Live calcium and mitochondrial imaging in the enteric nervous system of Parkinson patients and controls.

Parkinson's disease (PD) is a neurodegenerative disease with motor and non-motor symptoms, including constipation. Therefore, several studies have investigated the gastrointestinal tract, and more specifically the enteric nervous system (ENS), in search of an early biomarker of PD. Besides α-synuclein aggregation, mitochondrial dysfunction and dysregulation of intracellular Ca2+ concentration probably contribute to the pathogenesis of PD. Here we assessed neuronal and mitochondrial functioning in primary enteric neurons of PD patients and their healthy partners as controls. Using a unique combination of live microscopy techniques, applied to routine duodenum biopsies, we were able to record neuronal Ca2+ responses and mitochondrial membrane potential in these nerve tissues. We found that submucous neurons were not affected in PD patients, which suggests that these neurons are not involved in the pathogenesis or the gastrointestinal symptoms of PD. Our study provides for the first time functional information on live neurons in PD patients.