Effects of cannabinoid receptor ligands on acetylcholine-induced calcium oscillations in mouse pancreatic acinar cells

Abstract

Objective To investigate the effects of various CBR ligands on acetylcholine (Ach) -induced Ca2+ oscillations in acute isolated pancreatic acinar cells. Methods Patch-clamp whole-cell recordings were applied to measure ACh-induced intracellular Ca2+ oscillations in pancreatic acinar cells acutely dissociated from wild-type (WT), cannabinoid type 1 receptor (CB1R) knockout (KO), and cannabinoid type 2 receptor (CB2R) KO mice, and the pharmacological effects of various cannabinoid ligands on the Ca2+ oscillations were examined. Results Patch-clamp recordings demonstrated that all tested three CB2R agonists inhibited intracellular Ca2+ oscillations, 10 μmol/L of GW, GP1a, and JWH133 can reduced the 30 nmol/L ACh-induced Ca2+ oscillations current to (23.0±4.4)% (P=0.000, n=7), (11.0±4.6)% (P=0.000, n=6) and (26.0±4.2)% (P=0.000, n=9) respectively. In CB2R KO mice, the inhibitory effects of these 3 CB2R agonists were abolished, suggesting that their effect is mediated through the CB2R. In WT, CB1R KO and CB2R KO mice, Non-selective CB receptor agonists WIN55, 212-2 also inhibited Ca2+ oscillations, 10 μmol/L of WIN55, 212-2 can reduced the 30 nmol/L ACh-induced Ca2+ oscillations current to (7.0±3.5)% (P=0.000, n=6), (5.0±6.9)% (P=0.000, n=6) and (5.0±9.3)% (P=0.000, n=6) respectively. but endogenous Non-selective cannabinoid substance, 2-AG did not show the inhibitory effect. Conclusion Cannabinoid ligands modulate mouse pancreatic acinar cell Ca2+ oscillations in a complex manner, through CB receptors or non-CB receptors. CB2R rather than CB1R plays a critical role in the regulation of Ca2+ signals in mouse pancreatic acinar cells. Key words: Cannabinoid receptor; Calcium signals; Pancreatic acinar cells; Patch clamp