Transport of quinolinic acid into rabbit and rat brain

The transport metabolism of [³H]quinolinic acid in the central nervous system of rabbits and rats were studied. In vitro [³H]quinolinic acid was not readily accumulated by isolated choroid plexus. After the intraventricular injection of tracer quantities of [³H]quinolinic acid, the [³H]quinolinic acid did not enter the brain as readily as concurrently injected [¹⁴C]mannitol and was not metabolized, The permeability-surface area constant for [³H]quinolinic acid at the rat blood-brain barrier was 1.5±1.3×10^–5 sec^–1 compared to 2.8±0.4×10^–5 sec^–1 for [³H]mannitol. Our results suggest that: 1) [³H]quinolinic acid is transported in the CNS by passive diffusion and 2) is not metabolized.     

Toxicity of cisplatin to the central nervous system of male rabbits

The cytotoxic effects of platinum (Pt) were studied by intraparenchymal injection of 1 mg of cisplatin (CDDP) in male rabbits. Time-serial plasma Pt levels were used as CDDP clearance indices in brain and kidney tissues. The tissue samples were also examined histologically. Changes in the blood-brain barrier (BBB) were evaluated by horseradish peroxidase (HRP) extravasation. In the brain infusion group, Pt was detected in the plasma 30 min after the start of infusion. In the kidney, Pt was detected after 10 min of CDDP injection. The maximum plasma concentration of Pt in the brain group showed diffuse edema, neuronal necrosis, karyolysis, and HRP extravasation around the injection site. In contrast, the histological damage to kidneys was minimal. The results presented here show that direct infusion of CDDP caused the most extensive cytotoxicity in the brain. The low clearance rate of CDDP from the brain and BBB disruption may explain this behavior.     

宏基因组测序在中枢神经系统感染性疾病诊断中的应用及研究进展

中枢神经系统(central nervous system,CNS)感染是指由病毒、细菌或真菌等侵染中枢神经系统引起的急性或慢性炎症性(或非炎症性)疾病,致死率高,易引发严重后遗症。由于检测通量及灵敏度的限制,一半以上的中枢神经系统感染患者无法通过常规检测方法确定病原体。宏基因组测序是一种新兴的病原检测技术,能够极大地提升病原检出率。当前部分临床医生及相关从业人员对宏基因组测序的认识存在不足,限制了其在临床诊疗中的快速推广和应用。本文系统介绍了宏基因组测序整体流程,综述了该技术在中枢神经系统感染性疾病诊疗中的发展历程和最新研究进展,希望为中枢神经系统感染性疾病的诊断和治疗提供参考。     

Leptin transport in the central nervous system

Synthesized and released by the adipose tissue, leptin is the widely studied 167‐amino acid hormonal protein product of the obesity gene. Originally leptin was defined in association with satiety and energy balance and claimed to be an anti‐obesity factor that functioned via a feedback effect from adipocytes to hypothalamus. There is a growing body of evidence that emphasizes the importance of leptin in the regulation of food intake and body weight in animals and humans, alike. Other research findings point out that it plays a role in the regulation of the metabolism, sexual development, reproduction, hematopoiesis, immunity, gastrointestinal functions, sympathetic activation, and angiogenesis. The aim of this review is to evaluate the relation between leptin and the central nervous system (CNS). Copyright © 2009 John Wiley & Sons, Ltd.     

Basic Analysis of the Cerebrospinal Fluid: An Important Framework for Laboratory Diagnostics of the Impairment of the Central Nervous System

