bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Akaike information criterion (AIC) is not a sufficient condition to determine the number of ion channel states from single channel recordings
Authors: Liebovitch Larry S. , Tóth Tibor I. 
Published: January 2005

AbstractThe Akaike information criterion (AIC) and other criteria that trade off the goodness‐of‐fit against the number of parameters have been used to determine the number of ion channel states from single channel recordings. We show that, in general, such criteria are not valid. This is illustrated by an elementary example in which the AIC yields an incorrect result. The implications of these findings for the discrimination of different kinetic models of ion channels are discussed.
Studies on the coexistence of substance P with other putative transmitters in the nodose and petrosal ganglia
Authors: Helke C. J. , Niederer A. J. 
Published: January 2005

AbstractVisceral afferent neurons of the nodose and petrosal ganglia are immunoreactive (ir) for many neurotransmitters [e.g., substance P (SP), neurokinin A (NKA), calcitonin gene‐related peptide (CGRP), and dopamine (tyrosine hydroxylase‐ir; TH)]. Coexistence of SP‐ir with NKA‐, CGRP‐, or TH‐ir was studied in individual neurons of the rat ganglia using fluorescene immunocytochemistry. SP‐ and NKA‐ir were present in equal numbers of cells and were consistently colocalized. SP‐ and CGRP‐ir were found to be similarly distributed in scattered cells, concentrated mostly in the rostral pole of the nodose ganglion and in the petrosal ganglion. SP‐ir completely coexisted with CGRP‐ir. However, there was at least twice the number of CGRP‐ir neurons as SP‐ir neurons, and thus CGRP‐ir neurons that did not contain SP‐ir were also present. In contrast, SP‐ and TH‐ir had different distributions in both the nodose and the petrosal ganglia. SP‐ir was located in the more rostral regions of both the nodose and petrosal ganglia, whereas TH‐ir was detected throughout the entire nodose ganglion and only in the most caudal region of the petrosal ganglion. There was no coexistence of SP‐ and TH‐ir. These data demonstrate the differential localization and coexistence of putative transmitters in visceral sensory neurons in the nodose and petrosal ganglia.
Regrowth of damaged neurosecretory axons to fenestrated vessels of implanted peripheral tissues
Authors: Kadota Yoshiaki , Pettgrew Karen D. , Brightman Milton W. 
Published: January 2005

AbstractA major target of neurosecretory axons (NSA) is the bassal lamina around fenestrated blood vessels (FBV) in the neural lobe of the pituitary gland. We have posed the question of whether there is nerurovascular specificity. Do mature, regenerating NSA terminate selectively on the FBV of the neural lobe compared with the FBV of other tissues that normally are not innervated by NSA? Three types of tissue were transplanted between inbred Fisher rats. Fragments, about 1 mm3, of pineawl, adrenal medulla, and neural lobe wwere grafted bilaterally to the hypothalamic, retro‐chiasmatic area, which includes bundles of NSA from supraoptic and paraventricular neurosecretrory nuclei exclusively, but no FBV. Two and 4 weeks later, the grafts were prepared for the immunohistochemical localization of NSA and for electron micaroscopy. NSA‐FBV proximity was measured, and the number of NSA, FBV, and of NSA‐FBV associations was counted per surface area of each graft. Regenerating NSA can associate as closely with FBV of other tissues as they can with the FBV of the neural lobe. There does not appear to be specificity with respect to the closeness of association between neurosecretory terminals and fenestrated capillaries. However, the number of these associations is greater in neural lobe grafts than in adrenal or pineal grafts at 4 weeks. The number of FBV is also greatest, in neural lobe grafts at this time, an increase that would provide a greater opportunity for NSA‐FBV associations.
Monocular deprivation alters the development of synaptic structure in the ectostiatum of the zebra finch
Authors: Nixdorf Barbara E. 
Published: January 2005

