Michael Ugrumov
Russian Academy of Medical Sciences, Russia.
Title: Neuroplasticity in the Nigrostriatal system of MPTP-Treated Mice at Presymptomatic and early Symptomatic stages of Parkinsonism
Biography
Biography: Michael Ugrumov
Abstract
Parkinson’s disease (PD) is characterized by a long development at preclinical (asymptomatic) stage and the first appearance of motor dysfunctions at a loss of most dopaminergic (DA-ergic) neurons, nigral cell bodies and striatal axons, and a depletion of 60-70% DA in the striatum. The goal of this study was to search mechanisms of neuroplasticity serving to prevent motor dysfunctions at presymptomatic stage and the triggers of a transition to symptomatic stage evaluating DA synthesis (tyrosine hydroxylase (TH) mRNA, protein, activity), release (microdialysis in vivo, slices), uptake (slices), degradation (MAO mRNA, activity) at original models (Ugrumov et al., 2011). At presymptomatic stage motor dysfunctions were prevented due to plasticity of survived DA-ergic neurons that was manifested by enhanced TH activity, increased spontaneous and stimulated release of DA, and decreased MAO B activity. Noteworthy, striatal DA was synthesized not only in DA-ergic axons but also in non-dopaminergic neurons containing individual enzymes, TH or aromatic L-amino acid decarboxylase, in cooperation. At symptomatic stage, despite maintaining of DA synthesis in DA-ergic neurons at the control level and an increase of DA synthesis in monoenzymatic neurons, intercellular level of DA dropped up followed by an appearance of motor disorders. Major triggers of motor dysfunctions appeared to be a decrease of spontaneous and stimulated release of striatal DA and an increase of MAO A activity. PD models of preclinical and early clinical stages, specified in this study are suitable for development of preventive pharmacotherapy serving to improve compensatory processes and inhibit triggers of motor dysfunctions.