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APP accumulation and inflammation in the Ts65dn mouse, a model for Down's syndrome
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ABSTRACTS / Experimental Neurology 198 (2006) 558 – 597
MDMA in vivo could be reproduced in an in vitro model. We examined the ability of MDMA to (1) alter TH neurite outgrowth independent of the transplacental maternal/fetal interaction, and (2) influence survival of embryonic day 14 (E14) ventral mesencephalic (VM) cells cultured in the presence of striatal/target cells. VM and lateral ganglionic eminence (LGE; striatal/precursor) cells were dissected from E14 Fisher 344 rats, dissociated and plated on 48 well poly-d-lysine coated plates. Suspensions were plated as co-cultures of LGE cells (250,000 cells/well) covered with VM cells (250,000 cells/ well), or VM cells alone (500,000 cells/well). Cells were treated 24 h later with low (0.165 Ag), medium (0.825 Ag) or high (1.65 Ag) concentrations of MDMA and incubated for 96 h. Concentrations were based upon recently conducted pharmacokinetic studies in live animals. Although there were no differences between concentrations, THir cell survival was significantly increased in the treated co-cultures compared to controls ( P = 0.008). Additionally, THir neurite outgrowth was increased by 53% in treated co-cultures compared to controls. Upcoming studies will explore whether MDMA’s action at the DA transporter is responsible for the cascade of events that result in this robust increase in DA cell survival and neurite extension. Further examination of the mechanisms involved in this MDMA-mediated sprouting/survival phenomenon may provide useful information applicable in other areas of research such as enhancing DA survival in Parkinson’s disease and improving cell transplantation strategies. doi:10.1016/j.expneurol.2006.02.064
APP accumulation and inflammation in the Ts65dn mouse, a model for Down’s syndrome J. Lockrow 1, L. Willis 1, A.C. Granholm 1,2, K. Sambamurti 1 1 Neuroscience, Medical University of South Carolina, Charleston, USA 2 Center on Aging, Medical University of South Carolina, Charleston, USA Down’s syndrome (DS) is caused by a partial or complete trisomy of Chromosome 21. In addition to severe learning disabilities early in life, nearly all individuals with DS display the neuropathological features of Alzheimer’s disease by their fourth decade, including beta-amyloid plaques and the progressive degeneration of basal forebrain cholinergic neurons (BFCNs). A mouse model of DS containing a partial trisomy of Chromosome 16 (Ts65Dn) is marked by cognitive decline in early adulthood (4 – 6 months), and a similar loss in cholinergic neurons. Concomitant with this decrease in BFCNs is a rise in amyloid precursor protein (APP). In the present study, we have investigated the relative distribution of APP in adult and aged Ts65Dn mice, and preliminary data show an accumulation of APP associated with neurons containing enlarged endosomes. These enlarged endosomes suggest a disruption of normal endocytic cycling, and may serve to enhance levels of APP in these mice. We also analyzed several markers of inflammation, to determine if there is a neuroinflammatory component to this accumulation of
intracellular APP. Our preliminary data indicate an increase in inflammation compared to their normosomic littermates, and suggest an inflammatory role in the cognitive decline of the Ts65Dn mice. (Supported by NIH grant #AG12122). doi:10.1016/j.expneurol.2006.02.065
Effects of l-DOPA on the dynamics of potassium evoked dopamine release in a rat model of PD M. Lundblad 1,2, F. Pomerleau 3, G.A. Gerhardt 3, M.A. Cenci 2, I. Stro¨mberg 1 1 Section for Histology with Cell Biology, Integrative Medical Biology, Umea˚ universitet, Umea˚, Sweden 2 Basal Ganglia Pathophysiology Unit, Neuroscience Section, Dept. of Exp. Med. Sci, Lund University, Lund, Sweden 3 Department of Anatomy and Neurobiology, Center for Sensor Technology and the Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, USA In this study, we investigate the effects of 6-hydroxydopamine (6-OHDA) lesion and l-DOPA administration on potassium-evoked dopamine (DA) release. Female Sprague –Dawley rats were unilaterally injected with 6-OHDA in the medial forebrain bundle. DA release and reuptake were monitored using in vivo chronoamperometry with carbon fiber electrodes. Anaesthetized animals were put into a stereotactic frame and the electrode was inserted into the lateral striatum together with a potassium cloride ejection pipet. The electrochemical settings were optimized for DA measurements and the peak concentration after release as well as reuptake dynamics was studied. On the unlesioned side, the peak DA concentration after potassium evoked release amounted to about 3 AM which is in line with previous data obtained with this technique. On the lesioned side, the potassium evoked release produced a significantly lower peak concentration of about 0.25 AM. This clearly shows the effect of the DA denervating lesion. After l-DOPA administration, the peak concentration was significantly reduced in the unlesioned striatum but unchanged (or slightly increased) in the lesioned striatum. The reuptake of the released DA was significantly slower (about 50%) after l-DOPA administration on the lesioned side. In the unlesioned striatum, a nonsignificant trend of slower reuptake which amounted to about 20% was found. The slower uptake of DA after release in the lesioned striatum compared with the unlesioned striatum would enable the released DA to act on postsynaptic DA receptors for a substantially longer time and thereby increase the DA signal from the denervated striatum. This mechanism may contribute to the therapeutic effect of l-DOPA in DA denervated systems. The slower reuptake could also be a source of abnormal DA signaling since the temporal dynamics are significantly different compared to the unlesioned system. Several postsynaptic changes have been associated with complications of l-DOPA treatment (such as l-DOPA induced dyskinesia) which could indicate presynaptic abnormalities such as the changes in the dynamics of DA release presented here. We intend to further
