title: The chloride co-transporters, NKCC1 and KCC2, in experimental autoimmune encephalomyelitis (EAE).
abstract: Patients with multiple sclerosis (MS) often complain of neuropathic pain. According to the Gate Control Theory of Pain, spinal networks of GABAergic inhibitory interneurons are important in modulating nociceptive inputs from the periphery. Na+-K+-2Cl- co-transporter 1 (NKCC1) and K+-Cl- co-transporter 2 (KCC2) generally dictate the tone of GABA/glycine inhibition by regulating intracellular chloride concentrations. In this study, we investigated the role of NKCC1 and KCC2 in neuropathic pain observed in the animal model, experimental autoimmune encephalomyelitis (EAE), a commonly used model to study the pathophysiology of MS. Quantitative real-time polymerase chain reactions (qRT-PCR) analysis revealed no change in NKCC1 mRNA transcripts in dorsal root ganglia throughout EAE disease course. However, NKCC1 and KCC2 mRNA levels in the dorsal spinal cord were significantly reduced at disease onset and peak only to recover by the chronic time point. Similarly, Western blot data revealed a significant downregulation of NKCC1 and KCC2 in the dorsal spinal cord at disease onset but an upregulation of NKCC1 protein in the dorsal root ganglia at this time point. Treatment with bumetanide, an NKCC inhibitor, had no effect on mechanical hypersensitivity seen in mice with EAE even though it reversed the changes in the levels of NKCC1 and KCC2. We noted that bumetanide treatment, while effective at reversing the changes in monomeric KCC2 levels was ineffective at reversing the changes in oligomeric KCC2 which remained repressed. These results indicate that mechanical hypersensitivity in EAE is not mediated by altered levels of NKCC1.
authors.affiliation: Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada.
authors.forename: Muhammad Saad
authors.initials: MS
authors.lastname: Yousuf
authors.affiliation: Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada.
authors.forename: Kasia
authors.initials: K
authors.lastname: Zubkow
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Tenorio
authors.affiliation: Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada; Department of Pharmacology, University of Alberta, Edmonton, AB T6E 2H7, Canada; Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada. Electronic address: bradley.kerr@ualberta.ca.
authors.forename: Bradley
authors.initials: B
authors.lastname: Kerr
mesh_terms: D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D018450:Disease Progression; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression / Q000187:drug effects; D006930:Hyperalgesia / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D008810:Mice, Inbred C57BL; D063308:Myelin-Oligodendrocyte Glycoprotein; D009437:Neuralgia / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments; D012333:RNA, Messenger / Q000378:metabolism; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D064506:Solute Carrier Family 12, Member 2 / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D027981:Symporters / Q000378:metabolism*; D000096922:K Cl- Cotransporters
chemical_list: D002034:Bumetanide; D063308:Myelin-Oligodendrocyte Glycoprotein; D010446:Peptide Fragments; D012333:RNA, Messenger; D049994:Sodium Potassium Chloride Symporter Inhibitors; D064506:Solute Carrier Family 12, Member 2; D027981:Symporters; D000096922:K Cl- Cotransporters; C578878:Slc12a2 protein, mouse; C445081:myelin oligodendrocyte glycoprotein (35-55)
keywords: DRG; EAE; KCC2; NKCC1; spinal cord