発生生物学：母乳中の代謝物によって新生仔マウスの心臓の発達が促進される

A fatty acid in maternal milk is critical for the maturation of the heart in newborn mice, according to a paper published in Nature. The findings shed more light on the mechanisms of how environmental factors affect the development of newborn mouse hearts after birth.

Birth presents challenges to a newborn’s heart, requiring diverse changes and maturation of heart cells. For example, cardiomyocytes, the heart’s contractile cells, need to reshape their fuel preference from glucose to fatty acids so that the heart can efficiently beat for an entire lifetime. However, the mechanisms underlying this maturation process are not well understood.

Mercedes Ricote and colleagues showed that a fatty acid called γ-linolenic acid (GLA) in the maternal milk of mice is responsible for instructing metabolic adaptation of newborn hearts after birth. GLA cannot be synthesized by mice (or humans), so it must be ingested. Newborn mice fed milk from mothers who were on a fat-free diet could not survive beyond two days after birth; however, supplementing this milk with GLA restored normal survival in neonates. The researchers also identified retinoid X receptors in cardiomyocytes as the target that GLA binds to and activates to initiate the metabolic maturation process of heart-muscle cells.

The authors noted that this study focused on mice only, and whether GLA in human milk is similarly essential for newborn heart function or metabolic maturation remains to be investigated.