bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of atrial and brain natriuretic peptides upon cyclic GMP levels, potassium transport, and receptor binding in rat astrocytes
Authors: Beaumont K. , Tan P. K. 
Published: January 2005

AbstractThe ability of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) to alter cyclic GMP levels and NaKCl cotransport in rat neocortical astrocytes was determined. At concentrations of 10−9–10−M, rat ANP99–126(rANF), rat ANP102–126 (auriculin B), and rat ANP103–126 (atriopeptin III) stimulated 6‐ to 100‐fold increases in cyclic GMP levels. Porcine BNP (pBNP) and rat BNP (rBNP) were 20%–90% as effective as rANF over most of this concentration range, although 10−6M pBNP produced a greater effect than rANF. NaKCl cotransport as measured by bumetanide‐sensitive 86Rb + influx was not altered by exposure of astrocytes to 10−6M rANF, pBNP, or rBNP. Both pBNP and rBNP, as well as rat ANP103–123 (atriopeptin I) and des[gln18, ser19, gly20, leu21, gly22] ANF4−‐NH2 (C‐ANF4–23) strongly competed for specific 125I‐rANF binding sites in astrocyte membranes with affinities ranging from 0.03 to 0.4 nM, suggesting that virtually all binding sites measured at subnanomolar concentrations of 125I‐rANF were of the ANP‐C (ANF‐R2) receptor subtype. These receptors are thought to serve a clearance function (Maack et al.: Science 238:675–678, 1987) and may be linked to a guanylate cyclase activity that is chemically and pharmacologically distinct from that coupled to ANP‐A (ANF‐R1) receptors (Féthiere et al.:Mol Pharmacol35:584–592, 1989). ANP receptors on astrocytes may function in limiting the access of ANP and BNP to neurons involved in body fluid and cardiovascular regulation.
Characterization of HNK‐1 bearing glycoproteins in human peripheral nerve myelin
Authors: Van Den Berg L. H. , Sadiq S. A. , Thomas F. P. , Latov Norman 
Published: January 2005

AbstractThe HNK‐1 carbohydrate epitope, which is shared by several members of the immunoglobulin gene superfamily, is also the target epitope for IgM anti‐MAG autoantibodies in patients with demyelinating neuropathy. By Western blot analysis, there are 7 HNK‐1 immunoreactive glycoproteins in human peripheral nerve myelin, two of which have previously been identified as the myelin associated glycoprotein (MAG) and the Po glycoprotein. In this study, the remaining HNK‐1 bearing glycoprotein bands were characterized by immunoblot and NH2‐terminal sequence analysis, and were all identified as degradation products or aggregates of the Po glycoprotein. MAG and Po are therefore the only HNK‐1 bearing glycoproteins in human peripheral nerve myelin.
125I‐β‐nerve growth factor binding is reduced in rat brain after stress exposure
Authors: Taglialatela G. , Angelucci L. , Ramacci M. T. , Foreman P. J. , Perez‐Polo J. R. 
Published: January 2005

AbstractIn the central nervous system (CNS), the presence of nerve growth factor (NGF) and its receptor, NGFR, in cholinergic neurons has been demonstrated. In this study we report that, after exposure to stress, there was a reduction in total binding of NGF in the hippocampus and basal forebrain of 3.5‐month‐old rats without significant changes in the frontal cortex or cerebellum. Chronic treatment with acetyl‐l‐carnitine (ALCAR), that prevents some age‐related impairments of CNS, for 1.5 months, decreased NGF binding in hippocampus and basal forebrain but abolished the stress‐related reduction of NGF binding observed in the hippocampus of untreated rats.
Role of nerve growth factor in oxidant‐antioxidant balance and neuronal injury. II. A conditioning lesion paradigm
Authors: Jackson G. R. , Werrbach‐Perez K. , Perez‐Polo J. R. 
Published: January 2005

AbstractThe PC12 rat pheochromocytoma cell line is a nerve growth factor (NGF) responsive line that is protected by NGF from the toxic effects of hydrogen peroxidation. In part, NGF protection of PC12 cells acts through a shift in oxidant‐antioxidant metabolism by the enhancement of catalase activity. When PC12 cells are used in a conditioning lesion paradigm to study the effects of an initial sublethal peroxidative insult on subsequent responses to injury, a low dose conditioning lesion protects even in the absence of NGF. The magnitude of the protective effect exerted by the conditioning lesion, however, is augmented in the presence of NGF, since a significant cytoprotective effect is observed over a wider range of H2O2 concentrations. Neuronal injury due to treatment with a high dose of H2O2 (5 mM) has a cytotoxic effect that cannot be prevented by NGF treatment and is, in itself, not conditioning in nature. This in vitro model system lends itself to the development of explanations regarding the salutory effects of conditioning lesions at the molecular level.
A small subpopulation of progesterone receptor‐containing neurons in the guinea pig arcuate nucleus projects to the median eminence
Authors: Poulain P. , Warembourg M. , Jolivet A. 
Published: January 2005

