bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Cytokines in Lipopolysaccharide-Induced Facilitation of CGRP Release from Capsaicin-Sensitive Nerves in the Trachea: Studies with Interleukin-1β and Tumor Necrosis Factor-α
Authors: Hua Xiao-Ying , Chen Ping , Fox Alyson , Myers Robert R. 
Published: April 2018

Lipopolysaccharide (LPS), an endotoxin, produces pain behavior, inflammation, and changes in immune function. Many of these effects are secondary to the production of cytokines. In the present study, we investigated the effect of LPS on the releasing function of afferent terminals as measured by calcitonin gene-related peptide (CGRP) release inex vivoperfused rat trachea, and examined the possible role of the cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) as intermediaries in this effect. Systemic injection of LPS (0.75 mg/kg, i.p.) in adult rats induced an increase in body temperature followed by hypothermia, indicating ongoing infection. We observed that capsaicin-induced (0.1 μm) tracheal CGRP release was significantly enhanced in the LPS-treated animals after 5 hr. This enhancement of the peptide release by LPS was blocked by IL-1β tripeptide antagonist Lys-d-Pro-Thr (10 μm) and mimicked by IL-1β and TNF-α (10–100 pg/ml), suggesting that the potentiating effect of LPS on CGRP release is mediated by generation of IL-1β and TNF-α. IL-1β-induced augmentation of CGRP release was blocked by Lys-d-Pro-Thr. Additionally, the cyclooxygenase inhibitor ketorolac (10 μm) significantly attenuated the facilitatory effects of LPS and IL-1β, indicating involvement of prostanoids. These findings suggest that endotoxin treatment generated cytokines such as IL-1β and TNF-α that regulated the peripheral releasing function of primary sensory afferents by sensitizing the terminals and facilitating peptide release. This effect is prostanoid dependent.
Extracellular Synthesis of cADP-Ribose from Nicotinamide-Adenine Dinucleotide by Rat Cortical Astrocytes in Culture
Authors: Pawlikowska Ludmila , Cottrell Susan E. , Harms Matthew B. , Li Ya , Rosenberg Paul A. 
Published: April 2018

cADPR is an endogenous calcium-mobilizing agent that in vertebrates is synthesized from nicotinamide-adenine dinucleotide (NAD) by bifunctional enzymes with ADP-ribosyl cyclase and cADPR hydrolase activity. ADP-ribosyl cyclase and cADPR hydrolase activity have been reported in the brain, but the cellular localization of these activities has not been determined previously. In the present study, selective culturing techniques were employed to localize ADP-ribosyl cyclase activity and cADPR hydrolase activity to astrocytes or neurons in cultures derived from rat embryonic cerebral cortex. ADP-ribosyl cyclase activity was determined by incubating cultures with 1 mmNAD in the extracellular medium for 60 min at 37°C and measuring formation of cADPR by bioassay and by HPLC. Astrocyte cultures and mixed cultures of astrocytes and neurons had mean specific activities of 0.84 ± 0.06 and 0.9 ± 0.18 nmol cADPR produced/mg protein/hr, respectively. No detectable ADP-ribosyl cyclase activity was found in neuron-enriched/astrocyte-poor cultures. cADPR hydrolase activity was detectable by incubating cultures with 300 μmcADPR for 60 min at 37°C and assaying loss of cADPR or accumulation of ADPR. The demonstration of extracellular ADP-ribosyl cyclase and cADPR hydrolase activities associated with astrocytes may have important implications for the role of extracellular cADPR in signal transduction and in intercellular communication in the nervous system.
Neuropeptide Y-Mediated Long-Term Depression of Excitatory Activity in Suprachiasmatic Nucleus Neurons
Authors: van den Pol Anthony N. , Obrietan Karl , Chen Gong , B. Belousov Andrei 
Published: April 2018

