title: Clozapine protects dopaminergic neurons from inflammation-induced damage by inhibiting microglial overactivation.
abstract: Increasing evidence suggests a possible involvement of neuroinflammation in some psychiatric disorders, and also pharmacological reports indicate that anti-inflammatory effects are associated with therapeutic actions of psychoactive drugs, such as anti-depressants and antipsychotics. The purpose of this study was to explore whether clozapine, a widely used antipsychotic drugs, displays anti-inflammatory and neuroprotective effects. Using primary cortical and mesencephalic neuron-glia cultures, we found that clozapine was protective against inflammation-related neurodegeneration induced by lipopolysaccharide (LPS). Pretreatment of cortical or mesencephalic neuron-glia cultures with clozapine (0.1 or 1 μM) for 24 h attenuated LPS-induced neurotoxicity. Clozapine also protected neurons against 1-methyl-4-phenylpyridinium(+) (MPP(+))-induced neurotoxicity, but only in cultures containing microglia, indicating an indispensable role of microglia in clozapine-afforded neuroprotection. Further observation revealed attenuated LPS-induced microglial activation in primary neuron-glia cultures and in HAPI microglial cell line with clozapine pretreatment. Clozapine ameliorated the production of microglia-derived superoxide and intracellular reactive oxygen species (ROS), as well as the production of nitric oxide and TNF-α following LPS. In addition, the protective effect of clozapine was not observed in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for superoxide production in immune cells. Further mechanistic studies demonstrated that clozapine pretreatment inhibited LPS-induced translocation of cytosolic subunit p47(phox) to the membrane in microglia, which was most likely through inhibiting the phosphoinositide 3-kinase (PI3K) pathway. Taken together, this study demonstrates that clozapine exerts neuroprotective effect via the attenuation of microglia activation through inhibition of PHOX-generated ROS production and suggests potential use of antipsychotic drugs for neuroprotection.
authors.affiliation: Neuropharmacology Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Hu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhou
authors.forename: Dan
authors.initials: D
authors.lastname: Zhang
authors.forename: Sufen
authors.initials: S
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Qian
authors.forename: Hung-Ming
authors.initials: HM
authors.lastname: Wu
authors.forename: Po-See
authors.initials: PS
authors.lastname: Chen
authors.forename: Belinda
authors.initials: B
authors.lastname: Wilson
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Gao
authors.forename: Ru-band
authors.initials: RB
authors.lastname: Lu
authors.forename: Jau-Shyong
authors.initials: JS
authors.lastname: Hong
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D014150:Antipsychotic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D003024:Clozapine / Q000494:pharmacology*; D018920:Coculture Techniques; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D005434:Flow Cytometry; D007249:Inflammation / Q000139:chemically induced / Q000517:prevention & control*; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D018613:Microscopy, Confocal; D009410:Nerve Degeneration / Q000139:chemically induced / Q000517:prevention & control; D018696:Neuroprotective Agents / Q000494:pharmacology; D051381:Rats
chemical_list: D000893:Anti-Inflammatory Agents; D014150:Antipsychotic Agents; D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; D003024:Clozapine