Selective representation of vibrissa at the level of cerebellar Purkinje cells by way of climbing fibers in rats]

In the Rat peripheral information from snout vibrissae are transmitted to cerebellar Purkinje cells of Crus I and II by both mossy and climbing fibers. The climbing fiber pathway is organized in a very precise manner, a particular Purkinje cell being preferentially activated by a single vibrissa.     

The Purkinje fiber-myocardial cell region in the goat heart as studied by combined scanning electron microscopy and chemical digestion

The 3-dimensional architecture of the junctional region between Purkinje fibers and ordinary myocardial cells has been closely studied by combined scanning electron microscopy and chemical digestion in the goat heart. It was revealed that the Purkinje fibers forming the terminal arborization of the atrioventricular bundle are followed by transitional cells which are in contact with ordinary myocardial cells.     

The Purkinje fiber-myocardial cell region in the goat heart as studied by combined scanning electron microscopy and chemical digestion

Summary The 3-dimensional architecture of the junctional region between Purkinje fibers and ordinary myocardial cells has been closely studied by combined scanning electron microscopy and chemical digestion in the goat heart. It was revealed that the Purkinje fibers forming the terminal arborization of the atrioventricular bundle are followed by transitional cells which are in contact with ordinary myocardial cells.Acknowledgment. We wish to thank Professor M. Murakami and Professor K. Yamada for encouraging this study.     

Potassium currents in cardiac cells

The kinetic properties of the inwardly rectifying K current and the transient outward current in cardiac cells were investigated. In sheep Purkinje fibers superfused with Na-free K-free solution, time-dependent changes in the conductance of the inward rectifier are described. In patch clamp experiments the inward rectifier inactivates during hyperpolarization, as can be seen by a decrease in the open state probability. Using whole cell clamp on ventricular myocytes it is demonstrated that the inactivation during hyperpolarization is due to blocking of the channel by external Na, Mg and Ca. The channels responsible for the transient outward current in cow, sheep and rabbit Purkinje fibers are identified using single channel recording. It is demonstrated that in all three preparations the channels are K-selective. The channel in cow Purkinje cells has a large conductance and is regulated by voltage and internal Ca concentration. The channels identified in the sheep and rabbit cells have a much smaller conductance.     

Differential distribution of TASK-1, TASK-2 and TASK-3 immunoreactivities in the rat and human cerebellum

In this work, the distributions of some acid-sensitive two-pore-domain K⁺ channels (TASK-1, TASK-2 and TASK-3) were investigated in the rat and human cerebellum. Astrocytes situated in rat cerebellar tissue sections were positive for TASK-2 channels. Purkinje cells were strongly stained and granule cells and astrocytes were moderately positive for TASK-3. Astrocytes isolated from the hippocampus, cerebellum and cochlear nucleus expressed TASK channels in a primary tissue culture. Our results suggest that TASK channel expression may be significant in the endoplasmic reticulum of the astrocytes. The human cerebellum showed weak TASK-2 immunolabelling. The pia mater, astrocytes, Purkinje and granule cells demonstrated strong TASK-1 and TASK-3 positivities. The TASK-3 labelling was stronger in general, but it was particularly intense in the Purkinje cells and pia mater.Received 25 February 2004; received after revision 19 April 2004; accepted 28 April 2004     

Effects of altered thyroid state on the inhibition produced by locus coeruleus in purkinje cells in the rat

Summary The number of cerebellar Purkinje cells inhibited after locus coeruleus stimulation was found to be greater in hyperthyroid rats than in control healthy animals; these in turn showed a higher percentage of inhibited cells than hypothyroid rats. It is concluded that thyroid hormone is capable of modulating synaptic activity in the LC-PC pathway.     

Technique d'enregistrement de l'activité unitaire du cortex cérébelleux,chez le chat chronique

Summary A technique is described for chronic implantation of movable micro-electrodes in cerebellum of the cat, which is especially adapted for recording unit patterns (Purkinje cells) on the unrestrained animal during a learned motor sequence.     

Role of granular cells in the placement and distribution of synapses between ascending fibers and Purkinje cells of the rat cerebellum]

The study of rats irradiated during development shows that the establishment of the one-to-one relationship in the adult between climbing fibers and Purkinje cells which follows the immature multiply innervated stage mainly depends on granule cells formed before day 8. Climbing fibers ending upon a multiply innervated cell are intermingled on the same dendritic segments.     

