Prenatal administration of lipopolysaccharide induces sex-dependent changes in glutamic acid decarboxylase and parvalbumin in the adult rat brain

Abstract

Rationale: Recent clinical studies suggest GABA-ergic system abnormalities as a neuropathological mechanism of schizophrenia.

Objectives: In the present study, we examined the effect of chronic prenatal lipopolysaccharide (LPS) administration on immunohistochemical changes of glutamate decarboxylase (GAD67) and parvalbumin (PV)-expressing neurons in the medial prefrontal cortex and hippocampus of rats.

Results: These data demonstrated that prenatal LPS administration during the final 2 weeks of pregnancy induced schizophrenia-like behavioral symptoms, such as deficits in sensorimotor gating (prepulse inhibition) and impairments in social interactions and exploration, in adult offspring. Moreover, immunohistochemical analysis revealed that in our neurodevelopmental model of schizophrenia, decreases in the total number of PV- and GAD67-positive neurons in the medial prefrontal cortices of adult females prenatally exposed to LPS were observed, whereas these immunochemical changes were primarily detected in the hippocampus of males. Additionally, a decrease in PV-labeled axon terminals of GABA-ergic cells, likely reflecting the perisomatic inhibitory innervation of pyramidal neurons, was observed in the medial prefrontal cortices in both sexes.

Conclusion: This study provided evidence of a key role for the GABA system in neurodevelopment associated with the etiopathogenesis of schizophrenia and showed that the observed changes are sex-dependent. Moreover, this study is the first to present a model of schizophrenia based on prenatal LPS administration, which not only produced behavioral abnormalities but also changed the cytoarchitecture of the GABA inhibitory system.

Keywords: glutamic acid decarboxylase (GAD67); neurodevelopmental model of schizophrenia; parvalbumin (PV); sensorimotor gating; social interaction.