Premium
AKAP ‐dependent sensitization of Ca v 3.2 channels via the EP 4 receptor/c AMP pathway mediates PGE 2 ‐induced mechanical hyperalgesia
Author(s) -
Sekiguchi Fumiko,
Aoki Yuka,
Nakagawa Maiko,
Kanaoka Daiki,
Nishimoto Yuta,
TsubotaMatsunami Maho,
Yamanaka Rumi,
Yoshida Shigeru,
Kawabata Atsufumi
Publication year - 2013
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2012.02174.x
Subject(s) - protein kinase a , chemistry , dorsal root ganglion , stimulation , nociception , hyperalgesia , receptor , antagonist , patch clamp , medicine , endocrinology , sensitization , phosphorylation , biophysics , biochemistry , biology , anatomy , neuroscience , dorsum
Background and Purpose The Ca v 3.2 isoform of T ‐type Ca 2+ channels ( T channels) is sensitized by hydrogen sulfide, a pro‐nociceptive gasotransmitter, and also by PKA that mediates PGE 2 ‐induced hyperalgesia. Here we examined and analysed Ca v 3.2 sensitization via the PGE 2 /c AMP pathway in NG 108‐15 cells that express Ca v 3.2 and produce c AMP in response to PGE 2 , and its impact on mechanical nociceptive processing in rats. Experimental Approach In NG 108‐15 cells and rat dorsal root ganglion ( DRG ) neurons, T ‐channel‐dependent currents ( T currents) were measured with the whole‐cell patch‐clamp technique. The molecular interaction of Ca v 3.2 with A‐kinase anchoring protein 150 ( AKAP 150) and its phosphorylation were analysed by immunoprecipitation/immunoblotting in NG 108‐15 cells. Mechanical nociceptive threshold was determined by the paw pressure test in rats. Key Results In NG 108‐15 cells and/or rat DRG neurons, dibutyryl c AMP (db‐c AMP ) or PGE 2 increased T currents, an effect blocked by AKAP St‐Ht31 inhibitor peptide ( AKAPI ) or KT 5720, a PKA inhibitor. The effect of PGE 2 was abolished by RQ ‐00015986‐00, an EP 4 receptor antagonist. AKAP 150 was co‐immunoprecipitated with Ca v 3.2, regardless of stimulation with db‐c AMP , and Ca v 3.2 was phosphorylated by db‐c AMP or PGE 2 . In rats, intraplantar (i.pl.) administration of db‐c AMP or PGE 2 caused mechanical hyperalgesia, an effect suppressed by AKAPI , two distinct T ‐channel blockers, NNC 55‐0396 and ethosuximide, or ZnCl 2 , known to inhibit Ca v 3.2 among T channels. Oral administration of RQ ‐00015986‐00 suppressed the PGE 2 ‐induced mechanical hyperalgesia. Conclusion and Implications Our findings suggest that PGE 2 causes AKAP ‐dependent phosphorylation and sensitization of Ca v 3.2 through the EP 4 receptor/c AMP / PKA pathway, leading to mechanical hyperalgesia in rats.