleren Zone, dem Wimpernependym unterlagert, vor. Das Wimpernependym des 3. Ventrikels erreicht etwa gleichzeitig mit der morphologischen Reifung zwischen dem 5. und 10. Lebenstag die Fermentaktivität erwachsener Kontrolltiere. Morphologische und histochemische Differenzierung des Tanycytenependyms sind dagegen erst am 34. Lebenstag abgeschlossen. Wimpernependym und Tanycytenependym unterscheiden sich nicht nur morphologisch, sondern auch in ihrem Fermentmuster: ATPase fehlt im Wimpernependym, saure Phosphatase, Bernsteinsäuredehydrogenase, Cytochromoxidase und -Hydroxibuttersäuredehydrogenase zeigen keine Aktivität im Tanycytenependym. Die anderen nachgewiesenen Fermente besitzen — mit Ausnahme der Glucose-6-phosphat-Dehydrogenase — die relativ höchste Aktivität im Wimpernependym. Die Fermentaktivität tritt im Wimpernependym vorwiegend apikal, in den Tanycyten über die ganze Zelle verteilt und in den Fortsätzen auf. Das Enzymmuster des Wimpernependyms wird als Ausdruck eines oxidativen Energiestoffwechsels im Dienst der Wimpernmotorik gewertet. Die Fermentausstattung des Tanycytenependyms deutet auf möglicherweise hier ablaufende Synthesevorgänge hin.

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Summary The development of the lateral and third ventricle, histogenesis and chemodifferentiation of the ventricle ependyma and plexus chorioidei in rats (163 animals) are investigated by means of light microscopy. The age of the animals investigated ranged from the 14th day of embryonic life to the 40th day of life. Adult control animals were included in the investigation.The most essential structural elements of the ventricles are developed before birth. The adjustment to the increasing size of the brain, however, is completed only on the 30th day of life. The formation of the plexus chorioidei begins in the lateral ventricle on the 15th, in the third ventricle on the 17th day of embryonic life. The glycogen content of the plexus epithelium increases steadily until birth; from there on a reduction takes place until, on the 15th day of life, the glycogen is completely reduced. The post-natal increase in the activity of various dehydrogenases (NADH, NADPH, SDH, LDH, -HB-DH, Glu-6-DH), cytochrome oxidase, and acid phosphatase in the plexus epithelium is terminated on the 30th day of life approximately. The histogenesis of the originally stratified ependyma deriving from the matrix starts on the 18th embryonic day. The increase of enzymatic activity before birth is negligible. Ciliated ependyma is observed in the lateral ventricle; there the morphological differentiation of the medial wall (hippocampus formation) is terminated on the 3rd day of life, of the lateral wall (together with the reversion of the subependymal cell layers) between the 11th and 21st day of life. The chemodifferentiation is terminated on the 30th day of life. On the 19th embryonic day the differentiation of the ciliated and tanycyte ependyma starts in the third ventricle. The tanycyte ependyma is not ciliated; it sends long cell processes into the hypothalamus and to the basal surface of the diencephalon. It only lines the ventral region of the ventricle (Radix and Rec. infundibuli, Rec. inframammillaris) and is present in a narrow central zone, where it is demonstrable underneath the ciliated ependyma. Together with the morphological differentiation the ciliated ependyma of the third ventricle obtains an enzymatic activity comparable to adult control animals between the 5th and 10th day of life. The morphological and histochemical differentiation of the tanycyte ependyma is only completed on the 34th day of life. Ciliated ependyma and tanycyte ependyma differ not only morphologically but also in their enzymatic pattern. ATP-ase is not present in ciliated ependyma. There is no activity of acid phosphatase, succinate dehydrogenase, cytochrome oxidase, and -hydroxi-butyric acid dehydrogenase in the tanycyte ependyma. With the exception of glucose-6-phosphate dehydrogenase, all the enzymes investigated show the relatively highest activity in the ciliated ependyma. The enzymatic activity of the ciliated ependyma is predominantly found in the apical part of the cell, whereas in tanycytes it is evenly distributed over the cell and the processes. The enzymatic pattern of the ciliated ependyma is to be regarded as the expression of an oxidative energy metabolism which serves the motoricity of the cilia. The enzymatic pattern of the tanycyte ependyma seems to indicate a certain synthesizing activity.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft und den Universitätsbund Würzburg.