A brief exposure to light can shift the phase of mammalian circadian rhythms by 1 hr or more. Neuropeptide Y (NPY) administration to the hypothalamic suprachiasmatic nucleus, the circadian clock in the brain, also causes a phase shift in circadian rhythms. After a phase shift, the neural clock responds differently to light, suggesting that learning has occurred in neural circuits related to clock function. Thus, certain stimuli can produce effects that last for an extended period, but possible mechanisms of this long-term effect have not been previously examined at the cellular level. Here, we report that NPY caused a long-term depression in both electrical activity and intracellular calcium levels of neurons, as studied with whole-cell patch-clamp recording and Fura-2 digital imaging. In contrast to the immediate (1 sec) recovery after relief from glutamate receptor blockade, a brief single application of NPY (100 nm) depressed cytosolic Ca2+for >1 hr. The mechanism of this long-term calcium depression, a form of cellular learning, is dependent on the simultaneous release of glutamate and activation of NPY receptors, because both the extended response to NPY and any aftereffect were blocked by coapplication of glutamate receptor antagonists. Postsynaptic actions of NPY, mediated by both Y1- and Y2-like receptors, were short term and recovered rapidly. The primary site of long-term NPY actions may be on presynaptic glutamatergic axons, because the frequency of miniature excitatory postsynaptic currents in the presence of tetrodotoxin was reduced by transient exposure to NPY in both cultures and slices.
Immunohistochemical Distribution and Electron Microscopic Subcellular Localization of the Proteasome in the Rat CNS
Authors: Mengual Elisa , Arizti Paz , Rodrigo José , Giménez-Amaya José Manuel , Castaño JoséG. 
Published: April 2018

The proteasome multicatalytic proteinase (MCP) is a 20S complex that plays a major role in nonlysosomal pathways of intracellular protein degradation. A polyclonal antibody against rat liver MCP was used to investigate the distribution of MCP in the CNS of the rat and its subcellular localization within the neurons. As expected, MCP immunoreactivity (MCP-IR) was distributed ubiquitously in the rat CNS but not homogeneously. The most intensely stained neurons were the pyramidal cortical neurons of layer 5 and the motor neurons of the ventral horn in the spinal cord, which show an intense nuclear and cytoplasmatic MCP-IR and clearly stained processes. Additionally, some populations of large neurons in the mesencephalon and brainstem also displayed a moderate MCP-IR in their perikarya. The vast majority of neurons in the remaining structures did not show a strong cytoplasmatic MCP-IR, but their nuclei displayed an intense MCP-IR. The subcellular localization also was studied by immunoelectron microscopy. MCP-IR was intense in the neuronal nuclei, and significant staining also was found in the cytoplasm, dendritic, and axonic processes (including some myelinated axons) and in synaptic boutons, as illustrated in the cerebellar cortex. The distribution of MCP in the rat CNS and its subcellular localization are discussed in relation to (1) the distribution of calpain, the other major nonlysosomal cellular protease, and (2) the possible role of MCP in the degradation of regulatory proteins and key transcription factors that are essential in many neuronal responses.
Activity-Independent Segregation of Excitatory and Inhibitory Synaptic Terminals in Cultured Hippocampal Neurons
Authors: Benson Deanna L. , Cohen P. Aryeh 
Published: April 2018

Cultured hippocampal neurons were used as a model system to address experimentally the spatial and temporal sequence leading to the appropriate sorting of excitatory and inhibitory synaptic terminals to different cellular target domains and the role of neural activity in this process. By using antibodies against glutamic acid decarboxylase 65 (GAD65) and synaptophysin, we examined the development and segregation of GABAergic and non-GABAergic synaptic terminals on single neurons. Electron microscopy confirmed that GAD65-labeled swellings observed using light microscopy corresponded to synaptic boutons. From the time at which GABAergic terminals first appeared, they developed at a more rapid rate on neuronal somata than non-GABAergic terminals did, such that by 18 d in culture, 60% of the total boutons on somata were GABAergic. By contrast, the majority (70%) of boutons on dendrites were non-GABAergic. These data suggest that inhibitory synaptic terminals are targeted preferentially to or maintained on cell somata at the expense of excitatory terminals. Interestingly, non-GABAergic terminals were not inhibited from forming synapses on cell somata, because in the absence of GABAergic terminals they attained the same total somatic terminal density seen in the presence of GABAergic terminals. Chronic blockade of neuronal activity did not affect the differential targeting of GABAergic and non-GABAergic axons; however, it did reduce the extent of dendritic arborization. Our findings support a two-step model for synaptic segregation whereby the majority of terminals is initially targeted in an activity-independent manner to the appropriate cellular domains, but an additional developmental mechanism serves to further restrict and refine the original synaptic distribution.
Properties of Convergent Thalamocortical and Intracortical Synaptic Potentials in Single Neurons of Neocortex
Authors: Gil Ziv , Amitai Yael 
Published: April 2018

