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af Bjerkén, Sara
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Publications (10 of 15) Show all publications
af Bjerkén, S., Stenmark Persson, R., Barkander, A., Karalija, N., Pelegrina-Hidalgo, N., Gerhardt, G. A., . . . Strömberg, I. (2019). Noradrenaline is crucial for the substantia nigra dopaminergic cell maintenance. Neurochemistry International, 131, Article ID 104551.
Open this publication in new window or tab >>Noradrenaline is crucial for the substantia nigra dopaminergic cell maintenance
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2019 (English)In: Neurochemistry International, ISSN 0197-0186, E-ISSN 1872-9754, Vol. 131, article id 104551Article in journal (Refereed) Epub ahead of print
Abstract [en]

In Parkinson's disease, degeneration of substantia nigra dopaminergic neurons is accompanied by damage on other neuronal systems. A severe denervation is for example seen in the locus coerulean noradrenergic system. Little is known about the relation between noradrenergic and dopaminergic degeneration, and the effects of noradrenergic denervation on the function of the dopaminergic neurons of substantia nigra are not fully understood. In this study, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) was injected in rats, whereafter behavior, striatal KCl-evoked dopamine and glutamate releases, and immunohistochemistry were monitored at 3 days, 3 months, and 6 months. Quantification of dopamine-beta-hydroxylase-immunoreactive nerve fiber density in the cortex revealed a tendency towards nerve fiber regeneration at 6 months. To sustain a stable noradrenergic denervation throughout the experimental timeline, the animals in the 6-month time point received an additional DSP4 injection (2 months after the first injection). Behavioral examinations utilizing rotarod revealed that DSP4 reduced the time spent on the rotarod at 3 but not at 6 months. KCl-evoked dopamine release was significantly increased at 3 days and 3 months, while the concentrations were normalized at 6 months. DSP4 treatment prolonged both time for onset and reuptake of dopamine release over time. The dopamine degeneration was confirmed by unbiased stereology, demonstrating significant loss of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra. Furthermore, striatal glutamate release was decreased after DSP4. In regards of neuroinflammation, reactive microglia were found over the substantia nigra after DSP4 treatment. In conclusion, long-term noradrenergic denervation reduces the number of dopaminergic neurons in the substantia nigra and affects the functionality of the nigrostriatal system. Thus, locus coeruleus is important for maintenance of nigral dopaminergic neurons.

Keywords
DSP4, Dopamine, In vivo amperometry, In vivo chronoamperometry, Noradrenaline, Parkinson's disease
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-163942 (URN)10.1016/j.neuint.2019.104551 (DOI)31542295 (PubMedID)2-s2.0-85072404826 (Scopus ID)
Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-10
Jakobson Mo, S., Axelsson, J., Jonasson, L., Larsson, A., Ögren, M. J., Ögren, M., . . . Riklund, K. (2018). Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT – a clinical comparison. EJNMMI Research, 8, Article ID 100.
Open this publication in new window or tab >>Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT – a clinical comparison
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2018 (English)In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 8, article id 100Article in journal (Refereed) Published
Abstract [en]

Background: Dopamine transporter (DAT) imaging may be of diagnostic value in patients with clinically suspected parkinsonian disease. The purpose of this study was to compare the diagnostic performance of DAT imaging with positron emission computed tomography (PET), using the recently developed, highly DAT-selective radiopharmaceutical [18F]FE-PE2I (FE-PE2I), to the commercially available and frequently used method with [123I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) in early-stage idiopathic parkinsonian syndrome (PS).

Methods: Twenty-two patients with a clinical de novo diagnosis of PS and 28 healthy controls (HC) participating in an on-going clinical trial of FE-PE2I were analyzed in this study. Within the trial protocol, participants are clinically reassessed 2 years after inclusion. A commercially available software was used for automatic calculation of FP-CIT-specific uptake ratio (SUR). MRI-based volumes of interest combined with threshold PET segmentation were used for FE-PE2I binding potential relative to non-displaceable binding (BPND) quantification and specific uptake value ratios (SUVR).

