Merck
  • Home
  • Search Results
  • G protein-gated inwardly rectifying potassium channel subunits 1 and 2 are down-regulated in rat dorsal root ganglion neurons and spinal cord after peripheral axotomy.

G protein-gated inwardly rectifying potassium channel subunits 1 and 2 are down-regulated in rat dorsal root ganglion neurons and spinal cord after peripheral axotomy.

Molecular pain (2015-07-23)
Chuang Lyu, Jan Mulder, Swapnali Barde, Kristoffer Sahlholm, Hugo Zeberg, Johanna Nilsson, Peter Århem, Tomas Hökfelt, Kaj Fried, Tie-Jun Sten Shi
ABSTRACT

Increased nociceptive neuronal excitability underlies chronic pain conditions. Various ion channels, including sodium, calcium and potassium channels have pivotal roles in the control of neuronal excitability. The members of the family of G protein-gated inwardly rectifying potassium (GIRK) channels, GIRK1-4, have been implicated in modulating excitability. Here, we investigated the expression and distribution of GIRK1 and GIRK2 in normal and injured dorsal root ganglia (DRGs) and spinal cord of rats. We found that ~70% of the DRG neurons expressed GIRK1, while only <10% expressed GIRK2. The neurochemical profiles of GIRK1- and GIRK2-immunoreactive neurons were characterized using the neuronal markers calcitonin gene-related peptide, isolectin-B4 and neurofilament-200, and the calcium-binding proteins calbindin D28k, calretinin, parvalbumin and secretagogin. Both GIRK subunits were expressed in DRG neurons with nociceptive characteristics. However, while GIRK1 was widely expressed in several sensory neuronal subtypes, GIRK2 was detected mainly in a group of small C-fiber neurons. In the spinal dorsal horn, GIRK1- and -2-positive cell bodies and processes were mainly observed in lamina II, but also in superficial and deeper layers. Abundant GIRK1-, but not GIRK2-like immunoreactivity, was found in the ventral horn (laminae VI-X). Fourteen days after axotomy, GIRK1 and GIRK2 were down-regulated in DRG neurons at the mRNA and protein levels. Both after axotomy and rhizotomy there was a reduction of GIRK1- and -2-positive processes in the dorsal horn, suggesting a presynaptic localization of these potassium channels. Furthermore, nerve ligation caused accumulation of both subunits on both sides of the lesion, providing evidence for anterograde and retrograde fast axonal transport. Our data support the hypothesis that reduced GIRK function is associated with increased neuronal excitability and causes sensory disturbances in post-injury conditions, including neuropathic pain.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Monoclonal Anti-Neurofilament 200 (Phos. and Non-Phos.) antibody produced in mouse, clone N52, ascites fluid
Sigma-Aldrich
Sucrose, puriss., meets analytical specification of Ph. Eur., BP, NF
Sigma-Aldrich
Sucrose, BioUltra, for molecular biology, ≥99.5% (HPLC)
Sigma-Aldrich
Sucrose, meets USP testing specifications
Sigma-Aldrich
Sucrose, for molecular biology, ≥99.5% (GC)
Sigma-Aldrich
Sucrose, ≥99.5% (GC)
Sigma-Aldrich
Sucrose, BioReagent, suitable for cell culture, suitable for insect cell culture, ≥99.5% (GC)
Sigma-Aldrich
Sucrose, Grade I, suitable for plant cell culture
Sigma-Aldrich
Sucrose, BioXtra, ≥99.5% (GC)
Sigma-Aldrich
Sucrose, Grade II, suitable for plant cell culture
Sigma-Aldrich
Sucrose, ≥99.5%
Sigma-Aldrich
Sucrose, ACS reagent
Sigma-Aldrich
Ethyl alcohol, Pure, 190 proof, ACS spectrophotometric grade, 95.0%
Sigma-Aldrich
Triton X-100, laboratory grade
Sigma-Aldrich
Bacitracin, from Bacillus licheniformis, ≥65 IU/mg
Sigma-Aldrich
Sodium azide, ReagentPlus®, ≥99.5%
Sigma-Aldrich
Sodium azide, BioXtra
Sigma-Aldrich
Monoclonal Anti-β-Actin antibody produced in mouse, clone AC-15, ascites fluid
Sigma-Aldrich
Sodium azide, BioUltra, ≥99.5% (T)
Sigma-Aldrich
Sodium azide, purum p.a., ≥99.0% (T)
Sigma-Aldrich
Bacitracin, from Bacillus licheniformis, ≥65,000 IU/g
Sigma-Aldrich
Protease Inhibitor Cocktail, for use with mammalian cell and tissue extracts, DMSO solution