MANIPULATION OF THE DOPAMINE SYSTEM AFFECTS FETAL AND NEONATAL RESPONSES TO AN ARTIFICIAL NIPPLE

Rat fetuses respond to stimuli that they will encounter later while su ckling. When exposed to an artificial nipple (AN) E21 fetuses show ove rall behavioral activation, mouthing, facial wiping, and oral grasping of the AN. The present experiments examined fetal and neonatal respon ses to the AN after central nervous system injection of receptor-bindi ng drugs for the dopamine system. The D2 agonist drug quinpirole incre ased appetitive responses to the AN in the fetus and neonate. Activity at the D2 dopamine receptor promotes expression of fetal behavioral r esponses that are similar to those shown by the neonatal rat at the ni pple. Motor responses also were elicited in neonatal pups that normall y do not attach to the artificial nipple. These findings suggest that the dopamine system may regulate oral capture of the nipple in the neo natal rat. (C) 1996 John Wiley & Sons, Inc.