Regulation of Ca<sub>v</sub>3.2-mediated pain signals by hydrogen sulfide

Abstract

Hydrogen sulfide (H2S), an endogenous gasotransmitter, is generated from L-cysteine by 3 distinct enzymes including cystathionine-γ-lyase (CSE), and targets multiple molecules, thereby playing various roles in health and disease. H2S triggers or accelerates somatic pain and visceral nociceptive signals in the pancreas, colon and bladder by enhancing the activity of Cav3.2 T-type calcium channels. H2S also activates TRPA1, which participates in H2S-induced somatic pain signaling. However, Cav3.2 predominantly mediates colonic nociception by H2S, because genetic deletion of TRPA1 does not reduce H2S-induced colonic pain. The functional upregulation of the CSE/H2S/Cav3.2 system is involved in neuropathic pain and visceral pain accompanying pancreatitis and cystitis. Cav3.2 also appears to participate in irritable bowel syndrome (IBS), although the role of endogenous H2S generation by CSE in IBS is still open to question. In this review, we describe how H2S regulates pain signals, particularly by interacting with Cav3.2.