AbstractThe effects of monocular deprivation, beginning at hatching, were examined in the neuropil of ectostriatum, a visusal telencephalic projection area in birds. The Volume of ectostriatum, the number of synapses and subsynaptic features like the presynaptic terminal size and the length of the postsynaptic contact zone were quantified in juvenile (20 d) and adult (100 d) zebra finches. Monocular deprivation affects almost all of the parameters mentioned above in juvenile birds, but only one (i.e., the size of presynaptic terminals) is permanently altered in adulthood. Both hemispheres are affected in juvenile birds with respect to the volume of ectostriatum, the length of synaptic contact zones and the presynaptic terminal size when compared to normal values. In normal birds the number of synaptic contacts is established at 20 days and remains fairly constant at 100 days. In experimental birds there is an increase in synapse number during this time period. However, no interhemispheric differences or differences compared to normal animals could be identified. The presynaptic terminals in experimental birds are smallercompared to normal values in young (25% for the deprived side; 19% for the non‐deprived side) and adult (13% for the deprived side; 11% for the non‐deprived side) animals. The only permanent effect caused by monocular deprivation in the ectostriatum is characterized by smaller presynaptic terminals. It is surprising that the tectofugal pathway that is believed to be mostly ipsilateral is not very vulnerable to monocular deprivation in adult animals. It is even more surprising that the deprivation effects are seen on both sides of the brain. The implications of this plasticity will be discussed in this paper.
Cyclic AMP‐dependent protein phosphorylation in the rat anterior pituitary
Authors: Cain Scott T. , Pryor James Cliff , Nemeroff Charles B. 
Published: January 2005

AbstractThe activation of cyclic adenosine 3′5′‐monophosphate (cAMP)‐dependent protein kinases has been implicated as an integral mechanism in stimulus‐secretion coupling in the anterior pituitary. Therefore, we have investigated phosphorylation of endogenous protein substrates both in the presence and absence of cAMP in cell‐free extracts of the rodent anterior pituitary. Specific phosphoprotein substrates in the rat anterior pituitary, which are phosphorylated by a cAMP‐dependent protein kinase in vitro, were identified. Cyclic AMP potentiated the phosphorylation of proteins with apparent molecular weights of 85,000, 77,000, 63,000, 39,000, and 33,000 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Proteins with apparent molecular weights of 124,000, 93,000, 48,000, and 43,000 were phosphorylated only in the presence of cAMP and not in the basal condition. The results highlight edogenous protein substrates that may potentially be involved in cAMP‐dependent stimulus‐secretion coupling in the anterior pituitary.
Ultrastructural analysis of choline acetyltransferase‐immunoreactive sympathetic preganglionic neurons and their dendritic bundles in rat thoracic spinal cord
Authors: Markham Jeffrey A. , Vaughn James E. 
Published: January 2005

AbstractWe have used a monoclonal antibody against choline acetyltransferase (ChAT) to aid in the identification of sympathetic preganglionic neurons (SPNs) and to examine their ultrastructure in rat thoracic spinal cord. The clusters of ChAT‐immumnoreactive (ChAT‐IR) preganglionic cell bodies and their distinctive bundles of dendrites give rise to a ladder‐like appearance in horizontal light microscopic sections. This organization also produced a characteristic appearance of preganglionic neuropil when viewed electron microscopically. The intermediolateral (IML) nucleus contained numerous rostrocaudally oriented ChAT‐IR dendrites extended between the IML and the central autonomic region. Both the ChAT‐IR dendrites and somata of preganglionic neurons were intimately associated with astroglial processes. The cell bodies were typically covered over a large proportion of their surfacce by a thin astrocytic sheath, and this was associated with a paucity of axon terminals forming axosomatic synapses. Instead, the vast majority of synapses upon SPNs were of the axodendritic type. The most frequently observed type of axon terminal contained numerous round, clear vesicles along with several dense‐core vesicles (DCVs). In addition, some boutons contained a predominance of DCVs. Serial section analysis revealed that these apparently diverse morphological classes of synaptic boutons may simple represent variability of structure throughout a single terminal, with a greater proportion of DCVs being located distal to the synaptic specialization and a greater number of round, clear vesicles being present adjacent to the synapse. Analysis of the dendritic bundles revealed that individual dendrites, like the cell bodies, were often isolated from each other and the surrounding neuropil by astrocytic processes. This arrangement usually was interrupted only at regions of synaptic contact where astrocytic processes surrounded the synaptic complex as a whole. Thus, astroglial ensheathment of SPNs seems designed to minimize cross‐talk between the bundled dendrites, as well as to isolate or segregate the diverse afferent inputs known to impinge on these cells.
Synaptic organization of septal projections in the rat medial habenula: A wheat germ agglutinin—horseradish peroxidase and immunohistochemical study
Authors: Kawaja Michael D. , Flumerfelt Brian A. , Hrycyshyn Alan W. 
Published: January 2005

