Intestinal brush border membrane structure and function: effect of early postnatal undernutrition

Area of Science:

• Physiology
• Biochemistry
• Nutrition Science

Background:

• Early-life nutrition significantly impacts long-term physiological functions.
• Brush border enzymes and nutrient transporters are crucial for intestinal absorption.

Purpose of the Study:

• To investigate the effects of undernutrition during suckling on rat intestinal brush border enzymes and nutrient uptake at weaning.
• To analyze the chemical composition of the brush border membrane in response to nutritional deficiencies.

Main Methods:

• Assessing brush border enzyme activities (sucrase, alkaline phosphatase, lactase, leucine aminopeptidase).
• Measuring intestinal uptake of D-glucose and glycine in undernourished and control rats.
• Analyzing brush border membrane composition (protein, sialic acid, cholesterol, phospholipids) and lipid synthesis using [U-14C]D-Glucose.

Main Results:

• Undernutrition drastically reduced sucrase and alkaline phosphatase but elevated lactase and leucine aminopeptidase activities.
• Intestinal uptake of D-glucose and glycine was augmented in undernourished rats.
• Brush border membranes showed increased protein, sialic acid, cholesterol, and phospholipids, with enhanced lipid synthesis.

Conclusions:

• Early-life undernutrition profoundly alters intestinal brush border enzyme profiles and nutrient transport capacity.
• Changes in brush border membrane composition, particularly lipid synthesis, are adaptive responses to nutritional deficiencies.