Murine functional liver mass is reduced following partial small bowel resection

Introduction: Liver mass is regulated in precise proportion to body mass in health and is restored by regeneration following acute injury. Despite extensive experimental analyses, the mechanisms involved in this regulation have not been fully elucidated. Previous investigations suggest that signals from the bowel may play an important role. The purpose of the studies reported here was to determine the effect of proximal partial small bowel resection on liver mass in a murine model. Methods: Mice were subjected to a 50% proximal small bowel resection or sham surgery followed by primary anastomosis, then sacrificed at serial times for determination of liver:body mass ratio and analyses of liver tissue. Results: Liver:body weight ratio was significantly decreased 72 h after small bowel resection, and this decrease correlated with reduced functional liver mass as assessed by determination of total hepatic tissue protein and alanine transaminase (ALT) activity. Liver from bowel-resected animals demonstrated increased expression of LC3-II, a marker of autophagy, and also of pro-apoptotic Bax compared to anti-apoptotic Bcl-2. Conclusion: These data support a role for signals from the intestine in liver mass regulation, and they have potential implications regarding the pathogenesis of liver injury following small bowel resection.