ABSTRACT
OBJECTIVE: The aim of the present study was to investigate the effects of nitric oxide synthase (NOS) inhibitor on MK-801-elicited behaviors in rats in an attempt to elucidate the participation of NO in the pathophysiology of schizophrenia and to identify the possibility of NOS inhibitor's antipsychotic property. METHODS: Male Sprague-Dawley rats, weighing 250-300g, were given MK-801 in order to know behavioral changes induced by MK-801. Next time, animals were pretreated with Nomega-nitro-L-arginine (L-NA) as a NOS inhibitor and haloperidol before administration of MK-801, respectively. Separate behavioral rating scales were introduced for quantifying MK-801-induced locomotor activity, stereotyped behaviors and ataxia in order that these behaviors might be assessed independently. Animals were observed for 30 seconds and scored once every 10 min. during a period of 1 hour. RESULTS: 1) Locomotor activity and stereotyped behavior were significantly increased by MK-801 in rats. 2) Locomotor activity and stereotyped behavior were significantly diminished by pretreatment with haloperidol. 3) Locomotor activity and stereotyped behavior were also significantly diminished by pretreatment with L-NA. CONCLUSIONS: These findings suggest that NO may, in part, mediate behavioral changes induced by MK-801, and that inhibitors of NOS may have antipsychotic action.