AbstractIn female guinea pigs, a combination of retrograde tracing and immunofluorescence for progesterone receptors (PR) was applied to determine if PR‐immunoreactive (PR‐IR) neurons in the arcuate nucleus (AR) send their axons directly to the median eminence (ME). Axonal projections to the ME were studied by different techniques using fluorescent dyes. From 31 adult animals, ovariectomized and primed by estradiol, small deposits of Lucifer Yellow (LY) were made on the cut surface of the ME, either by direct application of LY crystals or by iontophoresis. These techniques were carried out on excised mediobasal hypothalamus maintained in vitro and allowed visualization of AR perikarya projecting to the ME after dye diffusion in the severed axons. In another group of ten immature animals primed by estradiol, Granular Blue (GB) was injected in the jugular vein. Blood‐borne GB was taken up in the ME by intact nerve endings and retrogradely transported to the perikarya of origin. PR‐IR neurons and perikarya filled with LY or retrogradely labeled by GB were intermingled with each other throughout the restrocaudal extent of the AR. Double‐labeled cells, displaying PR immunoreactivity and dye labeling, were observed consistently, but their number was small. This result demonstrates that some AR neurons sending axonal projections to the ME are target cells for progesterone. As the majority of PR‐IR neurons in the AR do not project to ME, it is suggested that most PR‐IR neurons present in this nucleus form local circuit projections or project to distant areas of the central nervous system.
Interleukin‐2 enhances chick and rat sympathetic, but not sensory, neurite outgrowth
Authors: Haugen P. Keely , Letourneau P. C. 
Published: January 2005

AbstractInteractions between the immune and nervous systems could be important for normal development and function of both. To determine if a lymphokine, interleukin‐2 (IL‐2), represents a link between these two systems, sympathetic and sensory neurons from embryonic chick and neonatal rat were cultured in media containing human recombinant IL‐2. In chick sympathetic chain and rat superior cervical ganglia cultures, IL‐2 enhanced the number of neurons with neurites and the lenght of those neurites significantly over control cultures. Sensory neurons from chick and rat dorsal root ganglia were not affected by culture in IL‐2. Sympathetic neuron response to IL‐2 was concentration‐dependent, with an optimum around 2‐0.2 U/ml (100‐10 pM). Immunofluorescence with an anti‐IL‐2 receptor antibody demonstrated specific staining of sympathetic neurons, but not sensory neurons, implying that sympathetic neurons may have a receptor for IL‐2 on their surface.
Amino acid mdification of proteins in regenerating sciatic nerves of rats
Authors: Chakraborty G. , Yu M. , Luo D. , Sturman J. A. , Ingoglia N. A. 
Published: January 2005

AbstractRecent experiments have shown that Arg, Lys, and Leu can be incorporated posttranslationally into proteins of regenerating sciatic nerves of rats. The presentexperiments investigate a mixture of 15 radioactie amino acids to determine if additonalo amino acids can be cojugated posttranslationally to protein of regenerating nerves. Proteins of regenerating sciatic nerves or rats were able to incorporate Arg, Lys, pRO, Val, Ala, Phe, and Ser in relatively large amounts and Asp, Glu, Thr, Gly Ile, His, and Tur in relatively low or undetectable amounts, in the most advanced potion of the regenerating nerves. Two‐Dimensional SDS PAGE showed incorporation of the amono acid mixture into distinct radioactive peaks with moleculer weights in the 80–90 kD, 22–46 kD, and 17 kD ranges with isoelectric point between 5.0 and 7.9. Most of the amono acids were incorporated into proteins in all of the molecular weight ranges. But Ser was incorporated in highest amounts in the 17 kD range. In some cases results indicated that single proteins were modified by several amino acids.While we do not yet know which amino acids modify specidic nerve proteins or the function of the modifications in nerve regenration, these studies demonstrate the participation of some but not all amono acids in posttranslational modification reactions and the selective modification of specific groups of nerve preoteins by these amono acids.
Identification of GTP‐ binding proteins in myelin and oligodendrocyte membranes
Authors: Braun P. E. , Horvath E. , Yong V. W. , Bernier L. 
Published: January 2005