Results: PET with FE-PE2I revealed significant differences between patients with a clinical de novo diagnosis of PS and healthy controls in striatal DAT availability (p < 0.001), with excellent accuracy of predicting dopaminergic deficit in early-stage PS. The effect sizes were calculated for FE-PE2I BPND (Glass’s Δ = 2.95), FE-PE2I SUVR (Glass’s Δ = 2.57), and FP-CIT SUR (Glass’s Δ = 2.29). The intraclass correlation (ICC) between FE-PE2I BPND FP-CIT SUR was high in the caudate (ICC = 0.923), putamen (ICC = 0.922), and striatum (ICC = 0.946), p < 0.001. Five of the 22 patients displayed preserved striatal DAT availability in the striatum with both methods. At follow-up, a non-PS clinical diagnosis was confirmed in three of these, while one was clinically diagnosed with corticobasal syndrome. In these patients, FE-PE2I binding was also normal in the substantia nigra (SN), while significantly reduced in the remaining patients. FE-PE2I measurement of the mean DAT availability in the putamen was strongly correlated with BPND in the SN (R = 0.816, p < 0.001). Olfaction and mean putamen DAT availability was correlated using both FE-PE2I BPND and FP-CIT SUR (R ≥ 0.616, p < 0.001).

Conclusion: DAT imaging with FE-PE2I PET yields excellent basic diagnostic differentiation in early-stage PS, at least as good as FP-CIT SPECT.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Parkinson's disease, PET, SPECT, Dopamine transporter (DAT), [F-18]FE-PE2I
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-154944 (URN)10.1186/s13550-018-0450-0 (DOI)000450488800002 ()30443684 (PubMedID)
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-05-07Bibliographically approved
Olmedo-Díaz, S., Estévez-Silva, H., Orädd, G., af Bjérken, S., Marcellino, D. & Virel, A. (2017). An altered blood–brain barrier contributes to brain iron accumulation and neuroinflammation in the 6-OHDA rat model of Parkinson's disease. Neuroscience, 362, 141-151
Open this publication in new window or tab >>An altered blood–brain barrier contributes to brain iron accumulation and neuroinflammation in the 6-OHDA rat model of Parkinson's disease
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2017 (English)In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 362, p. 141-151Article in journal (Refereed) Published
Abstract [en]

Brain iron accumulation is a common feature shared by several neurodegenerative disorders including Parkinson's disease. However, what produces this accumulation of iron is still unknown. In this study, the 6-hydroxydopamine (6-OHDA) hemi-parkinsonian rat model was used to investigate abnormal iron accumulation in substantia nigra. We investigated three possible causes of iron accumulation; a compromised blood-brain barrier (BBB), abnormal expression of ferritin, and neuroinflammation. We identified alterations in the BBB subsequent to the injection of 6-OHDA using gadolinium-enhanced magnetic resonance imaging (MRI). Moreover, detection of extravasated IgG suggested that peripheral components are able to enter the brain through a leaky BBB. Presence of iron following dopamine cell degeneration was studied by MRI, which revealed hypointense signals in the substantia nigra. The presence of iron deposits was further validated in histological evaluations. Furthermore, iron inclusions were closely associated with active microglia and with increased levels of L-ferritin indicating a putative role for microglia and L-ferritin in brain iron accumulation and dopamine neurodegeneration.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
brain-iron, 6-OHDA, MRI, blood-brain barrier, microglia
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-142910 (URN)10.1016/j.neuroscience.2017.08.023 (DOI)000412382100013 ()28842186 (PubMedID)
Available from: 2017-12-15 Created: 2017-12-15 Last updated: 2018-06-09Bibliographically approved
Kopra, J. J., Panhelainen, A., af Bjerken, S., Porokuokka, L. L., Varendi, K., Olfat, S., . . . Andressoo, J.-O. (2017). Dampened Amphetamine-Stimulated Behavior and Altered Dopamine Transporter Function in the Absence of Brain GDNF. Journal of Neuroscience, 37(6), 1581-1590
Open this publication in new window or tab >>Dampened Amphetamine-Stimulated Behavior and Altered Dopamine Transporter Function in the Absence of Brain GDNF
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2017 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 37, no 6, p. 1581-1590Article in journal (Refereed) Published
Abstract [en]

