Prenatal immune challenge induces developmental changes in the morphology of pyramidal neurons of the prefrontal cortex and hippocampus in rats

Pregnant Sprague-Dawley rats were administered with LPS (at E15- E16) or saline. The brains of offspring were processed for Golgi-Cox staining at postnatal days 10, 35 and 60. Dendritic length, branching, spine density and structure were quantified using Neurolucida software. At all ages, dendritic arbor was significantly reduced in mPFC and CA1 neurons of LPS-treated animals. Dendritic length was significantly reduced in the mPFC neurons of LPS group at P10 and 35 but returned to control values at P60. Opposite pattern was observed in CA1 region of LPS animals (normal values at P10 and 35, but a reduction at P60). LPS treatment significantly altered the structure of CA1 dendritic spines at P10. Spine density was found to be significantly lower only in layer V mPFC of P60 LPS rats. The study provides the first evidence that prenatal exposure to an immune activator dynamically affects spatio-temporal development of pyramidal neurons in mPFC and hippocampal that can potentially lead to aberrant neuronal connectivity and functions of these structures.