Cytoskeletal filaments of heart conducting system localized by antibody against a 55,000 dalton protein.

Cow heart conducting cells characteristically contain cytoplasmic intermediate-sized filaments. We report here the preparation of a specific antibody to a 55,000 dalton protein of isolated cow Purkinje fibres. Confirmation has been obtained that these filaments consist of the 55,000 dalton protein, using the indirect immunofluorescence technique. Cross-reaction is seen with vascular endothelium and smooth muscle cells of various origin, suggesting close identity of different types of intermediate-sized filaments.     

Cytoskeletal filaments of heart conducting system localized by antibody against a 55,000 dalton protein

Summary Cow heart conducting cells characteristically contain cytoplasmic intermediate-sized filaments. We report here the preparation of a specific antibody to a 55,000 dalton protein of isolated cow Purkinje fibres. Confirmation has been obtained that these filaments consist of the 55,000 dalton protein, using the indirect immunofluorescence technique. Crossreaction is seen with vascular endothelium and smooth muscle cells of various origin, suggesting close identity of different types of intermediate-sized filaments.     

Mechanisms of glial-guided neuronal migration in vitro and in vivo

Summary Our laboratory has developed an in vitro model system in which glial-guided neuronal migration can be observed in real time. Cerebellar granule neurons migrate on astroglial fibers by apposing their cell soma against the glial arm, forming a specialized migration junction, and extending a motile leading process in the direction of migration. In vitro assays indicate that the neuronal antigen astrotactin functions as a neuron-glia ligand, and is likely to play a role in the movement of neurons along glial fibers. In heterotypic recombinations of neurons and glia from mouse cerebellum and rat hippocampus, neurons migrate on heterotypic glial processes with a cytology, speed and mode of movement identical to that of neuronal migration on homotypic glial fibers, suggesting that glial fibers provide a permissive pathway for neuronal migration in developing brain. In vivo analyses of developing cerebellum demonstrate a close coordination of afferent axon ingrowth relative to target cell migration. These studies indicate that climbing fibers contact immature Purkinje neurons during the migration and settling of Purkinje cells, implicating a role for afferents in the termination of migration.     

Mechanisms of glial-guided neuronal migration in vitro and in vivo

Our laboratory has developed an in vitro model system in which glial-guided neuronal migration can be observed in real time. Cerebellar granule neurons migrate on astroglial fibers by apposing their cell soma against the glial arm, forming a specialized migration junction, and extending a motile leading process in the direction of migration. In vitro assays indicate that the neuronal antigen astrotactin functions as a neuron-glia ligand, and is likely to play a role in the movement of neurons along glial fibers. In heterotypic recombinations of neurons and glia from mouse cerebellum and rat hippocampus, neurons migrate on heterotypic glial processes with a cytology, speed and mode of movement identical to that of neuronal migration on homotypic glial fibers, suggesting that glial fibers provide a permissive pathway for neuronal migration in developing brain. In vivo analyses of developing cerebellum demonstrate a close coordination of afferent axon ingrowth relative to target cell migration. These studies indicate that climbing fibers contact immature Purkinje neurons during the migration and settling of Purkinje cells, implicating a role for afferents in the termination of migration.     

Sodium pump: its importance to intercellular communication in heart fibres.

The effect of ouabain on the electrical coupling of canine Purkinje cells was investigated. It was found that the glycoside decreases cell communication through an increase in junctional resistance, what supports the view that the sodium pump has an important role on the control of cell communication.     

Improved separation at low temperature of glycoproteins by Con A-Sepharose affinity chromatography in the presence of sodium dodecyl sulfate (SDS)

The Con A-Sepharose affinity chromatography of glycoproteins was even more effective at 4 degrees C than that at room temperature (26-28 degrees C) in the presence of sodium dodecyl sulfate (SDS). Application of this methodology to the separation of several glycoproteins from SDS-solubilized membrane proteins in rat cerebellum, including a glycoprotein characteristic of the Purkinje cells, was successful.     

Presence of giant mitochondria during cerebellar ontogenesis in reptiles

Summary Giant mitochondria were observed in the perikarya and dendrites of Purkinje cells in the developing cerebellar cortex of the lizardGallotia galloti at sevral stages previous to hatching. Such mitochondria are absent from the adult cerebellum.4 December 1986The authors would like to thank Prof. L. Puelles (Murcia University) for his critical assistance and the Edafology Department of La Laguna University for facilities offered, specially for the use of the electron microscope. This work has been pertially suported by a CAICYT research grant No. 909-2.     

