Characterization of sodium currents in mammalian sensory neurons cultured in serum-free defined medium with and without nerve growth factor

Omri, Gila; Meiri, Hamutal

doi:10.1007/bf01869102

Cited by 47 publications

(26 citation statements)

References 63 publications

(159 reference statements)

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“…The small decrease in spike amplitude observed after axotomy could be due to shunting of action currents due to microelectrode damage or to the decreased input resistance of the cells, but it is interesting to point out that nerve growth factor (NGF) has been shown to influence the expression of sodium channels in sensory neurones in tissue culture (Omri & Meiri, 1990;Aguayo, Weight & White, 1991). In this regard, we also observed a small decrease in action potential amplitude in submandibular neurones innervating an atrophied gland (Table 2), although it did reach only the P < 0 05 level of significance.…”

Section: Discussionmentioning

confidence: 99%

Effects of axotomy or target atrophy on membrane properties of rat sympathetic ganglion cells.

Sánchez-Vives

Gallego

1993

The Journal of Physiology

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SUMMARY1. The electrical properties of rat superior cervical ganglion cells were examined in vitro with intracellular microelectrodes after axotomy or atrophy of the submandibular salivary gland.2. Membrane time constant, input resistance and excitatory synaptic potentials (EPSPs) were decreased to about 50 % of their control values 7-10 days after axotomy.3. Axotomized ganglion cells also showed reduced action potentials and afterhyperpolarizations (AHPs). The AHP duration was reduced to 40 % of the control value.4. In 25 % of the axotomized cells, the action potential was followed by an afterdepolarization (ADP) instead of the AHP that was always present in control cells.

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Section: Discussionmentioning

confidence: 99%

Effects of axotomy or target atrophy on membrane properties of rat sympathetic ganglion cells.

Sánchez-Vives

Gallego

1993

The Journal of Physiology

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“…Previous studies of both immature Meiri et al 1987;Omri & Meiri, 1990;Schwartz, Palti & Meiri, 1990;Fedulova et al 1991) and adult (McLean et al 1988;Caffrey, Brown, Emanuel, Eng, Waxman & Kocsis, 1991) rat DRG neurones also revealed differences in some aspects of both the kinetics and the voltage dependence of macroscopic INa activation and inactivation. Kinetically, the TTX-resistant (TTXr) INa were much slower than the TTX-sensitive (TTXS) currents, in terms of both time to peak and kinetics of decay, while both the peak of the I-V relationship, the mid-point of the normalized conductance curve and the mid-point of the steady-state inactivation (h.) curve were significantly more depolarized for the TTXr INa.…”

Section: Introductionmentioning

confidence: 87%

“…Sodium currents were isolated essentially as described by Omri & Meiri (1990) for immature rat DRG cells. K+ channels were blocked using Cs+ as the major internal cation, and external TEA ions.…”

Section: Sodium Current Isolationmentioning

confidence: 99%

Characterization of TTX‐sensitive and TTX‐resistant sodium currents in small cells from adult rat dorsal root ganglia.

Elliott

1993

The Journal of Physiology

391

226

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SUMMARY1. The whole-cell patch-clamp technique was used to investigate the characteristics of two types of sodium current (INa) recorded at room temperature from small diameter (13-25 /Lm) dorsal root ganglion (DRG) cells, isolated from adult rats and maintained overnight in culture.2. Sodium currents were isolated pharmacologically. Internal Cs' and external tetraethylammonium (TEA) ions were used to suppress potassium currents. A combination of internal EGTA, internal F-, a low (10 gbM) concentration of external Ca2' and a relatively high (5 mM) concentration of internal and external Mg2+ was used to block calcium channels. The remaining voltage-dependent currents reversed direction at the calculated sodium equilibrium potential. Both the reversal potential and magnitude of the currents exhibited the expected dependence on the external sodium concentration.3. INa subtypes were characterized initially in terms of their sensitivity to tetrodotoxin (TTX). TTX-sensitive (TTX,) currents were at least 97 % suppressed by 041 /LM TTX. TTX-resistant (TTXr) INa were recorded in the presence of 0 3 ftM TTX and appeared to be reduced in amplitude by less than 50% in 75 /tM TTX (n= 1).4. As in earlier studies, the peak of the current-voltage relationship, the mid-point of the normalized conductance curve and the potential (Vh) at which the steady-state inactivation parameter (hoo) was 0-5 were found to be significantly more depolarized for the TTXrINa (by ca 10, 14 and 37 mV respectively). There was little difference in the slope at the mid-point of the normalized conductance curves (the mean slope factors were 5-1 mV for the TTX, INa and 4-9 mV for the TTXr current) but the h., curves for TTXr currents were significantly steeper than those for TTXS currents (mean slope factors of 3-8 and 11-5 mV respectively). Both the time to peak and the decay time constant of the peak current recorded from a holding potential of -67 mV were more than a factor of three slower for the TTXr INa than for the TTXS current.5. However, in direct contrast to the difference in activation and decay kinetics, 'slow' TTX. INa recovered from inactivation at -67 mV, or reprimed, more than a factor of ten faster than 'fast' TTXS INa. 7. The possible fundamental importance to DRG cells of such large differences in the voltage dependence of the inactivation systems (both resting inactivation and repriming kinetics) of the two sodium channel subtypes will be discussed.