Laboratory analysis of basic cerebrospinal fluid (CSF) parameters is considered as essential for any CSF evaluation. It can provide rapidly very valuable information about the status of the central nervous system (CNS). Our retrospective study evaluated parameters of basic CSF analysis in cases of either infectious or non-infectious CNS involvement. Neutrophils are effector cells of innate immunity. Predominance of neutrophils was found in 98.2% of patients with purulent inflammation in CNS. Lymphocytes are cellular substrate of adaptive immunity. We found their predominance in 94.8% of patients with multiple sclerosis (MS), 66.7% of patients with tick-borne encephalitis (TBE), 92.2% of patients with neuroborreliosis, 83.3% of patients with inflammatory response with oxidative burst of macrophages in CNS and 75.0% of patients with malignant infiltration of meninges (MIM). The simultaneous assessment of aerobic and anaerobic metabolism in CSF using the coefficient of energy balance (KEB) allows us to specify the type of inflammation in CNS. We found predominantly aerobic metabolism (KEB > 28.0) in 100.0% CSF of patients with normal CSF findings and in 92.8% CSF of patients with MS. Predominant faintly anaerobic metabolism (28.0 > KEB > 20.0) in CSF was found in 71.8% patients with TBE and in 64.7% patients with neuroborreliosis. Strong anaerobic metabolism (KEB < 10.0) was found in the CSF of 99.1% patients with purulent inflammation, 100.0% patients with inflammatory response with oxidative burst of macrophages and in 80.6% patients with MIM. Joint evaluation of basic CSF parameters provides sufficient information about the immune response in the CSF compartment for rapid and reliable diagnosis of CNS involvement.     

Entry of pathogens into the central nervous system

Abstract: The blood-brain barrier (BBB) is formed by the tight junctions of the cerebral capillary endothelium and the choroid plexus epithelium. The molecular anatomy of the tight junction resembles that of a polarized, transporting epithelium, suggesting some model cell culture systems can provide insight into traffic into the central nervous system. Pathogens target both the endothelium, causing encephalitis, and the choroid plexus, leading to meningitis. Routes of entry are diverse including paracellular and transcellular penetration. In addition, circulating microbial products can induce loss of BBB function. Understanding the heterogeneous molecular interactions between pathogens and the BBB may provide avenues to interrupt the devastating neurological sequelae that accompany central nervous system infections.     

Cytodiagnosis of neoplasms of the central nervous system in cerebrospinal fluid samples with an application of selective immunostains in differentiation.

In this study cytological findings in specimens of cerebrospinal fluid (CSF) of central nervous system (CNS) tumours (16 primaries, 57 metastatic and 12 suspicious) are presented, which were diagnosed over a period of 7 years in 85 patients (50 females and 35 males) with an age range of 2-76 years. The follow-up included information from clinicians and a review of medical charts, histological correlation and/or further investigations following cytodiagnosis. The patients clinically presented with signs and symptoms of meningeal involvement. The primary tumours included six medulloblastomas, eight gliomas (four glioblastomata multiforme, two anaplastic astrocytomas, and two ependymomas) and two germinomas. The metastatic tumours were 14 melanomas, 19 breast carcinomas, four leukaemias, six B-cell lymphomas, five adenocarcinomas of gastrointestinal origin, seven carcinomas of lung, one retinoblastoma and one neuroblastoma. Twelve cases were reported as suspicious. On further investigations, four of these were from a primary tumour (two glioblastomata multiforme and two anaplastic astrocytomas) while the other eight cases were of a metastasis (one B-cell lymphoma, three breast carcinomas, three melanomas and one adenocarcinoma of gastrointestinal origin). Using a panel of selective immunostains in some of the cases supported the cytological diagnosis and this was considered useful in furthering cytodiagnosis. In 75 of the patients the CSF samples were obtained on a spinal tap while in 10 patients the samples were received as ventricular CSF. There were no false-positive cases. The results of our study suggest that CSF cytology in the diagnosis of CNS tumours is quite reliable and reflects involvement of leptomeninges or the ventricles. Furthermore, the use of selective immunostains can be helpful in confirming the cytological impression and source of the tumour.     

Junctions in the central nervous system of the cat

Summary The leptomeningeal tissue of the choroid plexuses and of the brain surfaces have been studied by means of the freeze-etching technique. The pia-arachnoid membrane and the subdural neurothel represent the morphological barrier between the extracerebral tissue and the cerebrospinal compartment. The freeze-etch findings indicate that the arachnoid and neurothelial cells are coupled by extensive zonulae occludentes which seem to represent the structural basis of the barrier mechanism provided by these cell layers. Furthermore, it became evident that gap junctions of considerable structural heterogeneity occur on the pial and arachnoid cells of the interstitial choroidal compartment and of the free brain surfaces. The structural heterogeneity of the nexuses is taken as an indication of the plasticity of the leptomeningeal tissue. The different morphological characteristics of the nexal formations are discussed with respect to their probable functional meaning.This investigation was supported by the Deutsche Forschungsgemeinschaft SFB 114 (Bionach).     

