Glial cell line-derived neurotrophic factor acutely modulates the excitability of rat small-diameter trigeminal ganglion neurons innervating facial skin

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Abstract

Glial cell line-derived neurotrophic factor (GDNF) plays an important role in adult sensory neuron function. However, the acute effects of GDNF on primary sensory neuron excitability remain to be elucidated. The aim of the present study was to investigate whether GDNF acutely modulates the excitability of adult rat trigeminal ganglion (TRG) neurons that innervate the facial skin by using perforated-patch clamping, retrograde-labeling and immunohistochemistry techniques. Fluorogold (FG) retrograde labeling was used to identify the TRG neurons innervating the facial skin. The FG-labeled small- and medium-diameter GDNF immunoreactive TRG neurons, and most of these neurons also expressed the GDNF family receptor α-1 (GFRα-1). In whole-cell voltage-clamp mode, GDNF application significantly inhibited voltage-gated K+ transient (IA) and sustained (IK) currents in most dissociated FG-labeled small-diameter TRG neurons. This effect was concentration-dependent and was abolished by co-application of the protein tyrosine kinase inhibitor, K252b. Under current-clamp conditions, the repetitive firing during a depolarizing pulse were significantly increased by GDNF application. GDNF application also increased the duration of the repolarization phase and decreased the duration of the depolarization phase of the action potential, and these characteristic effects were also abolished by co-application of K252b. These results suggest that acute application of GDNF enhances the neuronal excitability of adult rat small-diameter TRG neurons innervating the facial skin, via activation of GDNF-induced intracellular signaling pathway. We therefore conclude that a local release of GDNF from TRG neuronal soma and/or nerve terminals may regulate normal sensory function, including nociception.

Introduction

Glial cell line-derived neurotrophic factor (GDNF) is known to have neurotrophic actions on different types of neurons in the central and peripheral nervous system, including primary afferent sensory neurons (Lapchak et al., 1996, Unsicker, 1996, Bennett et al., 1998, Bennett et al., 2000, Prince et al., 2005). The GDNF family ligands signal through a receptor complex consisting of the common transmembrane tyrosine kinase receptor Ret, and one of four ligand binding receptor components, called GDNF family receptors (GFRα-1 to -4), with GFRα-1 the preferred receptor for GDNF (Airaksinen and Saarma, 2002). During development, the survival of most sensory neurons is dependent on nerve growth factor (NGF), and these small- to medium-sized neurons express the NGF receptor trkA (Crowley et al., 1994, Koltzenburg, 1999; Quartu et al., 1996). However, during the late embryonic and postnatal period, some small- to medium-sized neurons that are initially trkA positive, switch dependency to GDNF and express GFRα-1 (Silverman and Kruger, 1988, Molliver et al., 1997, Bennett et al., 1998), suggesting that GDNF plays an important role in mature sensory neuron function. There is evidence that NGF, GDNF and BDNF (Brain-derived neurotorophic factor) differentially alter trigeminal ganglion (TRG) neuron survival, neurochemical properties and transient receptor potential vanilloid receptor type 1 (TRPV1)-mediated neuropeptide release (Prince et al., 2005). In fact, GFRα-1 is expressed by small-diameter dorsal root ganglion (DRG) neurons, particularly those which bind isolectin B4 (IB4), which is believed to play a role in nociception (Silverman and Kruger, 1988, Akkina et al., 2001, Bennett et al., 1998, Molliver et al., 1997). In addition, the axons of these neurons project onto the superficial layer of spinal dorsal horn (Holstege et al., 1998, Jongen et al., 1999, Kawamoto et al., 2000). Taken together, these findings suggest that GDNF and GFRα-1 expression by small-diameter sensory neurons is related to nociception.

There is increasing evidence of cross-excitation in the sensory ganglia, and recent studies have demonstrated that non-synaptically released diffusible chemical messengers, such as ATP, substance P (SP) and calcitonin gene-related peptide (CGRP), may modify the somatic excitability of neurons in the sensory ganglia (Amir and Devor, 1996, Amir and Devor, 2000, Takeda et al., 2005a, Takeda et al., 2005b, Zhang et al., 2007, Jing et al., 2008, Durham, 2008). For example, the release of SP in TRG neurons increases predominantly after peripheral inflammation, indicating that local paracrine mechanisms in the sensory ganglia contribute to the development of inflammation-induced sensory abnormalities (Matsuka et al., 2001, Takeda et al., 2005a, Takeda et al., 2005b). Quartu et al. (1996) have reported that human GDNF positive TRG neurons also expressed SP/CGRP immunoreactivity at all ages examined and satellite glia cell occasionally expressed GDNF. Recent studies demonstrated that small- and medium-diameter human TRG neurons also express GDNF and the GFRα-1 receptor (Quartu et al., 1999, Quartu et al., 2006), suggesting that local paracrine and/or autocrine mechanisms of GDNF within the trigeminal ganglia may contribute to modulation of the nociceptive TRG neuronal excitability.