AbstractThe synaptic organization of septal inputs to the rat habenular complex of the dorsal diencephalon was examined employing the anterograde tracer wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). The cellular distribution of substance P (sP) and choline acetyltransferase (ChAT) immunoreactivity was also studied at the light and electron microscopic level. Following placements of tracer within the entire septum, labeled axons were observed in the stria medullaris and in the medial and lateral subnuclei of the habenula. Following injections of tracer in the nuclei triangularis and septoffimbrialis of the posterior septum, the medial subnucleus was heavily labeled, whereas the lateral subnucleus was devoid of peroxidase activity. The medial subnucleus possessed labeled myelinated axons and terminals that contained clear, spherical vesicles and formed asymmetric contacts with dendritic spines and shafts. Terminals possessing WGA‐HRP activity also formed non‐synaptic junctions with other labeled or unlabeled terminals. sP and ChAT immunoreactivity in normal and colchicinetreated animals was confined to dendrites and somata within the medial habenula. Terminals containing clear spherical vesicles formed asymmetric synaptic contacts with these immunoreactive somatic and dendritic profiles. Based on the combined anterograde tracing and immunohistochemical data, it is proposed that septal projections provide a direct innervation to habenular neurons that contain ChAT or SP activity. These septal inputs may play an important role in the facilitation of the ChAT‐ and sP‐positive habenular neurons, both of which provide prominent afferent inputs to the interpdeuncular nucleus. Thus, neurons of the habenula and interpeduncular nucleus are under the direct and indirect influence of septal neurons within the limbic forebrain circuit.
Phorbol ester enhances synaptic transmission at crustacean neuromuscular junctions
Authors: Gilat E. , Hochner B. 
Published: January 2005

AbstractEffects of phorbol ester (PE) (4β‐phorbol‐12,13‐dibutyrate) on transmitter release were studied in the deep extensor neuromuscular system of the prawn, Macrobrachium rosenbergii. Our findings show that PE enhances transmiter release as indicated by an increase in the quantal content. PE had no past‐synaptic effects.The increase in release is accompanied by a slight decline in twin pulse facilitation, suggesting a minor increase in Ca2+ entry. The fact that the increase in Ca2+ entry has a minor contribution to the PE effect is supported by the following observations: the duration of facilitation was not affected by PE, and 3,4‐diaminopyridine (3,4‐DAP), which by itself increased release, did not reduce the effect of PE. The time course of release was measured from synaptic delay histograms, upon which PE had no effect. The finding indicates that protein kinase C (PKC) is probably not involved in the rate limiting step of the process of secretion. The log/log plot of the initial part of the delay histogram is not affected by PE, suggesting a lach of effect on cooperativity of the release process. Increased release by loading the presynaptic terminal with Ca2+ either by pretreatment with Ca2+ ionophore or by frequent stimulation prevented further increase in release by PE.We conclude that the main effect of PE is confined to stages of release that are secondary to the first elevation in presynaptic Ca2+. PKC in this system probably plays a role in long term modulation of release, and it can be activated in processes leading to presynaptic Ca2+ accumulation.
Chronic treatment with clozapine or haloperidol differentially regulates dopamine and serotonin receptors in rat brain
Authors: O'Dell Steven J. , Lahoste Gerald J. , Widmark Clifford B. , Shapiro Raymond M. , Potkin Steven G. , Marshall John F. 
Published: January 2005

