Differential changes in anatomical, molecular and functional determinants of intestinal glucose absorption during murine pregnancy

Pregnancy demands increased food intake and nutrient delivery to support the growing conceptus. The timing and regional specificity of adaptations in small intestinal (SI) anatomy and transport, and their functional consequences, remain unclear. We therefore assessed anatomy and expression of macronutrient transporters in the duodenum, jejunum, and ileum collected from time-mated pregnant C57BL/6 mice at gestational day (GD) 6.5, 12.5, or 17.5 and age-matched nonpregnant females. Ex vivo active glucose transport was measured in each SI region of nonpregnant and GD17.5 mice. The SI was 20% heavier (p < 0.001) and 10% longer (p = 0.027) and SI villi were 18% longer (p < 0.001) in late pregnant than nonpregnant mice. Differences in relative carbohydrate (Slc5a1, Slc2a2, and Slc2a5) and amino acid (Slc6a19) transporter expression between pregnancy stages were region-specific, while expression of the fatty acid transporter Fabp2 was lower in all pregnant groups. Despite anatomical and molecular changes in support of an increase in SI capacity for nutrient absorption, active glucose transport per unit area was similar in nonpregnant and late-pregnant mice. Increased nutrient demand during pregnancy may therefore be met largely through SI expansion and slower nutrient transit, although contributions of other nutrient transport mechanisms require evaluation.