Proteomic analysis of cerebrospinal fluid discriminates malignant and nonmalignant disease of the central nervous system and identifies specific protein markers

CNS diseases are often accompanied by changes in the protein composition of cerebrospinal fluid (CSF). SELDI-TOF-MS provides an approach for identifying specific protein markers of disease in biological fluids. We compared the CSF proteomes from patients with neoplastic and reactive/inflammatory CNS diseases to identify potential biomarkers. SELDI-TOF-MS was performed on CSF derived from lumbar puncture of 32 patients, including 10 with CNS malignancies, 12 with inflammatory or reactive conditions, and 10 with unknown CNS disease. Using the SAX-2 (strong anionic exchange) chip, we uncovered three conserved protein peak ranges within each disease category. For neoplastic diseases, we identified conserved peaks at 7.5-8.0 kDa (9/10 samples), 15.1-15.9 kDa (8/10 samples), and 30.0-32.0 kDa (5/10 samples). In reactive/inflammatory diseases, conserved peaks were found at 6.7-7.1 kDa (10/12 samples), 11.5-11.9 kDa (12/12 samples), and 13.3-13.7 kDa (9/12 samples). A protein from the 30.0 to 32.0 kDa peak range found in neoplastic CSF was identified by MALDI analysis as carbonic anhydrase, a protein overexpressed in many malignancies including high-grade gliomas. Similarly, cystatin C was identified in the 13.3-13.7 kDa peak range in non-neoplastic CSF and was most prominent in inflammatory conditions. Our approach provides a rational basis for identifying biomarkers that could be used for detection, diagnosis, and monitoring of CNS diseases.     

Mitochondrial calcium function and dysfunction in the central nervous system

The ability of isolated brain mitochondria to accumulate, store and release calcium has been extensively characterized. Extrapolation to the intact neuron led to predictions that the in situ mitochondria would reversibly accumulate Ca²⁺ when the concentration of the cation in the vicinity of the mitochondria rose above the ‘set-point’ at which uptake and efflux were in balance, storing Ca²⁺ as a complex with phosphate, and slowly releasing the cation when plasma membrane ion pumps lowered the cytoplasmic free Ca²⁺. Excessive accumulation of the cation was predicted to lead to activation of the permeability transition, with catastrophic consequences for the neuron. Each of these predictions has been confirmed with intact neurons, and there is convincing evidence for the permeability transition in cellular Ca²⁺ overload associated with glutamate excitotoxicity and stroke, while the neurodegenerative disease in which possible defects in mitochondrial Ca²⁺ handling have been most intensively investigated is Huntington's Disease. In this brief review evidence that mitochondrial Ca²⁺ transport is relevant to neuronal survival in these conditions will be discussed.     

Cellular and subcellular localization of 3H-diethylstilboestrol in the central nervous system

Summary The cellular and subcellular localization of radioactivity in the brain of immature female rats was determined by dry-mount autoradiography 2 h after iv injection of 1.0 g of (monethyl-³H) diethylstilboestrol per 100 g body weight. A specific topographic pattern of nuclear concentration of the synthetic oestrogen was obtained similar to that for ³H-oestradiol-17 in specific neurons of the basal hypothalamus, preoptic region and amygdala. In competition experiments, the nuclear concentration of radioactivity in all areas studied was inhibited by unlabeled oestradiol, while unlabeled testosterone had no effect. These data suggest that although oestradiol can bind to androgen receptors, the oestrogen receptor itself can account for the localization seen after the injection of ³H-oestradiol.This research was supported in part by US PHS Grant No. NS12933NIH Career Development Awardee No. NS00164The expert technical assistance of Ms. Riki Ison and Ms. Linda Furr is gratefully acknowledged.     

Thioredoxin and glutaredoxin system proteins—immunolocalization in the rat central nervous system

Background

The oxidoreductases of the thioredoxin (Trx) family of proteins play a major role in the cellular response to oxidative stress. Redox imbalance is a major feature of brain damage. For instance, neuronal damage and glial reaction induced by a hypoxic–ischemic episode is highly related to glutamate excitotoxicity, oxidative stress and mitochondrial dysfunction. Most animal models of hypoxia–ischemia in the central nervous system (CNS) use rats to study the mechanisms involved in neuronal cell death, however, no comprehensive study on the localization of the redox proteins in the rat CNS was available.

