| 1. |
- Kanno, T, et al.
(författare)
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Cellular function in multicellular system for hormone-secretion: electrophysiological aspect of studies on alpha-, beta- and delta-cells of the pancreatic islet
- 2002
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Ingår i: Neuroscience Research. - 0168-0102. ; 42:2, s. 79-90
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Forskningsöversikt (refereegranskat)abstract
- We review a neck method to explore the cellular functions in multicellular system by application of the perforated patch-clamp technique to intact pancreatic islet of Langerhans. Using this approach, the integrity of the islet is preserved and intercellular communication via gap junctions and paracrine processes are maintained. 13 using low-resistance patch electrodes, rapid current responses can be monitored wider voltage-clamp control. We have applied this methodology to answer questions not resolved by patch-clamp experiments on isolated single insulin-secreting, beta-cells. First, the role of a K+-current dependent on Ca2+-influx for the termination of burst of action potentials in beta-cells could be documented. Neither the current, nor the bursting pattern of electrical activity is preserved in isolated beta-cells. Second. the conductance of gap junctions (similar to1 nS) between beta-cells was determined. Third, electrical properties of glucagon-producing alpha- and somatostatin-secreting delta-cells and the different mechanisms for glucose-sensing in these cells could be explored. The findings emanating from these experiments may hake implications for neuroscience research such as the mechanism of oscillatory electrical activity in general anti processes involved in the glucose-sensing in some neurons, which response to changes of blood glucose concentration. (C) 2002 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
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| 2. |
- Björklund, Martin, et al.
(författare)
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Muscle stretch-induced modulation of noxiously activated dorsal horn neurons of feline spinal cord.
- 2004
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Ingår i: Neuroscience research. - : Elsevier BV. - 0168-0102 .- 1872-8111. ; 48:2, s. 175-184
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Tidskriftsartikel (refereegranskat)abstract
- The present work was designed to check for the possibility of interactions between mechanical innocuous and chemically induced noxious muscle afferent inputs on discharge behavior of nociceptive superficial dorsal horn neurons (SDHNs) of the spinal cord in decerebrated cats. The innocuous and noxious stimuli were applied separately and in combination, so that the effects of the innocuous stimulus on nociceptive processing could be evaluated. The innocuous stimulus consisted of ramp-and-hold stretches of the gastrocnemius muscles, whereas the noxious stimulus consisted of i.a. injections of bradykinin (BK; 0.5-1 ml, 50 microg/ml) into the arterial circulation of same muscles. Only neurons up to approximately 1mm depth and those that responded to noxious pinch of the gastrocnemius muscles were selected for further analysis. The activity of 16 dorsal horn neurons was recorded extracellularly with high-impedance glass microelectrodes, out of which seven responded to stretch, while 12 neurons responded to bradykinin injections. The bradykinin injections induced three types of responses: excitatory, inhibitory and mixed. The majority of the neurons that showed excitatory and mixed responses to bradykinin were also influenced by stretches applied directly after the bradykinin injection. In these neurons, the stretch usually counteracted the bradykinin-induced response, i.e. shortening and reducing bradykinin-induced excitation and re-exciting the cells after bradykinin-induced inhibition. The mechanism of the stretch modulation is proposed to reside in a segmental spinal control of the nociceptive transmission.
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| 3. |
- Schomburg, E D, et al.
(författare)
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Nociceptive input to ascending tract neurones forwarding information from low threshold cutaneous and muscle afferents in cats.
- 2000
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Ingår i: Neuroscience research. - 0168-0102. ; 38:1, s. 117-20
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Tidskriftsartikel (refereegranskat)abstract
- Effects of noxious skin stimulation (central foot pad and foot dorsum) by radiant heat were tested on neurones of ascending tracts with a main input from non-nociceptors. The dominating effect on ventral spinocerebellar tract neurones was a depression (mainly from the pad). Responses of spinocervical tract neurones were either facilitated (predominantly from the foot dorsum) or depressed (predominantly from the pad). The dominating effect on neurones tentatively classified as dorsal horn dorsal spinocerebellar tract neurones was facilitatory from both skin areas. Similar effects were evoked by selective actions of C-fibres when A-delta fibres were blocked by TTX.
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| 4. |
- Schomburg, E D, et al.
(författare)
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Nociceptive input to spinal interneurones in reflex pathways from group II muscle afferents in cats.
- 2000
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Ingår i: Neuroscience research. - 0168-0102. ; 38:4, s. 447-50
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Tidskriftsartikel (refereegranskat)abstract
- Effects of noxious stimulation of the skin by radiant heat were tested on responses of first order interneurones in reflex pathways from group II muscle afferents in mid-lumbar, lower-lumbar and sacral segments of the spinal cord. In mid- and lower-lumbar segments both background discharges and monosynaptically evoked responses of intermediate zone interneurones were facilitated. Those of mid-lumbar dorsal horn interneurones were also facilitated suggesting that both these interneuronal populations contribute to the facilitation of flexion reflexes by nociceptors. In contrast, the dominating effects of noxious heat on sacral dorsal horn group II interneurones were inhibitory. The effects evoked by selective activation of C fibres, after A-delta fibres had been blocked by TTX, were similar to those obtained before TTX application.
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| 5. |
- Skoglund, Thomas, 1969, et al.
(författare)
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Aspects of the organization of neurons and dendritic bundles in primary somatosensory cortex of the rat
- 2004
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Ingår i: Neurosci Res. - : Elsevier BV. - 0168-0102. ; 50:2, s. 189-98
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Tidskriftsartikel (refereegranskat)abstract
- In order to analyze some aspects of the spatial organization in the primary somatosensory cortex of the rat, we have reconstructed the positions of bundles of apical dendrites and neurons in a cortical prisms measuring 0.5 mm x 0.4 mm x cortical thickness, with special reference to a hypothetical columnar organization. Complete series of semithin (0.65 microm) sections were cut, tangentially from the pial surface down to the white matter, stained and digitizalized into a computer and represented as a stack of 2D images. The mean neuron density (N(V)-value) was (60 x 10(3) +/- 15 x 10(3)) neurons/mm3. The mean number of neurons beneath 1 mm2 of cortical surface (NC-value) was (113 x 10(3) +/- 8 x 10(3)) neurons/mm2. Well-defined bundles of apical dendrites emanating from layer V pyramidal cells were observed. The bundles consisted of 3-12 (mean 5 +/- 2) dendrites. The dendrites within a bundle converged while ascending towards the pial surface and reached a maximal close packing in layer IV. Superficially, the packing density decreased again. The mutual positions of the dendrites within the bundles shifted only slightly along their course towards the pial surface. The occurrence of bundles in tangential sections through layer IV was about 190 bundles/mm2 and the average number of neurons per bundle was estimated at approximately 600. However, when calculating Voronoi-diagrams, the number of neurons, which with this mathematical technique, is ascribed to each of the reconstructed dendritic bundles, varied between 200 and 1000. The possibility that the dendritic bundles are centers in cortical cell modules is discussed.
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