The effect of second-generation antipsychotic withdrawal on the occurrence of vacuous chewing movements in animal models: A review

Modulatory effect of olanzapine on neuronal nitric oxide synthase (nNOS) expression in the rat striatum

Nitric oxide (NO) has been thought to be a novel factor involved in the mechanisms of mental disorders pathogenesis for quite some time. However, little is known about potential crosstalk between neuronal NO signaling and neuroleptics action. The present work was, therefore, focused on gene expression of neuronal NO synthase (nNOS) in the brains of rats chronically treated with olanzapine, an atypical antipsychotic drug. Studies were carried out on adult, male Sprague-Dawley rats that were divided into 2 groups: control and experimental animals treated with olanzapine (28-day-long intraperitoneal injection, at dose 5 mg/kg daily). All individuals were killed under anesthesia and the whole brains excised. Immunohistochemical procedure was used for histological assessment of the whole brain, and for both descriptive and quantitative analysis of nNOS protein distribution in selected brain structures. Long-term treatment with olanzapine is reflected in different changes in the number of enzyme-expressing cells in the rat brain. Olanzapine decreased the number of nNOS-expressing cells and possibly reduced NO synthesis in the rat striatum. Olanzapine can be taken into account as a potential inhibitor of NO synthesis in the rat striatum.

Neuropharmacological effect of risperidone: From chemistry to medicine

As the second-oldest atypical antipsychotic, risperidone has a long history of off-label usage for treating behavioural and psychological signs and symptoms of dementia (BPSD), such as agitation, aggressiveness, and psychosis. Risperidone has been shown in several trials to have a statistically significant benefit when used in a therapeutic context. Several lines of evidence suggest a possible role of risperidone via the antagonistic effect of Dopamine D2 and 5HT-receptor in different neurological diseases like cognitive dysfunction of schizophrenia, neuroinflammation, Huntington's disease, and sleep cycle management. Therefore, the pharmacological interactions of risperidone in all these diseases were investigated. Some reports on the use of risperidone in the treatment of dopaminergic psychosis have been slightly conflicting. However, more research is needed to evaluate the role of risperidone in the treatment of these neurological diseases.

Parkinson's Disease-Related Brain Metabolic Pattern Is Expressed in Schizophrenia Patients during Neuroleptic Drug-Induced Parkinsonism

Drug-induced parkinsonism (DIP) is a frequent parkinsonian syndrome that appears as a result of pharmacotherapy for the management of psychosis. It could substantially hamper treatment and therefore its diagnosis has a direct influence on treatment effectiveness. Although of such high importance, there is a lack of systematic research for developing neuroimaging-based criteria for DIP diagnostics for such patients. Therefore, the current study was aimed at applying a metabolic brain imaging approach using the 18F-FDG positron emission tomography and spatial covariance analysis to reveal possible candidates for DIP markers. As a result, we demonstrated, to our knowledge, the first attempt at the application of the Parkinson's Disease-Related Pattern (PDRP) as a metabolic signature of parkinsonism for the assessment of PDRP expression for schizophrenia patients with DIP. As a result, we observed significant differences in PDRP expression between the control group and the groups with PD and DIP patients. Similar differences in PDRP expression were also found when the non-DIP schizophrenia patients were compared with the PD group. Therefore, our findings made it possible to conclude that PDRP is a promising tool for the development of clinically relevant criteria for the estimation of the risk of developing DIP.