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Browsing by Subject "MANF"

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  • Li, Mingchen (2021)
    Parkinson’s disease (PD) is a progressive chronic neurodegenerative disorder, which results in the selective loss of dopaminergic neurons in the substantia nigra (SN). The loss of these neurons results in the dysfunction of the nigrostriatal pathway bringing forth the characteristic motor symptoms seen in PD: postural instability, rigidity, slowness of movement and resting tremors. Non-motor symptoms, such as cognitive deficits, depression and impaired olfaction, typically emerge before motor symptoms. Currently available treatments only provide symptomatic relief with diminishing returns over time and no improvements on the overall outcome of the disease. Neurotrophic factors (NTF) have been of particular interest as a possible curative treatment for PD due to their potential for neuroprotection and neurorestoration. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an NTF that has shown promising results in numerous in vitro and in vivo studies of PD. However, therapy with MANF and other NTFs involves surgical intervention for local administration, as NTFs cannot cross the blood-brain barrier (BBB). Therefore, the therapeutic potential of a systemically administered NTF would be tremendous, as it would lead to a significantly more favorable risk-benefit ratio for the patient. The aim of the current investigation is to evaluate the efficacy of a next generation variant of MANF in the 6-hydroxydopamine toxin-induced unilateral lesion rat model of PD. Prior in vivo results suggested that subcutaneously injected MANF variant is able to penetrate the BBB. Amphetamine-induced rotational behavior (AMPH-ROTO) was used to evaluate the severity of the unilateral lesions during the experiment every other week until the end of the experiment at week eight. Animals were divided into treatment groups during week two based on their AMPH-ROTO results. Animals received MANF variant either subcutaneously through an implanted osmotic minipump at two different dosages or as a single dose divided into three separate intrastriatal injections. Tyrosine hydroxylase (TH) immunohistochemical staining was performed on brain sections collected from the striatum and SN for data analysis. In addition to AMPH-ROTO results, the efficacy of treatment was determined via the optical density of TH-positive striatal fibers and the number of TH-positive cells in the SN. Statistically significant differences (defined by p < 0.05 and a non-zero mean difference at a 95 % confidence interval) were observed only in the number of TH-positive cells in the SN favoring intrastriatal MANF variant treatment over both intrastriatal MANF and the vehicle treatment. The main concern regarding the validity of the results was related to the heterogeneous lesion sizes in different treatment groups possibly resulting in unsuccessful randomization due to excessive baseline differences. The inadvertent negative effects of this was further exacerbated by low a priori statistical power, which in the end had likely caused inflated effect sizes. Thus, assessment of the definitions of the used statistical parameters and the limitations of the experimental design suggest that presently, the efficacy of the MANF variant could not be evaluated reliably, in spite of the statistically significant result.
  • Renko, Juho-Matti (2012)
    Review of the literature: The purpose of the review is to go through what is known about mechanisms of actions of different neurotrophic factors (GDNF, neurturin, CDNF and MANF) and how they are transported within the brain. Neurotrophic factors are endogenous and secreted proteins which have a pivotal role in the development and maintenance of neurons. They support the survival of neurons and they can help them to recover from different injuries. Due to these functions neurotrophic factors might be beneficial for the treatment of neurodegenerative disorders like Parkinson's disease. There are a great deal of studies that clearly show the neuroprotective and neurorestrorative function of GDNF and neurturin on dopaminergic neurons. They are also studied in clinical studies with Parkinson's patients but the results have been partly contradictory. The signalling route of GDNF and neurturin via RET tyrosinekinasereceptor is fairly well known but the other mechanisms of action of these factors needs to be studied further. CDNF and MANF constitute a novel, evolutionarily conserved family of neurotrophic factors. They are shown to have neuroprotective and neurorestrorative actions on dopaminergic neurons both in vitro and in vivo in a rodent model of Parkinson's disease. The mechanisms of action of CDNF and MANF are not quite clear at the moment. There are two different domains in their structure both of which are likely to carry different functions. The N-terminal domains of these proteins are close to saposins, lipid and membrane binding proteins, some of which are shown to have neurotrophic and anti-apoptotic effects. The C-terminal domain of MANF, in turn, is structurally close to the SAP-domain of Ku70-protein which binds Bax in the cytoplasm and thus inhibits apoptosis mediated by Bax. CDNF and MANF might protect neurons both via intracellular mechanisms and extracellularly acting like a secreted neurotrophic factor. CDNF and GDNF are transported retrogradially from striatum to