Effect of intraluminal distension or ischemic strangulation obstruction of the equine jejunum on jejunal motilin receptors and binding of erythromycin lactobionate.

This study investigated how inflammation in a horse’s small intestine, specifically the jejunum, could decrease the number of motilin receptors and their corresponding mRNA, and alter the binding affinity of an antibiotic, erythromycin lactobionate, to these receptors. The findings indicate that inflammation may lead to a diminished response to prokinetic drugs, which stimulate gastrointestinal motility, in horses with gastrointestinal disease.

Research Methodology

• The study involved six adult horses, each of which was anesthetized before laparotomy surgeries were performed.
• Two segments of the jejunum in each horse underwent a sham (control) operation, two segments were treated with an ischemic strangulation obstruction (ISO), and two segments underwent intraluminal distension (ILD). These procedures were maintained for 120 minutes.
• Full-thickness biopsy samples were collected from each segment and smooth-muscle homogenates were prepared.
• The researchers used iodine 125-labeled synthetic porcine motilin to determine the affinity and distribution of motilin binding to the prepared muscle homogenates.
• The competition between iodine 125-labeled motilin and erythromycin lactobionate for binding to motilin receptors was investigated using displacement experiments.
• A quantitative real-time PCR technique was used to measure the motilin receptor mRNA content in the muscle preparations.

Research Findings

• The researchers found that the number of motilin receptors was significantly higher in the sham-operated segments compared to the ISO or the ILD segments. The ILD segments demonstrated the lowest number of motilin receptors.
• The expression of motilin receptor mRNA was considerably less in the ILD segments, but no significant change was noted in the ISO segments.
• The displacement of iodine 125-labeled motilin by erythromycin lactobionate did not significantly vary among the different jejunal segments.

Conclusions

• The researchers concluded that inflammation in the jejunum could cause downregulation and decreased production of motilin receptors.
• This phenomenon could contribute to an altered prokinetic response to erythromycin, a drug used to stimulate gastrointestinal motility, in horses suffering from gastrointestinal diseases.