Preweaning experience as a modifier of prenatal drug effects in rats and mice - a review

The effects of preweaning experience in rats and mice on neuroendocrine and behavioral end points and their implications for prenatal drug effects are reviewed. The hypothalamo-pituitary-adrenal axis and the dopaminergic syst em were shown to be affected. Behavior related to hippocampal, adrenocortic al functions and to the benzodiazepine receptor system was also modified. O ther paradigms (nociception, conditioned taste aversion) exhibited suscepti bility to such preweaning manipulations also. The effects of these early ex periences seem to be mediated through complex factors including neuroendocr ine responses of the pup to hypothermia and a permanent alteration of mothe r-infant interactions, with subsequent effects on neuroendocrine functions that are important for postnatal brain organization. Studies of interaction s between prenatal drug effects and preweaning manipulations have been perf ormed only with ethanol. When extending this work to other compounds, the s ystems and functions described above may provide some guidance in looking f or possible interactions. In most cases the preweaning manipulations allevi ated the effects of prenatal ethanol exposure. These findings may have impo rtant implications regarding the controversy about environmental influences affecting the outcome of exposure to neurobehavioral teratogens. (C) 1999 Elsevier Science Inc. All rights reserved.