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“…In vitro evidence has demonstrated that NGF influences sodium current expression and diversity in cultured adult rat DRG neurons (Omri and Meiri 1990). In particular, the percentage of cells with TTXR sodium conductances is increased by NGF (Aguayo and White 1992).…”

Section: Ngf Affects Expression Of Ttxr Sodium Conductances In Drg Nementioning

confidence: 99%

Role of neurotrophin signalling in the differentiation of neurons from dorsal root ganglia and sympathetic ganglia

2009

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Manipulation of neurotrophin (NT) signalling by administration or depletion of NTs, by transgenic overexpression or by deletion of genes coding for NTs and their receptors has demonstrated the importance of NT signalling for the survival and differentiation of neurons in sympathetic and dorsal root ganglia (DRG). Combination with mutation of the proapoptotic Bax gene allows the separation of survival and differentiation effects. These studies together with cell culture analysis suggest that NT signalling directly regulates the differentiation of neuron subpopulations and their integration into neural networks. The high-affinity NT receptors trkA, trkB and trkC are restricted to subpopulations of mature neurons, whereas their expression at early developmental stages largely overlaps. trkC is expressed throughout sympathetic ganglia and DRG early after ganglion formation but becomes restricted to small neuron subpopulations during embryogenesis when trkA is turned on. The temporal relationship between trkA and trkC expression is conserved between sympathetic ganglia and DRG. In DRG, NGF signalling is required not only for survival, but also for the differentiation of nociceptors. Expression of neuropeptides calcitonin gene-related peptide and substance P, which specify peptidergic nociceptors, depends on nerve growth factor (NGF) signalling. ret expression indicative of nonpeptidergic nociceptors is also promoted by the NGFsignalling pathway. Regulation of TRP channels by NGF signalling might specify the temperature sensitivity of afferent neurons embryonically. The manipulation of NGF levels "tunes" heat sensitivity in nociceptors at postnatal and adult stages. Brain-derived neurotrophic factor signalling is required for subpopulations of DRG neurons that are not fully characterized; it affects mechanical sensitivity in slowly adapting, low-threshold mechanoreceptors and might involve the regulation of DEG/ENaC ion channels. NT3 signalling is required for the generation and survival of various DRG neuron classes, in particular proprioceptors. Its importance for peripheral projections and central connectivity of proprioceptors demonstrates the significance of NT signalling for integrating responsive neurons in neural networks. The molecular targets of NT3 signalling in proprioceptor differentiation remain to be characterized. In sympathetic ganglia, NGF signalling regulates dendritic development and axonal projections. Its role in the specification of other neuronal properties is less well analysed. In vitro analysis suggests the involvement of NT signalling in the choice between the noradrenergic and cholinergic transmitter phenotype, in the expression of various classes of ion channels and for target connectivity. In vivo analysis is required to show the degree to which NT signalling regulates these sympathetic neuron properties in developing embryos and postnatally.

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Characterization of sodium currents in mammalian sensory neurons cultured in serum-free defined medium with and without nerve growth factor

Cited by 47 publications

References 63 publications

Effects of axotomy or target atrophy on membrane properties of rat sympathetic ganglion cells.

Effects of axotomy or target atrophy on membrane properties of rat sympathetic ganglion cells.

Characterization of TTX‐sensitive and TTX‐resistant sodium currents in small cells from adult rat dorsal root ganglia.

Role of neurotrophin signalling in the differentiation of neurons from dorsal root ganglia and sympathetic ganglia

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