ABSTRACTS / Experimental Neurology 198 (2006) 558 – 597
MDMA in vivo could be reproduced in an in vitro model. We examined the ability of MDMA to (1) alter TH neurite outgrowth independent of the transplacental maternal/fetal interaction, and (2) influence survival of embryonic day 14 (E14) ventral mesencephalic (VM) cells cultured in the presence of striatal/target cells. VM and lateral ganglionic eminence (LGE; striatal/precursor) cells were dissected from E14 Fisher 344 rats, dissociated and plated on 48 well poly-d-lysine coated plates. Suspensions were plated as co-cultures of LGE cells (250,000 cells/well) covered with VM cells (250,000 cells/ well), or VM cells alone (500,000 cells/well). Cells were treated 24 h later with low (0.165 Ag), medium (0.825 Ag) or high (1.65 Ag) concentrations of MDMA and incubated for 96 h. Concentrations were based upon recently conducted pharmacokinetic studies in live animals. Although there were no differences between concentrations, THir cell survival was significantly increased in the treated co-cultures compared to controls ( P = 0.008). Additionally, THir neurite outgrowth was increased by 53% in treated co-cultures compared to controls. Upcoming studies will explore whether MDMA’s action at the DA transporter is responsible for the cascade of events that result in this robust increase in DA cell survival and neurite extension. Further examination of the mechanisms involved in this MDMA-mediated sprouting/survival phenomenon may provide useful information applicable in other areas of research such as enhancing DA survival in Parkinson’s disease and improving cell transplantation strategies. doi:10.1016/j.expneurol.2006.02.064
APP accumulation and inflammation in the Ts65dn mouse, a model for Down’s syndrome J. Lockrow 1, L. Willis 1, A.C. Granholm 1,2, K. Sambamurti 1 1 Neuroscience, Medical University of South Carolina, Charleston, USA 2 Center on Aging, Medical University of South Carolina, Charleston, USA Down’s syndrome (DS) is caused by a partial or complete trisomy of Chromosome 21. In addition to severe learning disabilities early in life, nearly all individuals with DS display the neuropathological features of Alzheimer’s disease by their fourth decade, including beta-amyloid plaques and the progressive degeneration of basal forebrain cholinergic neurons (BFCNs). A mouse model of DS containing a partial trisomy of Chromosome 16 (Ts65Dn) is marked by cognitive decline in early adulthood (4 – 6 months), and a similar loss in cholinergic neurons. Concomitant with this decrease in BFCNs is a rise in amyloid precursor protein (APP). In the present study, we have investigated the relative distribution of APP in adult and aged Ts65Dn mice, and preliminary data show an accumulation of APP associated with neurons containing enlarged endosomes. These enlarged endosomes suggest a disruption of normal endocytic cycling, and may serve to enhance levels of APP in these mice. We also analyzed several markers of inflammation, to determine if there is a neuroinflammatory component to this accumulation of
intracellular APP. Our preliminary data indicate an increase in inflammation compared to their normosomic littermates, and suggest an inflammatory role in the cognitive decline of the Ts65Dn mice. (Supported by NIH grant #AG12122). doi:10.1016/j.expneurol.2006.02.065
Effects of l-DOPA on the dynamics of potassium evoked dopamine release in a rat model of PD M. Lundblad 1,2, F. Pomerleau 3, G.A. Gerhardt 3, M.A. Cenci 2, I. Stro¨mberg 1 1 Section for Histology with Cell Biology, Integrative Medical Biology, Umea˚ universitet, Umea˚, Sweden 2 Basal Ganglia Pathophysiology Unit, Neuroscience Section, Dept. of Exp. Med. Sci, Lund University, Lund, Sweden 3 Department of Anatomy and Neurobiology, Center for Sensor Technology and the Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, USA In this study, we investigate the effects of 6-hydroxydopamine (6-OHDA) lesion and l-DOPA administration on potassium-evoked dopamine (DA) release. Female Sprague –Dawley rats were unilaterally injected with 6-OHDA in the medial forebrain bundle. DA release and reuptake were monitored using in vivo chronoamperometry with carbon fiber electrodes. Anaesthetized animals were put into a stereotactic frame and the electrode was inserted into the lateral striatum together with a potassium cloride ejection pipet. The electrochemical settings were optimized for DA measurements and the peak concentration after release as well as reuptake dynamics was studied. On the unlesioned side, the peak DA concentration after potassium evoked release amounted to about 3 AM which is in line with previous data obtained with this technique. On the lesioned side, the potassium evoked release produced a significantly lower peak concentration of about 0.25 AM. This clearly shows the effect of the DA denervating lesion. After l-DOPA administration, the peak concentration was significantly reduced in the unlesioned striatum but unchanged (or slightly increased) in the lesioned striatum. The reuptake of the released DA was significantly slower (about 50%) after l-DOPA administration on the lesioned side. In the unlesioned striatum, a nonsignificant trend of slower reuptake which amounted to about 20% was found. The slower uptake of DA after release in the lesioned striatum compared with the unlesioned striatum would enable the released DA to act on postsynaptic DA receptors for a substantially longer time and thereby increase the DA signal from the denervated striatum. This mechanism may contribute to the therapeutic effect of l-DOPA in DA denervated systems. The slower reuptake could also be a source of abnormal DA signaling since the temporal dynamics are significantly different compared to the unlesioned system. Several postsynaptic changes have been associated with complications of l-DOPA treatment (such as l-DOPA induced dyskinesia) which could indicate presynaptic abnormalities such as the changes in the dynamics of DA release presented here. We intend to further