Aperçu: G.M.
Les comportements d'auto-mutilations (SIB) sont des traits dévastateurs du trouble du spectre de l"autisme (TSA). Bien
que les déficits de la sensation de douleur puissent être l'un des
facteurs qui sous-tendent le développement des SIB, les mécanismes n'ont
pas encore été abordés.
La
protéine synaptique Shank2 a été considérée comme un composant clé dans
le TSA, et les mutations du gène SHANK2 induisent le dysfonctionnement
des récepteurs N-méthyl-D-aspartate (NMDA), suggérant un lien entre les
récepteurs Shank2 et NMDA dans les TSA, récepteurs qui jouent un rôle central dans l'hypersensibilité à la douleur.La
protéine Shank2 est impliquée dans la douleur médiée par le récepteur
NMDA spinale, et les mutations de Shank2 peuvent supprimer la
signalisation NMDA-ERK dans la transmission de la douleur spinale.
Mol Pain. 2017 Jan;13:1744806916688902. doi: 10.1177/1744806916688902.
A critical role of spinal Shank2 proteins in NMDA-induced pain hypersensitivity
Yoon SY1,2, Kwon SG3, Kim YH1,2,4, Yeo JH3, Ko HG5, Roh DH3, Kaang BK5,6, Beitz AJ7, Lee JH8,9, Oh SB1,2.
Abstract
Background Self-injurious behaviors (SIBs) are devastating traits in autism spectrum disorder
(ASD). Although deficits in pain sensation might be one of the
contributing factors underlying the development of SIBs, the mechanisms
have yet to be addressed. Recently, the Shank2 synaptic protein has been
considered to be a key component in ASD, and mutations of SHANK2 gene
induce the dysfunction of N-methyl-D-aspartate (NMDA) receptors,
suggesting a link between Shank2 and NMDA receptors in ASD. Given that
spinal NMDA receptors play a pivotal role in pain hypersensitivity, we
investigated the possible role of Shank2 in nociceptive hypersensitivity
by examining changes in spontaneous pain following intrathecal NMDA
injection in S hank2-/- ( Shank2 knock-out, KO) mice. Results
Intrathecal NMDA injection evoked spontaneous nociceptive behaviors.
These NMDA-induced nociceptive responses were significantly reduced in
Shank2 KO mice. We also observed a significant decrease of NMDA currents
in the spinal dorsal horn of Shank2 KO mice. Subsequently, we examined
whether mitogen-activated protein kinase or AKT signaling is involved in
this reduced pain behavior in Shank2 KO mice because the NMDA receptor
is closely related to these signaling molecules. Western blotting and
immunohistochemistry revealed that spinally administered NMDA increased
the expression of a phosphorylated form of extracellular
signal-regulated kinase (p-ERK) which was significantly reduced in
Shank2 KO mice. However, p38, JNK, or AKT were not changed by NMDA
administration. The ERK inhibitor, PD98059, decreased NMDA-induced
spontaneous pain behaviors in a dose-dependent manner in wild-type mice.
Moreover, it was found that the NMDA-induced increase in p-ERK was
primarily colocalized with Shank2 proteins in the spinal cord dorsal
horn. Conclusion Shank2 protein is involved in spinal NMDA
receptor-mediated pain, and mutations of Shank2 may suppress NMDA-ERK
signaling in spinal pain transmission. This study provides new clues
into the mechanisms underlying pain deficits associated with SIB and
deserves further study in patients with ASD.
- PMID: 28326932
- DOI: 10.1177/1744806916688902
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