Objective: Mice and rats are important animal models for mast cell (MC) study. However, rat Mas-related-GPCR-B3 receptor (MRGPRB3) has been less studied than its mouse counterpart. Therefore, we aimed to characterize rat MRGPRB3.
Methods: Mrgprb3 mRNA expression was assessed in peritoneal cells (RPCs) and peritoneal MCs (RPMCs) of wild-type rats, RPCs of MC-deficient rats, and RBL-2H3 cells by reverse-transcriptase polymerase chain reaction (RT-PCR). RPMCs, MRGPRX2-transfected and non-transfected RBL-2H3 cells were activated by 15-30 min incubation with DNP-BSA, substance-P (SP), or compound-48/80. L732138 or CP96344 was used as a tachykinin/neurokinin-1-receptor antagonist. Histamine release from MCs was measured by HPLC fluorometry.
Results: Mrgprb3 mRNA expression was found in all cells, with the highest level in wild-type RPCs. All cells responded to DNP-BSA, but only MRGPRX2-transfected-RBL-2H3 cells and RPMCs responded to all activators. L732138 (0.1-10 μM) and CP96344 (1-100 μM) suppressed SP (10 μM)-induced RPMC activation. L732138 inhibition was dose independent, whereas CP96344 inhibition occurred in a dose-dependent manner. Additionally, only CP96344 suppressed SP (100 μM)- and compound-48/80 (10 μg/mL)-induced RPMC activation.
Conclusions: RPMCs expressing functional MRGPRB3 response upon MRGPRX2 ligands to regulated MC-mediated activities. It`s provide novel insights for future pseudo-allergic studies in rodents.
Keywords: Histamine; MRGPRB3; MRGPRX2; Mast cells; Rat.