Midbrain dopamine neuron dysfunction contributes to various psychiatric and neurological diseases, including drug addiction and Parkinson's disease. Because of its well established dopaminotrophic effects, the therapeutic potential of glial cell line-derived neurotrophic factor (GDNF) has been studied extensively in various disorders with disturbed dopamine homeostasis. However, the outcomes from preclinical and clinical studies vary, highlighting a need for a better understanding of the physiological role of GDNF on striatal dopaminergic function. Nevertheless, the current lack of appropriate animal models has limited this understanding. Therefore, we have generated novel mouse models to study conditional Gdnf deletion in the CNS during embryonic development and reduction of striatal GDNF levels in adult mice via AAV-Cre delivery. We found that both of these mice have reduced amphetamine-induced locomotor response and striatal dopamine efflux. Embryonic GDNF deletion in the CNS did not affect striatal dopamine levels or dopamine release, but dopamine reuptake was increased due to increased levels of both total and synaptic membrane-associated dopamine transporters. Collectively, these results suggest that endogenous GDNF plays an important role in regulating the function of dopamine transporters in the striatum.

Keywords
amphetamine, cyclic voltammetry, dopamine, dopamine transporter, GDNF, striatum
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-132628 (URN)10.1523/JNEUROSCI.1673-16.2016 (DOI)000393572400017 ()28096470 (PubMedID)
Available from: 2017-03-30 Created: 2017-03-30 Last updated: 2018-06-09Bibliographically approved
Hashemian, S., O'Rourke, C., Phillips, J. B., Strömberg, I. & af Bjerkén, S. (2015). Embryonic and mature astrocytes exert different effects on neuronal growth in rat ventral mesencephalic slice cultures. SpringerPlus, 4, Article ID 558.
Open this publication in new window or tab >>Embryonic and mature astrocytes exert different effects on neuronal growth in rat ventral mesencephalic slice cultures
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2015 (English)In: SpringerPlus, E-ISSN 2193-1801, Vol. 4, article id 558Article in journal (Refereed) Published
Abstract [en]

One obstacle with grafting of dopamine neurons in Parkinson's disease is the insufficient ability of the transplant to reinnervate the host striatum. Another issue is the prospective interaction between the donor fetal tissue and the adult astrocytes of the host. To study nerve fiber growth and its interaction with immature/mature astrocytes, ventral mesencephalic (VM) organotypic rat tissue cultures from embryonic days (E) 12, E14, and E18 were studied up to 35 days in vitro (DIV), and co-cultures of E14 VM tissue and mature green fluorescent protein (GFP)-positive astrocytes were performed. Generally, nerve fibers grew from the tissue slice either in association with a monolayer of migrated astroglia surrounding the tissue (glial-associated), or distal to the astroglia as non-glial-associated outgrowth. The tyrosine hydroxylase (TH)-positive glial-associated nerve fiber outgrowth reached a plateau at 21 DIV in E12 and E14 cultures. In E18 cultures, TH-positive neurons displayed short processes and migrated onto the astrocytes. While the non-glial-associated nerve fiber outgrowth dominated the E14 cultures, it was found absent in E18 cultures. The GFP-positive cells in the VM and GFP-positive astrocyte co-cultures were generally located distal to the monolayer of migrated fetal astrocytes, a few GFP-positive cells were however observed within the astrocytic monolayer. In those cases TH-positive neurons migrated towards the GFP-positive cells. Both the non-glial-and glial-associated nerve fibers grew onto the GFP-positive cells. Taken together, the glial-associated growth has limited outgrowth compared to the non-glial-associated nerve fibers, while none of the outgrowth types were hampered by the mature astrocytes.

