IMPACT OF PRENATAL TIO₂ EXPOSURE ON THE MATURATION OF EMBRYONIC RESPIRATORY CIRCUITS AND MICROGLIA

Early brain development relies on the coordinated maturation of neuronal circuits and their interactions with glial cells. Environmental factors can disrupt this process, yet the mechanisms linking early exposures to functional network alterations remain incompletely understood. Titanium dioxide nanoparticles (TiO₂), widely used in consumer products, have been suggested to interfere with neurodevelopment, but their impact on embryonic neural circuit maturation and underlying cellular mechanisms is still unclear.
We investigated the effects of prenatal TiO₂ exposure on the development of embryonic respiratory networks in mice. Functional maturation of these circuits was assessed using extracellular electrophysiological recordings, revealing alterations in the emergence and organization of respiratory-related rhythmic activity following exposure. Given accumulating evidence that microglial dysfunction can impair neuronal network development, we next examined whether these network alterations were associated with changes in microglial morphology.
Microglial cells were analyzed in brainstem regions involved in respiratory control using MorphoCellSorter, a software enabling unbiased, high-dimensional morphometric classification from histological images. Morphological parameters were extracted using principal component analysis, followed by Andrews curve–based scoring to position microglia along a continuum from highly ramified to amoeboid-like states. This analysis revealed exposure- and stage-dependent shifts in microglial morphological distributions at embryonic stages E16.5 and E18.5.
Together, these results suggest that prenatal TiO₂ exposure alters the functional maturation of respiratory networks and is associated with concomitant changes in microglial morphology. By integrating embryonic electrophysiology with advanced microglial morphometry, this work supports a role for microglia as a potential mediator of environmentally induced disruptions in neural circuit development.