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Die Arbeit hat der Medizinischen Fakultät Würzburg als Inauguraldissertation vorgelegen.     

The expression of transthyretin mRNA in the developing rat brain

Specific cDNA and oligonucleotide probes were used to study the appearance of transthyretin mRNA in developing rat brain using Northern gel analysis, cytoplasmic dot hybridization, and in situ hybridization. Transthyretin mRNA in embryonic rat brain was found to be confined to the epithelial layer of the choroid plexus primordia appearing first in the fourth ventricle, followed by appearance in the lateral ventricles, and subsequently in the third ventricle. Transthyretin mRNA was localized in these cells from early stages of neuroepithelium differentiation, showing that it is a sensitive marker for the differentiation of the choroid plexus within the fetal brain.     

兔侧脑室注射八肽胆囊收缩素抗血清对血浆自由脂肪酸浓度的影响

本工作根据抗原抗体间具有高度特异性的中和作用的原理,将微量 CCK-8抗血清注射入制备有埋藏套管的慢性实验兔的侧脑室内,观察在中和脑内外源性或内源性的 CCK-8后,血浆 FFA 浓度的变化,结果如下:1.侧脑室内注射正常兔血清,对血浆 FFA 浓度无明显影响;在注射 CCK-8同时注射兔正常血清,也不影响 CCK-8降低血浆 FFA 浓度的作用。2.侧脑室内注射 CCK-8抗血清能有效地阻断外源性脑室注射 CCK-8降低血浆 FFA 的作用,此阻断作用随 CCK-8抗血清剂量的增加而增强。3.侧脑室内单独注射 CCK-8抗血清,血浆 FFA 浓度明显升高,这一作用可能是由于中和了脑内内源性 CCK-8的作用所致。以上结果表明,CCK-8脑室注射引起的血浆 FFA 降低的作用具有一定的特异性;而在正常生理情况下,脑内释放的内源性 CCK-8可能参与血浆 FFA 代谢的调节。     

Effect of ethanol and probenecid on the excretory function of the cerebral choroid plexus in rats

Probenecid at a dose 100 and 200 mg/kg, i.v. has been found to decrease in a dose-dependent manner the level of radioactivity of cerebrospinal fluid (CSF) measured at 1, 15, 30 and 60 min. after the intravenous injection of 14C-tyrosine, 14C-tryptophan and 14C-DOPA. Ethanol at a dose 2 and 4 g/kg, i. p. has not changed the level of radioactivity of the CSF. It is suggested that mentioned in the literature an increased accumulation of the labeled tyrosine, tryptophan and DOPA in the brain structures after their intravenous injection is not related to the inhibitory effect of ethanol on the excretory function of the choroid plexus of the brain. On the other hand, it is concluded that probenecid is able to inhibit the excretion from the brain of some acid compounds including tyrosine, tryptophan and DOPA.     

Protein synthesis and transport by the rat choroid plexus and ependyma

Summary Light (LM-ARG) and electron microscope (EM-ARG) autoradiographs were prepared from immature rat choroid plexus and ependyma at 5, 10, 30, and 60 min and 16 h following intraperitoneal administration of [³H]- labeled amino acid mixtures. Intracellular protein synthesis and transport were ascertained in lateral and fourth ventricle choroid plexus epithelium by quantitative EM-ARG at the several post-injection intervals. ARG were also prepared from choroid plexuses cultured for one day, pulse labeled for one hour and reincubated for various periods in nonradioactive media. Significant labeling of both attached and free apical protrusions (blebs) was observed in both choroid plexus and ependyma in vivo and in choroid plexus in vitro. This phenomenon was interpreted as a physiologically significant mechanism for protein transport (apocrine secretion) by epithelia into the cerebrospinal fluid (CSF).This study was supported in part by N.I.H. Research Grant NS 12906