Keywords
Organotypic culture, Ventral mesencephalon, Mature astrocytes, Developmental stages
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-110567 (URN)10.1186/s40064-015-1362-3 (DOI)000361917700003 ()26435904 (PubMedID)
Available from: 2015-11-06 Created: 2015-10-23 Last updated: 2018-06-07Bibliographically approved
Hashemian, S., Marschinke, F., af Bjerkén, S. & Strömberg, I. (2014). Degradation of proteoglycans affects astrocytes and neurite formation in organotypic tissue cultures. Brain Research, 1564, 22-32
Open this publication in new window or tab >>Degradation of proteoglycans affects astrocytes and neurite formation in organotypic tissue cultures
2014 (English)In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1564, p. 22-32Article in journal (Refereed) Published
Abstract [en]

Chondroitin sulfate proteoglycans (CSPGs) promote nerve growth during development, and inhibit axonal growth in the adult CNS after injury. Chondroitinase ABC (ChABC) and methyl-umbelliferyl-β-d-xyloside (β-xyloside), two enzymes that degrade CSPGs, promote regeneration after injury, however, they demonstrate opposing results in tissue culture. To elucidate the effect of the two enzymes, organotypic tissue cultures, treated with ChABC or β-xyloside, were employed to monitor nerve fiber outgrowth and astrocytic migration. Rat ventral mesencephalon (VM) and spinal cord (SC) from embryonic day (E) 14 and E18 were treated early, from the plating day for 14 days in vitro, or late where treatment was initiated after being cultured for 14 days. In the early treatment of E14 VM and SC cultures, astrocytic migration and nerve fiber outgrowth were hampered using both enzymes. Early treatment of E18 cultures reduced the astrocytic migration, while nerve growth was promoted by β-xyloside, but not by ChABC. In the late treated cultures of both E14 and E18 cultures, no differences in distances that astrocytes migrated or nerve fiber growth were observed. However, in β-xyloside-treated cultures, the confluency of astrocytic monolayer was disrupted. In E18 cultures both early and late treatments, neuronal migration was present in control cultures, which was preserved using ChABC but not β-xyloside. In conclusion, ChABC and β-xyloside had similar effects and hampered nerve fiber growth and astrocytic migration in E14 cultures. In E18 cultures nerve fiber growth was stimulated and neuronal migration was hampered after β-xyloside treatment while ChABC treatment did not exert these effects.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
CSPGs; Spinal cord; Ventral mesencephalon; ChABC; β-xyloside
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-87978 (URN)10.1016/j.brainres.2014.03.043 (DOI)000336703900003 ()
Available from: 2014-04-16 Created: 2014-04-16 Last updated: 2018-06-08Bibliographically approved
Nevalainen, N., Af Bjerkén, S., Gerhardt, G. A. & Strömberg, I. (2014). Serotonergic nerve fibers in l-DOPA-derived dopamine release and dyskinesia. Neuroscience, 260, 73-86
Open this publication in new window or tab >>Serotonergic nerve fibers in l-DOPA-derived dopamine release and dyskinesia
2014 (English)In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 260, p. 73-86Article in journal (Refereed) Published
Abstract [en]

