ABSTRACT
A beam-walking apparatus has been evaluated for its ability to detect motor impairments in mice acutely treated with the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg, s.c., single or double administration). Mice subjected to MPTP lesioning showed deficits in motor performance on the beam-walking task, for up to 6 days post-MPTP administration, as compared to saline-treated controls. In addition, MPTP-treated mice were detected to have a marked depletion in striatal dopamine levels and a concomitant reduction in substantia nigra (SN) tyrosine hydroxylase (TH) immunoreactivity, at 7 days post-MPTP administration, indicative of dopaminergic neuronal loss. Pre-administration of the potent MAO-B inhibitor R-(-)-deprenyl at 3 or 10 mg/kg, 30 min, s.c, significantly inhibited the MPTP-induced reduction in SN TH-immunoreactivity, striatal dopamine depletions and impairments in mouse motor function. The data described in the present study provides further evidence that functional deficits following an acute MPTP dosing schedule in mice can be quantified and are related to nigro-striatal dopamine function.
Subject(s)
Brain/physiopathology , Dopamine/deficiency , Ethology/instrumentation , Gait Disorders, Neurologic/diagnosis , Neuropharmacology/instrumentation , Parkinsonian Disorders/diagnosis , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/adverse effects , Animals , Brain/metabolism , Corpus Striatum/drug effects , Corpus Striatum/pathology , Corpus Striatum/physiopathology , Dose-Response Relationship, Drug , Ethology/methods , Gait Disorders, Neurologic/physiopathology , Gait Disorders, Neurologic/prevention & control , Male , Mice , Mice, Inbred C57BL , Monoamine Oxidase Inhibitors/therapeutic use , Neural Pathways/drug effects , Neural Pathways/metabolism , Neural Pathways/physiopathology , Neuropharmacology/methods , Parkinsonian Disorders/physiopathology , Parkinsonian Disorders/prevention & control , Predictive Value of Tests , Selegiline/therapeutic use , Substantia Nigra/drug effects , Substantia Nigra/metabolism , Substantia Nigra/physiopathology , Tyrosine 3-Monooxygenase/metabolismABSTRACT
BACKGROUND: Data indicates anti-oxidant, anti-inflammatory and pro-cognitive properties of noradrenaline and analyses of post-mortem brain of Alzheimer's disease (AD) patients reveal major neuronal loss in the noradrenergic locus coeruleus (LC), the main source of CNS noradrenaline (NA). The LC has projections to brain regions vulnerable to amyloid deposition and lack of LC derived NA could play a role in the progression of neuroinflammation in AD. Previous studies reveal that intraperitoneal (IP) injection of the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) can modulate neuroinflammation in amyloid over-expressing mice and in one study, DSP-4 exacerbated existing neurodegeneration. METHODS: TASTPM mice over-express human APP and beta amyloid protein and show age related cognitive decline and neuroinflammation. In the present studies, 5 month old C57/BL6 and TASTPM mice were injected once monthly for 6 months with a low dose of DSP-4 (5 mg kg-1) or vehicle. At 8 and 11 months of age, mice were tested for cognitive ability and brains were examined for amyloid load and neuroinflammation. RESULTS: At 8 months of age there was no difference in LC tyrosine hydroxylase (TH) across all groups and cortical NA levels of TASTPM/DSP-4, WT/Vehicle and WT/DSP-4 were similar. NA levels were lowest in TASTPM/Vehicle. Messenger ribonucleic acid (mRNA) for various inflammatory markers were significantly increased in TASTPM/Vehicle compared with WT/Vehicle and by 8 months of age DSP-4 treatment modified this by reducing the levels of some of these markers in TASTPM. TASTPM/Vehicle showed increased astrocytosis and a significantly larger area of cortical amyloid plaque compared with TASTPM/DSP-4. However, by 11 months, NA levels were lowest in TASTPM/DSP-4 and there was a significant reduction in LC TH of TASTPM/DSP-4 only. Both TASTPM groups had comparable levels of amyloid, microglial activation and astrocytosis and mRNA for inflammatory markers was similar except for interleukin-1 beta which was increased by DSP-4. TASTPM mice were cognitively impaired at 8 and 11 months but DSP-4 did not modify this. CONCLUSION: These data reveal that a low dose of DSP-4 can have varied effects on the modulation of amyloid plaque deposition and neuroinflammation in TASTPM mice dependent on the duration of dosing.
Subject(s)
Amyloid beta-Protein Precursor/genetics , Benzylamines/administration & dosage , Mutation , Norepinephrine/biosynthesis , Plaque, Amyloid/drug effects , Presenilin-1/genetics , Presenilin-1/metabolism , Transgenes/drug effects , Amyloid beta-Protein Precursor/antagonists & inhibitors , Amyloid beta-Protein Precursor/metabolism , Animals , Benzylamines/toxicity , Corpus Striatum/drug effects , Corpus Striatum/metabolism , Drug Administration Schedule , Humans , Inflammation/genetics , Inflammation/metabolism , Inflammation/prevention & control , Mice , Mice, Inbred C57BL , Mice, Transgenic , Norepinephrine/antagonists & inhibitors , Norepinephrine/genetics , Plaque, Amyloid/genetics , Plaque, Amyloid/metabolism , Presenilin-1/antagonists & inhibitorsABSTRACT
A high-throughput liquid chromatography/tandem mass spectrometry method has been developed for the quantitative assessment of 1-methyl-4-phenylpyridinium (MPP+) in brain tissue samples. This separation is based on reversed phase chromatography using formic acid and acetonitrile as the mobile phase. Using gradient separation conditions, MPP+ was resolved within 5 min and detected using tandem mass spectrometry in the positive ion electrospray mode. The limit of detection for MPP+ was found to be 1 fmol on column with a signal to noise ratio of 3:1. The assay has been used routinely in our laboratory for the measurement of MPP+ levels in brain tissue from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, and can be used to distinguish neuroprotective efficacy and monoamine oxidase inhibition.
Subject(s)
1-Methyl-4-phenylpyridinium/analysis , Brain/metabolism , Chromatography, High Pressure Liquid/methods , Mass Spectrometry/methods , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/analysis , 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/chemistry , 1-Methyl-4-phenylpyridinium/chemistry , 1-Methyl-4-phenylpyridinium/toxicity , Animals , Antiparkinson Agents/pharmacology , Brain/cytology , Brain/drug effects , Brain Chemistry , Male , Mice , Reproducibility of Results , Selegiline/pharmacology , Sensitivity and Specificity , Time Factors , Tissue DistributionABSTRACT
The paper covers continuing efforts to discover novel, potent and selective oxytocin antagonists. Further benzofuran derivatives with potent oxytocin antagonist activity and good pharmacokinetic parameters are reported. Efforts to improve the in vivo activity of the series are described.
