Postpartum changes in the endocannabinoid metabolome of human breast milk

Abstract

The endocannabinoid system, made up of receptors, enzymes and endogenous ligands, plays a diverse role in reproductive health and central nervous system development, function and protection. Human breast milk has detectable levels of specific endocannabinoids which stimulate the suckle reflex in the baby's brain promoting feeding. Our motivation for this work is to characterize the endocannabinoid metabolome in human milk and explore how the post‐partum period (2, 6, 10 weeks) modulates the metabolome in breastmilk from women with and without gestational diabetes mellitus (GDM). Using mass spectrometry, the fatty acid esters and their corresponding glycerols are easily detected in 50 μL of human milk. The ethanolamides are present in lower concentrations and require a larger milk sample for detection. Two‐way ANOVA treatment of our results demonstrates a decrease in arachidonoylglycerol (AG), eicosapentaenoylglycerol (EPG) and eicosanoylglycerol (EG) over the 10 weeks post‐partum. Oleoylglycerol (OG) peaked at 6 weeks postpartum and then declined. Additionally, endocannabinoids in milk samples from healthy women and women who were diagnosed with GDM behaved similarly. This study provides an opportunity for exploring and understanding the mechanism by which endocannabinoids are regulated in human milk.