p-MPPI hydrochloride is a selective 5-HT1A receptor antagonist with high affinity for 5-HT1A receptors. p-MPPI hydrochloride can crosses the blood-brain barrier, and has clear antidepressant and anxiolytic-like effects^[1][2]. In Vitro: p-MPPI hydrochloride has no agonist activity in both in vitro and in vivo tests of pre- and post-synaptic 5-HT1A receptor activity^[1]. In Vivo: p-MPPI hydrochloride (0.5-4.5 mg/kg; i.p.) shows anxiolytic-like profile in the murine elevated plus-maze^[2].