Gastrointestinal Dopamine in Inflammatory Bowel Diseases: A Systematic Review

Background: an increased prevalence of gastro-duodenal ulceration was described almost sixty years ago as prodromal to idiopathic Parkinson's disease, while duodenal ulcers have been rarely diagnosed in patients with schizophrenia. The cytoprotective role of dopamine in animal models of gastrointestinal ulcerations has also been described. Interestingly, Parkinson's disease (PD) might share common pathophysiological links with inflammatory bowel disease (IBD) as epidemiological and genetic links already suggest. Thus, the aim of our study was to review the existing literature on the role of the gastrointestinal dopaminergic system in IBD pathogenesis and progression. Methods: a systematic search was conducted according to the PRISMA methodology. Results: twenty-four studies satisfied the predetermined criteria and were included in our qualitative analysis. Due to different observations (cross-sectional studies) as well as experimental setups and applied methodologies (in vivo and in vitro studies) a meta-analysis could not be performed. No ongoing clinical trials with dopaminergic compounds in IBD patients were found. Conclusions: the impairment of the dopaminergic system seems to be a significant, yet underestimated, feature of IBD, and more in-depth observational studies are needed to further support the existing preclinical data.