Methods

The aim of this work was to study the distribution of the following proteins of the thioredoxin and glutathione/glutaredoxin (Grx) systems in the rat CNS by immunohistochemistry: Trx1, Trx2, TrxR1, TrxR2, Txnip, Grx1, Grx2, Grx3, Grx5, and γ-GCS, peroxiredoxin 1 (Prx1), Prx2, Prx3, Prx4, Prx5, and Prx6. We have focused on areas most sensitive to a hypoxia–ischemic insult: Cerebellum, striatum, hippocampus, spinal cord, substantia nigra, cortex and retina.

Results and conclusions

Previous studies implied that these redox proteins may be distributed in most cell types and regions of the CNS. Here, we have observed several remarkable differences in both abundance and regional distribution that point to a complex interplay and crosstalk between the proteins of this family.

General significance

We think that these data might be helpful to reveal new insights into the role of thiol redox pathways in the pathogenesis of hypoxia–ischemia insults and other disorders of the CNS.This article is part of a Special Issue entitled Human and Murine Redox Protein Atlases.     

Acanthamoeba invasion of the central nervous system

Pathogenic Acanthamoeba are known to infect the CNS, resulting in fatal granulomatous encephalitis. The mechanisms associated with the pathogenesis remain unclear; however pathophysiological complications involving the CNS most likely include induction of pro-inflammatory responses, invasion of the blood-brain barrier and the connective tissue and neuronal damage leading to brain dysfunction. The routes of entry include the olfactory neuroepithelium pathway and/or lower respiratory tract, followed by haematogenous spread. Skin lesions may provide direct entry into the bloodstream, bypassing the lower respiratory tract. For the haematogenous route, entry of amoebae into the CNS most likely occurs at the sites of the blood-brain barrier. Recent studies have identified several molecular mechanisms associated with Acanthamoeba traversal of the blood-brain barrier and targeting those may help develop therapeutic interventions and/or design preventative strategies.     

Fast axonal transport in central nervous system and peripheral nervous system axons following axotomy

After axotomy, changes in the composition of fast axonally transported proteins ( FTP ) within the peripheral nervous system (PNS) axons have been reported. The most significant and reproducible changes involved polypeptides found within the molecular weight range of 31.0 to 14.5 kilodaltons ( Bisby , 1980). We wished to determine whether similar changes following axotomy occur in axons of the central nervous system (CNS). Intracranial axotomy of the left optic tract was performed stereotaxically in rats. Six days post axotomy 50 muCi 35[S]-methionine was injected into the vitreous body of both eyes. FTP were isolated within the optic nerves 2 h after isotope injection. The nerve segments were processed for SDS-PAGE, fluorography, and compared to similarly prepared fluorographs of normal and eight day post-axotomy sciatic nerve segments. The labelling of 5 major polypeptide bands (S1, MW congruent to 28,000; S2a , MW congruent to 25,000; S2b , MW congruent to 23,000; T1, MW congruent to 20,200; and T2, MW congruent to 17,000) was studied by laser densitometry. Band S2b showed a highly significant (p less than 0.001) increase in concentration, while bands S1 and T1 demonstrated highly significant decreases in concentration following axotomy of the sciatic nerve. In contrast, after axotomy of the retinal ganglion cell axons the only significant change was a decrease (p less than 0.05) in T1. We suggest that failure of CNS axons to respond similarly to PNS axons following axotomy may be related to the failure of CNS axons to regenerate.     

Peripheral Taenia infection increases immunoglobulins in the central nervous system

Human cysticercosis is a disease caused by larvae of the cestode Taenia solium. It is an important common cause of adult-onset seizures world-wide where it exacts a debilitating toll on the health and well-being of affected communities. It is commonly assumed that the major symptoms associated with cysticercosis are a result of the direct presence of larvae in the brain. As a result, the possible effects of peripherally located larvae on the central nervous system are not well understood. To address this question, we utilised the Taenia crassiceps intra-peritoneal murine model of cysticercosis, where larvae are restricted to the peritoneal cavity. In this model, previous research has observed behavioural changes in rodents but not the development of seizures. Here we used ELISAs, immunoblotting and the Evans Blue test for blood–brain barrier permeability to explore the central effects of peripheral infection of mice with T. crassiceps. We identified high levels of parasite-targeting immunoglobulins in the sera of T. crassiceps-infected mice. We show that the T. crassciceps larvae themselves also contain and release host immunoglobulins over time. Additionally, we describe, for the first known time, significantly increased levels of IgG within the hippocampi of infected mice, which are accompanied by changes in blood–brain barrier permeability. However, these T. crassiceps-induced changes were not accompanied by alterations to the levels of proinflammatory, pro-seizure cytokines in the hippocampus. These findings contribute to the understanding of systemic and neuroimmune responses in the T. crassiceps model of cysticercosis, with implications for the pathogenesis of human cysticercosis.     

