The effects of clozapine and haloperidol on astrocyte function and morphology

Abstract

Schizophrenia is a chronic debilitating psychiatric disorder affecting approximately 1% of the population worldwide. The disorder is characterised by positive symptoms, negative symptoms, and clinical deficits in cognition. Current therapeutic agents, known as antipsychotics, all display some level of dopamine antagonism thereby reducing symptoms of psychosis. It has been suggested that abnormal astrocyte function is involved in aberrant neurotransmitter signalling and neuroinflammation seen in schizophrenia. The effect of antipsychotics on astrocyte cell function is still being explored. Using a human astrocyte culture model, this study aims to determine the effect of typical and atypical antipsychotics, haloperidol and clozapine, on cytokine levels, the intracellular signalling molecule Extracellular Signal-Regulated kinase 1/2 (ERK 1/2), astrocyte morphology and survival. Human astrocytes were cultured and pre-treated with clozapine or haloperidol for 1h, then stimulated with TNFα/IL-17A for 18h. Cytokine analysis was carried out using Enzyme Linked Immunoabsorbent Assay (ELISA). Changes in astrocyte morphology was analysed using immunocytochemistry, with glial fibrillary acidic protein (GFAP) and vimentin protein expressions labelling astrocytes. The results of this study showed that both clozapine and haloperidol attenuated TNFα/IL-17A induced expression of IL-6 in human astrocytes. Under pro-inflammatory conditions, pre-treatment with both clozapine and haloperidol did not change astrocyte morphology. Furthermore, an MTT assay showed that both clozapine and haloperidol did not affect cell viability. To quantify changes in extracellular signal-regulated kinases 1 and 2 (ERK 1/2), astrocytes were exposed to clozapine or haloperidol for 15 mins and processed for western immunoblotting. This study demonstrated that haloperidol, but not clozapine, significantly increased ERK 1/2 phosphorylation in human astrocytes. Taken together, we are able to ascertain that clozapine and haloperidol change the role of astrocytes in inflammation and cellular signalling in schizophrenia.