PZ-1657 hydrochloride (Compound 57) is a potent, selective and orally active 5-HT7 receptor inverse agonist with a Ki of 5 nM. PZ-1657 hydrochloride can inhibit the constitutive cAMP production mediated by the Gs signaling pathway (EC50 = 2.93 nM). PZ-1657 hydrochloride can significantly reduce the MMP-9 activity mediated by 5-HT7 receptors in the hippocampus of mice, and the effect is comparable to that of SB-269970 (HY-15370). PZ-1657 hydrochloride can reverse the cognitive deficits observed in the rat novel object recognition test induced by Phencyclidine without affecting the animals spontaneous activities. PZ-1657 hydrochloride can be used for the research of emotional disorders, such as depression and bipolar disorder[1].