AKAP‐dependent sensitization of Cav3.2 channels via the EP4 receptor/cAMP pathway mediates PGE2‐induced mechanical hyperalgesia. (16th January 2013)

• Record Type: Journal Article
• Authors: Sekiguchi, Fumiko; Aoki, Yuka; Nakagawa, Maiko; Kanaoka, Daiki; Nishimoto, Yuta; Tsubota‐Matsunami, Maho; Yamanaka, Rumi; Yoshida, Shigeru; Kawabata, Atsufumi
• Is Part Of: British journal of pharmacology. Volume 168:Number 3(2013:Feb.)
• Page Start: 734
• Page End: 745
• Publication Date: 2013-01-16
• Subjects: Cav3.2 T‐type calcium channel -- mechanical hyperalgesia -- PGE2 -- EP4 receptor -- PKA -- A‐kinase anchoring protein 150 (AKAP150); Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/j.1476-5381.2012.02174.x
• Languages: English
• ISSNs: 0007-1188

Abstract

Abstract : Background and Purpose: The Cav 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 PGE2 ‐induced hyperalgesia. Here we examined and analysed Cav 3.2 sensitization via the PGE2 /cAMP pathway in NG108‐15 cells that express Cav 3.2 and produce cAMP in response to PGE2, and its impact on mechanical nociceptive processing in rats. Experimental Approach: In NG108‐15 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 Cav 3.2 with A‐kinase anchoring protein 150 (AKAP150) and its phosphorylation were analysed by immunoprecipitation/immunoblotting in NG108‐15 cells. Mechanical nociceptive threshold was determined by the paw pressure test in rats. Key Results: In NG108‐15 cells and/or rat DRG neurons, dibutyryl cAMP (db‐cAMP) or PGE2 increased T currents, an effect blocked by AKAP St‐Ht31 inhibitor peptide (AKAPI) or KT5720, a PKA inhibitor. The effect of PGE2 was abolished by RQ‐00015986‐00, an EP4 receptor antagonist. AKAP150 was co‐immunoprecipitated with Cav 3.2, regardless of stimulation with db‐cAMP, and Cav 3.2 was phosphorylated by db‐cAMP or PGE2 . In rats, intraplantar (i.pl.) administration of db‐cAMP or PGE2 caused mechanical hyperalgesia, an effect suppressed by AKAPI, two distinct T‐channel blockers, NNC 55‐0396 and ethosuximide, or ZnCl2, known to inhibit Cav 3.2 among T channels. Oral administration of RQ‐00015986‐00 suppressed the PGE2 ‐induced mechanical hyperalgesia. Conclusion and Implications: Our findings suggest that PGE2 causes AKAP‐dependent phosphorylation and sensitization of Cav 3.2 through the EP4 receptor/cAMP/PKA pathway, leading to mechanical hyperalgesia in rats.