Instmctions): Grafting of dopamine (DA) neurons provides benefit in some individuals with Parkinson's disease (PD), however, overall efficacy is less than would be predicted from the degree of DA replacement provided in many individuals. Similarly, while DA grafts in parkinsonian rats can completely reverse amphetamine-induced rotations, more complex motor behaviors often show little to no improvement. Many issues thought to underlie lack of graft success in PD are being investigated. Primary among these is low cell survival following grafting into the aged, parkinsonian brain. However, we hypothesize that there are critical factors not yet considered that contribute to the overall lack of graft success. Specifically, the primary site for afferent input of nigral DA and cortical glutamate neurons are medium spiny neurons (MSNs) within striatum. The numerous dendritic """"""""spines"""""""" found on normal MSNs are critical sites of synaptic integration for DA and glutamate signaling. In advanced PD there is a marked atrophy of dendrites and spines on MSNs (McNeill, 1988;Zaja-Milatovic, 2005;Stephens, 2005). The premise of this project is that these severe morphological alterations will have grave consequences for cell replacement therapies despite the number of cells grafted. Pathological alterations of neuron structure would also be expected to negatively impact traditional dopamine replacement pharmacotherapies. Similar to PD, mice and rats with severe DA depletion also show significant decrease in spine density on MSNs. Importantly, a new mechanism involving dysregulation of intraspine Cavl.3 Ca2+ channels has been found to account for this spine loss. Indeed, absence of Cavl.3 channels in transgenic mice or administration of the Cavl.3 antagonist nimodipine to 6-OHDA lesioned rats can prevent spine loss in the presence of severe striatal DA depletion (Day, 2006). Identification of this mechanism allows testing the hypotheses put forth in this project: 1) degenerative changes in spine density of MSN has a detrimental impact on DA graft efficacy;2) altered spine morphology plays a role in the development of levodopa-induced and/or DA graft-induced dyskinetic behaviors. The proposed studies will employ the well-established rat model of parkinsonism and dyskinesia. Using light and electron microscopic analyses and multiple behavioral profiles, we will compare therapeutic benefit and/or development of abnormal behaviors between DA-depleted rats with normal spine morphology to those with significant spine atrophy. We will further investigate how the risk factor of advanced age may impact potential dendritic spine regeneration.
(See Instructions): Project 1 will provide novel insight into the role of striatal pathology, specifically loss of dendritic spines on medium spiny output neurons, on dopamine replacement therapy. These studies may allow for improved treatment efficacy for patients with Parkinson's disease.
|Fischer, D Luke; Manfredsson, Fredric P; Kemp, Christopher J et al. (2017) Subthalamic Nucleus Deep Brain Stimulation Does Not Modify the Functional Deficits or Axonopathy Induced by Nigrostriatal ?-Synuclein Overexpression. Sci Rep 7:16356|
|Fischer, D Luke; Kemp, Christopher J; Cole-Strauss, Allyson et al. (2017) Subthalamic Nucleus Deep Brain Stimulation Employs trkB Signaling for Neuroprotection and Functional Restoration. J Neurosci 37:6786-6796|
|Collier, Timothy J; Srivastava, Kinshuk R; Justman, Craig et al. (2017) Nortriptyline inhibits aggregation and neurotoxicity of alpha-synuclein by enhancing reconfiguration of the monomeric form. Neurobiol Dis 106:191-204|
|Kneynsberg, Andrew; Collier, Timothy J; Manfredsson, Fredric P et al. (2016) Quantitative and semi-quantitative measurements of axonal degeneration in tissue and primary neuron cultures. J Neurosci Methods 266:32-41|
|Polinski, Nicole K; Manfredsson, Fredric P; Benskey, Matthew J et al. (2016) Impact of age and vector construct on striatal and nigral transgene expression. Mol Ther Methods Clin Dev 3:16082|
|Madhavan, Lalitha; Daley, Brian F; Davidson, Beverly L et al. (2015) Sonic Hedgehog Controls the Phenotypic Fate and Therapeutic Efficacy of Grafted Neural Precursor Cells in a Model of Nigrostriatal Neurodegeneration. PLoS One 10:e0137136|
|Grabinski, Tessa M; Kneynsberg, Andrew; Manfredsson, Fredric P et al. (2015) A method for combining RNAscope in situ hybridization with immunohistochemistry in thick free-floating brain sections and primary neuronal cultures. PLoS One 10:e0120120|
|Paumier, Katrina L; Luk, Kelvin C; Manfredsson, Fredric P et al. (2015) Intrastriatal injection of pre-formed mouse ?-synuclein fibrils into rats triggers ?-synuclein pathology and bilateral nigrostriatal degeneration. Neurobiol Dis 82:185-199|
|Polinski, Nicole K; Gombash, Sara E; Manfredsson, Fredric P et al. (2015) Recombinant adenoassociated virus 2/5-mediated gene transfer is reduced in the aged rat midbrain. Neurobiol Aging 36:1110-20|
|Fischer, D Luke; Collier, Timothy J; Cole-Strauss, Allyson et al. (2015) High-Frequency Stimulation of the Rat Entopeduncular Nucleus Does Not Provide Functional or Morphological Neuroprotection from 6-Hydroxydopamine. PLoS One 10:e0133957|
Showing the most recent 10 out of 32 publications