The neuro-gliovascular unit is a crucial structure for providing a balanced well-functioning environment for neurons and their synapses. Activation of the immune system during the developmental period is believed to affect the gliovascular unit, which may trigger neurodevelopmental and neurological/neuropsychiatric diseases. In this study, we hypothesized that vulnerability of the male brain to a neonatal insult was conditioned by sex-dependent differences in the impairment of the hippocampal gliovascular unit. Male and female C57BL/6J pups received lipopolysaccharide (LPS) (1 mg/kg) or saline on postnatal day (P) 5. Brains were collected at P12 and morphological quantifications of hippocampal fibrillary glial acid protein (GFAP+) astrocytes and ionized calcium binding adaptor molecule 1 (Iba1+) microglia were performed by using 3-D image analysis together with measuring the length of CD31+ and aquaporin-4 (AQP4+) vessels. We found a significant increase in the length of CD31+ capillaries in the male LPS group compared to the saline group, however, coverage of capillaries by astrocytic end-feet (AQP4+) was significantly reduced. In contrast, there was a significant increase in AQP4+ capillary length in female pups one week after LPS injection. GFAP+ astrocytes via morphological changes in the hippocampus showed significant enhancement in the activity one week following LPS injection in male mice. We propose that neonatal inflammation could induce susceptibility to neurodevelopmental disorders through modification of hippocampal gliovascular interface in a sex-dependent manner.The Author(s).