Evaluation of Small Intestinal Motility in a Rat Model of Irritable Bowel Syndrome

Background: The correlation between small intestinal motility alteration and irritable bowel syndrome (IBS) is not well evaluated. Aims: To assess the small intestinal and colonic transits in an IBS rat model with restraint stress and determine the role of small intestinal motility in the IBS pathophysiology.Methods: Restraint stress was utilized to make adolescent IBS rat models that were evaluated for clinical symptoms, including stool frequency and diarrhea. The small intestinal motility and transit rate were also evaluated. The amounts of mRNA encoding corticotropin-releasing hormone, mast cell, and serotonin (5-Hydroxytryptamine; 5-HT) receptor 3a were quantified using real-time polymerase chain reaction (PCR); the 5-HT expression was evaluated using immunostaining.Results: Restraint stress significantly increased the number of fecal pellet outputs, stool water content, and small intestinal motility in the IBS rat models. There was no difference in real-time PCR results, but immunostaining analysis revealed that 5-HT expression in the small intestine was significantly increased in the IBS rat models.Conclusions: In the adolescent rat model of IBS with restraint stress, we observed an increase in small intestinal and colonic motility. In the small intestine, enhanced 5-HT secretion in the distal portion may be involved in increasing the small intestinal motility.

Parkinson' disease medication alters rat small intestinal motility and microbiota composition

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.

Calcium-sensing Receptor (CaSR) Agonist- R568 Inhibits Small Intestinal Motility of Mice through Neural and Non-neural Mechanism

Gastrointestinal motility (GI) disorder causes symptoms such as dyspepsia, abdominal distention, and constipation and severely affects the quality of life. The calcium (Ca2+)-sensing receptor (CaSR) expressed in the digestive tract...