AbstractMyelin membranes purified from mouse and rat brain are associated with alpha subunits of four signal transducing guanosine triphosphate (GTP)‐ binding proteins: Go, Gi, Gs, and ras. Four low‐molecular‐weight (Mr) GTP‐binding proteins are also present, as demonstrated by the binding of GTP to proteins immobilized in nitrocellulose. This latter group is more prominent at early stages of myelination and remains associated with isolated myelin membranes despite repetitive cycles of purification. At least one nonmyelin subcellular membrane fraction possesses the same proteins. The total membrane fraction of cultured oligodendrocytes is associated with both groups of GTP‐binding proteins. None of the well‐known myelin proteins bound GTP by the procedure described.
Opioids influence neurotransmitter phenotypic expression in chick embryonic neuronal cultures
Authors: Vernadakis A. , Kentroti S. 
Published: January 2005

AbstractThere is considerable interest in the role of endogenous opioid peptides in neural growth and differentiation. In this study we used neuron‐enriched cultures derived from 3‐day‐old chick embryos to test the effects of endogeneous enkephalins on neurotransmitter phenotypic expression. Cultures were grown in serum‐free chemically defined medium and were treated with either Met‐enkephalin antiserum (anti‐Met) to immunoneutralize enkephalins, or with naloxone, a universal opioid receptor antagonist, to block receptor‐mediated actions of released endogenous opioids. The enzyme activities of choline acetyl‐transferase (ChAT) and tyrosine hydroxylase (TH) were used as markers for cholinergic and catecholaminergic phenotypic expression, respectively. We found that cultures treated with anti‐Met or naloxone exhibited strikingly different neuronal growth patterns as compared to controls. In addition, ChAT activity was enhanced by anti‐Met, and TH activity by both anti‐Met and naloxone. These findings lend support to the possibility that neuropeptides may be co‐localized with neurotransmitters and that peptides released into the microenvironment affect neuronal phenotypic expression by differential receptor subtypes.
Reversibility of ganglioside effects on astrocyte morphology
Authors: Dekker A. , Manthorpe M. , Varon S. 
Published: January 2005

AbstractThe B‐subunit of cholera toxin (BCT) induces a morphological change in cultured rat cerebral astrocytes from flat (epithelioid) to stellate (process‐bearing). This stellation is reversed by the gangliosides GM1 and GD1a at concentrations of 10 μM or higher. Upon changing to a ganglioside‐free medium, the flat astrocyted reacquire the stellate morphology within 3 hr, indicating that the antistellation effect of gangliosides is reversible. The possibility that this reversibility was due to a loss of exogenously acquired gangliosides from the cell membrane can be ruled out since pretreatment with GM1, but not GD1a, which does not bind BCT, results in an increased responsiveness to BCT, which was identical whether measured immediately after withdrawal of the ganglioside or 3 hr later. Asialo‐GM1, which neither binds BCT nor reverses BCT‐induced stellation by itself, prevents the return to stellation after withdrawal of the gangliosides. These data suggest that while gangliosides remain associated with the cell, their effect on astrocytes can change from opposing to permitting the stellate morphology.
Toxicity of 6‐hydroxydopamine and dopamine for dopaminergic neurons in culture
Authors: Michel P. P. , Hefti F. 
Published: January 2005

AbstractToxicity of 6‐hydroxydopamine (6‐OHDA) and dopamine were studied in cultures of dissociated fetal rat mesencephalic cells. To assess survival and function of dopaminergic cells we quantified the number of tyrosine hydroxylase‐positive cells and measured dopamine uptake. Non‐dopaminergic cells were monitored by counting the number of cells visible with phase‐contrast microscopy and measuring GABA uptake. 6‐OHDA, in contrast to MPP +, which selectively destroyed dopaminergic neurons, was found to be a non‐selective neurotoxin in this culture system. Between 10 and 100 μM, dopaminergic and non‐dopaminergic cells were destroyed. At concentrations frequently used to lesion catecholaminergic neurons in vivo, 6‐OHDA resulted in structural fixation and loss of viability of dopaminergic and non‐dopaminergic cells. Dopamine produced the same actions at slightly higher concentrations. One hundred to 300 μM was toxic for all cell types, and concentrations above 300 μM resulted in fixation. The findings suggest that 6‐OHDA cannot be considered a selective toxin for catecholaminergic neurons in vitro. The demonstrated toxicity of dopamine tends to support speculations that processes related to dopamine metabolism may play a role in the pathogenesis of Parkinson's disease.
Expression of glial fibrillary acidic protein and vimentin in mouse lens epithelial cells during development in vivo and during proliferation and differentiation in vitro: Comparison with the developmental appearance of GFAP in the mouse central nervous system
Authors: Boyer S. , Maunoury R. , Gomès D. , de Néchaud B. , Hill A. M. , Dupouey P. 
Published: January 2005

