Vulnerability of peripheral catecholaminergic neurons to MPTP is not regulated by α-synuclein

Although generally considered a prototypical movement disorder, Parkinson's disease is commonly associated with a broad-spectrum of non-motor symptoms, including autonomic dysfunctions caused by significant alterations in catecholaminergic neurons of the peripheral sympathetic nervous system. Here we present evidence that α-synuclein is highly expressed by sympathetic ganglion neurons throughout embryonic and postnatal life and that it is found in tyrosine hydroxylase-positive sympathetic fibers innervating the heart of adult mice. However, mice deficient in α-synuclein do not exhibit any apparent alterations in sympathetic development. Sympathetic neurons isolated from mouse embryos and early postnatal mice are sensitive to the parkinsonian drug MPTP/MPP+ and intoxication requires entry of the neurotoxin through the noradrenaline transporter. Furthermore, recovery of noradrenaline from cardiac sympathetic fibers is reduced in adult mice treated with MPTP systemically. However, MPP+-induced sympathetic neuron loss in vitro or MPTP-induced cardiac noradrenaline depletion in vivo is not modified in mice lacking α-synuclein. This is in clear contrast with the observation that dopaminergic neurons of the central nervous system are significantly less vulnerable to MPTP/MPP+ in the absence of α-synuclein, suggesting different actions of this molecule in central and peripheral catecholaminergic neurons.