ianeptine is an atypical antidepressant.1 It is an agonist of the μ- receptor (MOR; EC50s = 194 and 641 nM for human and mouse receptors, respectively, in a BRET assay for G protein activation) and also has effects on the glutamate system.1,2 Tianeptine (30 mg/kg) decreases immobility in the forced swim test in wild-type, but not MOR knockout mice, indicating antidepressant-like activity dependent on MORs.3 It increases locomotor activity at a dose of 30, but not 10 mg/kg, in the open field test and increases paw withdrawal latency in the hot-plate test in mice.