|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Methamphetamine, a psychostimulant, produced abnormal jaw movements such as licking and biting, which behavior is regarded as an animal model of dyskinesia in human. The intracerebroventricular administration of histamine produces anorexia and arousal states in cats and rats. However, the possible involvement of histaminergic system in the actions of methamphetamine is still unclear. Therefore, we examined the effects of histaminergic agents on methamphetamine-induced abnormal jaw movements such as licking and biting, and the effects of dopaminergic agents including methamphetamine on the histaminergic system using microdialysis method in rat brain. From the findings obtained here, it is suggest that central histaminergic system has an inhibitory role in methamphetamine-induced abnormal jaw movements such as licking and biting. Interestingly, when abnormal jaw movements was observed in methamphetamine-treated rats, histamine release of striatum was significantly increased in compared with the saline-treated rats. Pretreatments with sulpiride (10mg/kg)and haloperidol (0.5 mg/kg), dopamine D2 antagonists, blocked the methamphetamine-induced elevations in histamine release in the rat striatum, whereas SCH23390 (0.1 mg/kg), a dopamine D1 receptor antagonist, could not. In this study, we could clarify the inhibitory role of histaminergic system through dopamine D2-receptors in abnormal jaw movements such as licking and biting.