Detection of catechol-O-methyltransferase Val158Met polymorphism by a novel PCR-RFLP based method

The transition from G to A at nucleotide 21881 of the human catechol-O-methyltransferase [COMT] gene producing a functional genetic polymorphism [Val158Met], has been shown to render an enzyme with reduced activity that has been associated with psychiatric disorders. A new PCR-RFLP method for the detection of this polymorphism is described. The method utilizes the same restriction enzyme commonly used for the PCR-RFLP detection of Val158Met, NlaIII. However, the SNP-containing fragment to be amplified was selected as to extremely simplify the restriction fragments pattern generated resulting in a faster separation on 2.5% agarose gel electrophoresis. The presence of a valine or methionine allele is associated with a 108bp or 72bp fragment, respectively. Electrophoresis conditions were optimized to decrease separation time and distance down to 16 minutes and 3 cm, respectively. The method has been successfully applied to determine allele frequencies for the COMT gene in a novel population from Syria and were found to be 48% and 52% for the Val allele and Met allele, respectively

[Effects of the activation of histamine H3 receptors on the locomotor activity induced by dopaminergic treatment in the reserpine-treated rat model of Parkinson's disease]

The present study was designed to investigate the effects of the activation of histamine H3 receptors, by selective agonist, on dopaminergic treatment-induced locomotor behavior in a rat model of Parkinson's disease and L-DOPA-induced dyskinesia. Imetit, histamine H3 receptor agonist reduced the enhanced locomotor activity induced by L-DOPA 100 and 200 mg/kg, in a dose-dependent manner. The number of horizontal counts, following the injection of Imetit 7 mg/kg in combination with L-DOPA 200 mg/kg in reserpinised rats, was 1040 +/- 274 count/2h, which was significantly reduced compared to the horizontal activity following the injection of L-DOPA 200 mg/kg alone in reserpinised rats. The vertical count was significantly reduced by injection of imetit 7 mg/kg in combination with L-DOPA 200 mg/kg [560 +/- 110 count/2h]. The highest dose of Imetit 7 mg/kg that extensively reduced all locomotor parameters tested, did not significantly modify the increase in horizontal or vertical activity produced by quinpirole dopamine D2 agonist. The data suggest that histamine H3 receptor agonists can modulate the behavioural effects of L-DOPA, and may be useful for the treatment of the dyskinesia associated with long-term L-DOPA treatment of Parkinson's disease

[Spinophilin gene expression in 6-OHDA-lesioned rat model of parkinson's disease and L-DOPA-induced dyskinesia]

The hypothesis that alterations of proteins that mediate dopaminergic signal transduction might be involved in the altered dopaminergic receptors in Parkinson's disease and L-DOPA-induced dyskinesia was explored. We measured transcript expression of spinophilin, a protein enriched in.dendritic spines that modulates excitatory neurotransmission and involved in dopamine [DA] signaling in the striatum and cerebral cortex of 6- hydroxydopamine [6-OHDA-lesioned rats model of Parkinson's disease and following chronic treatment with L-DOPA which induces dyskinesia [L-DOPA-induced dyskinesia LID]. The transcript encoding spinophilin, was decreased by 27% and 18% respectively in, lesioned and unlesioned sides of the rostral striatum. Acute and chronic treatment with L- DOPA produced an increase in transcript levels of spinophilin in the rostral and caudal striatum, and somatosensory cortex but not in the motor cortex. These alterations in spinophilin and mRNA levels in 6-OHDA-Iesioned rat model of Parkinson's disease and L-DOPA-induced dyskinesia provide further evidence for the role of spinophilin in the neural mechanisms underlying altered dopaminergic receptors in PD and LID