AbstractLong‐term administration of the atypical neuroleptic clozapine (CLZ) poses a much lower risk of extrapyramidal side effects (EPS) than does the use of typical neuroleptics such as haloperidol (HAL). To investigate the neural mechanisms of the differing CNS activities of these two drugs, we used quantitative autroadiography to measure changes in dopamine and serotonin receptors in rats after injection with CIZ or HAL for 21 days at clinically relevant dose ratios. Levels of D1, D2, and 5‐HT2 receptors were determined in frontal cortex, caudate‐putamen, and nucleus accumbens. Rats that received CLZ chronically showed CNS receptor changes markedly different from those in chronic HAL‐treated animals. Whereas rats treated chronically with HAL showed enhanced striatal D2 binding (average increase of 42%), those treated with CLZ did not. In contrast, CLZ, but not chronic HAL, induced enhanced striatal D1 binding (average increase of 43%). Finally, CLZ treatment decreased 5‐HT2 receptor binding by an average of 37%, while HAL had no significant effect. The effects of chronic HAL or CLZ treatment on receptors were similar in all forebrain areas examined. However, since D1 and 5‐HT2 receptors are more abundant that D2 sites in limbic and neocortical areas, the preferential modulation of D1 and 5‐HT2 receptors by CLZ suggests a greater impact of this atypical neuroleptic on activity of the limbic system than that achieved by the typical neuroleptic, HAL. These findings suggest that the clinical profile of atypical nuroleptics such as CLZ may be attributed to their effects on a receptor profile differing in pharmacological characteristics and anatomical distribution from that affected by typical neuroleptics.
The benzodiazepine receptor inverse agonist DMCM decreases serotonergic transmission in rat hippocampus: An in viovo electrophysiological study
Authors: Lista Alvaro , Blier Pierre , De Montigny Claude 
Published: January 2005

AbstractThe intravenous administration of the benzodiazepine inverse agonist DMCM (6,7‐dimethoxy‐4‐ethyl‐β‐carboline‐3‐carboxylic acid methyl ester) dose‐dependently reduced the efficacy of electrial stimulation of the 5‐HT pathway in depressing the firing activity of rat hippocampus pyramidal neurons. This effect was prevented by the benzodiazepine receptor antagonist flumazenil and reversed by the benzodiazepine receptor agonist diazepam. This indicates that DMCM alters‐5HT transmission in the rat dorsal hippocampus via benzodiazepine receptors and that these receptors have both agonist and inverse agonist sites.
Analysis of a multiple‐contact synapse missing a normally obligatory postsynaptic neuron: An Electron microscopic Study in the compound eye of musca domestica
Authors: Fröhlich A. 
Published: January 2005

AbstractIn the compound eye of the adult female fly Musca domestica, photoreceptors form populations of multiple‐contact output synapes, stereotypic in their architecture and in the identity of the four postsynaptic elements. Two postsynaptic elements, always, originating from monopolar interneurons L1 and L2, lie side by side beneath the elongated presynaptic bar. Beneath each end of the bar, a further postsynaptic contact is located. These contacts most often are two processes either of amacrine cells or of epithelial glial cells. Monopolar cell L3 may be postsynaptic as well, with either an amacrine or a glial process completing the tetrad.To learn more about the factors determining connectivity and synaptic architecture, a three‐dimensional reconstruction of serial electron microscopic sections was used to analyze a population of photoreceptor synapses at which one of the normally obligatory postsynaptic neurons, L1, was missing.In this abnormal case, the synapses make the normal four postsynaptic contacts in only 39% of the cases, otherwise making three (39%) or two (22%) contacts. Specificity of connectivity is preserved faithfully except that beta processes of T1 cells were postsynaptic at 2% of the synapses, where they do not normally contribute. In contrast to normal synapses, where amacrine and glial cell processes cell processes are mutual exclusive, such pairings could coexist in the aberrant synapse (27% of all synapses). All postsynaptic cells contributed the normal of processes to a synaptic site, except for three synapses each with a supernumerary amacrine cell process. The postsynaptic cells therefore may be involved in regulating the number of their contacts made to a synaptic site.
Ontogeny of somatostatin mRNA‐containing perikarya in the rat central nervous system
Authors: Fitzpatrick‐McElligott Sandra , Card J. Partrick , O'Kane Teresa M. , Baldino Frank 
Published: January 2005