substantia nigra. MANF, unlike the others, is transported from striatum to the frontal cortex. MANF and CDNF are shown to have better diffusion properties in the brain parenchyma than GDNF. Experimental part: We studied, by means of microdialysis, the effects of CDNF, MANF and GDNF on the dopaminergic neurotransmission of naive rats within the striatum. Neurotrophic factors (10 µg) and PBS as a negative control were injected into the left striatum in stereotaxic surgery. After this rats recovered one week before the first mircodialysis. The second mircodialysis was performed three weeks after the surgery. The samples were collected from the left striatum of freely moving rats. During the microdialysis neurotransmission was stimulated by replacing the perfusion solution with hypertonic potassium solution and with amphetamine solution. The concentration of dopamine, DOPAC, HVA and 5-HIAA was measured from the dialysate samples. In vivo TH-activity experiment was carried out for three rats in each group. NSD1015 was injected i.p.after which rats were decapitated and their striatums were dissected. The concentration of L-DOPA, dopamine and metabolites on the treated and untreated hemisphere were analyzed from the tissue samples. The amount of L-DOPA in the striatum after NSD1015-treatment indicates how active TH-enzyme is. There were no significant differences in the concentrations of dopamine and metabolites during the baseline. MANF and CDNF increased the release of dopamine from the nerve terminals compared to GDNF and PBS one week after the surgery. Three weeks after the surgery there was still significant increase in the release of dopamine in MANF group compared to GDNF group. Also the dopamine-DOPAC-turnover was increased significantly in MANF group compared to GDNF and PBS groups one week after the surgery. DOPAC/HVA -ratio was significantly smaller in GDNF group than in other groups one week after the surgery. These findings suggest that MANF potentiates dopaminergic neurotransmission most drasticly. The effects of MANF seem to last longer time than the effects of other neurotrophic factors. CDNF seems to increase the release of dopamine from the nerve terminals as well. The potentiation of dopaminergic neurotransmission could be due to increased biosynthesis of dopamine or due to the potentiation of the function of nerve terminals. In the results of the TH-activity experiment there was a trend according to which L-DOPA is synthesized less after the neurotrophic factor treatment that after the PBS treatment. This suggests that neurotrophic factors might decrease the activity of TH-enzyme.
  • Pöyhönen, Suvi (2017)
    Cortical stroke induces a chain of events that results in secondary injury in the ipsilateral thalamus. Inflammation is a key player in the delayed injury. Microglia, the resident innate immune cells of the brain, seem to have an important role in the initiation and maintenance of the inflammation. After infarct they are rapidly activated and start to proliferate and release proinflammatory cytokines. They may even phagocytose viable neurons, a phenomenon called "phagoptosis". Many studies, which have aimed at inhibition of the the detrimental function of microglia, suggest that inhibition of microglia might offer promising therapeutical targets. However, microglia are also involved in the resolution and the repair phase after infarct, which makes development of novel therapies challenging. The only approved treatment for ischemic stroke, a fibrinolytic agent, has a very narrow therapeutic time window. Thus, new treatments are urgently needed. Modulation of inflammation may offer a wider therapeutic time window. In this study, we investigated the effects of two potentially neurotrophic factors, CDNF (cerebral dopamine neurotrophic factor) and MANF (mesencephalic astrocyte-derived neurotrophic factor), as well as a specific vitronectin receptor blocker, cRGDfV, on the prevention of neuronal death in thalamus in a transient murine cortical stroke model. MANF and CDNF are proteins released during stress of the endoplasmic reticulum (ER). They have been shown to protect neurons during ER stress and to reduce the production of some proinflammatory mediators. The vitronectin receptor blocker has in vitro inhibited microglial phagoptosis. The treatments were administered as single injections to the thalamus 7 days after the stroke onset. CDNF and MANF alleviated functional deficits, but did not protect thalamic neurons from death or affect the accumulation of phagocytic microglia. cRGDfV neither enhanced functional outcome nor protected neurons from death. The mechanisms of action were not investigated. In addition, we investigated, whether the death of thalamic neurons in the cortical stroke results in sensitization to pain. Central post-stroke pain has been reported on stroke patients and it has been associated with the death or the disturbances in the function of thalamic neurons. However, in spite of significant reduction in the number of neurons in the ipsilateral thalamus and the increase in the accumulation of phagocytic microglia on day 30 after stroke, we did not observe any significant sensitization to pain caused by thermal or mechanical stimuli on days 3, 14 and 28 after stroke. In conclusion, transient ischemic cortical stroke doesn't seem to induce sensitization to pain. MANF and CDNF seem to alleviate functional deficiencies, but they do not protect thalamic neurons from delayed death.