Two different modes of action (long- and short-term effects) have been reported to explain the excitatory effects of GDNF. Long-term treatment with GDNF modulates synapses made by the midbrain dopaminergic neurons (Lin et al., 1993, Brizard et al., 2006). Amperometric recording demonstrates that treatment with GDNF can enhance quantal release of synaptic neurotransmitters in cultured dopaminergic neurons (Pothos et al., 1998). Also, GDNF up-regulates tetrodotoxin-resistant (TTX-R) sodium channels in small-diameter DRG neurons after their axons are injured (Cummins et al., 2000). In addition to those long-term effects, it has also been reported that acute application of GDNF to midbrain dopaminergic neurons suppresses A-type potassium channels and potentiates neuronal excitability through a mechanism that involves activation of mitogen activated protein (MAP) kinase (Yang et al., 2001). Wang et al. (2003) reported acute potentiation of voltage-gated Ca2+ channels and excitatory synaptic transmission in dopaminergic neurons by GDNF application. Therefore, these data suggest that GDNF may acutely modulate voltage-gated ion channels in normal neuronal excitability rather than the long-term regulation of survival.

Voltage-gated potassium (K+) channels are important physiological regulators of membrane excitability in sensory ganglia (Ficker and Heinemann, 1992, Peace and Duchen, 1994, Lawson, 2006, Dang et al., 2004, Takeda et al., 2006). DRG and TRG neurons express three distinct classes of K+ currents in varying quantities: dominant-sustained (K-current; IK), fast-inactivating transient (A-current; IA, corresponding to A-type K+ current) and slow-inactivating transient (D-current; ID) currents (Evervill et al., 1999; Takeda et al., 2004, Yoshida and Matsumoto, 2005). Our laboratory previously reported that in TTX-R small-diameter TRG neurons, a reduction in IA current density contributed to the increased excitability seen after temporomandibular (TMJ) inflammation (Takeda et al., 2006). More recently, it was also documented that BDNF enhances DRG neuron excitability via the suppression of IK (Zhang et al., 2008). Taken together, these results led us to hypothesize that acute application of GDNF may modify nociceptive TRG neuronal excitability. This idea was further supported by the evidence that, in a transgenic mouse that over-expressed GDNF in the skin, IB4 positive/GDNF responsive DRG neurons exhibited significantly lower thresholds to mechanical stimulation than wild-type neurons (hyperalgesia) (Albers et al., 2006).

Therefore, the aim of the present study was to test the hypothesis that acute application of GDNF modulates the neuronal excitability of TRG neurons innervating the facial skin, by using perforated patch-clamp combined with retrograde-labeling and immunohistochemistry.

Section snippets

Material and methods

The experiments were approved by the Animal Use and Care Committee of Nippon Dental University and were consistent with the ethical guidelines of the International Association for the Study of Pain (Zimmermann, 1983). Every effort was made to minimize the number of animals used and their suffering.

Immunoreactivity of GDNF and GFRα-1 in the TRG neurons innervating facial skin

According to our previous immunohistochemical examinations (Takeda et al., 2007a, Takeda et al., 2007b), TRG cell bodies were classified according to size as small (<30 μm), medium (30–39 μm) or large (>40 μm). As shown in Fig. 1A, small- and medium-diameter TRG neurons were immunoreactive for GDNF as described previously (Quartu et al., 1999). Most of these neurons (88%) were also immunoreactive for the GFRα-1 (Fig. 1B and C). The size frequency distribution of GDNF and GFRα-1 immunoreactive TRG

Discussion

The present study provides evidence that acute application of GDNF enhances the neuronal excitability of adult rat small-diameter TRG neurons, which innervate the facial skin in the absence of neuropathic and inflammatory conditions. This potentiation of small-diameter TRG neuronal excitability is mediated by inhibition of voltage-gated outward K+ channels via the activation of GDNF-induced intracellular signaling pathway. These alternations in cellular excitability may account for enhanced

Acknowledgments

This study was supported by a Grant-in-Aid for Scientific Research from the Japanease Society for Promotion of Science (No. 21592377).

References (86)

  • Y. Matsuka et al.

    Concurrent of ATP and substance P within guinea pig trigeminal ganglia in vivo

    Brain Res.

    (2001)
  • M.J. Millan

    The induction of pain: an integrative review

    Prog. Neurobiol.

    (1999)
  • D.C. Molliver et al.

    IB-4-binding DRG neurons switch from NGF to GDNF dependence in early postnatal life

    Neuron

    (1997)
  • G. Paratcha et al.

    The neural cell adhesion molecule NCAM is an alternative signaling receptor for GDNF family ligands

    Cell

    (2003)
  • D. Poteryaev et al.

    GDNF triggers a novel Ret-independent SRc kinase family-coupled signaling via a GPI-linked GDNF receptor alpha 1

    FEBS Lett.

