ABSTRACT
Stressful stimuli during pregnancy induce complex effects that influence the development of offspring. These effects can be prevented by environmental manipulations during the early postnatal period. Repeated restraint during the last week of pregnancy was used as a model of prenatal stress, and adoption at birth was used to change the postnatal environment. No differences were found in various physical landmarks, except for testis descent, for which all prenatally stressed pups showed a 1-day delay in comparison with control rats, regardless of the postnatal adoption procedure. Levels of dopamine (DA) D(2) and glutamate (Glu) N-methyl-D-aspartate (NMDA) receptors were differentially regulated in different forebrain regions of cross-fostered adult offspring. Increased concentrations of cortical D(2) receptors detected in stressed pups, raised by a gestationally stressed biological mother, were not detected when the pups were raised by a control mother. Control pups raised by a foster mother whether gestationally stressed or not had higher levels of NMDA receptors in cortical areas. These findings suggest that the normal expression of DA and Glu receptors is influenced by in utero experience and by lactation. The complex pattern of receptor changes reflects the high vulnerability of DA and Glu systems to variations both in prenatal and in postnatal environment, particularly for cortical D(2) receptors and NMDA receptors in cerebral cortex and nucleus accumbens. In contrast, testis descent appears to be more susceptible to prenatal than to postnatal environmental events.