AbstractThe distribution of neuronal perikarya containing somatostatin mRNA in the developing rat brain was investigated with in situ hybridization histochemistry. This study describes the expression of somatostatin mRNA during selected perinatal stages and demonstrates regional changes in somatostatin mRNA expression at the single cell level. The mRNA expression closely parallels previously reported development localization of the peptide (Inagaki et al., 1982; Shiosaka et al., 1982). As early as embryonic day 13 (E13), somatostatin mRNA was observed in discrete spinal cord and brainstem regions. At birth, densely hybridized somata could be seen primarily in ventral and caudal brain areas with small scattered neurons in the hippocampus and dorsal neocortex. After birth, somatostatin mRNA increased in forebrain regions, such as the hippocampus, dorsal neocortex, and caudate. By postnatal day 14 (P14), the distribution in the telencephalic and diencephalic regions approached thata of the adult brain. Several brain regions manifested large changes in the density of somatostatin mRNA hybridization during development. For example, the cerebellar vermis and brainstem contained somatostatin mRNa perikarya during early postnatal development but decreased in these regions in the adult. During perinatal development, increases in somatostatin mRNA content were the results of increases in both the number of neurons containing somatostatin mRNA as well as in the amount of this mRNA expressed in each cell. As the brain differentiates, the apparent numbers of somatostatin mRNA containing neurons in certain brain regions are reduced. These data provide evidence for transient somatostatinergic neurons during early development in discrete areas of the occipital cortex, pyriform cortex, cerebellum, and brainstem and suggest that this peptide may play a role in the development of these regions.
Is dystrophin present in the nerve terminal nat the neuromuscular junction? An immunoshistochemical study of the heterozygote dystrophic (mdx) mouse
Authors: Huard Johnny , Fortier Louis‐Philippe , Labrecque Claude , Dansereau Guy , Tremblay Jacques P. 
Published: January 2005

AbstractNeuromuscular junctions (NMJs) were identified by revealing the presence of cholinergic receptors (AChR) with α‐bungarotoxin coupled to the fluorescent dye cascade blue in 9‐ and 60‐day‐old normal and heterozygote mdx mice. Dystrophin was detected by an immunoperoxidase technique. All the muscle fibers of the normal animals observed in cross sections were immunorective for dystrophin and an accumulation of dystrophin was observed at all NMJs identified by α‐bungarotoxin. In the 9‐day‐old mdx heterozygote animals, dystrophin positive, negative, and partially positive muscle cross sections were observed. Four different observations were made in these heterozygote animals on the coexistence of AChR and dystrophin. First, α‐bungarotoxin sites (i.e., NMJs) were observed on dystrophin positive muscle fiber cross sections with an accumulation of dystorphin positive fibers without a dystrophin accumulation at NMJs. Third, there was a coexistence of α‐bungarotoxin and dystrophin labelling at NMJs of muscle fibers with perimeters labelling negative for dystrophin. Fourth, NMJs identified by α‐bungarotoxin, were observed on muscle fibers negative for dystrophin even at the NMJ. These observations suggest that dystrophin is present not only in the muscle membrance but also in the presynaptic nerve terminals.
A light and electron microscopic study of dystrophin localization at the mouse neuromuscular junction
Authors: Huard Johnny , Fortier Louis‐Philippe , Dansereau Guy , Labrecque Claude , Tremblay Jacques P. 
Published: January 2005

AbstractDuchenne muscular dystrophy (DMD) is characterized by a lack of dystrophin expression. Dystrophin is a 420 Kd protein localized in the muscle sarcolemma that most likely provides stability to the muscle plasma membrane. Neuromuscular junctions (NMJs) were localized by revealing either the acetylcholine receptors (AChRs) with α‐bungarotoxin coupled with cascade blue or by revealing desmin, a protein found in higher concentration at the NMJs using immunochemistry. An accumulation of dystrophin was observed in normal mice by immunoperoxidase labelling at NMJs identified with these markers. Dystrophin was pinpointed on the postjunctional folds of NMJs by electron microscopy and was more abundant on the postjunctional membrane than on the remaining muscle membrane. Our observations are similar to previous observations suggesting that dystrophin may interact with the AChRs.