Early maternal deprivation and prepulse inhibition: the role of the postdeprivation environment.

Early postnatal maternal deprivation leads to a variety of biochemical and behavioural alterations in the offspring, some of which do not develop until adulthood, like deficits in prepulse inhibition. Since a number of these deficits are similar to abnormalities observed in schizophrenic patients, maternal deprivation has been proposed as an interesting model for schizophrenia. However, little is still known about the processes that determine these long-term consequences. Previous experiments showed that the strain of rats and the deprivation procedure are important factors. In the present set of experiments, we focussed on the postdeprivation period. We showed that rearing normal Wistar rats in social isolation from weaning disrupts prepulse inhibition. However, if maternally deprived Wistar rats were reared in social isolation, the prepulse inhibition was normal. We further showed that if only half of the litters were maternally deprived at postnatal day 9, the animals had only a small disruption in prepulse inhibition compared to animals that came from litters where all the animals were deprived. In a final experiment, we crossfostered maternally deprived mothers to nondeprived pups and vice versa. This experiment showed that both the nondeprived pups raised by a deprived mother and the deprived pups raised by a nondeprived mother had small deficits in prepulse inhibition. Taken together, these data clearly show that the postdeprivation period is of crucial importance for the development of prepulse inhibition deficits in maternally deprived rats. We present a working model in order to explain the long-term behavioural consequences of maternal deprivation.