The effects of mid-late gestational maternal immune activation in rats on behaviours related to the negative and cognitive symptoms of schizophrenia

Abstract

Maternal immune activation (MIA) related to prenatal infection increases the risk of schizophrenia in offspring. Previous studies in our lab have demonstrated that rats exposed to MIA during mid- or late-gestation exhibit some schizophrenia-like behavioural changes, but do not exhibit marked changes in behaviours related to the negative symptoms or cognitive deficits of schizophrenia. Other studies suggest that gestational day 14 (GD14) may be the most sensitive gestational time-point with regard to MIA exposure. Therefore, we aim to replicate these findings and characterize the effects of GD14 MIA on rodent behaviour related to the negative and cognitive symptoms of schizophrenia. On GD14, pregnant rats were injected with either a viral mimic, PolyI:C (MIA) or saline (Control). MIA-exposed rats exhibited reduced novel object preference in the novel object recognition test of learning and memory, an effect that was most pronounced for male rats. Rats exposed to MIA at GD14 did not exhibit alterations in social interaction, sucrose preference and anxiety-like behaviour on the elevated plus maze or open field. These findings indicate that MIA exposure in rats produces an animal model of cognitive impairments, but not necessarily the negative symptoms of schizophrenia.