Maternal Immune Activation Leads to Lasting Sex-Specific Changes in Behavior and Hippocampal Morphological and Molecular Features in 12-Month-Old Rat Offspring.

Maternal immune activation (MIA) during pregnancy is a recognized risk factor for neurodevelopmental and neurodegenerative disorders, including Alzheimer's disease. Although the long-term consequences of prenatal inflammation have been extensively investigated, the influence of biological sex on age-related behavioral and hippocampal alterations remains insufficiently understood. MIA was induced in pregnant Wistar rats by the intraperitoneal administration of lipopolysaccharide (100 μg/kg) on gestational day 17. Male and female offspring were examined at 12 months of age. Behavioral patterns were assessed using the Morris water maze and elevated plus maze. Hippocampal neuronal morphology and microglial and astrocytic phenotypes were evaluated by histology and IHC, while the expression of genes associated with inflammation, neurodegeneration, neuroplasticity, oxidative stress, and neurogenesis was determined by RT-qPCR. Prenatal LPS exposure produced persistent behavioral alterations in both sexes but with distinct phenotypes. Both male and female offspring exhibited increased anxiety-like behavior, whereas females showed reduced exploratory activity during spatial memory testing. Female offspring demonstrated more pronounced hippocampal pathology, including an increased relative number of pyknotic hyperchromic neurons, a reduced ramified-to-amoeboid microglia ratio, decreased