J Neural Transm [Gen Sect] (1995) 100:257-262 Journal of Neural Transmission 9 Springer-Verlag 1995 Printed in Austria Delayed changes in neural visinin-like calcium-binding protein gene expression caused by acute phencyclidine administration Short Communication Y. Kajimoto 1, O. Shirakawa 1, T. Kuno 2, N. Nishino 1, and H. Nakai 1 Departments of 1Psychiatryand Neurology, and 2pharmacology, Kobe University School of Medicine, Kobe, Japan Accepted February 18, 1995 Summary. Phencyclidine (PCP) induces a psychotomimetic state that closely resembles schizophrenia, and PCP-treated animals can serve as a model for schizophrenia. The effects of PCP on the gene expression of NVP-1, a novel Ca2+-binding protein, were studied in rats. After 24 hours, the NVP-1 mRNA level in the nucleus accumbens showed a significant decrease of 42%. This result suggests that alterations in Ca2+-binding protein may be involved in the pathology of PCP-induced psychosis and, presumably, schizophrenia. Keywords: Phencyclidine (PCP), neural visinin-like Ca2+-binding protein (NVP), gene expression, rat, brain, schizophrenia. Introduction Phencyclidine (PCP) induces a psychotomimetic state that closely resembles schizophrenia. Indeed, PCP-intoxicated patients have been mistaken by expe- rienced psychiatrists for schizophrenics before obtaining the history of drug use. Amphetamine-induced psychosis has long provided a useful model for the study of schizophrenia. But, this model has a number of shortcomings, including its inability to model the negative symptoms of schizophrenia. In contrast, PCP-induced psychosis appears to reproduce both positive (e.g., paranoid delusions, hallucinations) and negative (e.g., emotional withdrawal, motor retardation) schizophrenic symptoms. PCP, therefore, has been used as a model of psychosis to study brain mechanisms involved in schizophrenia (Javitt and Zukin, 1991). Study of the neurochemical changes in the brain of PCP-treated animals should provide useful information about the pathogen- esis of schizophrenia. Calcium ions (Ca 2+) have a key role in transmembrane signaling and in the intracellular transmission of signals. In many cases the function of Ca 2+ de-