Inhibition of Cav3.2 calcium channels: A new target for colonic hypersensitivity associated with low‐grade inflammation

Article date: April 2019

By: Elodie Picard, Frederic Antonio Carvalho, Francina Agosti, Emmanuel Bourinet, Denis Ardid, Alain Eschalier, Laurence Daulhac, Christophe Mallet in Volume 176, Issue 7, pages 950-963

Background and Purpose

Abdominal pain associated with low‐grade inflammation is frequently encountered in irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) during remission. Current treatments are not very effective and new therapeutic approaches are needed. The role of CaV3.2 channels, which are important in other chronic pain contexts, was investigated in a murine model of colonic hypersensitivity (CHS) associated with low‐grade inflammation.

Experimental Approach

Low doses of dextran sulfate sodium (DSS; 0.5%) were chronically administered to C57BL/6j mice in drinking water. Their inflammatory state was assessed by systemic and local measures of IL‐6, myeloperoxidase, and lipocalin‐2 using elisa. Colonic sensitivity was evaluated by the visceromotor responses to colorectal distension. Functional involvement of CaV3.2 channels was assessed with different pharmacological (TTA‐A2, ABT‐639, and ethosuximide) and genetic tools.

Key Results

DSS induced low‐grade inflammation associated with CHS in mice. Genetic or pharmacological inhibition of CaV3.2 channels reduced CHS. Cav3.2 channel deletion in primary nociceptive neurons in dorsal root ganglia (CaV3.2Nav1.8 KO mice) suppressed CHS. Spinal, but not systemic, administration of ABT‐639, a peripherally acting T‐type channel blocker, reduced CHS. ABT‐639 given intrathecally to CaV3.2Nav1.8 KO mice had no effect, demonstrating involvement of CaV3.2 channels located presynaptically in afferent fibre terminals. Finally, ethosuximide, which is a T‐type channel blocker used clinically, reduced CHS.

Conclusions and Implications

These results suggest that ethosuximide represents a promising drug reposition strategy and that inhibition of CaV3.2 channels is an attractive therapeutic approach for relieving CHS in IBS or IBD.

DOI: 10.1111/bph.14608

View this article