morphinans and Parkinson-Disease

Topics: Adult; Antiparkinson Agents; Basal Ganglia Diseases; Biperiden; Chronic Disease; Clinical Trials as Topic; Cyclohexylamines; Evaluation Studies as Topic; Handwriting; Humans; Male; Middle Aged; Morphinans; Movement Disorders; Parkinson Disease; Psychiatric Status Rating Scales; Schizophrenia; Sulfonic Acids; Time Factors; Tranquilizing Agents

The synthesis of several 1-alkyl-1,2,3,4-tetrahydroisoquinolines, which may play an important role in Parkinson's disease, has been achieved by modified Pictet-Spengler cyclization of the formyliminium ion. The direct cytotoxicity and preventative effects towards MPP(+)-mediated death of PC12 cells were estimated. The cytotoxicities of 1-alkyl-TIQs were apoptotic and depended on their lipophilic properties. Conversely, introducing the N-propargyl substituent reduced cytotoxicity. 1-Methyl-, 1-methyl-N-propargyl- and 1-cyclopropyl-TIQ partially inhibited MPP(+)-induced cell death, whereas relatively large alkyl substituents at the first position did not enhance the viability of PC12 cells. In summary, our findings suggest a crucial role for the N-propargyl functional group for the effective reduction of cytotoxicity, and show the importance of size and lipophilicity of substituents at the 1-position of 1-alkyl-TIQs.

Topics: Animals; Apoptosis; Caspase Inhibitors; Caspases; Cell Death; Monoamine Oxidase; Morphinans; Parkinson Disease; PC12 Cells; Rats; Structure-Activity Relationship; Tetrahydroisoquinolines

Long-term therapy with L-3,4-dihydroxyphenylalanine (L-DOPA) in parkinsonian patients is known to lead to dyskinesia within a few years, and repeated administration of L-DOPA is also likely to alter the expression of kappa opioid receptors in the basal ganglia, especially the striatum and substantia nigra pars reticulata, suggesting that kappa opioid receptors might be deeply involved in motor functions. Therefore, effects of TRK-820 ((E)-N-[17-(cyclopropylmethyl)-4,5alpha-epoxy-3,14-dihydroxymorphinan-6beta-yl]-3-(furan-3-yl)-N-methylprop-2-enamide monohydrochloride), a selective kappa opioid receptor agonist, were investigated on rotational behavior in unilateral 6-hydroxydopamine (6-OHDA)-treated rats (hemi-parkinsonian rats) and on L-DOPA-induced dyskinesia produced by administering L-DOPA to hemi-parkinsonian rats for 3 weeks (dyskinesia rats). A single administration of subcutaneous TRK-820 significantly increased spontaneous ipsilateral rotational behavior of hemi-parkinsonian rats at 30 microg/kg though the efficacy was moderate and also significantly inhibited L-DOPA-induced dyskinesia at 10 and 30 microg/kg; this inhibition was reversed in the presence of nor-binaltorphimine, a kappa opioid receptor antagonist. In vivo microdialysis study, TRK-820 (30 microg/kg, s.c.) significantly inhibited L-DOPA-derived extracellular dopamine content in the 6-OHDA-treated striatum in dyskinesia rats, but not in hemi-parkinsonian rats. Moreover, the development of L-DOPA-induced dyskinesia was suppressed by the 3-week co-administration of TRK-820 (3 and 10 microg/kg, s.c.) with L-DOPA. These results have suggested that TRK-820 ameliorates L-DOPA-induced dyskinesia with a moderate anti-parkinsonian effect by inhibiting L-DOPA-induced excessive dopamine release through kappa opioid receptors only in dyskinesia rats; therefore, TRK-820 is expected to become a useful agent for the treatment of L-DOPA-induced dyskinesia.

Topics: Amantadine; Animals; Behavior, Animal; Disease Models, Animal; Dyskinesias; Extracellular Space; Levodopa; Male; Microdialysis; Morphinans; Neostriatum; Oxidopamine; Parkinson Disease; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Rotation; Spiro Compounds; Time Factors

Chronic inflammation mediated by microglial cells is the fundamental process contributing to the death of dopamine (DA)-producing neurons in the brain. Production of inflammatory products by these microglial cells characterizes the slow destructive process in Parkinson's disease (PD). The activation of microglial cells and the generation of pro-inflammatory cytokines that characterize PD are mediated by several different signaling pathways, with the activation of the respiratory burst by microglial cells being a critical event in the ultimate toxicity of DA-neurons. The work on our lab is concerned with understanding the mechanisms of activation, response, and therapeutic targets of microglial cells, with the aim to provide more effective treatments for PD and other inflammatory diseases of the CNS.

Topics: Brain; Chronic Disease; Cytokines; Dopamine; Humans; Inflammation; Microglia; Morphinans; Parkinson Disease

The mechanisms involved in the induction and regulation of inflammation resulting in dopaminergic (DA) neurotoxicity in Parkinson's disease (PD) are complex and incompletely understood. Microglia-mediated inflammation has recently been implicated as a critical mechanism responsible for progressive neurodegeneration.. Mesencephalic neuron-glia cultures and reconstituted cultures were used to investigate the molecular mechanisms of sinomenine (SN)-mediated anti-inflammatory and neuroprotective effects in both the lipopolysaccharide (LPS)- and the 1-methyl-4-phenylpyridinium (MPP+)-mediated models of PD.. SN showed equivalent efficacy in protecting against DA neuron death in rat midbrain neuron-glial cultures at both micro- and sub-picomolar concentrations, but no protection was seen at nanomolar concentrations. The neuroprotective effect of SN was attributed to inhibition of microglial activation, since SN significantly decreased tumor necrosis factor-alpha (TNF-alpha, prostaglandin E2 (PGE2) and reactive oxygen species (ROS) production by microglia. In addition, from the therapeutic point of view, we focused on sub-picomolar concentration of SN for further mechanistic studies. We found that 10(-14) M of SN failed to protect DA neurons against MPP+-induced toxicity in the absence of microglia. More importantly, SN failed to show a protective effect in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for extracellular superoxide production in immune cells. Furthermore, we demonstrated that SN reduced LPS-induced extracellular ROS production through the inhibition of the PHOX cytosolic subunit p47phoxtranslocation to the cell membrane.. Our findings strongly suggest that the protective effects of SN are most likely mediated through the inhibition of microglial PHOX activity. These findings suggest a novel therapy to treat inflammation-mediated neurodegenerative diseases.

Topics: Animals; Animals, Newborn; Anti-Inflammatory Agents; Cell Death; Cell Line; Coculture Techniques; Dopamine; Dose-Response Relationship, Drug; Encephalitis; Enzyme Inhibitors; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Morphinans; NADPH Oxidases; Neurons; Neuroprotective Agents; Parkinson Disease; Rats; Rats, Inbred F344; Tumor Necrosis Factor-alpha