ABSTRACT
Dopamine supersensitivity psychosis (DSP) is an unstable clinical condition observed in individuals with schizophrenia who have been treated with an antipsychotic medication at a high dosage and/or for a long period. An up-regulation of dopamine D2 receptors (DRD2) is thought to be involved in the essential pathology of DSP. An antipsychotic agent with both tight binding to DRD2 and a long half-life is generally effective for treating DSP, but a patient who meets the criteria of treatment-resistant schizophrenia sometimes needs treatment with clozapine. We report the case details of two patients whose DSP was not controlled with several antipsychotics but was successfully controlled with asenapine.Asenapine binds to a broad range of dopamine receptors and serotonin receptors, and it is thus distinct from other atypical antipsychotics. The unique profile of asenapine may contribute to the control of severe DSP symptoms in individuals with schizophrenia.
ABSTRACT
The present experiments were performed to investigate effects of a Kampo (Japanese herbal) medicine, Kambaku-taiso-to (Gan-mai-da-zao-tang), on incidence of yawning in rats. Physostigmine, a cholinesterase inhibitor, 0.05-0.1mg/kg s. c., induced yawning responses with a marked effect at 0.05mg/kg. Pilocarpine, a muscarinic receptor agonist, 1-2mg/kg s. c., also induced yawning responses, the maximum effect being observed at a dose of 2mg/kg. Talipexole, a dopaminergic D-2 receptor agonist, 0.02mg/kg s. c., also induced yawning. Kambaku-taiso-to, 250-1, 000mg/kg, was orally administered 30min before injection of physostigmine, pilocarpine or talipexole. The yawning induced by both cholinergic and dopaminergic agents was reduced in a dose-dependent manner by Kambaku-taiso-to. All the yawning responses to cholinergic and dopaminergic agents were also reduced by rauwolscine 0.5mg/kg, yohimbine 2.5mg/kg, α-2 adrenoceptor antagonists, and by scopolamine 0.5mg/kg—muscarinic receptor antagonist. The present findings thus suggest that Kambaku-taiso-to exerts a suppressive effect on the incidence of yawning, and dopaminergic and cholinergic suppression and the indirect suppressive mechanism mediated by the central adrenergic nerve are associated with this suppression.
ABSTRACT
The present experiments were performed to investigate the potential role of Kambaku taiso-to (Gan mai da zao tang) in modifying the occurrence of yawning in rats. Subcutaneous injection of talipexole, a selective dopamine D-2 receptor agonist, at 5-100μg/kg, elicits yawning behavior for over one hour, the maximal effect being observed at a dose of 25μg/kg. Kambaku-taiso-to significantly suppressed the incidence of yawning induced by talipexole. These results suggest that Kambaku-taiso-to exerts a suppressive effect on the incidence of yawning.