We explored differences in the properties of convergent afferent inputs to single neurons in the barrel area of the neocortex. Thalamocortical slices were prepared from mature mice. Recordings were made from neurons in layer V, and either thalamocortical afferents or horizontal intracortical axons were stimulated. Monosynaptic EPSPs from both sources had latencies shorter than 1.8 msec and low shape variance. Disynaptic thalamocortical IPSPs had latencies longer than 1.8 msec. All neuronal types, as defined by intrinsic firing patterns, received both thalamocortical and intracortical monosynaptic input. The shape parameters (rate of rise and half-width) of monosynaptic EPSPs from the two inputs did not differ significantly. The rate of rise of EPSPs varied considerably across cells, but the rates of rise of thalamocortical and intracortical EPSPs onto single cells were strongly correlated.The relative thresholds for activation of synaptic excitation and inhibition were strikingly different between the two tracts: thalamocortical stimulation induced GABAA-dependent IPSPs at stimulus intensities equal to or less than those required for evoking EPSPs in 35% (24 of 68) of the cells. In contrast, the threshold response to intracortical stimulation was always an EPSP, and only stronger stimuli could generate di- or polysynaptic IPSPs.We suggest that postsynaptic factors may tend to equalize the waveforms of EPSPs from thalamocortical and intracortical synapses onto single neurons. A major difference between the two convergent tracts is that the thalamocortical pathway much more effectively activates feedforward inhibitory circuits than does the horizontal intracortical pathway.
Differential Survival of Cajal–Retzius Cells in Organotypic Cultures of Hippocampus and Neocortex
Authors: Del Rı́o José A. , Heimrich Bernd , Supèr Hans , Borrell Vı́ctor , Frotscher Michael , Soriano Eduardo 
Published: April 2018

Cajal–Retzius (CR) cells are transient, pioneer neurons of layer I of the cortex that are believed to play essential roles in corticogenesis, e.g., in neuronal migration and synaptogenesis. Here we have used calretinin immunostaining to study the characteristics, survival, and fate of CR cells in single organotypic slice cultures of mouse neocortex and hippocampus deprived of their extrinsic afferents. In neocortical explants, CR cells were observed after 1–3 din vitro(DIV), but they disappeared after 5–7 DIV, which is similar to their time of degenerationin vivo. The disappearance of CR cells in neocortical slices was prevented by incubation with tetrodotoxin and the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3,-dione but not by 2-amino-5-phosphonopentanoic acid, suggesting that neuronal activity and non-NMDA glutamate receptors may trigger CR cell death in the neocortex.In contrast to the situationin vivo, in which many hippocampal CR cells disappear at approximately the third postnatal week, CR cells survived in single hippocampal cultures after long incubation times (31 DIV), with their morphology essentially unaltered. In contrast, fewer CR cells were found when hippocampal slices were cocultured with explants from the entorhinal cortex. Because CR cells are transient synaptic targets for entorhinohippocampal afferents, these findings suggest a role for entorhinal afferents in the degeneration of CR cells in the hippocampus. In conclusion, this study shows different survival properties of CR cells in organotypic slice cultures of hippocampus and neocortex, and it suggests that different mechanisms are involved in the regulation of the process of naturally occurring CR cell death in the two cortical regions.
Multiple Receptors Involved in Peripheral α2, μ, and A1Antinociception, Tolerance, and Withdrawal
Authors: Aley K. O. , Levine Jon D. 
Published: April 2018

