Characterisation of the consequences of maternal immune activation on distinct cell populations in the developing rat spinal cord.

Maternal immune activation (MIA) during gestation has been implicated in the development of neurological disorders such as schizophrenia and autism. Epidemiological studies have suggested that the effect of MIA may depend on the gestational timing of the immune challenge and the region of the central nervous system (CNS) in question. This study investigated the effects of MIA with 100 µg/kg lipopolysaccharide at either Embryonic days (E)12 or E16 on the oligodendrocytes, microglia and astrocytes of the offspring spinal cord. At E16, MIA decreased the number of olig2+ and Iba-1+ cells in multiple grey and white matter regions of the developing spinal cord 5 h after injection. These decreases were not observed at postnatal day 14. In contrast, MIA at E12 did not alter Olig2+ or Iba-1+ cell number in the developing spinal cord 5 h after injection, however, Olig2+ cell number was decreased in the ventral grey matter of the P14 spinal cord. No changes were observed in glial fibrillary acidic protein (GFAP) expression at P14 following MIA at either E12 or E16. These data suggest that E16 may be a window of immediate vulnerability to MIA during spinal cord development, however, the findings also suggest that the developmental process may be capable of compensation over time. Potential changes in P14 animals following the challenge at E12 are indicative of the complexity of the effects of MIA during the developmental process.