Translocation of indigenous bacteria from the gastrointestinal tract of mice after oral ricinoleic acid treatment.

A single dose of ricinoleic acid, the active component of castor oil, administered intragastrically to specific pathogen-free mice produced significant alterations in the proximal small intestinal mucosa. Two hours after drug administration, the duodenal villi were markedly shortened with massive exfoliation of columnar and goblet cells. This disruption of the mucosal barrier resulted in continuity between the intestinal lumen and the lamina propria of the villi. Because of the loss of the mucosal barrier, bacteria of the indigenous gastrointestinal flora translocated from the gastrointestinal lumen to the mesenteric lymph nodes, spleen, and liver. The peak incidence of bacterial translocation occurred 4 days after the ricinoleic acid treatment. Strictly anaerobic bacteria, which normally colonize the gastrointestinal tract at greater levels than aerobic or facultatively anaerobic bacteria, were translocated at a greater incidence to the mesenteric lymph nodes than were the other indigenous bacteria. The mucosa began regenerating within 4 h after the ricinoleic acid treatment and viable translocated bacteria were no longer cultured from the mesenteric lymph nodes by 7 days after treatment.