Heterogeneity of cannabinoid ligand-induced modulations in intracellular Ca2+ signals of mouse pancreatic acinar cells in vitro

Abstract

We recently reported that a CBR agonist, GW405833 (GW), reduced both the ACh-induced Ca oscillations and the L-arginine-induced Ca signal enhancement in mouse pancreatic acinar cells, suggesting that GW-induced inhibition may prevent the pathogenesis of acute pancreatitis. In this study, we aim to evaluate the effects of other cannabinoid ligands on Ca signaling in acinar cells. Patch-clamp whole-cell recordings were applied to measure ACh-induced intracellular Ca oscillations in pancreatic acinar cells acutely dissociated from wild-type (WT), CBR knockout (KO), and CBR KO mice, and the pharmacological effects of various cannabinoid ligands on the Ca oscillations were examined. We found that all the 8 CBR agonists tested inhibited ACh-induced Ca oscillations. Among them, GW, JWH133, and GP1a caused potent inhibition with IC values of 5.0, 6.7, and 1.2 μmol/L, respectively. In CBR KO mice or in the presence of a CBR antagonist (AM630), the inhibitory effects of these 3 CBR agonists were abolished, suggesting that they acted through the CBRs. The CBR agonist ACEA also induced inhibition of Ca oscillations that existed in CBR KO mice and in the presence of a CBR antagonist (AM251), suggesting a non-CBR effect. In WT, CBR KO, and CBR KO mice, a nonselective CBR agonist, WIN55,212-2, inhibited Ca oscillations, which was not mediated by CBRs or CBRs. The endogenous cannabinoid substance, 2-arachidonoylglycerol (2-AG), did not show an inhibitory effect on Ca oscillations. In conclusion, CBR agonists play critical roles in modulating Ca signals in mouse pancreatic acinar cells, while other cannabinoid ligands modulate Ca oscillations in a heterogeneous manner through a CB receptor or non-CB-receptor mechanism.

Pharmacological Properties, Therapeutic Potential and Molecular Mechanisms of JWH133, a CB2 Receptor-Selective Agonist

“…Suppression of JNK and stimulation of p38 as well as the MK2signaling pathways may be responsible for mediating the beneficial effects of CB2R stimulation during acute pancreatitis. Moreover, Xia et al (2019) showed that JWH133 prevented acetylcholine-induced Ca 2+ oscillations in mouse pancreatic acinar cells, whereas CB2R-knockout or AM630 blocked the suppressive effects of JWH133. Thus, CB2R activation might play a novel role in modulating the physiology and pathophysiology of pancreatic acinar cells.…”

Cannabis, cannabinoid receptors, and endocannabinoid system: yesterday, today, and tomorrow

“…Xia et al intent to answer another important question in cannabinoid research field, the heterogeneity. In the research article "Heterogeneity of cannabinoid ligand-induced modulations in intracellular Ca 2+ signals of mouse pancreatic acinar cells in vitro" authors report a heterogenic effects of cannabinoid ligands on the intracellular Ca 2+ signals in mouse pancreatic acinar cells, demonstrating that cannabinoid ligands exhibit the modulations of intracellular Ca 2+ signals in a heterogenic manner through both cannabinoid receptors and non-receptor mechanisms [9]. In article "Protective effect of cannabinoid receptor 2specific agonist GW405833 on concanavalin A-induced acute liver injury", authors report that CB 2 R agonist GW405833 protects liver cells against acute concanavalin A-induced toxicity through the CB 2 Rs expressed in liver immune cells.…”

Molecular mechanisms of pain in acute pancreatitis: recent basic research advances and therapeutic implications

“…Analogously to the findings made in the human pancreas, both CB1R and CB2R have been detected in mouse PACs ( Michalski et al, 2007 ; Linari et al, 2009 ; Huang et al, 2016 ). In vitro studies ( Linari et al, 2009 ; Petrella et al, 2010 ; Cao et al, 2012 ; Huang et al, 2016 ; Xia et al, 2019 ) on CBR in freshly isolated PACs are summarized here ( Supplementary Table 7 ). Of note is that while CBR agonists did not affect basal or carbachol- and cerulein-induced amylase secretion, a non-selective CBR agonist inhibited KCl-elicited elevation in amylase ( Linari et al, 2009 ) as well as reduced cerulein-induced IL-6 and MCP-1 secretion in PACs ( Petrella et al, 2010 ).…”