Menthol Modulates Pacemaker Potentials through TRPA1 Channels in Cultured Interstitial Cells of Cajal from Murine Small Intestine

Abstract

Background/Aims: ICCs are the pacemaker cells responsible for slow waves in gastrointestinal (GI) smooth muscle, and generate periodic pacemaker potentials in current-clamp mode. Methods: The effects of menthol on the pacemaker potentials of cultured interstitial cells of Cajal (ICCs) from mouse small intestine were studied using the whole cell patch clamp technique. Results: Menthol (1 - 10 μM) was found to induce membrane potential depolarization in a concentration-dependent manner. The effects of various TRP channel antagonists were examined to investigate the receptors involved. The addition of the TRPM8 antagonist, AMTB, did not block menthol-induced membrane potential depolarizations, but TRPA1 antagonists (A967079 or HC-030031) blocked the effects of menthol, as did intracellular GDP_βS. Furthermore, external and internal Ca²⁺ levels were found to depolarize menthol-induced membrane potentials, whereas external Na⁺ was not. Y-27632 (a Rho kinase inhibitor), SC-560 (a selective COX 1 inhibitor), NS-398 (a selective COX 2 inhibitor), ozagrel (a thromboxane A2 synthase inhibitor) and SQ-29548 (highly selective thromboxane receptor antagonist) were used to investigate the involvements of Rho-kinase, cyclooxygenase (COX), and the thromboxane pathway in menthol-induced membrane potential depolarizations, and all inhibitors were found to block the effect of menthol. Conclusions: These results suggest that menthol-induced membrane potential depolarizations occur in a G-protein-, Ca²⁺-, Rho-kinase-, COX-, and thromboxane A₂-dependent manner via TRPA1 receptor in cultured ICCs in murine small intestine. The study shows ICCs are targeted by menthol and that this interaction can affect intestinal motility.

Acute Cholecystitis Reduces Interstitial Cells of Cajal in Porcine Gallbladder Through Decreased mRNA Synthesis

“…Moreover, it has been shown that ICCs undergo apoptosis over time, and that ICC regeneration is required for the maintenance of normal ICC networks in healthy tissues [29]. Furthermore, menthol-induced membrane potential depolarizations, that occur in G-protein, Ca 2+ pathways via TRPA1 M2 and M3 receptors, were shown to be involved in this process [30,31]. Various factors, including regional obstruction and subsequent proximal dilation, and nervous system and immune system injury can lead to ICC damage and loss [26].…”

Effects of Gamisoyo-San Decoction, a Traditional Chinese Medicine, on Gastrointestinal Motility

“…Interstitial cells of Cajal (ICCs) regulate normal GI function and mediate neuromuscular signaling [32,33]. Therefore, ICCs have an important role in controlling GI motility.…”

Cellular and Molecular Targets of Menthol Actions

“…It appears that menthol in the range of submicromolar to low-micromolar concentrations, causes activation of TRPA1 channel, whereas at higher concentrations menthol leads to a reversible blockade of the channel (Karashima et al, 2007). Menthol has also been shown to induce membrane depolarizations by activating TRPA1 channels in interstitial cells of Cajal (Kim et al, 2016). While activation of TRPM8 by menthol occurs with an EC 50 of approximately in the range of 4–80 μM (McKemy et al, 2002; Peier et al, 2002; Behrendt et al, 2004), higher menthol concentrations are required for modulation of other thermosensitive TRP channels.…”