Parkinson's disease (PD) is known to be associated with altered gastrointestinal function and microbiota composition. Altered gastrointestinal function is key in the development of small intestinal bacterial overgrowth, which is a comorbidity often observed in PD patients. Although PD medication could be an important confounder in the reported alterations, its effect per se on the microbiota composition or the gastrointestinal function at the site of drug absorption has not been studied. To this end, healthy (i.e., not PD model) wild-type Groningen rats were employed and treated with dopamine, pramipexole (in combination with levodopa/carbidopa), or ropinirole (in combination with levodopa/carbidopa) for 14 sequential days. Rats treated with dopamine agonists showed a significant reduction in the small intestinal motility and an increase in bacterial overgrowth in the distal small intestine. Importantly, significant alterations in microbial taxa were observed between the treated and vehicle groups, analogous to the changes previously reported in human PD vs HC microbiota studies. These microbial changes included an increase in Lactobacillus and Bifidobacterium, and decrease in Lachnospiraceae and Prevotellaceae. Importantly, certain Lactobacillus species correlated negatively with the plasma levels of levodopa. Overall, the results highlight the significant effect of PD medication per se on the gut microbiota, and the disease-associated comorbidities, including gastrointestinal dysfunction and small intestinal bacterial overgrowth.
Parkinson' disease medication alters rat small intestinal motility and microbiota composition