Cardiovascular development: towards biomedical applicability

During cardiogenesis, the epicardium grows from the proepicardial organ to form the outermost layer of the early heart. Part of the epicardium undergoes epithelial-mesenchymal transformation, and migrates into the myocardium. These epicardium-derived cells differentiate into interstitial fibroblasts, coronary smooth muscle cells, and perivascular fibroblasts. Moreover, epicardium-derived cells are important regulators of formation of the compact myocardium, the coronary vasculature, and the Purkinje fiber network, thus being essential for proper cardiac development. The fibrous structures of the heart such as the fibrous heart skeleton and the semilunar and atrioventricular valves also depend on a contribution of these cells during development. We hypothesise that the essential properties of epicardium-derived cells can be recapitulated in adult diseased myocardium. These cells can therefore be considered as a novel source of adult stem cells useful in clinical cardiac regeneration therapy.     

Cbln and C1q family proteins – New transneuronal cytokines

The C1q family is characterized by a C-terminal conserved global C1q domain, which is structurally very similar to the tumor necrosis factor homology domain. Although some C1q family members are expressed in the central nervous system, their functions have not been well characterized. Cbln1, a member of the Cbln subfamily of the C1q family, is predominantly expressed in cerebellar granule cells. Interestingly, Cbln1 was recently shown to play two unique roles at excitatory synapses formed between cerebellar granule cells and Purkinje cells: the formation and stabilization of synaptic contact, and the control of functional synaptic plasticity by regulating the postsynaptic endocytosis pathway. Since other Cbln subfamily members, Cbln2-Cbln4, are expressed in various regions of developing and mature brains, Cbln subfamily proteins may generally serve as a new class of transneuronal regulators of synapse development and synaptic plasticity in various brain regions.     

Sodium pump: Its importance to intercellular communication in heart fibres

Summary The effect of ouabain on the electrical coupling of canine Purkinje cells was investigated. It was found that the glycoside decreases cell communication through an increase in junctional resistance, what supports the view² that the sodium pump has an important role on the control of cell communication.This work was supported by Grant No. HL-10897 from the National Heart and Lung Institute, Bethesda, Maryland; from the P.R. Heart Association and from the General Research Support Grant.     

Voltage-gated sodium currents in cerebellar Purkinje neurons: functional and molecular diversity

Purkinje neurons, the sole output of the cerebellar cortex, deliver GABA-mediated inhibition to the deep cerebellar nuclei. To subserve this critical function, Purkinje neurons fire repetitively, and at high frequencies, features that have been linked to the unique properties of the voltage-gated sodium (Nav) channels expressed. In addition to the rapidly activating and inactivating, or transient, component of the Nav current (I_NaT) present in many types of central and peripheral neurons, Purkinje neurons, also expresses persistent (I_NaP) and resurgent (I_NaR) Nav currents. Considerable progress has been made in detailing the biophysical properties and identifying the molecular determinants of these discrete Nav current components, as well as defining their roles in the regulation of Purkinje neuron excitability. Here, we review this important work and highlight the remaining questions about the molecular mechanisms controlling the expression and the functioning of Nav currents in Purkinje neurons. We also discuss the impact of the dynamic regulation of Nav currents on the functioning of individual Purkinje neurons and cerebellar circuits.     

Improved separation at low temperature of glycoproteins by Con A-Sepharose affinity chromatography in the presence of sodium dodecyl sulfate (SDS)

Summary The Con A-Sepharose affinity chromatography of glycoproteins was even more effective at 4°C than that at room temperature (26–28°C) in the presence of sodium dodecyl sulfate (SDS). Application of this methodology to the seperation of several glycoproteins from SDS-solubilized membrane proteins in rat cerebellum, including a glycoprotein characteristics of the Purkinje cells, was sucessful.Acknowledgments. A part of this research was supported by a Grantin-Aid for Scientific Research from the Ministry of Education, Science and Culture (No. 58480150), and also by a grant from National Center of Nervous, Mental and Muscular Disorders (NCNMMD) of the Ministry of Health and Welfare (No.83-11) in Japan.