Long-term neurobehavioural impact of the postnatal environment in rats: manipulations, effects and mediating mechanisms

The major characteristics of the postnatal environment of the rat pup are its mother and littermates. The pup, which is poorly developed at birth, matures rapidly in this environment, and regulates the behaviour and physiology of the dam and littermates, as well as vice versa. The study of the impact of the rat's postnatal environment on its long-term neurobehavioural development is of fundamental importance. In fact, it is one of the major examples-at the interface of the biological, social and medical sciences-of animal models for the study of the interaction between the environment and the genome in both the acute and chronic regulation of the phenotype. Specific experimental manipulations of the rat postnatal environment have been demonstrated to exert robust and marked effects on neurobiological, physiological and behavioural phenotypes in adulthood. In the present review we present some of the major findings, including some original data, and discuss what these existing data can tell us about the long-term neurobehavioural effects of the postnatal environment in rats, the external and internal mechanisms that mediate these effects, and the most appropriate directions for future basic and applied research in this area. (C) 2003 Elsevier Science Ltd. All rights reserved.