Fig. 2.
Morphine cross activates hGRPR/Ca2+ signaling pathway when hGRPR is co-expressed with hMOR1Y. (A) Both morphine (1 μM) and GRP (1 nM) induced calcium responses in hGRPR-expressing HEK 293 cells transfected with and hMOR1Y. (B) Morphine (1 μM) did not induce calcium response in hGRPR-expressing HEK293 cells transfected with hMOR1. (C) Morphine (1 μM) did not induce calcium response in HEK 293 cells singly expressing hMOR1Y (purple) or hGRPR (grey). Data are presented as mean ± SD. Each experiment was done three times and at least 30 cells were analyzed each time. GRP, gastrin-releasing peptide; hGRPR, human gastrin-releasing peptide receptor; hMOR, human μ-opioid receptor.