We examined the interactions among three classes of peripherally-acting antinociceptive agents (μ-opioid, α2-adrenergic, and A1-adenosine) in the development of tolerance and dependence to their antinociceptive effects. Antinociception was determined by assessing the degree of inhibition of prostaglandin E2(PGE2)-induced mechanical hyperalgesia, using the Randall-Selitto paw-withdrawal test.Tolerance developed within 4 hr to the antinociceptive effect of the α2-adrenergic agonist clonidine; dependence also occurred at that time, demonstrated as a withdrawal hyperalgesia that was precipitated by the α2-receptor antagonist yohimbine. These findings are similar to those reported previously for tolerance and dependence to μ and A1peripheral antinociception (Aley et al., 1995).Furthermore, cross-tolerance and cross-withdrawal between μ, A1, and α2agonists occurred. The observations of cross-tolerance and cross-withdrawal suggest that all three receptors are located on the same primary afferent nociceptors. In addition, the observations suggest that the mechanisms of tolerance and dependence to the antinociceptive effects of μ, A1, and α2are mediated by a common mechanism.Although any of the agonists administered alone produce antinociception, we found that μ, A1, and α2receptors may not act independently to produce antinociception, but rather may require the physical presence of the other receptors to produce antinociception by any one agonist. This was suggested by the finding that clonidine (α2-agonist) antinociception was blocked not only by yohimbine (α2-antagonist) but also by PACPX (A1-antagonist) and by naloxone (μ-antagonist), and that DAMGO (μ-agonist) antinociception and CPA (A1-agonist) antinociception were blocked not only by naloxone (μ-antagonist) and PACPX (A1-antagonist), respectively, but also by yohimbine (α2-antagonist). This cross-antagonism of antinociception occurred at the ID80dose for each antagonist at its homologous receptor. To test the hypothesis that the physical presence of μ-opioid receptor is required not only for μ antinociception but also for α2antinociception, antisense oligodeoxynucleotides (ODNs) for the μ-opioid and α2C-adrenergic receptors were administered intrathecally to reduce the expression of these receptors on primary afferent neurons. These studies demonstrated that μ-opioid ODN administration decreased not only μ-opioid but also α2-adrenergic antinociception; A1antinociception was unaffected. In contrast, α2C-adrenergic ODN decreased antinociception induced by all three classes of antinociceptive agents.In conclusion, these data suggest that peripheral antinociception induced by μ, α2, and A1agonists requires the physical presence of multiple receptors. We propose that there is a μ, A1, α2receptor complex mediating antinociception in the periphery. In addition, there is cross-tolerance and cross-dependence between μ, A1, and α2antinociception, suggesting that their underlying mechanisms are related.
Cellular, Subcellular, and Subsynaptic Distribution of AMPA-Type Glutamate Receptor Subunits in the Neostriatum of the Rat
Authors: Bernard Véronique , Somogyi Peter , Bolam J. Paul 
Published: April 2018

Glutamate released in the basal ganglia is involved in the expression of clinical symptoms of neurodegenerative diseases like Parkinson’s or Huntington’s. Neostriatal neurons are the targets of glutamatergic inputs derived from the cortex and the thalamus acting via AMPA-type as well as other glutamate receptors. To determine the location of subunits of the AMPA subclass of glutamate receptors (GluR) in the rat neostriatum, we applied multiple immunocytochemical techniques using anti-peptide antibodies against the GluR1, GluR2/3, and GluR4 subunits at both the light and electron microscopic levels. All medium spiny efferent neurons, some of which were identified as striatonigral neurons, displayed immunoreactivity for GluR1 and GluR2/3 subunits. Double immunofluorescence revealed that at least 70–90% of parvalbumin-immunopositive GABAergic interneurons were immunoreactive for each of GluR1, GluR2/3, or GluR4 subunits and that at least 40% of choline acetyltransferase-immunopositive cholinergic interneurons were immunopositive for GluR1 or GluR4 subunits. The majority of nitric oxide synthase-immunopositive neurons had no detectable immunoreactivity for any of the AMPA receptor subunits. Electron microscopic analysis confirmed the presence of immunoreactivity for GluR1 and GluR2/3 in the perikarya of spiny neurons and interneurons and GluR4 in perikarya of interneurons only. GluR1 and GluR2/3 subunits were detected in dendrites and spines. A significant population of extrasynaptic receptors was revealed by pre-embedding immunogold labeling along the plasma membranes of perikarya, dendrites, and spines. Receptors were concentrated in the postsynaptic membrane specialization of asymmetrical synapses, as revealed by the postembedding immunogold method. Quantitative analysis demonstrated that immunoreactivity for the GluR1 and GluR2/3 subunits is higher at the periphery than at the middle of the postsynaptic membrane specialization.Our results demonstrate that AMPA receptor subunits are distributed widely and heterogeneously among striatal neurons and are concentrated on the postsynaptic membrane of asymmetrical synaptic specializations, although extrasynaptic receptors are also present.
Monoamine Oxidase Inhibition Causes a Long-Term Prolongation of the Dopamine-Induced Responses in Rat Midbrain Dopaminergic Cells
Authors: Mercuri Nicola B. , Scarponi Mariangela , Bonci Antonello , Siniscalchi Antonio , Bernardi Giorgio 
Published: April 2018

