SRR and schizophrenia: A number of preclinical studies in rodents have demonstrated that lowering brain levels of D-serine by reducing the activity of serine racemase (SR), the enzyme responsible for catalyzing formation of D-serine from L-serine (e.g., Figure 1), can produce symptoms reminiscent of clinical symptoms in schizophrenia: stereotypies, cognitive deficits, disruption of prepulse inhibition (measure of sensorimotor gating), persistent latent inhibition (measures inhibitory learning and cognitive flexibility), and deficits in social interaction (6, 19–22, 35).