This project will focus on the adaptive properties of catecholamine neurons as they relate to neuronal injury. Our principal hypothesis is that dopamine (DA) exerts both a synaptic and a non-synaptic influence on target cells in the dorsal striatum and that after DA-depleting lesions non-synaptic communication and gross motor behavior is spared until DA loss is extensive, whereas synaptic communication and more subtle motoric capabilities are disrupted in rough proportion to the injury. In the proposed experiments we will continue our examination of an animal model in which partial injury of the DA-containing projections of the nigrostriatal pathway is produced in rats by the intracerebral injection of 6-hydroxydopamine (6-OHDA). Four sets of experiments are proposed: First, we will determine the extent to which a dopaminergic influence is preserved after the partial loss of the DA input to dorsal striatum as a function of lesion size, post-operative time, and the availability of L-DOPA. Neurobiological measures of the impact of DA on its targets in intact and lesioned animals will include: acetylcholine (Ach) release (a D2-mediated response), cAMP production (primarily and D1-response), and GABA release (a complex interaction involving both D1 and D2 sites). Second, we will carry out parallel studies using behavioral endpoints, including food and water intake, motor activity, operant reaction time, and a neurological test battery. In the third experimental series we will explore the basis for the discrepancies between terminal loss and functional deficits, focussing on lesion-induced changes in DA synthesis, DA autoreceptor sensitivity, and changes glutamatergic input. Finally, we will examine the changes related to tyrosine hydroxylase (TH) gene expression after partial injury of DA neurons, comparing our results from those obtained in response to damage to noradrenergic neurons. Alterations in the amount of TH supplied to the nerve terminal will be examined, as will changes in the stability of TH within the terminal. The rate of TH synthesis also will be measured, focusing on rate of TH gene transcription and translation. We believe that the findings that will emerge from this research will have implications for understanding the cause and treatment of Parkinsonism, and will also provide important information regarding the neurobiology of dopaminergic neurons and their interactions with neurons in the basal ganglia.

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University of Pittsburgh
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Jaumotte, Juliann D; Wyrostek, Stephanie L; Zigmond, Michael J (2016) Protection of cultured dopamine neurons from MPP(+) requires a combination of neurotrophic factors. Eur J Neurosci 44:1691-9
Ayadi, Amina El; Zigmond, Michael J; Smith, Amanda D (2016) IGF-1 protects dopamine neurons against oxidative stress: association with changes in phosphokinases. Exp Brain Res 234:1863-1873
Napier, T Celeste; Corvol, Jean-Christophe; Grace, Anthony A et al. (2015) Linking neuroscience with modern concepts of impulse control disorders in Parkinson's disease. Mov Disord 30:141-9
Zigmond, Michael J; Smeyne, Richard J (2014) Exercise: is it a neuroprotective and if so, how does it work? Parkinsonism Relat Disord 20 Suppl 1:S123-7
Jaumotte, Juliann D; Zigmond, Michael J (2014) Comparison of GDF5 and GDNF as neuroprotective factors for postnatal dopamine neurons in ventral mesencephalic cultures. J Neurosci Res 92:1425-33
Ahrens, Allison M; Nobile, Cameron W; Page, Lindsay E et al. (2013) Individual differences in the conditioned and unconditioned rat 50-kHz ultrasonic vocalizations elicited by repeated amphetamine exposure. Psychopharmacology (Berl) 229:687-700
Zigmond, Michael J; Cameron, Judy L; Hoffer, Barry J et al. (2012) Neurorestoration by physical exercise: moving forward. Parkinsonism Relat Disord 18 Suppl 1:S147-50
Cohen, Ann D; Zigmond, Michael J; Smith, Amanda D (2011) Effects of intrastriatal GDNF on the response of dopamine neurons to 6-hydroxydopamine: time course of protection and neurorestoration. Brain Res 1370:80-8
El Ayadi, Amina; Zigmond, Michael J (2011) Low concentrations of methamphetamine can protect dopaminergic cells against a larger oxidative stress injury: mechanistic study. PLoS One 6:e24722
Allen, Erika; Carlson, Kirsten M; Zigmond, Michael J et al. (2011) L-DOPA reverses motor deficits associated with normal aging in mice. Neurosci Lett 489:1-4

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