Axotomy-induced parallel increases in electrical and dye coupling between identified neurons of Helisoma

Murphy, A. D.; Hadley, RD; Kater, Stanley B.

doi:10.1523/jneurosci.03-07-01422.1983

Cited by 71 publications

(37 citation statements)

References 36 publications

(41 reference statements)

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“…6D), but this difference was statistically insignificant. The different effects of MFA inhibition on the tracer transfer vs. electrical coupling is consistent with the effects of other inhibitors in previous studies (Murphy et al, 1983;Ransom and Kettenmann, 1990;Sontheimer et al, 1991).…”

Section: Effect Of Mfa On Electrical Couplingsupporting

confidence: 90%

Electrical coupling of astrocytes in rat hippocampal slices under physiological and simulated ischemic conditions

Wang

Kimelberg

et al. 2009

Glia

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Mammalian protoplasmic astrocytes are extensively coupled through gap junction channels but the biophysical properties of these channels under physiological and ischemic conditions in situ are not well defined. Using confocal morphometric analysis of biocytin-filled astrocytic syncytia in rat hippocampal CA1 stratum radiatum we found that each astrocyte directly couples, on average, to 11 other astrocytes with a mean interastrocytic distance of 45 microm. Voltage-independent and bidirectional transjunctional currents were always measured between directly coupled astrocyte pairs in dual voltage-clamp recordings, but never from astrocyte-NG2 glia or astrocyte-interneuron pairs. The electrical coupling ratio varied considerably among astrocytes in developing postnatal day 14 rats (P14, 0.5-12.4%, mean = 3.6%), but became more constant in young adult P21 rats (0.18-3.9%, mean = 1.6%), and the coupling ratio declined exponentially with increasing pair distance. Electrical coupling was not affected by short-term oxygen-glucose deprivation (OGD) treatment, but showed delayed inhibition in an acidic extracellular pH of 6.4. Combination of acidic pH (6.4) and OGD, a condition that better represents cerebral ischemia in vivo, accelerated the inhibition of electrical coupling. Our results show that, under physiological conditions, 20.7-24.2% of K(+) induced currents can travel from any astrocytic soma in CA1 stratum radiatum to the gap junctions of the nearest neighbor astrocytes, but this should be severely inhibited as a consequence of the OGD and acidosis seen in the ischemic brain.

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Section: Effect Of Mfa On Electrical Couplingsupporting

confidence: 90%

Electrical coupling of astrocytes in rat hippocampal slices under physiological and simulated ischemic conditions

Wang

Kimelberg

et al. 2009

Glia

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“…No or little voltagedependent inactivation has been described for gap junctions formed by Cx43 (Swenson, Jordan, Beyer & Paul, 1989;Traub et al 1994), which, on the other hand, support dye diffusion between coupled cells. It is possible that although the gap junctional channels were permeable to the dye molecules in the present study, the number of open gap junctions was too low to support sufficient dye spreading (Murphy, Hadley & Kater, 1983) in the 25-40 min allowed for dye diffusion. Taking the single channel conductances obtained for Cx43 (expressed in transfected HeLa cells, 60 and 40 pS; Traub et al 1994) the upper estimate of the junctional conductance in a mouse chromaffin cell pair (approximately 400 pS) would correspond to 7-10 open gap junctional channels.…”

Section: Electrical Coupling In Mouse Adrenal Chromaffin Cellsmentioning

confidence: 77%

Low‐conductance intercellular coupling between mouse chromaffin cells in situ

Moser

1998

The Journal of Physiology

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Patch‐clamp experiments were used to compare membrane properties of mouse chromaffin cells in thin tissue slices and of isolated cells in primary culture. The mean membrane input resistance (Rin) and membrane capacitance were 3.1 ± 0.5 GΩ and 9.1 ± 0.5 pF in situ and 9.9 ± 1.8 GΩ and 8.2 ± 0.2 pF in isolated cells. Spike‐like currents were observed on top of the calcium currents during depolarizations in thirty out of forty‐nine cells in situ. They were not seen in isolated cells nor after addition of Cd2+ (100 μM) and TTX (10 μM) to the perfusate of the slices. The mean Rin of cells which displayed current spikes (2.3 ± 0.18 GΩ) was significantly smaller than that of cells lacking spikes (3.9 ± 0.25 GΩ). It is suggested that the current spikes represent intercellular currents which result from action potential firing in neighbouring cells during the depolarization of the patch‐clamped cell. Investigation of capacitative currents induced by square voltage pulses showed a slow component in twenty‐four out of twenty‐seven cells in situ. It is concluded that a large fraction of mouse chromaffin cells in situ are electrically coupled. From the slow capacitative currents and the amplitude of the intercellular current spikes a junctional conductance between chromaffin cells of below 1 nS was deduced. This junctional conductance appears to be too low to support spreading of electrical activity in cases where a single cell is stimulated by an action potential. However, the junctional conductance could allow longer depolarizations of one cell or simultaneous firing of several cells to trigger electrical activity in neighbouring cells.

