Total parenteral nutrition-induced changes in gut mucosal function: atrophy alone is not the issue

Area of Science:

• Gastroenterology
• Nutrition Science
• Surgical Research

Background:

• Total parenteral nutrition (TPN) is linked to gut atrophy and barrier dysfunction, potentially causing bacterial translocation (BT).
• The relationship between TPN, gut barrier function, and BT is inconsistent in animal models.
• Macromolecular permeability may increase independently of BT during TPN.

Purpose of the Study:

• To investigate the relationship between TPN routes, gut atrophy, bacterial translocation, and macromolecular permeability.
• To determine if lipid content in TPN affects gut barrier function.
• To elucidate the mechanisms underlying gut-origin septic states during TPN.

Main Methods:

• Male Sprague-Dawley rats received isocaloric TPN via enteral, parenteral, or combined routes, or were fed ad libitum.
• A subset of rats received TPN with or without lipids.
• Gut barrier function was assessed by measuring lactulose permeability.

Main Results:

• TPN via combined enteral and parenteral routes maintained intestinal histology similar to enteral feeding or ad libitum feeding.
• Parenteral TPN caused gut atrophy and cecal bacterial overgrowth, but did not increase BT.
• All TPN groups showed significantly increased gut permeability to lactulose; lipid content had no effect.

Conclusions:

• Gut atrophy, BT, and macromolecular permeability are not necessarily interconnected during TPN.
• Increased macromolecular leakage from the gut may precede BT in TPN or trauma-related septic states.
• BT might be a consequence, not a cause, of gut-origin septic episodes.