Does prenatal stress affect latent inhibition? It depends on the gender.

The present experiment was designed to examine the effects of prenatal stress and gender in latent inhibition. Prenatal stress has been proposed as a risk factor both for depression and for schizophrenia, and both of these syndromes are associated with alterations in the functional state of the dopamine system. There is also some evidence that prenatal stress can produce changes in dopamine activity, although the details of the stress-induced changes are a matter of debate. Latent inhibition (LI), which is strongly dependent on dopaminergic activity, consists in delayed Pavlovian conditioning about a stimulus that previously signalled no consequence. We induced prenatal stress by exposing gestating dams to a daily constraint stress during the last week of pregnancy. We tested the rats for LI of conditioned taste aversion by exposing them to sucrose for 3 days prior to conditioning. Irrespective of stress or gender, latent inhibition was observed but the degree of LI varied as a function of both prenatal stress and gender. Unstressed males showed less LI than unstressed females, but prenatal stress increased the amount of LI only in the males. These results are inconsistent with the use of prenatal stress as an animal model for schizophrenia. A model is proposed that accounts for the relationships between gender, dopamine function, cognitive changes and psychiatric pathology.