Phosphorylation state-dependent modulation of spinal glycine receptors alleviates inflammatory pain.
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ABSTRACT: Diminished inhibitory neurotransmission in the superficial dorsal horn of the spinal cord is thought to contribute to chronic pain. In inflammatory pain, reductions in synaptic inhibition occur partially through prostaglandin E2- (PGE2-) and PKA-dependent phosphorylation of a specific subtype of glycine receptors (GlyRs) that contain ?3 subunits. Here, we demonstrated that 2,6-di-tert-butylphenol (2,6-DTBP), a nonanesthetic propofol derivative, reverses inflammation-mediated disinhibition through a specific interaction with heteromeric ??GlyRs containing phosphorylated ?3 subunits. We expressed mutant GlyRs in HEK293T cells, and electrophysiological analyses of these receptors showed that 2,6-DTBP interacted with a conserved phenylalanine residue in the membrane-associated stretch between transmembrane regions 3 and 4 of the GlyR ?3 subunit. In native murine spinal cord tissue, 2,6-DTBP modulated synaptic, presumably ?? heteromeric, GlyRs only after priming with PGE2. This observation is consistent with results obtained from molecular modeling of the ?-? subunit interface and suggests that in ?3?GlyRs, the binding site is accessible to 2,6-DTBP only after PKA-dependent phosphorylation. In murine models of inflammatory pain, 2,6-DTBP reduced inflammatory hyperalgesia in an ?3GlyR-dependent manner. Together, our data thus establish that selective potentiation of GlyR function is a promising strategy against chronic inflammatory pain and that, to our knowledge, 2,6-DTBP has a unique pharmacological profile that favors an interaction with GlyRs that have been primed by peripheral inflammation.
SUBMITTER: Acuna MA
PROVIDER: S-EPMC4922714 | biostudies-literature | 2016 Jul
REPOSITORIES: biostudies-literature
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