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Effect of carbamazepine on tetrodotoxin-resistant Na+ channels in trigeminal ganglion neurons innervating to the dura.

ABSTRACT: Migraine is a neurological disorder characterized by recurrent and disabling severe headaches. Although several anticonvulsant drugs that block voltage-dependent Na+ channels are widely used for migraine, far less is known about the therapeutic actions of carbamazepine on migraine. In the present study, therefore, we characterized the effects of carbamazepine on tetrodotoxin-resistant (TTX-R) Na+ channels in acutely isolated rat dural afferent neurons, which were identified by the fluorescent dye DiI. The TTX-R Na+ currents were measured in medium-sized DiIpositive neurons using the whole-cell patch clamp technique in the voltage-clamp mode. While carbamazepine had little effect on the peak amplitude of transient Na+ currents, it strongly inhibited steady-state currents of transient as well as persistent Na+ currents in a concentration-dependent manner. Carbamazepine had only minor effects on the voltage-activation relationship, the voltage-inactivation relationship, and the use-dependent inhibition of TTX-R Na+ channels. However, carbamazepine changed the inactivation kinetics of TTX-R Na+ channels, significantly accelerating the development of inactivation and delaying the recovery from inactivation. In the current-clamp mode, carbamazepine decreased the number of action potentials without changing the action potential threshold. Given that the sensitization of dural afferent neurons by inflammatory mediators triggers acute migraine headaches and that inflammatory mediators potentiate TTX-R Na+ currents, the present results suggest that carbamazepine may be useful for the treatment of migraine headaches.

SUBMITTER: Han JE

PROVIDER: S-EPMC6205941 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Effect of carbamazepine on tetrodotoxin-resistant Na+ channels in trigeminal ganglion neurons innervating to the dura.

Han Jin-Eon JE Cho Jin-Hwa JH Nakamura Michiko M Lee Maan-Gee MG Jang Il-Sung IS

The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology 20181025 6

Migraine is a neurological disorder characterized by recurrent and disabling severe headaches. Although several anticonvulsant drugs that block voltage-dependent Na+ channels are widely used for migraine, far less is known about the therapeutic actions of carbamazepine on migraine. In the present study, therefore, we characterized the effects of carbamazepine on tetrodotoxin-resistant (TTX-R) Na+ channels in acutely isolated rat dural afferent neurons, which were identified ...[more]

PMID: 30402025

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Project description:BackgroundDorsal root ganglia (DRG) somata from rodents have provided an excellent model system to study ion channel properties and modulation using electrophysiological investigation. As in other vertebrates, zebrafish (Danio rerio) DRG are organized segmentally and possess peripheral axons that bifurcate into each body segment. However, the electrical properties of zebrafish DRG sensory neurons, as compared with their mammalian counterparts, are relatively unexplored because a preparation suitable for electrophysiological studies has not been available.Methodology/principal findingsWe show enzymatically dissociated DRG neurons from juvenile zebrafish expressing Isl2b-promoter driven EGFP were easily identified with fluorescence microscopy and amenable to conventional whole-cell patch-clamp studies. Two kinetically distinct TTX-sensitive Na(+) currents (rapidly- and slowly-inactivating) were discovered. Rapidly-inactivating I(Na) were preferentially expressed in relatively large neurons, while slowly-inactivating I(Na) was more prevalent in smaller DRG neurons. RT-PCR analysis suggests zscn1aa/ab, zscn8aa/ab, zscn4ab and zscn5Laa are possible candidates for these I(Na) components. Voltage-gated Ca(2+) currents (I(Ca)) were primarily (87%) comprised of a high-voltage activated component arising from ω-conotoxin GVIA-sensitive Ca(V)2.2 (N-type) Ca(2+) channels. A few DRG neurons (8%) displayed a miniscule low-voltage-activated component. I(Ca) in zebrafish DRG neurons were modulated by neurotransmitters via either voltage-dependent or -independent G-protein signaling pathway with large cell-to-cell response variability.Conclusions/significanceOur present results indicate that, as in higher vertebrates, zebrafish DRG neurons are heterogeneous being composed of functionally distinct subpopulations that may correlate with different sensory modalities. These findings provide the first comparison of zebrafish and rodent DRG neuron electrical properties and thus provide a basis for future studies.

Dataset Information

Effect of carbamazepine on tetrodotoxin-resistant Na+ channels in trigeminal ganglion neurons innervating to the dura.

Publications

Effect of carbamazepine on tetrodotoxin-resistant Na<sup>+</sup> channels in trigeminal ganglion neurons innervating to the dura.

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