Microglial activation and responses to vasculature that result from an acute LPS exposure.

•Subcutaneous injection of 2 mg/kg LPS resulted in the activation of 55 to 65% of the microglia present in the hippocampus and cortex within 24 h.•However, none of the microglia had “phagocytic type” morphology that is normally seen in areas of neurodegeneration, and no neurodegeneration was observed in brain via Fluorojade C labeling.•The activated microglial soma and proximal enlarged processes became elongated and more closely associated with brain vasculature.•We hypothesize that by forming a much closer associations with vasculature the activated microglia would be more effective in preventing bacterial entry into the brain.