    (1999)
  • M. Quartu et al.

    Glial cell line-derived neurotrophic factor-like immunoreactivity in human trigeminal ganglion and nucleus

    Brain Res.

    (1999)
  • M. Quartu et al.

    GDNF family ligand receptor components Ret and GFR alpha-1 in the human trigeminal ganglion and sensory nuclei

    Brain Res. Bull.

    (2006)
  • J.K. Sandhu et al.

    Astrocyte-secreted GDNF and glutathione antioxidant system protect neurons against 6OHDA cytotoxicity

    Neurobiol. Dis.

    (2009)
  • W.D. Snider et al.

    Tackling pain at the source. new ideas about nociceptors

    Neuron

    (1998)
  • M. Takeda et al.

    Activation of GABAB receptor inhibits the excitability of rat small diameter trigeminal root ganglion neurons

    Neuroscience

    (2004)
  • M. Takeda et al.

    Activation of NK1 receptor of trigeminal root ganglion via substance P paracrine mechanism contributes to the mechanical allodynia in the temporomandibular joint inflammation in rats

    Pain

    (2005)
  • M. Takeda et al.

    Enhanced excitability of rat trigeminal root ganglion neurons via decrease in A-type potassium currents following temporomandibular joint inflammation

    Neuroscience

    (2006)
  • M. Takeda et al.

    Somatostatin inhibits the excitability of rat small-diameter trigeminal ganglion neurons that innervate nasal mucosa and project to the upper cervical dorsal horn via activation of somatostatin 2a receptor

    Neuroscience

    (2007)
  • M. Takeda et al.

    Enhanced excitability of nociceptive trigeminal ganglion neurons by satellite glial cytokine following peripheral inflammation

    Pain

    (2007)
  • M. Takeda et al.

    Contribution of activated interleukin receptors in trigeminal ganglion neurons to hyperalgesia via satellite glial interleukin-1β paracrine mechanism

    Brain Behav. Immun.

    (2008)
  • M. Takeda et al.

    Contribution of activation of satellite glia in the sensory ganglia to pathological pain

    Neurosci. Biobehav. Rev.

    (2009)
  • T. Tanimoto et al.

    Immunohistochemical co-expression of carbonic anhydrase II with Kv1.4 and TRPV1 in rat small-diameter trigeminal ganglion neurons

    Brain Res.

    (2005)
  • Y. Tsuboi et al.

    Alternation of the second branch of the trigeminal nerve activity following inferior alveolar nerve transection in rats

    Pain

    (2004)
  • L. Vulchanova et al.

    Cytotoxic targeting of isolectin IB4-binding sensory neurons

    Neuroscience

    (2001)
  • P.J. Waddell et al.

    Electrophysiological properties of subpopulations of rat dorsal root ganglion neurons in vitro

    Neuroscience

    (1990)
  • M. Zimmermann

    Ethical guidelines for investigations experimental pain in conscious animals

    Pain

    (1983)
  • M.S. Airaksinen et al.

    The GDNF family: signaling biological functions and therapeutic value

    Nat. Neurosci.

    (2002)
  • K.M. Albers et al.

    Glial cell line-derived neurotorophic factor expression in skin alters the mechanical sensitivity of cutaneous nociceptors

    J. Neurosci.

    (2006)
  • R. Amir et al.

    Chemically mediated cross-excitation in rat dorsal root ganglia

    J. Neurosci.

    (1996)
  • R. Amir et al.

    Functional cross-excitation between afferent A- and C-neurons in dorsal root ganglia

    Neuroscience

    (2000)
  • D.L. Bennett et al.

    A distinct subgroup of small DRG cells express GDNF receptor components and GDNF is protective for these neurons after nerve injury

    J. Neurosci.

    (1998)
  • D.L. Bennett et al.

    The glial cell line-derived neurotrophic factor family receptor components are differentially regulated within sensory neurons after nerve injury

    J. Neurosci.

    (2000)
  • D.L. Bennett

    Neurotrophic factors: important regulators of nociceptive function

    Neuroscientist

    (2001)
  • A. Blesch et al.

    GDNF gene delivery to injured adult CNS motor neurons promotes growth, expression of neurotrophic neuropeptides CGRP, and cellular protection

    J. Comp. Neurol.

    (2001)
  • T.R. Cummins et al.

    Glial-derived neurotrophic factor upregulates expression of functional SNS and NaN sodium channels and their currents in axotomized dorsal root ganglion neurons

    J. Neurosci.

    (2000)
  • K. Dang et al.

    Gastric ulcers reduce A-type potassium currents in rat gastric sensory neurons

    Am. J. Physiol. Gatrointest. Liver Physiol.

    (2004)
  • P. Durbec et al.

    GDNF signaling through the Ret receptor tyrosine kinase

    Nature

    (1996)
  • P.L. Durham

    Inhibition of calcitonin-gene related peptide function: a promising strategy for treating migraine

    Headache

    (2008)
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