Lactobacillus reuteri as an enhancer of milk production via the hypothalamic-pituitary axis

The microbiome has been shown to influence the secretion of the hormone oxytocin. Milk production depends on the ability of the pituitary to secrete prolactin and oxytocin. Lactobacillus reuteri, a Gram-positive gut symbiont, is of particular interest due to its association with presence of oxytocin neurons. PL/J and QSi5 mice were compared to determine the relationship between intestinal hypertrophy, the abundance of L. reuteri, and the activity of the hypothalamic-pituitary axis. Microscopy of H&E stained tissue sections were used to compare intestinal villus length in non-parous controls and lactating females. FISH was used to quantify L. reuteri in paraffin sections prepared from PBS-flushed proximal small intestine (SI). Serum oxytocin concentrations in blood collected from females at day 10 of lactation was measured by ELISA. There appears to be greater L. reuteri in PL/J than QSi5 with both strains showing significant decreases as lactation progresses. Concentrations of serum oxytocin for both strains are similar. Increase in SI weights of QSi5 with progression through pregnancy and lactation is likely due to the lengthening of the villi. However, other factors may be involved as PL/J exhibited increasing villi lengths with little change in overall proximal SI weight through pregnancy and lactation. This project was completed with contributions from Darryl L. Hadsell, PhD, from the Baylor College of Medicine, Childrens Nutrition Research Center.