Animal experiment:

Rats[2]A 1.0 mg/kg dose and a higher dose (3.0 mg/kg) of Risperidone are chosen for study. Beginning on postnatal day 14, subcutaneous injections of Risperidone are performed daily until postnatal day 42. Within each study, three groups of roughly equal numbers of rats receive injections of 1.0 mg/kg of Risperidone, 3.0 mg/kg of Risperidone, or the vehicle used for the Risperidone solution as a control. Within each litter, there are 1-2 pups of the same sex that receive the same treatment. Injections of Risperidone are performed in a room just outside of the housing room. Prior to weaning, the pups are removed from the home cage and placed in a separate cage during injections[2].

Risperidone hydrochloride is a serotonin 5-HT2 receptor blocker and a potent dopamine D2 receptor antagonist, with Kis of 0.16, 1.4 nM for 5-HT2 and D2 receptor, respectively. 5-HT2 Receptor|0.16 nM (Ki)|D2 receptor|1.4 nM (Ki)

Risperidone is serotonin 5-HT2 receptor blocker as shown by displacement of radioligand binding (Ki=0.16 nM), activity on isolated tissues (EC50=0.5 nM). Risperidone is also a potent dopamine D2 receptor antagonist as indicated by displacement of radioligand binding (Ki=1.4 nM), activity in isolated striatal slices (IC50=0.89 nM)[1]. Risperidone increases the production of IL-10 and MDC as well as the proinflammatory cytokines, such as IL-6, IL-8, and TNF-α, but decreases the production of IP-10 and IL-12[2].

Long-Evans rats receive daily subcutaneous injections of vehicle or 1 of 2 doses of risperidone (1.0 and 3.0 mg/kg per day) from postnatal Days 14 to 42. Weight gain during development is slightly yet significantly reduced in risperidone-treated rats. In the first 2 experiments, early-life Risperidone administration is associated with increased locomotor activity at 1 week post administration through approximately 9 months of age, independent of changes in weight gain[2].

[1]. Chen ML, et al. Risperidone modulates the cytokine and chemokine release of dendritic cells and induces TNF-α-directed cellapoptosis in neutrophils. Int Immunopharmacol. 2012 Jan;12(1):197-204. [2]. Bardgett ME, et al. Adult rats treated with risperidone during development are hyperactive. Exp Clin Psychopharmacol. 2013 Jun;21(3):259-67.