Functional efficacy of the MAO-B inhibitor safinamide in murine substantia nigra pars compacta dopaminergic neurons in vitro: a comparative study with tranylcypromine

Output Details

Safinamide (SAF) is currently used to treat Parkinson's disease (PD) symptoms based on its theoretical ability to potentiate the dopamine (DA) signal, blocking monoamine oxidase (MAO) B. The present work aims to highlight the functional relevance of SAF as an enhancer of the DA signal, by evaluating its ability to prolong recovery from DAmediated firing inhibition of DAergic neurons of the substantia nigra pars compacta (SNpc), compared to another MAO antagonist, tranylcypromine (TCP). Using multielectrode array (MEA) and single electrode extracellular recordings of spontaneous spikes from presumed SNpc DAergic cells in vitro, we show that SAF (30 uM) mildly prolongs the DA-mediated firing inhibition, as opposed to the profound effect of TCP (10 uM). In patch-clamp recordings, we found that SAF (30 uM) significantly reduced the number of spikes evoked by depolarizing currents in SNpc DAergic neurons, in a sulpiride (1 uM) independent manner. According to our results, SAF marginally potentiates the DA signal in SNpc DAergic neurons, while exerting an inhibitory effect on the postsynaptic excitability acting on membrane conductances. Thus, we propose that the therapeutic effects of SAF in PD patients partially depends on MAO inhibition, while other MAO-independent sites of action could be more relevant.

Meet the Authors

  • Beatrice Zarrilli, MSc

    Key Personnel: Team Vila

    Fondazione Santa Lucia

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    Cecilia Giacomet, MSc

    Key Personnel: Team Vila

    Policlinico Tor Vergata

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    Francesca Cossa, PhD

    Key Personnel: Team Vila

    Fondazione Santa Lucia

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    Mauro Federici

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    Nicola Berretta, PhD

    Collaborating PI: Team Vila

    Fondazione Santa Lucia

  • Nicola Mercuri, MD, PhD

    Co-PI (Core Leadership): Team Vila

    University of Rome Tor Vergata, Fondazione Santa Lucia