Animal models of gastrointestinal problems in Parkinson's disease.

Gastrointestinal (GI) symptoms are being increasingly recognized as early, common, and severe features of Parkinson's disease (PD), and they are important determinants of quality of life and disability throughout the disease course. In addition, the concept that GI symptoms could represent "pre-motor" PD has been hotly debated and has recently become a driving force for investigations into the pathophysiology and neuropathology of PD. Clinical data has been supported by many pathological studies demonstrating α-synuclein neuritic pathology and neuronal loss in central and peripheral areas relevant to GI function. As understanding has matured concerning the impact of GI dysmotility on patients and its potential relationship to incipient PD, behavioral and neuropathological examination of the GI tract has become a critical aspect of evaluation and validation of PD animal models. This review will briefly summarize GI symptoms and neuropathology in PD important to model in animals, behavioral and neuropathological examination of the GI tract in animals, and the current state of modeling parkinsonian GI dysfunction in animal model systems.