Far from being simply a passive supplier of food, the mouse placenta protects the developing fetus from brain damage if the mother is deprived of food.

Kevin Broad and Barry Keverne at the University of Cambridge, UK, studied developing embryos and placentas taken from mothers that had gone 24 hours without food about mid-way through gestation — a stage in pregnancy that is crucial for the development of a brain region called the hypothalamus. The authors found shifts in gene expression, including upregulation in the placenta of genes involved in autophagy, a process by which cells degrade their own components. Meanwhile, in the hypothalamus the expression of genes linked to neural development was enhanced.

The authors suggest that the placenta breaks down its own tissues, recycling proteins inside its cells to provide a steady supply of nutrients to the developing hypothalamus.

Proc. Natl Acad. Sci. USA 10.1073/pnas.1106022108 (2011)