clozapine and Nerve-Degeneration

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.

Topics: Animals; Anti-Inflammatory Agents; Antipsychotic Agents; Blotting, Western; Cell Survival; Clozapine; Coculture Techniques; Dopaminergic Neurons; Flow Cytometry; Inflammation; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Microglia; Microscopy, Confocal; Nerve Degeneration; Neuroprotective Agents; Rats

In the present work, we investigated if an impairment of dopaminergic neurons after subchronic haloperidol treatment might be a possible physiopathologic substrate of the "early onset" vacuous chewing movements (VCMs) in rats. For this purpose, different antipsychotics were used to analyse a possible relationship between VCMs development and morphological alterations of tyrosine-hydroxylase-immunostained (TH-IM) neurons. Rats treated twice a day with haloperidol displayed a significant increase of VCMs that was both time- (2-4 weeks) and dose (0.1-1 mg/kg) dependent. Immunocytochemical analysis showed a shrinkage of TH-IM cell bodies in substantia nigra pars compacta and reticulata and a reduction of TH-immunostaining in the striatum of haloperidol treated rats with the arising of VCMs. No differences were observed in TH-IM neurons of ventral tegmental area and nucleus accumbens vs. control rats. The atypical antipsychotics risperidone (2 mg/kg, twice a day), amisulpride (20 mg/kg, twice a day) and clozapine (10 mg/kg, twice a day) did not produce any nigro-striatal morphological changes or VCMs. TH-IM nigro-striatal neuron morphological alterations and VCMs were still present after three days of withdrawal in rats treated for four weeks with haloperidol (1 mg/kg). Both the main morphological changes and the behavioural correlate disappeared after three weeks of withdrawal. These results suggest that haloperidol induces a morphological impairment of the dopaminergic nigro-striatal neurons which is directly associated with the arising, permanency and disappearance of VCMs in rats.

Topics: Amisulpride; Animals; Antipsychotic Agents; Clozapine; Dopamine; Dose-Response Relationship, Drug; Drug Administration Schedule; Dyskinesia, Drug-Induced; Haloperidol; Male; Mastication; Neostriatum; Nerve Degeneration; Neural Pathways; Neurons; Rats; Rats, Sprague-Dawley; Risperidone; Substance Withdrawal Syndrome; Substantia Nigra; Sulpiride

P450 enzymes in the CYP2D subfamily have been suggested to contribute to the susceptibility of individuals in developing Parkinson's disease. We have used specific anti-peptide antisera and peroxidase immunohistochemistry to investigate the expression of CYP2D enzymes in the rat brain and some possible factors that may affect their regulation. In male Wistar rats, CYP2D1 was not detected in the basal ganglia or in any other brain region. CYP2D2 was weakly expressed within neurones of the subthalamic nucleus, substantia nigra and interpeduncular nucleus as well as in the hippocampus, dentate gyrus, red nucleus and pontine nucleus. CYP2D3 and CYP2D4 were absent from the basal ganglia, although moderate amounts of CYP2D3 were detected within fibres of the oculomotor root, and very low levels of CYP2D4 were present in white matter tracts. In contrast, CYP2D5 was extensively expressed in the basal ganglia, including neurones in the subthalamic nucleus, substantia nigra and interpeduncular nucleus, as well as other areas of the brain, including the ventral tegmental area, piriform cortex, hippocampus, dentate gyrus, medial habenular nucleus, thalamic nucleus and pontine nucleus. Lesioning of the nigro-striatal tract to cause almost a complete loss of tyrosine hydroxylase containing neurones in the substantia nigra, also reduced the number of neurones expressing CYP2D5 by 50%, indicating that CYP2D5 is expressed in dopaminergic neurones. Castration of pre-pubertal or adult Wistar rats had no effect on the number of CYP2D5-positive neurones in the substantia nigra. Although Dark Agouti rats lack hepatic CYP2D2, expression in the midbrain was similar to that of Wistar rats; furthermore, there was no difference in expression or distribution between male and female rats. In contrast to naive rats, extensive expression of CYP2D4 was found throughout the basal ganglia and in other brain nuclei in Wistar rats treated with not only clozapine, but also saline, suggesting that CYP2D4 may be induced as a result of mild stress. The function of CYP2D enzymes in the brain remains unknown, but their selective localisation suggests a physiological role in neuronal activity and in adaptation to abnormal situations.

Topics: Animals; Antibody Specificity; Basal Ganglia; Brain Chemistry; Clozapine; Cytochrome P-450 Enzyme System; Dopamine; Enzyme-Linked Immunosorbent Assay; Female; GABA Antagonists; Isoenzymes; Liver; Male; Microsomes; Nerve Degeneration; Orchiectomy; Oxidopamine; Parkinson Disease; Rats; Rats, Wistar; Substantia Nigra; Sympathomimetics

In this study, we tested the hypothesis that chronic administration of phencyclidine (PCP), an N-methyl-D-aspartate (NMDA) receptor antagonist, would cause a long-lasting behavioral sensitization associated with neuronal toxicity. Female Sprague-Dawley rats were administered PCP (20 mg/kg, i.p.) once a day for 5 days, withdrawn for 72 hr, placed in locomotor activity chambers, and challenged with 3.2 mg/kg PCP. Following assessment of locomotor activity, the rats were killed and their brains processed for analysis of apoptosis by either electron microscopy or terminal dUTP nick-end labeling (TUNEL). In study I, PCP challenge produced a much more robust and long-lasting increase in locomotor activity in rats chronically treated with PCP than in those chronically treated with saline. In study II, clozapine pretreatment blunted the degree of sensitization caused by PCP. In study I, a marked increase in TUNEL-positive neurons was found in layer II of the olfactory tubercle and piriform cortex of rats chronically treated with PCP. Many of these neurons had crescent-shaped nuclei consistent with apoptotic condensation and margination of nuclear chromatin under the nuclear membrane. Acute PCP had no effect. Electron microscopy revealed that PCP caused nuclear condensation and neuronal degeneration consistent with apoptosis. Cell counts in layer II of the piriform cortex revealed that chronic PCP treatment resulted in the loss of almost 25% of the cells in this region. However, an increase in glial fibrillary acidic protein (GFAP)-positive cells in the molecular layer suggests that this neurotoxicity also may involve necrosis. In study II, the PCP-induced neuronal degeneration was essentially completely abolished by clozapine pretreatment. This pattern of degeneration was found to coincide with the distribution of the mRNA of the NR1 subunit of the NMDA receptor. The relevance of these data to a PCP model of chronic NMDA receptor hypofunction is discussed.

Topics: Animals; Antipsychotic Agents; Apoptosis; Behavior, Animal; Clozapine; Drug Resistance; Excitatory Amino Acid Antagonists; Female; Genetic Techniques; Limbic System; Microscopy, Electron; Motor Activity; Nerve Degeneration; Olfactory Pathways; Phencyclidine; Rats; Rats, Sprague-Dawley; Time Factors