Differential display polymerase chain reaction reveals increased expression of striatal rat glia-derived nexin following chronic clozapine treatment

Abstract

Clozapine is considered a prototype of the 'so-called' atypical antipsychotic drug class. It has affinity for a broad range of receptors and, in comparison to typical antipsychotic drugs, produces less extrapyramidal side effects. However, its mechanism of action remains unclear. Differential display polymerase chain reaction (ddPCR) was implemented in this study to contribute to the current understanding of this mechanism at the genetic level and to identify novel genes regulated by clozapine. This technique generated approximately 2400 gene sequences that were analyzed for differential gene expression following protracted clozapine treatment. One of these sequences, originally termed Clozapine Regulated Gene (CRG), was shown to be significantly upregulated following the treatment. Northern hybridization confirmation of this finding revealed that chronic clozapine administration caused a five-fold increase in CRG mRNA. Elongation of the 5 0 -and 3 0 -ends of CRG indicated that the fragment was in fact rat gliaderived nexin mRNA. Western blotting demonstrated that levels of the mRNA's associated protein also increased comparably (three-fold) following chronic treatment with the antipsychotic drug. This study presents a possible neuroprotective role of nexin in clozapine treatment, particularly in the prevention of neuronal proteolytic degradation, since nexin has been shown to be a protease inhibitor.

Clozapine Augments Delta, Theta, and Right Frontal EEG Alpha Power in Schizophrenic Patients

“…Moreover, Danos et al [23] found differences in alpha-related thalamo-cortical circuits between schizophrenic patients and normal controls, an observation that is of particular interest in view of the association between alpha activity and cognitive behavioural states. Thus, clozapine mediated influences on septal and thalamic areas via neuroprotective substances such as recently discovered clozapine induced Nexin gene upregulation in striatum [24] or selective reversal of stress-induced blockade of prefrontal plasticity [25] may be important clues in understanding the mechanisms and loci of its special therapeutic advantages.…”

Knockdown of mortalin within the medial prefrontal cortex impairs normal sensorimotor gating

“…Immunoblotting was performed to assess mortalin protein expression. Rat brain tissues (mPFC, NAcc, and striatum) were dissected and homogenized as previously described (Chong et al,2004). In brief, 10 μg of each protein sample was separated, transferred to a nitrocellulose membrane and subsequently incubated with the primary antibodies (mouse antimortalin (1:1000; R&D Systems, Minneapolis, MN) or mouse anti‐GAPDH (1:5000; Millipore, Billerica, MA).…”

Chronic Olanzapine Treatment Causes Differential Expression of Genes in Frontal Cortex of Rats as Revealed by DNA Microarray Technique

“…Chong et al (2004) showed that chronic administration of clozapine in rats for 28 days upregulated mRNA and protein for rat glia-derived nexin in brains of exposed animals. The authors suggest a possible neuroprotective role for nexin, a protease inhibitor, in clozapine treatment, most likely in the prevention of neuronal proteolytic degradation (Chong et al, 2004).…”

“…Chong et al (2004) showed that chronic administration of clozapine in rats for 28 days upregulated mRNA and protein for rat glia-derived nexin in brains of exposed animals. The authors suggest a possible neuroprotective role for nexin, a protease inhibitor, in clozapine treatment, most likely in the prevention of neuronal proteolytic degradation (Chong et al, 2004). In a different microarray-based study, Chong et al (2002) administered haloperidol in rats for 28 days and discovered that it upregulated both mRNA and protein for synapsin II gene by 450% in the striatum of exposed rats.…”