title: Coupling of serotonergic input to NMDA receptor-phosphorylation following peripheral nerve injury via rapid, synaptic up-regulation of ND2.
abstract: Evidence implicates serotonergic input to spinal dorsal horn neurons in shifting the NMDA receptor (NMDAR) into a high functional output profile after spinal nerve ligation (SNL). We investigated the involvement of adaptor protein NADH dehydrogenase subunit 2 (ND2) in NMDAR-phosphorylation and spinal hyperexcitability secondary to peripheral nerve injury. Immunofluorescence for ND2 was found in dorsal horn neurons immunopositive for NMDAR subunit NR1. Co-localization of ND2 with postsynaptic marker PSD-95 was significantly increased 60min after SNL (Rr 0.77 vs Rr 0.06 in sham controls; z=-242.85; p<0.01 at Fisher's exact test). Western blot analyses confirmed ND2 up-regulation both in cytoplasmic (S2) and synaptic (P3) compartments (p<0.01 at the Student's t test). SNL was followed by increased co-localization of ND2 with the phosphorylated form (serine 896) of NR1 (pNMDA). Spinal superfusion with ND2 inhibitor rotenone prevented up-regulation of ND2 (Rr 0.06 after rotenone vs Rr 0.78 in vehicle-treated controls, z=-253.22, p<0.01) and pNR1 in P3. C fiber-evoked dorsal horn field potentials were increased 60min after SNL by superfusion with NMDA agonist cis-ACPD at 100nM (p<0.01 at the Bonferroni test), however cis-ACPD was effective only at 10μM following prior administration of rotenone. Rotenone also abolished enhancement of evoked potentials induced by simultaneous stimulation of NMDA and 5-HR2B receptors in uninjured rats. Increased postsynaptic up-regulation of ND2/pNMDAR 60min after SNL was prevented by prior administration of selective 5-HT2B antagonist SB204741. These results support a pivotal role for ND2 in coupling serotonergic input to NMDAR-activation during neuropathic pain.
authors.affiliation: Department of Neurosciences, School of Medicine and Dentistry, University of the Basque Country, PO Box 699, 48080 Bilbao, Spain.
authors.forename: Zigor
authors.initials: Z
authors.lastname: Aira
authors.affiliation: Department of Neurosciences, School of Medicine and Dentistry, University of the Basque Country, PO Box 699, 48080 Bilbao, Spain.
authors.forename: Itsaso
authors.initials: I
authors.lastname: Buesa
authors.affiliation: Preventive Medicine and Public Health, Faculty of Pharmacy, University of the Basque Country, 01006 Vitoria-Gasteiz, Araba, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Rada
authors.affiliation: Department of Neurosciences, School of Medicine and Dentistry, University of the Basque Country, PO Box 699, 48080 Bilbao, Spain; Movement Disorders and Autonomic Unit, Neurology Service, Cruces University Hospital, Basque Health Service (Osakidetza), Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Gómez-Esteban
authors.affiliation: Department of Neurosciences, School of Medicine and Dentistry, University of the Basque Country, PO Box 699, 48080 Bilbao, Spain. Electronic address: jonjatsu.azkue@ehu.es.
authors.forename: Jon Jatsu
authors.initials: JJ
authors.lastname: Azkue
mesh_terms: D000818:Animals; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D059348:Peripheral Nerve Injuries / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D059326:Serotonergic Neurons / Q000187:drug effects / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D012402:Rotenone; D009245:NADH Dehydrogenase; C574662:NADH dehydrogenase subunit 2, rat
keywords: Descending pathways; Electrophysiology; Neuropathic pain; Rat