Early Gestational Maternal Diet Programs Wiring of Developing Central Gustatory Circuits by Microglia

A key process in central sensory circuit development involves activity-dependent “pruning” of early exuberant terminals. Here, we studied gustatory terminal field maturation in the postnatal mouse nucleus of the solitary tract (NST) during normal development and in mice where their mothers were fed a low NaCl diet for a limited period during early embryonic development. “Pruning” of terminal fields in controls involved the complement system and appears driven by NaCl-elicited taste activity. In contrast, offspring of mothers with the early dietary manipulation failed to “prune” gustatory terminal fields even though peripheral taste activity developed normally. The ability to “prune” in these mice was rescued by activating myeloid cells postnatally, and conversely, “pruning” was arrested in controls with the loss of myeloid cell function. The altered “pruning” and myeloid cell function appears programmed before the peripheral gustatory system is assembled and corresponds to the embryonic period when microglia progenitors migrate into the brain.