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“…The dissection, the physiological saline, and the electrophysiological recording and display techniques have been described (16,17). For these experiments, either isolated buccal ganglia or buccal ganglia attached to the central ring of ganglia via the cerebrobuccal connectives were used.…”

Section: Introductionmentioning

confidence: 99%

Peptidergic modulation of patterned motor activity in identified neurons of Helisoma

Murphy¹,

Lukowiak²,

Stell

1985

Proc. Natl. Acad. Sci. U.S.A.

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The neuroaftive peptides SCPB (small cardioactive peptide B) and FMRFamide (Phe-Met-Arg-Phe-NH2), both originally isolated from molluscs, have potent modulatory effects upon the production of patterned motor activity in identified neurons (e.g., B5 and B19) in the buccal ganglia of the snail Helisoma. Such patterned motor activity has previously been shown to underlie feeding behavior. (7,8).Several aspects of the neural basis of feeding in the snail Helisoma trivolvis have been described. Cyclical activity of many identified effector neurons and elements of the central pattern generator has been characterized (9-11). In addition, the monoamines serotonin (12) and dopamine (13) have been shown to activate or modulate such patterned motor activity (PMA) associated with feeding and generated by neurons in the buccal ganglia. As a first step in characterizing the potential roles of neuroactive peptides in regulating feeding behavior in Helisoma, we report here that two neuroactive peptides, originally discovered in molluscs, have profound effects on the production of PMA (which apparently represents "fictive feeding") by buccal ganglion neurons. Small cardioactive peptide B (SCPB, Met-Asn-Tyr-Leu-Ala-PhePro-Arg-Met-NH2; ref. 14) has stimulatory effects upon the generation of PMA that resemble, at least superficially, those described for serotonin (5-hydroxytryptamine) and dopamine. In contrast, FMRFamide (Phe-Met-Arg-Phe-NH2; ref.15) inhibits and, at a sufficient concentration (10-5 M), effectively suppresses PMA in the buccal ganglia. SCP has been indicated, by chromatographic techniques, to occur in Helisoma central nervous system (see table 1 in ref. 14). We show here that the buccal ganglion ofHelisoma contains both neurons with SCPB-like immunoreactivity and neurons with anti-FMRFamide immunoreactivity.MATERIALS AND METHODS Albino specimens of Helisoma trivolvis were used; they were obtained from stocks maintained in the laboratory of A. G. M. Bulloch (University of Calgary) and derived from the Oregon Red stock of S. B. Kater's laboratory (University of Iowa). The dissection, the physiological saline, and the electrophysiological recording and display techniques have been described (16,17). For these experiments, either isolated buccal ganglia or buccal ganglia attached to the central ring of ganglia via the cerebrobuccal connectives were used. There was no detectable difference in the effects of peptides upon PMA whether or not the central ganglia were attached, but the rate of spontaneous PMA varies considerably and tends to be higher in isolated buccal ganglia. Once it had been determined that SCPB was excitatory and FMRFamide was inhibitory, relatively quiescent preparations were used for SCPB experiments and relatively active preparations were used for FMRFamide experiments. The synthetic peptides, SCPB (Peninsula Laboratories, San Carlos, CA) and FMRFamide (Sigma), were used. Saline volume (<0.5 ml) in the recording chamber was maintained by suction from the surface, and solutions were changed ...

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Axotomy-induced parallel increases in electrical and dye coupling between identified neurons of Helisoma

Cited by 71 publications

References 36 publications

Electrical coupling of astrocytes in rat hippocampal slices under physiological and simulated ischemic conditions

Electrical coupling of astrocytes in rat hippocampal slices under physiological and simulated ischemic conditions

Low‐conductance intercellular coupling between mouse chromaffin cells in situ

Peptidergic modulation of patterned motor activity in identified neurons of Helisoma

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