The 5-HT (5-hydroxytryptamine) system has been assigned a key role in the development of 3,4-dihydroxyphenyl-l-alanine (l-DOPA)-induced dyskinesia, mainly due to 5-HT neuronal ability to decarboxylate l-DOPA into dopamine. Nevertheless, knowledge of l-DOPA-induced events that could lead to development of dyskinesias are limited and therefore the present work has evaluated (i) the role of the 5-HT system in l-DOPA-derived dopamine synthesis when dopamine neurons are present, (ii) l-DOPA-induced effects on striatal dopamine release and clearance, and on 5-HT nerve fiber density, and (iii) the behavioral outcome of altered 5-HT transmission in dyskinetic rats. Chronoamperometric recordings demonstrated attenuated striatal l-DOPA-derived dopamine release (∼30%) upon removal of 5-HT nerve fibers in intact animals. Interestingly, four weeks of daily l-DOPA treatment yielded similar-sized dopamine peak amplitudes in intact animals as found after a 5-HT-lesion. Moreover, chronic l-DOPA exposure attenuated striatal 5-HT nerve fiber density in the absence of dopamine nerve terminals. Furthermore, fluoxetine-induced altered 5-HT transmission blocked dyskinetic behavior via action on 5-HT1A receptors. Taken together, the results indicate a central role for the 5-HT system in l-DOPA-derived dopamine synthesis and in dyskinesia, and therefore potential l-DOPA-induced deterioration of 5-HT function might reduce l-DOPA efficacy as well as promote the upcoming of motor side effects.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
l-DOPA, dyskinesia, 5-HT, in vivo chronoamperometry, fluoxetine, WAY-100 635
National Category
Neurosciences Other Basic Medicine
Identifiers
urn:nbn:se:umu:diva-84741 (URN)10.1016/j.neuroscience.2013.12.029 (DOI)000330598100007 ()24361918 (PubMedID)
Available from: 2014-01-20 Created: 2014-01-20 Last updated: 2018-06-08Bibliographically approved
Nevalainen, N., Af Bjerkén, S., Lundblad, M., Gerhardt, G. A. & Strömberg, I. (2011). Dopamine release from serotonergic nerve fibers is reduced in L-DOPA-induced dyskinesia. Journal of Neurochemistry, 118(1), 12-23
Open this publication in new window or tab >>Dopamine release from serotonergic nerve fibers is reduced in L-DOPA-induced dyskinesia
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2011 (English)In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 118, no 1, p. 12-23Article in journal (Refereed) Published
Abstract [en]

L-DOPA is the most commonly used treatment for symptomatic control in patients with Parkinson's disease. Unfortunately, most patients develop severe side-effects, such as dyskinesia, upon chronic l-DOPA treatment. The patophysiology of dyskinesia is unclear; however, involvement of serotonergic nerve fibers in converting l-DOPA to dopamine has been suggested. Therefore, potassium-evoked dopamine release was studied after local application of l-DOPA in the striata of normal, dopamine- and dopamine/serotonin-lesioned l-DOPA naïve, and dopamine-denervated chronically l-DOPA-treated dyskinetic rats using in vivo chronoamperometry. The results revealed that local l-DOPA administration into normal and intact hemisphere of dopamine-lesioned l-DOPA naïve animals significantly increased the potassium-evoked dopamine release. l-DOPA application also increased the dopamine peak amplitude in the dopamine-depleted l-DOPA naïve striatum, although these dopamine levels were several-folds lower than in the normal striatum, whereas no increased dopamine release was found in the dopamine/serotonin-denervated striatum. In dyskinetic animals, local l-DOPA application did not affect the dopamine release, resulting in significantly attenuated dopamine levels compared with those measured in l-DOPA naïve dopamine-denervated striatum. To conclude, l-DOPA is most likely converted to dopamine in serotonergic nerve fibers in the dopamine-depleted striatum, but the dopamine release is several-fold lower than in normal striatum. Furthermore, l-DOPA loading does not increase the dopamine release in dyskinetic animals as found in l-DOPA naïve animals, despite similar density of serotonergic innervation. Thus, the dopamine overflow produced from the serotonergic nerve fibers appears not to be the major cause of dyskinetic behavior.

Keywords
5-HT, chronoamperometry, L-DOPA-induced dyskinesia, SERT
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-50743 (URN)10.1111/j.1471-4159.2011.07292.x (DOI)21534956 (PubMedID)
Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2018-06-08Bibliographically approved
Lundblad, M., af Bjerkén, S., Cenci, A. M., Pomerleau, F., Gerhardt, G. A. & Strömberg, I. (2009). Chronic intermittent L-DOPA treatment induces changes in dopamine release. Journal of Neurochemistry, 108(4), 998-1008
Open this publication in new window or tab >>Chronic intermittent L-DOPA treatment induces changes in dopamine release
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2009 (English)In: Journal of Neurochemistry, ISSN 0022-3042, E-ISSN 1471-4159, Vol. 108, no 4, p. 998-1008Article in journal (Refereed) Published
Abstract [en]

