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BACKGROUND AND AIMS: Parkinson disease (PD) is a more general disease than thought previously and involves prominent nonmotor manifestations (e.g. anosmia, hyposmia). Olfactory dysfunction can precede onset of motor symptoms by up to 10 years and they might provide biomarkers of the pathogenetic process. The initiating neurobiological bases for such disturbance are still elusive. However, recent findings suggest a degree of independence of olfactory dysfunction from nigrostriatal dopamine (DA). The aim of this study was to assess the extent of influence of biochemical imbalance in the left and right olfactory bulbs (OBs) on olfaction in old (1 or 1.5 year) mice caused by 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) intoxication. METHODS: The olfactory capability was evaluated using a battery set of olfaction tests: The Buried Food Test (BFT), Olfactory Discrimination Test (ODT), Olfactory Sensitivity Test (OST). Noradrenaline (NE) and DA metabolism was evaluated by High-performance liquid chromatography (HPLC) method. RESULTS: Intraperitoneal administration of MPTP caused significant reduction in NE and DA contents, observed mostly in the right OB at 7 and 180 days post intoxication. Interestingly, diminished noradrenergic projection and intensification of compensatory mechanism in the right OB exerted disturbing effect in some olfaction test (OST, BFT). Compared to controls, MPTP mice displayed insensitivity to low concentration odors in the OST and spend more time to find a buried food in the BFT. CONCLUSIONS: Results of the study strong indicate on lateralization in the OBs. Reasons for this phenomenon are unknown, although they may reflect lateralized differences in the function of the two sides of OBs. Diminished NE projection may play more important role in odor sensitivity than DA and may be related to dysfunction in odor recognition (hyposmia).The present findings seem to justify future studies about possible role of NE for therapeutic manipulation in PD.
Parkinson’s disease (PD) is a neurodegenerative disorders causing not only motor dysfunction, but also cognitive disturbance. The pattern of cognitive deficits in PD often includes: executive impairments, episodic memory deficits and visuospatial dysfunctions. It also became evident that inflammatory processes play an important role in the pathophysiology of PD. Neurodegeneration intense brain immune activation and “cytokine storm” which might induce hyper-excitability of neuronal circuits and might reduce neuronal plasticity and cause impairments in learning and memory abilities. The role of cytokines in regulation of inflammatory responses in different brain regions during PD is unclear. It still remains to be fully understood as to how cytokines participate in the molecular and cellular mechanisms of deficits in learning, memory and cognition in PD. Loss of dopaminergic neurons in acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models is associated with massive and prolonged glial response and increased production and release of inflammatory mediators. To assess the inflammatory response following MPTP intoxication, we measured the IL-6, IL-1β and TNFα gene expression by real-time quantitative RT-PCR following the Morris water maze behavioral test that was provided at 7 days, 3 and 6 months from the intoxication. Our results indicate that neuroinflammatory activity in MPTP model was not restricted to the nigrostriatal system but also involved hippocampal and cortical areas, regions there are essential for cognitive functions such as working and long - term memory, not only in mice. To evaluate spatial learning and memory abilities of mice the mean latency of reaching the platform, the swimming distance, the time spent in the goal quadrant and crossing parameters were estimated. We found that these parameters correlated with level of mRNA expression of cytokines in hippocampus and cortex.
BACKGROUND AND AIMS: A neuroprotective or disease modifying treatment of Parkinson’s disease (PD) still remains an unmet need. The non-clinical and clinical studies have indicated that cyclic nucleotide phosphodiesterase (PDE) inhibitors represent a novel class of drugs which may be useful in treating neuroinflammation disorders. The present study was designed to examine the efficacy of PDE inhibitors, ibudilast (IBD) and vinpocetine (VPC) in the mice model of PD induced by 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP). METHODS: 3 months-old male C57Bl/10Tar mice were treated with IBD (0, 20, 30, 40 or 50 mg/kg) BID for 9 days or VPC (0, 10, 20 or 30 mg/kg) once daily for 8 consecutive days (beginning 2 days or 1 day prior to MPTP (60 mg/kg) intoxication, respectively). Rotarod test was conducted on day 3 post MPTP injection. Mice were sacrificed 7 days after MPTP intoxication. IL-1β, IL-6, TNF-α and GDNF mRNA expression in the striatum was examined by the Real Time RT-PCR method. Western blot analysis was used to estimate tyrosine hydroxylase (TH) expression, micro- and astroglia activation markers (Iba1 and GFAP, respectively). Dopamine (DA) metabolism was evaluated by HPLC method. RESULTS: Chronic administration of PDE inhibitors attenuated astroglial reactivity and increased glial cell-derived neurotrophic factor (GDNF) gene expression in the striatum. IBD reduced TNF-α, IL-6 and IL-1β expressions, whereas VPC had no impact on elevated levels of TNF-α. Moreover,  mice receiving 40 mg/ kg IBD showed significant improvement in the locomotor activity compared to control. However, PDE inhibitors did not change DA metabolism and TH expression in the striatum. CONCLUSIONS: The findings provide evidence for the glia-derived protective properties of PDE inhibitors in the MPTP-induced model of PD. This response may be promising for the better outcome in the later stages of neurodegeneration. However, the further study is needed to confirm such possibility.