The way monoamine oxidase (MAO) modulates the depression of the firing rate and the hyperpolarization of the membrane caused by dopamine (DA) on rat midbrain dopaminergic cells was investigated by means of intracellular recordingsin vitro. The cellular responses to DA, attributable to the activation of somatodendritic D2/3 autoreceptors, were prolonged and did not completely wash out after pharmacological blockade of both types (A and B) of MAO. On the contrary, depression of the firing rate and membrane hyperpolarization induced by quinpirole (a direct D2 receptor agonist) were not affected by MAO inhibition. Furthermore, although the inhibition of DA reuptake by cocaine and nomifensine caused a short-term prolongation of DA responses, the combined inhibition of MAO A and B enzymes caused a long-term prolongation of DA effects. Moreover, the effects of DA were not largely prolonged during the simultaneous inhibition of MAO and the DA reuptake system. Interestingly, the actions of amphetamine were not clearly augmented by MAO inhibition.From the present data it is concluded that the termination of DA action in the brain is controlled mainly by MAO enzymes. This long-term prolongation of the dopaminergic responses suggests a substitutive therapeutic approach that uses MAO inhibitors and DA precursors in DA-deficient disorders in which continuous stimulation of the dopaminergic receptors is preferable.
Neurogenesis in the Dentate Gyrus of the Adult Tree Shrew Is Regulated by Psychosocial Stress and NMDA Receptor Activation
Authors: Gould Elizabeth , McEwen Bruce S. , Tanapat Patima , Galea Liisa A. M. , Fuchs Eberhard 
Published: April 2018

These studies were designed to determine whether adult neurogenesis occurs in the dentate gyrus of the tree shrew, an animal phylogenetically between insectivores and primates, and to explore the possibility that this process is regulated by stressful experiences and NMDA receptor activation. We performed immunohistochemistry for cell-specific markers and the thymidine analog bromodeoxyuridine (BrdU), a marker of DNA synthesis that labels proliferating cells and their progeny, on the brains of adult tree shrews subjected to psychosocial stress or NMDA receptor antagonist treatment. Cells that incorporated BrdU in the dentate gyrus of adult tree shrews were primarily located in the subgranular zone, had morphological characteristics of granule neuron precursors, and appeared to divide within 24 hr after BrdU injection. Three weeks after BrdU injection, BrdU-labeled cells had neuronal morphology, expressed the neuronal marker neuron specific enolase, and were incorporated into the granule cell layer. Vimentin-immunoreactive radial glia were observed in the dentate gyrus with cell bodies in the subgranular zone and processes extending into the granule cell layer.Exposure to acute psychosocial stress resulted in a rapid decrease in the number of BrdU-labeled cells in the dentate gyrus. In contrast, blockade of NMDA receptors, with the NMDA receptor antagonist MK-801, resulted in an increase in the number of BrdU-labeled cells in the dentate gyrus. These results indicate that adult neurogenesis occurs in the tree shrew dentate gyrus and is regulated by a stressful experience and NMDA receptor activation. Furthermore, we suggest that these characteristics may be common to most mammalian species.
Widespread Peroxynitrite-Mediated Damage in Alzheimer’s Disease
Authors: Smith Mark A. , Richey Harris Peggy L. , Sayre Lawrence M. , Beckman Joseph S. , Perry George 
Published: April 2018

Increasing evidence suggests that oxidative damage to proteins and other macromolecules is a salient feature of the pathology of Alzheimer’s disease. Establishing the source of oxidants is key to understanding what role they play in the pathogenesis of Alzheimer’s disease, and one way to examine this issue is to determine which oxidants are involved in damage.In this study, we examine whether peroxynitrite, a powerful oxidant produced from the reaction of superoxide with nitric oxide, is involved in Alzheimer’s disease. Peroxynitrite is a source of hydroxyl radical-like reactivity, and it directly oxidizes proteins and other macromolecules with resultant carbonyl formation from side-chain and peptide-bond cleavage. Although carbonyl formation is a major oxidative modification induced by peroxynitrite, nitration of tyrosine residues is an indicator of peroxynitrite involvement. In brain tissue from cases of Alzheimer’s disease, we found increased protein nitration in neurons, including but certainly not restricted to those containing neurofibrillary tangles (NFTs). Conversely, nitrotyrosine was undetectable in the cerebral cortex of age-matched control brains. This distribution is essentially identical to that of free carbonyls.These findings provide strong evidence that peroxynitrite is involved in oxidative damage of Alzheimer’s disease. Moreover, the widespread occurrence of nitrotyrosine in neurons suggests that oxidative damage is not restricted to long-lived polymers such as NFTs, but instead reflects a generalized oxidative stress that is important in disease pathogenesis.