3,4-Dihydroxyphenyl-l-alanine (l-DOPA)-induced dyskinesia often develops as a side effect of chronic l-DOPA therapy. This study was undertaken to investigate dopamine (DA) release upon l-DOPA treatment. Chronoamperometric measurements were performed in unilaterally DA-depleted rats, chronically treated with l-DOPA, resulting in dyskinetic and non-dyskinetic animals. Normal and lesioned l-DOPA naïve animals were used as controls. Potassium-evoked DA releases were significantly reduced in intact sides of animals undertaken chronic l-DOPA treatment, independent on dyskinetic behavior. Acute l-DOPA further attenuated the amplitude of the DA release in the control sides. In DA-depleted striata, no difference was found in potassium-evoked DA releases, and acute l-DOPA did not affect the amplitude. While immunoreactivity to serotonin uptake transporter was higher in lesioned striata of animals displaying dyskinetic behavior, no correlation could be documented between serotonin transporter-positive nerve fiber density and the amplitude of released DA. In conclusions, the amplitude of potassium-evoked DA release is attenuated in intact striatum after chronic intermittent l-DOPA treatment. No change in amplitude was found in DA-denervated sides of either dyskinetic or non-dyskinetic animals, while release kinetics were changed. This indicates the importance of studying DA release dynamics for the understanding of both beneficial and adverse effects of l-DOPA replacement therapy.

Keywords
3, 4-dihydroxyphenyl-l-alanine, 3, 4-dihydroxyphenyl-l-alanine induced dyskinesia, 5-hydroxytryptamine or serotonin, chronoamperometry, dopamine, serotonin transporter
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-3140 (URN)10.1111/j.1471-4159.2008.05848.x (DOI)19196428 (PubMedID)
Available from: 2008-05-02 Created: 2008-05-02 Last updated: 2018-06-09Bibliographically approved
Hascup, E. R., af Bjerkén, S., Hascup, K. N., Pomerleau, F., Huettl, P., Strömberg, I. & Gerhardt, G. A. (2009). Histological studies of the effects of chronic implantation of ceramic-based microelectrode arrays and microdialysis probes in rat prefrontal cortex.. Brain Research, 1291, 12-20
Open this publication in new window or tab >>Histological studies of the effects of chronic implantation of ceramic-based microelectrode arrays and microdialysis probes in rat prefrontal cortex.
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2009 (English)In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1291, p. 12-20Article in journal (Refereed) Published
Abstract [en]

Chronic implantation of neurotransmitter measuring devices is essential for awake, behavioral studies occurring over multiple days. Little is known regarding the effects of long term implantation on surrounding brain parenchyma and the resulting alterations in the functional properties of this tissue. We examined the extent of tissue damage produced by chronic implantation of either ceramic microelectrode arrays (MEAs) or microdialysis probes. Histological studies were carried out on fixed tissues using stains for neurons (cresyl violet), astrocytes (GFAP), microglia (Iba1), glutamatergic nerve fibers (VGLUT1), and the blood-brain barrier (SMI-71). Nissl staining showed pronounced tissue body loss with microdialysis implants compared to MEAs. The MEAs produced mild gliosis extending 50-100 microm from the tracks, with a significant change in the affected areas starting at 3 days. By contrast, the microdialysis probes produced gliosis extending 200-300 microm from the track, which was significant at 3 and 7 days. Markers for microglia and glutamatergic fibers supported that the MEAs produce minimal damage with significant changes occurring only at 3 and 7 days that return to control levels by 1 month. SMI-71 staining supported the integrity of the blood-brain barrier out to 1 week for both the microdialysis probes and the MEAs. This data support that the ceramic MEA's small size and biocompatibility are necessary to accurately measure neurotransmitter levels in the intact brain. The minimal invasiveness of the MEAs reduce tissue loss, allowing for long term (>6 month) electrochemical and electrophysiological monitoring of brain activity.

Keywords
Neurotransmitter, Microelectrode, Amperometry, Microglia, Immunohistochemistry, Biosensor
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-32006 (URN)10.1016/j.brainres.2009.06.084 (DOI)19577548 (PubMedID)
Available from: 2010-03-03 Created: 2010-02-26 Last updated: 2018-06-08Bibliographically approved
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