Reserpine (Serpalan) is an alkaloid isolated from the root of Rauwolfia serpentina. As an inhibitor of vesicular monoamine transporter 2 (VMAT2), it suppresses the uptake of norepinephrine into storage vesicles, leading to depletion of catecholamines and serotonin in central and peripheral nerve terminals. It has antihypertensive and antipsychotic effects and can be used to induce gastric ulcer and depression models.

Compared to the control group, alternate-day subcutaneous injections of reserpine solution (1 mg/kg s.c.) for three days significantly increased the duration of vacuous chewing, tongue protrusion, and facial twitching in rats. Reserpine reduced glutamate uptake in the cortical region of rats and caused a significant depletion of vasopressin/oxytocin - neurophysin-like immunoreactivity (LI) and CRH-L1 in the rat's median eminence. Additionally, reserpine notably restored performance in the delayed response task in monkeys. At a dose of 5 mg/kg, reserpine significantly increased pointless jaw movements in monkeys and reduced grooming behavior across all age groups in rats. A subcutaneous injection of 5 mg/kg reserpine in intact rats decreased extracellular dopamine levels to 4% of baseline values. The impact of reserpine on performance in a visual discrimination task, a reference memory task not reliant on the prefrontal cortex, was minimal.

Reserpine was demonstrated to inhibit efflux pumps in 11, 21, and 48 out of the 102 unrelated clinical isolates tested, resulting in a fourfold decrease in the IC50 values and MICs of sparfloxacin, moxifloxacin, and ciprofloxacin, respectively.