Glial cell line-derived neurotrophic factor (GDNF) acutely modulates spinal nociceptive transmission through GFRa1-RET multireceptor complex. Chiara Salio, Francesco Ferrini, Sangu Muthuraju, Adalberto Merighi Name and email address OR IASP member number of the abstract sponsor: Francesco Ferrini; francesco.ferrini@unito.it; IASP member number: 57241 Contact and affiliation information for presenting author: Chiara Salio: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; chiara.salio@unito.it. Contact and affiliation information for all other listed authors: Francesco Ferrini: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; francesco.ferrini@unito.it. Sangu Muthuraju: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; muthuraju67@gmail.com. Adalberto Merighi: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; Istituto Nazionale di Neuroscienze (INN), University of Turin, Corso Raffaello 30, 1025, Torino, Italy; adalberto.merighi@unito.it. Aim of investigation: Although glial cell line-derived neurotrophic factor (GDNF) is a trophic factor with important implications both in neuronal survival and synaptic plasticity, its role as pain modulator has been poorly investigated. Methods: To understand if GDNF has a role in the activation of spinal nociceptive pathways, we used calcium-imaging and immunohistochemistry on spinal cord slices from postnatal mice. Results: GDNF is expressed in primary afferent fibres (PAFs) and released upon capsaicin stimulation. Blocking GDNF function with an anti-GDNF neutralizing antibody in vitro reveals an inhibitory control on capsaicin-induced ERK phosphorylation in spinal laminae I-II neurons. Moreover, exogenous application of GDNF reduces the capsaicin-induced calcium increase in laminae I-II neurons by acting on a GFRa1-RET multireceptor complex. The specificity of the GDNF effect was assessed by using phosphatidylinositol-phospholipase C, an enzyme that specifically cleaves the GPI linkage of the GFRα1 receptor, thus inactivating the multireceptor complex. Experiments with antagonist of NMDA receptors (AP5) and blocker of N-type Ca2+ channels (ω-Conotoxin GVIA) clarify that the GDNF effect requires the activation of pre-synaptic NMDA receptors and N-type Ca2+ channels, thus suggesting a pre-synaptic site of action. In parallel, we performed immunohistochemical studies at both the light and ultrastructural level to understand the circuitry involved in the effect of GDNF. The trophic factor is expressed in a sub-population of nociceptive peptidergic PAFs, also expressing calcitonin gene-related peptide (CGRP) and somatostatin (SST), but not brain-derived neurotrophic factor (BDNF) and substance P (SP). Instead, GFRa1 and RET are localized on nociceptive non-peptidergic isolectin B4 (IB4)-positive PAFs. Conclusions: Our data show that GDNF, released from peptidergic terminals, exerts a pre-synaptic fast inhibition of the capsaicin-induced response through GFRa1-RET complex expressed on non-peptidergic PAFs. Acknowledgments: This work was supported by grants of the Italian MiUR (Fondi PRIN 2008) and Compagnia di San Paolo (Torino, Italy) to Adalberto Merighi. Selection of topics: Systems (Physiology, Anatomy, Animal Models) Spinal Nociceptive Mechanism
Glial cell line-derived neurotrophic factor (GDNF) acutely modulates spinal nociceptive transmission through GFRa1-RET multireceptor complex
SALIO, Chiara;FERRINI, Francesco Maria;MERIGHI, Adalberto
2012-01-01
Abstract
Glial cell line-derived neurotrophic factor (GDNF) acutely modulates spinal nociceptive transmission through GFRa1-RET multireceptor complex. Chiara Salio, Francesco Ferrini, Sangu Muthuraju, Adalberto Merighi Name and email address OR IASP member number of the abstract sponsor: Francesco Ferrini; francesco.ferrini@unito.it; IASP member number: 57241 Contact and affiliation information for presenting author: Chiara Salio: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; chiara.salio@unito.it. Contact and affiliation information for all other listed authors: Francesco Ferrini: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; francesco.ferrini@unito.it. Sangu Muthuraju: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; muthuraju67@gmail.com. Adalberto Merighi: Department of Veterinary Morphophysiology, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy; Istituto Nazionale di Neuroscienze (INN), University of Turin, Corso Raffaello 30, 1025, Torino, Italy; adalberto.merighi@unito.it. Aim of investigation: Although glial cell line-derived neurotrophic factor (GDNF) is a trophic factor with important implications both in neuronal survival and synaptic plasticity, its role as pain modulator has been poorly investigated. Methods: To understand if GDNF has a role in the activation of spinal nociceptive pathways, we used calcium-imaging and immunohistochemistry on spinal cord slices from postnatal mice. Results: GDNF is expressed in primary afferent fibres (PAFs) and released upon capsaicin stimulation. Blocking GDNF function with an anti-GDNF neutralizing antibody in vitro reveals an inhibitory control on capsaicin-induced ERK phosphorylation in spinal laminae I-II neurons. Moreover, exogenous application of GDNF reduces the capsaicin-induced calcium increase in laminae I-II neurons by acting on a GFRa1-RET multireceptor complex. The specificity of the GDNF effect was assessed by using phosphatidylinositol-phospholipase C, an enzyme that specifically cleaves the GPI linkage of the GFRα1 receptor, thus inactivating the multireceptor complex. Experiments with antagonist of NMDA receptors (AP5) and blocker of N-type Ca2+ channels (ω-Conotoxin GVIA) clarify that the GDNF effect requires the activation of pre-synaptic NMDA receptors and N-type Ca2+ channels, thus suggesting a pre-synaptic site of action. In parallel, we performed immunohistochemical studies at both the light and ultrastructural level to understand the circuitry involved in the effect of GDNF. The trophic factor is expressed in a sub-population of nociceptive peptidergic PAFs, also expressing calcitonin gene-related peptide (CGRP) and somatostatin (SST), but not brain-derived neurotrophic factor (BDNF) and substance P (SP). Instead, GFRa1 and RET are localized on nociceptive non-peptidergic isolectin B4 (IB4)-positive PAFs. Conclusions: Our data show that GDNF, released from peptidergic terminals, exerts a pre-synaptic fast inhibition of the capsaicin-induced response through GFRa1-RET complex expressed on non-peptidergic PAFs. Acknowledgments: This work was supported by grants of the Italian MiUR (Fondi PRIN 2008) and Compagnia di San Paolo (Torino, Italy) to Adalberto Merighi. Selection of topics: Systems (Physiology, Anatomy, Animal Models) Spinal Nociceptive MechanismFile | Dimensione | Formato | |
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