Many data suggest involvement of inflammation in neurodegeneration. However, the exact mechanisms of this cooperation are poorly understood. We have previously shown that induction of inflammatory reaction, both before and after injury of the striatum, affects regeneration of dopaminergic neurons. In the present research we studied the role of inflammatory reaction in non-injured striatum. We used myelin oligodendrocyte glycoprotein (MOG) 35-55 in complete Freund’s adjuvant (CFA) to elicit experimental autoimmune encephalomyelitis (EAE) mice model. As determined by HPLC, striatal dopamine (DA) and serotonin levels in mice treated with either MOG 35-55 in CFA or CFA alone were significantly higher compared to vehicle-treated controls on 13th day after induction. The ratio of homovanilic acid/dopamine (HVA/DA) and 3, 4 dihydroxyphenylacetic acid/dopamine (DOPAC/DA) were significantly lower in the MOG and CFA groups on 13th day, indicating decreased DA metabolism. Noradrenaline (NA) concentration did not differ between groups. Moreover, the striatal mRNA IL-1ß and TNF-? levels were elevated during induction phase of EAE in both groups, as determined by RT-PCR. Our data indicate regulatory connection between dopaminergic and immune systems.
17β-estradiol (E2) have been shown to reduce damage of the nigrostriatal system following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The immunosuppressive properties of this hormone may be involved in estrogen-mediated nigro-striatal neuroprotection. We studied the chronic effects of two doses of E2: 0.25 and 2.5 mg per pellet (21-days release) administered 7 days prior MPTP treatment in C57BL male mice (12 months old) on MPTP-induced dopaminergic neurons degeneration and infl ammatory reaction in nigrostriatal pathway. We estimated striatal: tyrosine hydroxylase (TH) and dopamine (DA) level; glial fi brillary acidic protein (GFAP), cytokines (IL-1β, IL-6, TNFα, TGFβ1, IFNg), trophic factor (GDNF) and adhesion molecules (ICAM-1 and VCAM-1) gene expression at 1,7 and 21 days post MPTP intoxication. We showed that only the lower E2 dose (0.25 mg) exerted a neuroprotective effect upon nigrostriatal system. E2 0.25 pre-treatment attenuated the MPTP-induced loss of striatal DA at 1 day time-point and TH at 7- and 21-day time-points. E2 0.25 also diminished the early MPTP-induced increase of the striatal IFNg, IL-1β, TGFβ, ICAM-1, VCAM-1 and GFAP levels but failed to suppress the MPTP-induced increase of striatal TNFα. E2 0.25 also induced an increase of the striatal GDNF and IL-6 gene expression. In contrast, higher E2 doses did not affect the expression of the investigated infl ammatory mediators, expect the GFAP gene expression (increase of the GFAP expression after E2 2.5 administration). We conclude that E2 has a critical dosing effect on dopaminergic neurons survival, only physiologic levels of E2 are neuroprotective in male mice. The neuroprotective effects of E2 might mediate through a modulation of molecular factors of neuroinfl ammatory reaction.
Cognitive dysfunctions are common features of multiple sclerosis. The exact mechanism of their appearance is unknown. The disconnection of some parts of the cortex reflecting an axonal loss, neuronal damage and alterations in synaptic transmission, have been postulated. In the present study, an autoimmune encephalomyelitis (EAE), a common model of multiple sclerosis, was induced passively by lymphocytes transfer, to evoke a one-phase disease in Lewis rats. The inflammatory reactions and neural injury in the hippocampus and frontal cortex were investigated. We found a decrease of the number of CA1 and CA4 pyramidal neurons by about 25% on 30 dpi and by about 50% in CA1 region on 90 dpi. This was accompanied by prolonged astroglial activation and by a rise of the pro-inflammatory cytokine mRNA expression (IL-1β, IL-6 and TNFα). A significant rise of NGF and BDNF was also found. In the frontal cortex, neural degeneration was not so evident. A slight astrocyte activation and a strong increase of expression of IL 6 on 30 dpi and IL1β and TNFα on 90 dpi was seen. Learning and memory abilities (Morris water-maze tests) were also evaluated 30 and 90 dpi. The mean latency of reaching the platform, the swimming distance, the time spent in the goal quadrant and crossing parameters were estimated. The reaction of animals suffering from EAE was not different from that of the control group, in any of the tasks except 20% higher chance for reaching the platform on 30 dpi. We demonstrated therefore the lack of correlation between strong neuroinflammation in the hippocampus and cortex and the deficits in memory and learning ability at a late phase of the disease. However, the severity of motor impairment during earlier stages of the disease made difficult identification of any early cognitive deficits. The possibility exists that early deficits could be later compensated due to simultaneously occurring compensatory processes involving activity of neurotrophic factors.
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