Prenatal dexamethasone exposure, postnatal development, and adulthood prepulse inhibition and latent inhibition in Wistar rats

Prenatal stress is an important risk factor in schizophrenia, and the aetiological factors mediating this relationship are central to the neurodevelopmental hypothesis of schizophrenia. The glucocorticoid receptor (GR) agonist dexamethasone (DEX) is commonly prescribed for prenatal conditions, and results in GR activation, which is part of the stress response. To investigate animal evidence for whether prenatal DEX leads to development of schizophrenia-like phenotypes, Wistar rats were prenatally exposed to DEX (0.1mg/kg/day) between the gestational days 15 and 21, and tested in two paradigms known to be disrupted in schizophrenia patients: prepulse inhibition (PPI) and latent inhibition (LI). A cross-fostering design was used to allow dissociation of any direct prenatal effects on offspring from effects dependent on DEX exposure of the rearing dam. Pup birth weight was reduced by prenatal DEX treatment. DEX-treated dams demonstrated increased pup-directed behaviour. There were additive effects of prenatal DEX treatment and DEX treatment of rearing dam in terms of reduced body weight in adulthood. In one of two replications, PPI was increased by prenatal DEX in males only and specific to the highest prepulse intensity. There was no evidence that LI was disrupted by prenatal DEX treatment. This study does not provide support for the hypothesis that prenatal DEX exposure leads to schizophrenia-like deficits in PPI or LI, suggesting that GR prenatal programming is not a mechanism of direct relevance to the neurodevelopmental hypothesis of schizophrenia.