  • Jaskari, Iida (2022)
    Multiple sclerosis is a progressive inflammatory disease of the central nervous system that affects young adults. The pathological hallmark of MS is the degradation and loss of oligodendrocytes resulting in demyelination. Damage to axons caused by demyelination severely impairs physical function. Currently there is no cure for MS, but current drugs aim to modify the course of the disease and relieve symptoms. However, they are unable to promote the repair of damaged myelin sheaths, and thus new therapies are needed. In this study, the effect of V-MANF on remyelination was investigated in two commonly used experimental toxin models. V-MANF is a modification of the endoplasmic reticulum located protein MANF, which has been found to have neuroprotective and regenerative properties. Additionally, MANF can regulate ER stress, which contributes to demyelination in MS. The effect of V-MANF on lysolecithin-induced demyelination was examined in organotypic cerebellar brain sections from C57B/6 mice. The study was conducted exceptionally using the brains of adult mice because they are a better model for neurodegenerative diseases. However, when analyzing the results, it was found that there was no demyelination in the tissue cultures, so the effect of V-MANF could not be analyzed. In the other study, C57B/6 mice were given dietary cuprizone for six weeks, followed by daily intranasal administration of either V-MANF or vehicle for seven days. Mice were subjected to behavioral experiments, in which a light/dark box test showed that V-MANFs had a potential anxiolytic effect in mice receiving cuprizone. No significant demyelination was observed by immunohistochemical analysis and therefore the effect of V-MANF on remyelination could not be assessed. However, the results of the study can be utilized in the design of further studies.
  • Kontti, Arttu (2014)
    Parkinson's disease causes changes in the basal ganglia GABAergic neurotransmission in addition to the well-known dopaminergic changes. These GABAergic modulations may cause somed of the symptoms not responding well to the standard dopaminergic medication. Neurotrophic factors are a group of endogenous proteins showing promise as a future treatment for Parkinson's disease. They are known to have neuroprotective and neurorestorative effects on the dopaminergic cells. Their effects to the GABAergic cells are still mostly unknown. Intrastriatal injection of GDNF to rats caused significantly slower weight gain compared to CDNF, MANF one week after stereotaxic operation (p=0,002 for CDNF vs. GDNF and p<0,001 for MANF vs. GDNF). Difference to the vehicle (phosphate buffered saline) used as a negative control was not statistically significant (p=0,055). Three weeks after the operation the differences between the treatment groups were no longer statistically significant. Because of problems with the separation in analysis, microdialysis samples remain still to be analysed. To help the analysis of GABA in the future we determined the analytical parameters of the analytical apparatus. We also defined differences in probe permeability between 1 mm and 2 mm probes and between old and new batches. GABA analysis was performed with a HPLC-fluorometric detection of o-phtaldialdehyde-derived GABA. Detection limit for old apparatus was 7,2 nM and for new apparatus 6,2 nM in a sample of 15 µl (0,11 pmol and 93 fmol respectively). Quantification limits defined were 22 nM and 19 nM (0,33 pmol and 0,28 pmol) for the old and the new apparatus, respectively. Upper limit of quantification was estimated to be 246 nM (3,7 pmol). Probes had significant differences in permeability between 1 mm and 2 mm probes, as well as between batches. The variance of permeability of 1 mm probes was estimated to be approximately twofold compared to the 2 mm probes. Furthermore the permeability of 1 mm probes varied between batches significantly. An average of permeability of the old batch was 34 % lower than that of a new batch (p<0,001).