Androgen and progesterone metabolism in the central and peripheral nervous system

This paper summarizes the most recent data obtained in the authors' laboratory on the metabolism of testosterone and progesterone in neurons, in the glia, and in neuroblastoma cells. The activities of the 5α-reductase (the enzyme that converts testosterone into dihydrotestosterone, DHT), and of the 3α-hydroxysteroid dehydrogenase (the enzyme that converts DHT into 5α-androstane-3α,17β-diol, 3α-diol) have been first evaluated in primary cultures of neurons, oligodendrocytes and type-1 and -2 astrocytes, obtained from the fetal or neonatal rat brain. All the cultures were used on the fifth day. The formation of DHT or 3α-diol was evaluated incubating the different cultures with labeled testosterone or DHT as substrates. The results obtained indicate that the formation of DHT takes place preferentially in neurons; however, type-2 astrocytes and oligodendrocytes also possess considerable 5α-reductase activity, while type-1 astrocytes show a much lower enzymatic concentration. A completely different localization was observed for 3α-hydroxysteroid dehydrogenase; the formation of 3α-diol appears to be prevalently, if not exclusively, present in type-1 astrocytes; 3α-diol is formed in very low yields by neurons, type-2 astrocytes and oligodendrocytes. The compartmentalization of two strictly correlated enzymes (5α-reductase and 3α-hydroxysteroid dehydrogenase) in separate central nervous system (CNS) cell populations suggests the simultaneous participation of neurons and glial cells in the 5α-reductive metabolism of testosterone. Subsequently it has been shown that, similarly to what happens when testosterone is used as the substrate, the 5α-reductase which metabolizes progesterone into 5α-pregnane-3,20-dione (DHP) shows a significantly higher activity in neurons than in glial cells; however, type-1 and -2 astrocytes as well as oligodendrocytes also possess some ability to 5α-reduce progesterone. On the other hand, 3α-hydroxysteroid dehydrogenase, the enzyme which converts DHP into 5α-pregnane-3α-ol-20-one, appears to be present mainly in type-1 astrocytes; much lower levels of this enzyme are present in neurons and in type-2 astrocytes. At variance with the previous results obtained using androgens as precursors, oligodendrocytes show considerable 3α-hydroxysteroid dehydrogenase activity, even if this is statistically lower than that present in type-1 astrocytes. The existence of isoforms of the enzyme involved in androgen and progesterone metabolism is discussed.Finally, the ability of the human neuroblastoma cell line SH-SY5Y to metabolize androgens and progesterone was studied incubating the cells in the presence of labeled testosterone or progesterone to measure, respectively, the formation of DHT or DHP (5α-reductase activity). 3α-Hydroxysteroid dehydrogenase activity was studied by evaluating the conversion of labeled DHT into 3α-diol. The results demonstrate that undifferentiated neuroblastoma cells possess a significant 5α-reductase activity, as shown by the considerable conversion of testosterone into DHT; moreover, this enzymatic activity seems to be significantly stimulated following cell differentiation induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), but not after differentiation induced by retinoic acid (RA). The 5α-reductase present in SH-SY5Y cells is also able to convert progesterone into DHP. In undifferentiated cell, this conversion is about 8 times higher than that of testosterone into DHT. Under the influences of TPA and RA, the formation of DHP follows the same pattern observed for that of DHT. SH-SY5Y cells also appear to possess the enzyme 3α-hydroxysteroid dehydrogenase, since they are able to convert DHT into 3α-diol. This enzymatic activity is not altered following TPA-induced differentiation, and appears to be decreased following treatment with RA. It is suggested that the SH-SY5Y cell line may represent a useful “in vitro” model for the study of the mechanisms involved in the control of androgen and progesterone metabolism in nervous cells.