AbstractAnalysis of glial fibrillary acidic protein (GFAP) and vimentin in mouse lens epithelial cells (MLEC) during ontogenesis revealed a two‐step developmental expression similar to that observed in astrocytcs. Vimentin was first immunostained at E11 corresponding with the closure of the lens vesicle, whereas GFAP was detected only after a further 7 days (E18); this protein appeared simultaneously in the mouse lens and CNS. In the latter case, it was present in the hypothalamic tanycytes and spinal cord. This similarity in the timing of appearance of GFAP in the non‐neural MLEC and in fetal astrocytes suggests a common mechanism for its expression in tissues of different embryological origin. However, it has previously been observed that, in contrast to the situation in astrocytes, GFAP disappears from differentiating MLEC in vivo. We have shown that in vitro this protein also disappears rapidly from MLEC in the presence of fetal calf serum (FCS). However, the use of mouse serum instead of FCS inhibited the migration of MLEC out of the explant, and in these cells GFAP persisted.
Immunohistochemical localisation of nerve growth factor in a subpopulation of chick spinal ganglion neurons
Authors: Keller A. , Williams R. , Vahaviolos J. , Auffray C. , Rush R. A. 
Published: January 2005

AbstractWe have previously isolated and sequenced the chicken nerve growth factor (NGF) gene and now, from the deduced amino acid sequence, selected and produced peptides suitable for use as antigens. Antisera raised against these peptides inhibit the biological activity of a partially purified preparation of native chicken NGF and, when used in immunocytochemical studies, allow the visualisation of sensory neurons accumulating endogenous NGF. Immunoreactive cells form a distinct population of small neurons which may correspond to the well‐described neurons generated in the dorsomedial area of spinal ganglia. We conclude that two subpopulations of neurons exist within dorsal root ganglia, whose requirements for, and use of, NGF may be quite distinct.
Patterns of cerebral cortex mRNA expression
Authors: Bernal J. , Godbout M. , Hasel K. W. , Travis G. H. , Sutcliffe J. G. 
Published: January 2005

AbstractA pool of 163 clones, isolated by screening 60,000 members of a Macaca fascicularis cerebral cortex cDNA library with a cortex‐minus‐cerebellum subtracted probe prepared by the phenol enhancement method, was analyzed by Northern blot hybridization studies. One hundred fifty‐three of these clones corresponded to 22 RNAs whose abundance was at least 2‐fold higher in cerebral cortex poly (A)+ RNA samples than in samples of cerebellar poly(A)+ Seven of these RNAs, represented by 131 clones, were undetectable in cerebellum. Only 10 of the 163 clones proved to be false positives. The abundance of several of these cortex‐enriched RNAs was altered in Alzheimer's disease brains. Several RNAs that were present in cerebral cortex but undetectable in cerebellum were generally enriched in telencephalon, although none was restricted to the cortex. One of the cortex enriched RNAs, whose nucleotide sequence is presented, encoded monkey preprocholecystokinin. Overall, this study provides insights into the powers and limitations of subtractive hybridization and into the patterns of gene expression in the central nervous system.
Isolation, characterization, and substrate properties of the external limiting membrane from the avian embryonic optic tectum
Authors: Kröger S. , Niehörster L. 
Published: January 2005

AbstractThe external limiting membrane of the avian embryonic optic tectum is isolated by mechanically separating the neuronal mesencephalon from the overlying mesenchymal tissue. The preparation consists of a basal lamina which is covered on its neural side by endfeet of neuroepithelial cells and has attached to it on its meningeal side a collageneous stroma, containing blood vessels. The external limiting membrane can be flat‐mounted on a piece of nitrocellulose filter as mechanical support. It covers an area between 0.3 and 1 the cm2, depending on the age of me donor embryo. The endfeet can be removed together with all cellular components of the meninges by treatment with 2% Triton‐X‐100 or with distilled water. The basal lamina itself is approximately 80 nm thick and consists of two laminae rarae and a central lamina densa. Immunohistochemical staining reveals that the basal lamina in the embryo, after isolation and after detergent extraction of the isolated preparation, contains type IV collagen, nidogen, laminin, and low density heparan sulfate proteoglycan as do other basement membranes. Antibodies against the neural cell adhesion molecule (N‐CAM), chondroitin sulfate proteoglycan, and fibronectin fail to stain the external limiting membrane, but these proteins were clearly identified in the blood vessel‐containing meninges or in the optic tectum.The flat‐mounted external limiting membrane preparation was used as substrate to culture several different neural tissues of central and peripheral origin. Explants of neural crest cells, dorsal root ganglia, and sympathetic ganglia can be cultured on the external limiting membrane. All explants grow well on the basal lamina preparations whether the endfeet are attached or detergent‐extracted prior to explantation; however, neurite outgrowth from sympathetic ganglia is reduced in the presence of the endfeet. Although the endfoot‐lined external limiting membrane represents at least part of the immediate environment encountered by retinal axons as they invade the optic tectum and despite its excellent properties as a substrate for retinal axons in vitro, cues guiding the orientation of axons were not detected in the flat‐mounted preparation.
Prolonged ongoing discharges of sensory nerves as recorded in isolated nerves in the rat
Authors: Baik‐Han E. J. , Kim K. J. , Chung Jin Mo 
Published: January 2005

AbstractWhether or not injury to a mammalian sensory nerve produces prolonged discharges is a controversial issue. Because of this controversy and its potential ramifications in both experimental and clinical conditions, we examined discharges in sectioned sensory nerves of the rat. In anesthetized rats, either a dorsal root or a saphenous nerve was isolated by sectioning both proximally and distally. Multi‐unit recordings from these isolated nerves showed low levels of prolonged ongoing discharges often lasting for at least 2 hr. Furthermore, results from short‐term (1–2 days) survival surgeries indicated that prolonged ongoing discharges could last for days. Sectioning the ventral root produced discharges for only a short period. Various pieces of evidence suggested that the sources of impulse generation are multiple, occurring in the middle of an uninjured axon at a site away from the injury, as well as at the injured site. There is circumstantial evidence which suggests that these prolonged discharges are produced in physiological conditions or at least under normal experimental conditions.
Novel NGF‐induced proteins in PC12 cells: Immunological evidence for their presence in brain nerve endings using a single monoclonal antibody
Authors: Kohtz D. Stave , Puszkin S. 
Published: January 2005

AbstractA monoclonal antibody, S‐11D9, detected a group of novel polypeptides whose expression was induced 6 hr after incubation of PC12 cells with nerve growth factor. The antigens also were visualized by immune precipitation and Western blotting in synaptic vesicles, clathrin‐coated vesicles, and synaptic plasma membrane prepared from bovine brain. A large polypeptide was detected on the synaptic plasma membrane; an intermediate size protein was visualized on the plasma membrane and on both synaptic and clathrin‐coated vesicles, while a smaller molecule was found only on brain Golgi‐enriched membrane preparations. Immunofluorescence labeling with S‐11D9 on nerve growth factor‐stimulated PC12 cells showed the antigens distributed in the cytoplasm and concentrated in discrete areas on the tip of most neurites. The particular distribution of these proteins in vesicles and synaptic plasma membrane and the finding that the different antigens share a common epitope recognized by a single monoclonal antibody open the possibility that these molecules are related markers for organelle transport pathways in nerve cells.
Diffusible factor(s) from adult rat sciatic nerve increases cell number and neurite outgrowth of cultured embryonic ventral mesencephalic tyrosine hydroxylase‐positive neurons
Authors: Collier T. J. , Sladek C. D. , Gallagher M. J. , Gereau R. W. , Springer J. E. 
Published: January 2005

AbstractDissociated embryonic rat ventral mesencephalon containing the developing A8‐A10 dopamine (DA) neurons was cultured alone or in the presence of a 10 mm segment of adult rat sciatic nerve that had been explanted and maintained in separate culture for 72 hours prior to introduction to mesencephalic cultures. Nerve segments were contained in a co‐culture basket, so that midbrain cells and nerve shared medium but were not in physical contact. The number and morphology of cultured DA neurons was assessed via immunocytochemistry for tyrosine hydroxylase (TH). Co‐cultures of ventral midbrain tissue and nerve exhibited an increased number of TH‐positive neurons, with larger neuronal perikarya, and increased length and complexity of neurites, than cultures of midbrain tissue alone. Increased number and growth of TH‐positive neurons was obtained with as little as 2 days of exposure to nerve. This evidence suggests that a diffusible, soluble factor(s) from sciatic nerve can enhance the number and development of TH‐positive neurons detected in cultures of embryonic ventral mesencephalon.